From cad810f21b803229eb11403f9209855525a25d57 Mon Sep 17 00:00:00 2001 From: Steve Block Date: Fri, 6 May 2011 11:45:16 +0100 Subject: Merge WebKit at r75315: Initial merge by git. Change-Id: I570314b346ce101c935ed22a626b48c2af266b84 --- PerformanceTests/PageLoad/ChangeLog | 46 + PerformanceTests/PageLoad/svg/LICENSES | 37 + .../PageLoad/svg/files/33041-Samurai.svg | 215 + .../PageLoad/svg/files/42450-under the see.svg | 3946 + .../svg/files/42470-flower_from_my_garden_v2.svg | 1914 + .../PageLoad/svg/files/44057-drops on a blade.svg | 1770 + .../PageLoad/svg/files/Harvey_Rayner.svg | 679 + .../PageLoad/svg/files/az-lizard_benji_park_01.svg | 283 + PerformanceTests/PageLoad/svg/files/bamboo_01.svg | 6383 ++ PerformanceTests/PageLoad/svg/files/cacuts_01.svg | 1706 + PerformanceTests/PageLoad/svg/files/cowboy.svg | 4110 + .../PageLoad/svg/files/crawfish2_ganson.svg | 7865 ++ PerformanceTests/PageLoad/svg/files/deb9frac1.svg | 6323 ++ .../PageLoad/svg/files/food_leif_lodahl_01.svg | 56 + PerformanceTests/PageLoad/svg/files/france.svg | 663 + .../svg/files/francobollo_gnome_ezechi_02.svg | 202 + .../PageLoad/svg/files/gearflowers.svg | 8342 ++ PerformanceTests/PageLoad/svg/files/hereGear4.svg | 2808 + PerformanceTests/PageLoad/svg/files/mtsthelens.svg | 1629 + .../PageLoad/svg/files/mtsthelens0.jpg | Bin 0 -> 57004 bytes PerformanceTests/PageLoad/svg/files/world-iso.svg | 288 + PerformanceTests/PageLoad/svg/files/worldcup.svg | 14668 ++++ PerformanceTests/PageLoad/svg/svg.pltsuite | 19 + PerformanceTests/Parser/ChangeLog | 11 + PerformanceTests/Parser/html-parser.html | 19 + PerformanceTests/Parser/resources/html5.html | 85096 +++++++++++++++++++ PerformanceTests/Parser/resources/runner.js | 95 + PerformanceTests/Parser/xml-parser.html | 19 + PerformanceTests/SunSpider/ChangeLog | 1083 + PerformanceTests/SunSpider/SunSpider.make | 4 + PerformanceTests/SunSpider/TODO | 70 + PerformanceTests/SunSpider/UNCOVERED | 99 + PerformanceTests/SunSpider/hosted/json2.js | 481 + PerformanceTests/SunSpider/hosted/sunspider.css | 31 + PerformanceTests/SunSpider/hosted/sunspider.html | 81 + PerformanceTests/SunSpider/hosted/versions.html | 54 + PerformanceTests/SunSpider/make-hosted | 112 + PerformanceTests/SunSpider/resources/TEMPLATE.html | 58 + .../SunSpider/resources/driver-TEMPLATE.html | 115 + .../SunSpider/resources/results-TEMPLATE.html | 108 + .../resources/sunspider-analyze-results.js | 268 + .../resources/sunspider-compare-results.js | 380 + .../resources/sunspider-standalone-compare.js | 26 + .../resources/sunspider-standalone-driver.js | 60 + PerformanceTests/SunSpider/sunspider | 244 + .../SunSpider/sunspider-compare-results | 161 + PerformanceTests/SunSpider/tests/parse-only/LIST | 4 + .../parse-only/concat-jquery-mootools-prototype.js | 12699 +++ .../SunSpider/tests/parse-only/jquery-1.3.2.js | 4376 + .../tests/parse-only/mootools-1.2.2-core-nc.js | 4003 + .../tests/parse-only/prototype-1.6.0.3.js | 4320 + .../SunSpider/tests/sunspider-0.9.1/3d-cube.js | 337 + .../SunSpider/tests/sunspider-0.9.1/3d-morph.js | 54 + .../SunSpider/tests/sunspider-0.9.1/3d-raytrace.js | 441 + .../SunSpider/tests/sunspider-0.9.1/LIST | 26 + .../tests/sunspider-0.9.1/access-binary-trees.js | 50 + .../tests/sunspider-0.9.1/access-fannkuch.js | 66 + .../tests/sunspider-0.9.1/access-nbody.js | 169 + .../tests/sunspider-0.9.1/access-nsieve.js | 38 + .../sunspider-0.9.1/bitops-3bit-bits-in-byte.js | 32 + .../tests/sunspider-0.9.1/bitops-bits-in-byte.js | 21 + .../tests/sunspider-0.9.1/bitops-bitwise-and.js | 28 + .../tests/sunspider-0.9.1/bitops-nsieve-bits.js | 32 + .../tests/sunspider-0.9.1/controlflow-recursive.js | 25 + .../SunSpider/tests/sunspider-0.9.1/crypto-aes.js | 422 + .../SunSpider/tests/sunspider-0.9.1/crypto-md5.js | 286 + .../SunSpider/tests/sunspider-0.9.1/crypto-sha1.js | 224 + .../tests/sunspider-0.9.1/date-format-tofte.js | 299 + .../tests/sunspider-0.9.1/date-format-xparb.js | 417 + .../SunSpider/tests/sunspider-0.9.1/math-cordic.js | 95 + .../tests/sunspider-0.9.1/math-partial-sums.js | 33 + .../tests/sunspider-0.9.1/math-spectral-norm.js | 51 + .../SunSpider/tests/sunspider-0.9.1/regexp-dna.js | 1712 + .../tests/sunspider-0.9.1/string-base64.js | 135 + .../tests/sunspider-0.9.1/string-fasta.js | 85 + .../tests/sunspider-0.9.1/string-tagcloud.js | 265 + .../tests/sunspider-0.9.1/string-unpack-code.js | 68 + .../tests/sunspider-0.9.1/string-validate-input.js | 89 + .../SunSpider/tests/sunspider-0.9/3d-cube.js | 337 + .../SunSpider/tests/sunspider-0.9/3d-morph.js | 54 + .../SunSpider/tests/sunspider-0.9/3d-raytrace.js | 441 + .../SunSpider/tests/sunspider-0.9/LIST | 26 + .../tests/sunspider-0.9/access-binary-trees.js | 50 + .../tests/sunspider-0.9/access-fannkuch.js | 66 + .../SunSpider/tests/sunspider-0.9/access-nbody.js | 169 + .../SunSpider/tests/sunspider-0.9/access-nsieve.js | 38 + .../sunspider-0.9/bitops-3bit-bits-in-byte.js | 32 + .../tests/sunspider-0.9/bitops-bits-in-byte.js | 21 + .../tests/sunspider-0.9/bitops-bitwise-and.js | 28 + .../tests/sunspider-0.9/bitops-nsieve-bits.js | 32 + .../tests/sunspider-0.9/controlflow-recursive.js | 25 + .../SunSpider/tests/sunspider-0.9/crypto-aes.js | 422 + .../SunSpider/tests/sunspider-0.9/crypto-md5.js | 286 + .../SunSpider/tests/sunspider-0.9/crypto-sha1.js | 224 + .../tests/sunspider-0.9/date-format-tofte.js | 299 + .../tests/sunspider-0.9/date-format-xparb.js | 417 + .../SunSpider/tests/sunspider-0.9/math-cordic.js | 95 + .../tests/sunspider-0.9/math-partial-sums.js | 33 + .../tests/sunspider-0.9/math-spectral-norm.js | 51 + .../SunSpider/tests/sunspider-0.9/regexp-dna.js | 1712 + .../SunSpider/tests/sunspider-0.9/string-base64.js | 135 + .../SunSpider/tests/sunspider-0.9/string-fasta.js | 85 + .../tests/sunspider-0.9/string-tagcloud.js | 265 + .../tests/sunspider-0.9/string-unpack-code.js | 68 + .../tests/sunspider-0.9/string-validate-input.js | 89 + PerformanceTests/SunSpider/tests/ubench/LIST | 9 + .../SunSpider/tests/ubench/function-closure.js | 7 + .../tests/ubench/function-correct-args.js | 6 + .../SunSpider/tests/ubench/function-empty.js | 6 + .../SunSpider/tests/ubench/function-excess-args.js | 6 + .../tests/ubench/function-missing-args.js | 6 + .../SunSpider/tests/ubench/function-sum.js | 7 + .../SunSpider/tests/ubench/loop-empty-resolve.js | 2 + .../SunSpider/tests/ubench/loop-empty.js | 2 + .../SunSpider/tests/ubench/loop-sum.js | 5 + PerformanceTests/SunSpider/tests/v8-v4/LIST | 7 + .../SunSpider/tests/v8-v4/v8-crypto.js | 1695 + .../SunSpider/tests/v8-v4/v8-deltablue.js | 877 + .../SunSpider/tests/v8-v4/v8-earley-boyer.js | 4683 + .../SunSpider/tests/v8-v4/v8-raytrace.js | 933 + .../SunSpider/tests/v8-v4/v8-regexp.js | 1613 + .../SunSpider/tests/v8-v4/v8-richards.js | 537 + PerformanceTests/SunSpider/tests/v8-v4/v8-splay.js | 377 + PerformanceTests/SunSpider/tests/v8-v5/LIST | 7 + .../SunSpider/tests/v8-v5/v8-crypto.js | 1695 + .../SunSpider/tests/v8-v5/v8-deltablue.js | 877 + .../SunSpider/tests/v8-v5/v8-earley-boyer.js | 4683 + .../SunSpider/tests/v8-v5/v8-raytrace.js | 933 + .../SunSpider/tests/v8-v5/v8-regexp.js | 1613 + .../SunSpider/tests/v8-v5/v8-richards.js | 537 + PerformanceTests/SunSpider/tests/v8-v5/v8-splay.js | 377 + PerformanceTests/SunSpider/tests/v8-v6/LIST | 7 + .../SunSpider/tests/v8-v6/v8-crypto.js | 1695 + .../SunSpider/tests/v8-v6/v8-deltablue.js | 877 + .../SunSpider/tests/v8-v6/v8-earley-boyer.js | 4683 + .../SunSpider/tests/v8-v6/v8-raytrace.js | 902 + .../SunSpider/tests/v8-v6/v8-regexp.js | 1613 + .../SunSpider/tests/v8-v6/v8-richards.js | 537 + PerformanceTests/SunSpider/tests/v8-v6/v8-splay.js | 393 + PerformanceTests/SunSpider/xcopy.excludes | 3 + 140 files changed, 221239 insertions(+) create mode 100644 PerformanceTests/PageLoad/ChangeLog create mode 100644 PerformanceTests/PageLoad/svg/LICENSES create mode 100644 PerformanceTests/PageLoad/svg/files/33041-Samurai.svg create mode 100644 PerformanceTests/PageLoad/svg/files/42450-under the see.svg create mode 100644 PerformanceTests/PageLoad/svg/files/42470-flower_from_my_garden_v2.svg create mode 100644 PerformanceTests/PageLoad/svg/files/44057-drops on a blade.svg create mode 100644 PerformanceTests/PageLoad/svg/files/Harvey_Rayner.svg create mode 100644 PerformanceTests/PageLoad/svg/files/az-lizard_benji_park_01.svg create mode 100644 PerformanceTests/PageLoad/svg/files/bamboo_01.svg create mode 100644 PerformanceTests/PageLoad/svg/files/cacuts_01.svg create mode 100644 PerformanceTests/PageLoad/svg/files/cowboy.svg create mode 100644 PerformanceTests/PageLoad/svg/files/crawfish2_ganson.svg create mode 100644 PerformanceTests/PageLoad/svg/files/deb9frac1.svg create mode 100644 PerformanceTests/PageLoad/svg/files/food_leif_lodahl_01.svg create mode 100644 PerformanceTests/PageLoad/svg/files/france.svg create mode 100644 PerformanceTests/PageLoad/svg/files/francobollo_gnome_ezechi_02.svg create mode 100644 PerformanceTests/PageLoad/svg/files/gearflowers.svg create mode 100644 PerformanceTests/PageLoad/svg/files/hereGear4.svg create mode 100644 PerformanceTests/PageLoad/svg/files/mtsthelens.svg create mode 100644 PerformanceTests/PageLoad/svg/files/mtsthelens0.jpg create mode 100644 PerformanceTests/PageLoad/svg/files/world-iso.svg create mode 100644 PerformanceTests/PageLoad/svg/files/worldcup.svg create mode 100644 PerformanceTests/PageLoad/svg/svg.pltsuite create mode 100644 PerformanceTests/Parser/ChangeLog create mode 100644 PerformanceTests/Parser/html-parser.html create mode 100644 PerformanceTests/Parser/resources/html5.html create mode 100644 PerformanceTests/Parser/resources/runner.js create mode 100644 PerformanceTests/Parser/xml-parser.html create mode 100644 PerformanceTests/SunSpider/ChangeLog create mode 100644 PerformanceTests/SunSpider/SunSpider.make create mode 100644 PerformanceTests/SunSpider/TODO create mode 100644 PerformanceTests/SunSpider/UNCOVERED create mode 100644 PerformanceTests/SunSpider/hosted/json2.js create mode 100644 PerformanceTests/SunSpider/hosted/sunspider.css create mode 100644 PerformanceTests/SunSpider/hosted/sunspider.html create mode 100644 PerformanceTests/SunSpider/hosted/versions.html create mode 100755 PerformanceTests/SunSpider/make-hosted create mode 100644 PerformanceTests/SunSpider/resources/TEMPLATE.html create mode 100644 PerformanceTests/SunSpider/resources/driver-TEMPLATE.html create mode 100644 PerformanceTests/SunSpider/resources/results-TEMPLATE.html create mode 100644 PerformanceTests/SunSpider/resources/sunspider-analyze-results.js create mode 100644 PerformanceTests/SunSpider/resources/sunspider-compare-results.js create mode 100644 PerformanceTests/SunSpider/resources/sunspider-standalone-compare.js create mode 100644 PerformanceTests/SunSpider/resources/sunspider-standalone-driver.js create mode 100755 PerformanceTests/SunSpider/sunspider create mode 100755 PerformanceTests/SunSpider/sunspider-compare-results create mode 100644 PerformanceTests/SunSpider/tests/parse-only/LIST create mode 100644 PerformanceTests/SunSpider/tests/parse-only/concat-jquery-mootools-prototype.js create mode 100644 PerformanceTests/SunSpider/tests/parse-only/jquery-1.3.2.js create mode 100644 PerformanceTests/SunSpider/tests/parse-only/mootools-1.2.2-core-nc.js create mode 100644 PerformanceTests/SunSpider/tests/parse-only/prototype-1.6.0.3.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/3d-cube.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/3d-morph.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/3d-raytrace.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/LIST create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/access-binary-trees.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/access-fannkuch.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/access-nbody.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/access-nsieve.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/bitops-3bit-bits-in-byte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/bitops-bits-in-byte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/bitops-bitwise-and.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/bitops-nsieve-bits.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/controlflow-recursive.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/crypto-aes.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/crypto-md5.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/crypto-sha1.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/date-format-tofte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/date-format-xparb.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/math-cordic.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/math-partial-sums.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/math-spectral-norm.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/regexp-dna.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/string-base64.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/string-fasta.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/string-tagcloud.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/string-unpack-code.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9.1/string-validate-input.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/3d-cube.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/3d-morph.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/3d-raytrace.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/LIST create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/access-binary-trees.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/access-fannkuch.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/access-nbody.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/access-nsieve.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/bitops-3bit-bits-in-byte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/bitops-bits-in-byte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/bitops-bitwise-and.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/bitops-nsieve-bits.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/controlflow-recursive.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/crypto-aes.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/crypto-md5.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/crypto-sha1.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/date-format-tofte.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/date-format-xparb.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/math-cordic.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/math-partial-sums.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/math-spectral-norm.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/regexp-dna.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/string-base64.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/string-fasta.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/string-tagcloud.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/string-unpack-code.js create mode 100644 PerformanceTests/SunSpider/tests/sunspider-0.9/string-validate-input.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/LIST create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-closure.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-correct-args.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-empty.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-excess-args.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-missing-args.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/function-sum.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/loop-empty-resolve.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/loop-empty.js create mode 100644 PerformanceTests/SunSpider/tests/ubench/loop-sum.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/LIST create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-crypto.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-deltablue.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-earley-boyer.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-raytrace.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-regexp.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-richards.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v4/v8-splay.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/LIST create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-crypto.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-deltablue.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-earley-boyer.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-raytrace.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-regexp.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-richards.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v5/v8-splay.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/LIST create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-crypto.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-deltablue.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-earley-boyer.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-raytrace.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-regexp.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-richards.js create mode 100644 PerformanceTests/SunSpider/tests/v8-v6/v8-splay.js create mode 100644 PerformanceTests/SunSpider/xcopy.excludes (limited to 'PerformanceTests') diff --git a/PerformanceTests/PageLoad/ChangeLog b/PerformanceTests/PageLoad/ChangeLog new file mode 100644 index 0000000..64ba517 --- /dev/null +++ b/PerformanceTests/PageLoad/ChangeLog @@ -0,0 +1,46 @@ +2010-12-31 Adam Barth + + Rubber-stamped by Eric Seidel. + + Move PageLoadTests to PerformanceTests/PageLoad + https://bugs.webkit.org/show_bug.cgi?id=51771 + + Update URLs to point to the new directory name. + + * svg/svg.pltsuite: + +2006-12-26 Eric Seidel + + Reviewed by olliej. + + * svg/svg.pltsuite: re-enable word-iso.svg after fixing http://bugs.webkit.org/show_bug.cgi?id=11987 + +2006-12-26 Eric Seidel + + Reviewed by bradee-oh. + + Add new PageLoadTests directory (this one) + Add LICENSES file to explain where each SVG came from. + + * ChangeLog: Added. + * svg/LICENSES: Added. + * svg/files/33041-Samurai.svg: Added. + * svg/files/42470-flower_from_my_garden_v2.svg: Added. + * svg/files/Harvey_Rayner.svg: Added. + * svg/files/az-lizard_benji_park_01.svg: Added. + * svg/files/bamboo_01.svg: Added. + * svg/files/cacuts_01.svg: Added. + * svg/files/cowboy.svg: Added. + * svg/files/crawfish2_ganson.svg: Added. + * svg/files/deb9frac1.svg: Added. + * svg/files/food_leif_lodahl_01.svg: Added. + * svg/files/france.svg: Added. + * svg/files/francobollo_gnome_ezechi_02.svg: Added. + * 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We have outlined the licenses of the various files (and where we found them on the net) below: + + +Public domain or Creative Commons (as implied by inclusion in OpenClipart): +http://openclipart.org/clipart//plants/bamboo_01.svg +http://openclipart.org/clipart//plants/cacuts_01.svg +http://openclipart.org/clipart//food/crawfish2_ganson.svg +http://openclipart.org/clipart//food/food_leif_lodahl_01.svg +http://openclipart.org/clipart//logos/francobollo_gnome_ezechi_02.svg +http://openclipart.org/clipart//animals/az-lizard_benji_park_01.svg + +Other (freely distributable): +http://svg-whiz.com/svg/map/world-iso.svgz + +LGPL or compatible (as implied by inclusion in KDE SVN) +http://websvn.kde.org/trunk/tests/ksvgtests/custom/worldcup.svg +http://websvn.kde.org/trunk/tests/ksvgtests/custom/cowboy.svg +http://websvn.kde.org/trunk/tests/ksvgtests/custom/mtsthelens.svg +http://websvn.kde.org/trunk/tests/ksvgtests/custom/france.svg + +LGPL: +http://www.kde-look.org/content/show.php?content=19524 + +GPL: +http://www.kde-look.org/content/show.php?content=19064 +http://www.kde-look.org/content/show.php?content=31481 +http://www.kde-look.org/content/files/42450-under%20the%20see.svg +http://www.kde-look.org/content/files/42470-flower_from_my_garden_v2.svg +http://www.kde-look.org/content/files/44057-drops%20on%20a%20blade.svg +http://www.kde-look.org/content/files/33041-Samurai.svgz + + +CC Attribution-NoDerivs 2.5 (as implied by submission to the SVG Logo contest) +http://www.svglogo.com/Harvey_Rayner.svg + diff --git a/PerformanceTests/PageLoad/svg/files/33041-Samurai.svg b/PerformanceTests/PageLoad/svg/files/33041-Samurai.svg new file mode 100644 index 0000000..1fd617d --- /dev/null +++ b/PerformanceTests/PageLoad/svg/files/33041-Samurai.svg @@ -0,0 +1,215 @@ + + + + + + + + + + + + + + + + + + + + + + + image/svg+xml + + Samurai + Wed Dec 28 14:31:06 EST 2005 + + + Sean E. 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+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 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+file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/42470-flower_from_my_garden_v2.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/44057-drops%20on%20a%20blade.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/Harvey_Rayner.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/az-lizard_benji_park_01.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/bamboo_01.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/cacuts_01.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/cowboy.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/crawfish2_ganson.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/deb9frac1.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/food_leif_lodahl_01.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/france.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/francobollo_gnome_ezechi_02.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/gearflowers.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/hereGear4.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/mtsthelens.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/world-iso.svg +file:///WEBKIT_PATH/PerformanceTests/PageLoad/svg/files/worldcup.svg diff --git a/PerformanceTests/Parser/ChangeLog b/PerformanceTests/Parser/ChangeLog new file mode 100644 index 0000000..37a9f2e --- /dev/null +++ b/PerformanceTests/Parser/ChangeLog @@ -0,0 +1,11 @@ +2010-12-31 Adam Barth + + Rubber-stamped by Eric Seidel. + + Move HTML and XML parser benchmarks into PerformanceTests/Parser + https://bugs.webkit.org/show_bug.cgi?id=51772 + + Add a ChangeLog for tracking changes to the Parser PerformanceTest. + + * ChangeLog: Added. + diff --git a/PerformanceTests/Parser/html-parser.html b/PerformanceTests/Parser/html-parser.html new file mode 100644 index 0000000..bb2c73c --- /dev/null +++ b/PerformanceTests/Parser/html-parser.html @@ -0,0 +1,19 @@ + + +

+
+
+
diff --git a/PerformanceTests/Parser/resources/html5.html b/PerformanceTests/Parser/resources/html5.html
new file mode 100644
index 0000000..ccb95bc
--- /dev/null
+++ b/PerformanceTests/Parser/resources/html5.html
@@ -0,0 +1,85096 @@
+HTML5 (including next generation additions still in development)
+
+  
Abstract

+
+  
This specification evolves HTML and its related APIs to ease the
+  authoring of Web-based applications. The most recent additions
+  include a device element to enable video conferencing,
+  as well as all the features added as part of the earlier HTML5
+  effort.

+
+
+  
Status of this document

+
+  
This is a work in progress! This document is
+  changing on a daily if not hourly basis in response to comments and
+  as a general part of its development process. Comments are very
+  welcome, please send them to whatwg@whatwg.org. Thank
+  you.

+
+  
Outstanding feedback
+  is tracked; all e-mails sent to the list above receive a reply. The
+  level of outstanding feedback is charted to allow
+  progress to be evaluated.

+
+  
Implementors should be aware that this specification is not
+  stable. Implementors who are not taking part in the
+  discussions are likely to find the specification changing out from
+  under them in incompatible ways. Vendors interested in
+  implementing this specification before it eventually reaches the
+  call for implementations should join the WHATWG mailing list and take part in the
+  discussions.

+
+  
This specification is intended to replace (be the new version of)
+  what was previously the HTML5, HTML4, XHTML1, and DOM2 HTML
+  specifications.

+
+
+
+  
Table of contents

+  
+
+
    
+ 
  1. 1 Introduction
+  
      
+   
    1. 1.1 Is this HTML5?
      2. 
+   
    2. 1.2 Background
      3. 
+   
    3. 1.3 Audience
      4. 
+   
    4. 1.4 Scope
      5. 
+   
    5. 1.5 History
      6. 
+   
    6. 1.6 Design notes
+    
        
+     
      1. 1.6.1 Serializability of script execution
        2. 
+     
      2. 1.6.2 Compliance with other specifications
      7. 
+   
    7. 1.7 HTML vs XHTML
      8. 
+   
    8. 1.8 Structure of this specification
+    
        
+     
      1. 1.8.1 How to read this specification
        2. 
+     
      2. 1.8.2 Typographic conventions
      9. 
+   
    9. 1.9 A quick introduction to HTML
      10. 
+   
    10. 1.10 Conformance requirements for authors
+    
        
+     
      1. 1.10.1 Presentational markup
        2. 
+     
      2. 1.10.2 Syntax errors
        3. 
+     
      3. 1.10.3 Restrictions on content models and on attribute values
      11. 
+   
    11. 1.11 Recommended reading
    2. 
+ 
  2. 2 Common infrastructure
+  
      
+   
    1. 2.1 Terminology
+    
        
+     
      1. 2.1.1 Resources
        2. 
+     
      2. 2.1.2 XML
        3. 
+     
      3. 2.1.3 DOM trees
        4. 
+     
      4. 2.1.4 Scripting
        5. 
+     
      5. 2.1.5 Plugins
        6. 
+     
      6. 2.1.6 Character encodings
      2. 
+   
    2. 2.2 Conformance requirements
+    
        
+     
      1. 2.2.1 Dependencies
        2. 
+     
      2. 2.2.2 Extensibility
      3. 
+   
    3. 2.3 Case-sensitivity and string comparison
      4. 
+   
    4. 2.4 Common microsyntaxes
+    
        
+     
      1. 2.4.1 Common parser idioms
        2. 
+     
      2. 2.4.2 Boolean attributes
        3. 
+     
      3. 2.4.3 Keywords and enumerated attributes
        4. 
+     
      4. 2.4.4 Numbers
+      
          
+       
        1. 2.4.4.1 Non-negative integers
          2. 
+       
        2. 2.4.4.2 Signed integers
          3. 
+       
        3. 2.4.4.3 Real numbers
          4. 
+       
        4. 2.4.4.4 Percentages and lengths
          5. 
+       
        5. 2.4.4.5 Lists of integers
          6. 
+       
        6. 2.4.4.6 Lists of dimensions
        5. 
+     
      5. 2.4.5 Dates and times
+      
          
+       
        1. 2.4.5.1 Months
          2. 
+       
        2. 2.4.5.2 Dates
          3. 
+       
        3. 2.4.5.3 Times
          4. 
+       
        4. 2.4.5.4 Local dates and times
          5. 
+       
        5. 2.4.5.5 Global dates and times
          6. 
+       
        6. 2.4.5.6 Weeks
          7. 
+       
        7. 2.4.5.7 Vaguer moments in time
        6. 
+     
      6. 2.4.6 Colors
        7. 
+     
      7. 2.4.7 Space-separated tokens
        8. 
+     
      8. 2.4.8 Comma-separated tokens
        9. 
+     
      9. 2.4.9 References
        10. 
+     
      10. 2.4.10 Media queries
      5. 
+   
    5. 2.5 URLs
+    
        
+     
      1. 2.5.1 Terminology
        2. 
+     
      2. 2.5.2 Dynamic changes to base URLs
        3. 
+     
      3. 2.5.3 Interfaces for URL manipulation
      6. 
+   
    6. 2.6 Fetching resources
+    
        
+     
      1. 2.6.1 Protocol concepts
        2. 
+     
      2. 2.6.2 Encrypted HTTP and related security concerns
        3. 
+     
      3. 2.6.3 Determining the type of a resource
      7. 
+   
    7. 2.7 Common DOM interfaces
+    
        
+     
      1. 2.7.1 Reflecting content attributes in IDL attributes
        2. 
+     
      2. 2.7.2 Collections
+      
          
+       
        1. 2.7.2.1 HTMLCollection
          2. 
+       
        2. 2.7.2.2 HTMLAllCollection
          3. 
+       
        3. 2.7.2.3 HTMLFormControlsCollection
          4. 
+       
        4. 2.7.2.4 HTMLOptionsCollection
          5. 
+       
        5. 2.7.2.5 HTMLPropertiesCollection
        3. 
+     
      3. 2.7.3 DOMTokenList
        4. 
+     
      4. 2.7.4 DOMSettableTokenList
        5. 
+     
      5. 2.7.5 Safe passing of structured data
        6. 
+     
      6. 2.7.6 DOMStringMap
        7. 
+     
      7. 2.7.7 DOM feature strings
        8. 
+     
      8. 2.7.8 Exceptions
        9. 
+     
      9. 2.7.9 Garbage collection
      8. 
+   
    8. 2.8 Namespaces
    3. 
+ 
  3. 3 Semantics, structure, and APIs of HTML documents
+  
      
+   
    1. 3.1 Documents
+    
        
+     
      1. 3.1.1 Documents in the DOM
        2. 
+     
      2. 3.1.2 Security
        3. 
+     
      3. 3.1.3 Resource metadata management
        4. 
+     
      4. 3.1.4 DOM tree accessors
        5. 
+     
      5. 3.1.5 Creating documents
      2. 
+   
    2. 3.2 Elements
+    
        
+     
      1. 3.2.1 Semantics
        2. 
+     
      2. 3.2.2 Elements in the DOM
        3. 
+     
      3. 3.2.3 Global attributes
+      
          
+       
        1. 3.2.3.1 The id attribute
          2. 
+       
        2. 3.2.3.2 The title attribute
          3. 
+       
        3. 3.2.3.3 The lang and xml:lang attributes
          4. 
+       
        4. 3.2.3.4 The xml:base
+  attribute (XML only)
          5. 
+       
        5. 3.2.3.5 The dir attribute
          6. 
+       
        6. 3.2.3.6 The class attribute
          7. 
+       
        7. 3.2.3.7 The style attribute
          8. 
+       
        8. 3.2.3.8 Embedding custom non-visible data
        4. 
+     
      4. 3.2.4 Element definitions
+      
          
+       
        1. 3.2.4.1 Attributes
        5. 
+     
      5. 3.2.5 Content models
+      
          
+       
        1. 3.2.5.1 Kinds of content
+        
            
+         
          1. 3.2.5.1.1 Metadata content
            2. 
+         
          2. 3.2.5.1.2 Flow content
            3. 
+         
          3. 3.2.5.1.3 Sectioning content
            4. 
+         
          4. 3.2.5.1.4 Heading content
            5. 
+         
          5. 3.2.5.1.5 Phrasing content
            6. 
+         
          6. 3.2.5.1.6 Embedded content
            7. 
+         
          7. 3.2.5.1.7 Interactive content
          2. 
+       
        2. 3.2.5.2 Transparent content models
          3. 
+       
        3. 3.2.5.3 Paragraphs
        6. 
+     
      6. 3.2.6 Annotations for assistive technology products (ARIA)
      3. 
+   
    3. 3.3 APIs in HTML documents
      4. 
+   
    4. 3.4 Interactions with XPath and XSLT
      5. 
+   
    5. 3.5 Dynamic markup insertion
+    
        
+     
      1. 3.5.1 Opening the input stream
        2. 
+     
      2. 3.5.2 Closing the input stream
        3. 
+     
      3. 3.5.3 document.write()
        4. 
+     
      4. 3.5.4 document.writeln()
        5. 
+     
      5. 3.5.5 innerHTML
        6. 
+     
      6. 3.5.6 outerHTML
        7. 
+     
      7. 3.5.7 insertAdjacentHTML()
    4. 
+ 
  4. 4 The elements of HTML
+  
      
+   
    1. 4.1 The root element
+    
        
+     
      1. 4.1.1 The html element
      2. 
+   
    2. 4.2 Document metadata
+    
        
+     
      1. 4.2.1 The head element
        2. 
+     
      2. 4.2.2 The title element
        3. 
+     
      3. 4.2.3 The base element
        4. 
+     
      4. 4.2.4 The link element
        5. 
+     
      5. 4.2.5 The meta element
+      
          
+       
        1. 4.2.5.1 Standard metadata names
          2. 
+       
        2. 4.2.5.2 Other metadata names
          3. 
+       
        3. 4.2.5.3 Pragma directives
          4. 
+       
        4. 4.2.5.4 Other pragma directives
          5. 
+       
        5. 4.2.5.5 Specifying the document's character encoding
        6. 
+     
      6. 4.2.6 The style element
        7. 
+     
      7. 4.2.7 Styling
      3. 
+   
    3. 4.3 Scripting
+    
        
+     
      1. 4.3.1 The script element
+      
          
+       
        1. 4.3.1.1 Scripting languages
          2. 
+       
        2. 4.3.1.2 Restrictions for contents of script elements
          3. 
+       
        3. 4.3.1.3 Inline documentation for external scripts
        2. 
+     
      2. 4.3.2 The noscript element
      4. 
+   
    4. 4.4 Sections
+    
        
+     
      1. 4.4.1 The body element
        2. 
+     
      2. 4.4.2 The section element
        3. 
+     
      3. 4.4.3 The nav element
        4. 
+     
      4. 4.4.4 The article element
        5. 
+     
      5. 4.4.5 The aside element
        6. 
+     
      6. 4.4.6 The h1, h2,
+  h3, h4,
+  h5, and h6
+  elements
        7. 
+     
      7. 4.4.7 The hgroup element
        8. 
+     
      8. 4.4.8 The header element
        9. 
+     
      9. 4.4.9 The footer element
        10. 
+     
      10. 4.4.10 The address element
        11. 
+     
      11. 4.4.11 Headings and sections
+      
          
+       
        1. 4.4.11.1 Creating an outline
      5. 
+   
    5. 4.5 Grouping content
+    
        
+     
      1. 4.5.1 The p element
        2. 
+     
      2. 4.5.2 The hr element
        3. 
+     
      3. 4.5.3 The pre element
        4. 
+     
      4. 4.5.4 The blockquote element
        5. 
+     
      5. 4.5.5 The ol element
        6. 
+     
      6. 4.5.6 The ul element
        7. 
+     
      7. 4.5.7 The li element
        8. 
+     
      8. 4.5.8 The dl element
        9. 
+     
      9. 4.5.9 The dt element
        10. 
+     
      10. 4.5.10 The dd element
        11. 
+     
      11. 4.5.11 The figure element
        12. 
+     
      12. 4.5.12 The figcaption element
        13. 
+     
      13. 4.5.13 The div element
      6. 
+   
    6. 4.6 Text-level semantics
+    
        
+     
      1. 4.6.1 The a element
        2. 
+     
      2. 4.6.2 The em element
        3. 
+     
      3. 4.6.3 The strong element
        4. 
+     
      4. 4.6.4 The small element
        5. 
+     
      5. 4.6.5 The cite element
        6. 
+     
      6. 4.6.6 The q element
        7. 
+     
      7. 4.6.7 The dfn element
        8. 
+     
      8. 4.6.8 The abbr element
        9. 
+     
      9. 4.6.9 The time element
        10. 
+     
      10. 4.6.10 The code element
        11. 
+     
      11. 4.6.11 The var element
        12. 
+     
      12. 4.6.12 The samp element
        13. 
+     
      13. 4.6.13 The kbd element
        14. 
+     
      14. 4.6.14 The sub and sup elements
        15. 
+     
      15. 4.6.15 The i element
        16. 
+     
      16. 4.6.16 The b element
        17. 
+     
      17. 4.6.17 The mark element
        18. 
+     
      18. 4.6.18 The ruby element
        19. 
+     
      19. 4.6.19 The rt element
        20. 
+     
      20. 4.6.20 The rp element
        21. 
+     
      21. 4.6.21 The bdo element
        22. 
+     
      22. 4.6.22 The span element
        23. 
+     
      23. 4.6.23 The br element
        24. 
+     
      24. 4.6.24 The wbr element
        25. 
+     
      25. 4.6.25 Usage summary
      7. 
+   
    7. 4.7 Edits
+    
        
+     
      1. 4.7.1 The ins element
        2. 
+     
      2. 4.7.2 The del element
        3. 
+     
      3. 4.7.3 Attributes common to ins and del elements
        4. 
+     
      4. 4.7.4 Edits and paragraphs
        5. 
+     
      5. 4.7.5 Edits and lists
      8. 
+   
    8. 4.8 Embedded content
+    
        
+     
      1. 4.8.1 The img element
+      
          
+       
        1. 4.8.1.1 Requirements for providing text to act as an alternative for images
+        
            
+         
          1. 4.8.1.1.1 A link or button containing nothing but the image
            2. 
+         
          2. 4.8.1.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations
            3. 
+         
          3. 4.8.1.1.3 A short phrase or label with an alternative graphical representation: icons, logos
            4. 
+         
          4. 4.8.1.1.4 Text that has been rendered to a graphic for typographical effect
            5. 
+         
          5. 4.8.1.1.5 A graphical representation of some of the surrounding text
            6. 
+         
          6. 4.8.1.1.6 A purely decorative image that doesn't add any information
            7. 
+         
          7. 4.8.1.1.7 A group of images that form a single larger picture with no links
            8. 
+         
          8. 4.8.1.1.8 A group of images that form a single larger picture with links
            9. 
+         
          9. 4.8.1.1.9 A key part of the content
            10. 
+         
          10. 4.8.1.1.10 An image not intended for the user
            11. 
+         
          11. 4.8.1.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images
            12. 
+         
          12. 4.8.1.1.12 General guidelines
            13. 
+         
          13. 4.8.1.1.13 Guidance for markup generators
            14. 
+         
          14. 4.8.1.1.14 Guidance for conformance checkers
        2. 
+     
      2. 4.8.2 The iframe element
        3. 
+     
      3. 4.8.3 The embed element
        4. 
+     
      4. 4.8.4 The object element
        5. 
+     
      5. 4.8.5 The param element
        6. 
+     
      6. 4.8.6 The video element
        7. 
+     
      7. 4.8.7 The audio element
        8. 
+     
      8. 4.8.8 The source element
        9. 
+     
      9. 4.8.9 The track element
        10. 
+     
      10. 4.8.10 Media elements
+      
          
+       
        1. 4.8.10.1 Error codes
          2. 
+       
        2. 4.8.10.2 Location of the media resource
          3. 
+       
        3. 4.8.10.3 MIME types
          4. 
+       
        4. 4.8.10.4 Network states
          5. 
+       
        5. 4.8.10.5 Loading the media resource
          6. 
+       
        6. 4.8.10.6 Offsets into the media resource
          7. 
+       
        7. 4.8.10.7 The ready states
          8. 
+       
        8. 4.8.10.8 Playing the media resource
          9. 
+       
        9. 4.8.10.9 Seeking
          10. 
+       
        10. 4.8.10.10 Timed tracks
+        
            
+         
          1. 4.8.10.10.1 Timed track model
            2. 
+         
          2. 4.8.10.10.2 Sourcing in-band timed tracks
            3. 
+         
          3. 4.8.10.10.3 Sourcing out-of-band timed tracks
            4. 
+         
          4. 4.8.10.10.4 Guidelines for exposing cues in various formats as
+  timed track cues
            5. 
+         
          5. 4.8.10.10.5 Timed track API
            6. 
+         
          6. 4.8.10.10.6 Event definitions
          11. 
+       
        11. 4.8.10.11 WebSRT
+        
            
+         
          1. 4.8.10.11.1 Syntax
            2. 
+         
          2. 4.8.10.11.2 Parsing
          12. 
+       
        12. 4.8.10.12 User interface
          13. 
+       
        13. 4.8.10.13 Time ranges
          14. 
+       
        14. 4.8.10.14 Event summary
          15. 
+       
        15. 4.8.10.15 Security and privacy considerations
        11. 
+     
      11. 4.8.11 The canvas element
+      
          
+       
        1. 4.8.11.1 The 2D context
+        
            
+         
          1. 4.8.11.1.1 The canvas state
            2. 
+         
          2. 4.8.11.1.2 Transformations
            3. 
+         
          3. 4.8.11.1.3 Compositing
            4. 
+         
          4. 4.8.11.1.4 Colors and styles
            5. 
+         
          5. 4.8.11.1.5 Line styles
            6. 
+         
          6. 4.8.11.1.6 Shadows
            7. 
+         
          7. 4.8.11.1.7 Simple shapes (rectangles)
            8. 
+         
          8. 4.8.11.1.8 Complex shapes (paths)
            9. 
+         
          9. 4.8.11.1.9 Focus management
            10. 
+         
          10. 4.8.11.1.10 Text
            11. 
+         
          11. 4.8.11.1.11 Images
            12. 
+         
          12. 4.8.11.1.12 Pixel manipulation
            13. 
+         
          13. 4.8.11.1.13 Drawing model
            14. 
+         
          14. 4.8.11.1.14 Examples
          2. 
+       
        2. 4.8.11.2 Color spaces and color correction
          3. 
+       
        3. 4.8.11.3 Security with canvas elements
        12. 
+     
      12. 4.8.12 The map element
        13. 
+     
      13. 4.8.13 The area element
        14. 
+     
      14. 4.8.14 Image maps
+      
          
+       
        1. 4.8.14.1 Authoring
          2. 
+       
        2. 4.8.14.2 Processing model
        15. 
+     
      15. 4.8.15 MathML
        16. 
+     
      16. 4.8.16 SVG
        17. 
+     
      17. 4.8.17 Dimension attributes
      9. 
+   
    9. 4.9 Tabular data
+    
        
+     
      1. 4.9.1 The table element
        2. 
+     
      2. 4.9.2 The caption element
        3. 
+     
      3. 4.9.3 The colgroup element
        4. 
+     
      4. 4.9.4 The col element
        5. 
+     
      5. 4.9.5 The tbody element
        6. 
+     
      6. 4.9.6 The thead element
        7. 
+     
      7. 4.9.7 The tfoot element
        8. 
+     
      8. 4.9.8 The tr element
        9. 
+     
      9. 4.9.9 The td element
        10. 
+     
      10. 4.9.10 The th element
        11. 
+     
      11. 4.9.11 Attributes common to td and th elements
        12. 
+     
      12. 4.9.12 Processing model
+      
          
+       
        1. 4.9.12.1 Forming a table
          2. 
+       
        2. 4.9.12.2 Forming relationships between data cells and header cells
        13. 
+     
      13. 4.9.13 Examples
      10. 
+   
    10. 4.10 Forms
+    
        
+     
      1. 4.10.1 Introduction
+      
          
+       
        1. 4.10.1.1 Writing a form's user interface
          2. 
+       
        2. 4.10.1.2 Implementing the server-side processing for a form
          3. 
+       
        3. 4.10.1.3 Configuring a form to communicate with a server
          4. 
+       
        4. 4.10.1.4 Client-side form validation
        2. 
+     
      2. 4.10.2 Categories
        3. 
+     
      3. 4.10.3 The form element
        4. 
+     
      4. 4.10.4 The fieldset element
        5. 
+     
      5. 4.10.5 The legend element
        6. 
+     
      6. 4.10.6 The label element
        7. 
+     
      7. 4.10.7 The input element
+      
          
+       
        1. 4.10.7.1 States of the type attribute
+        
            
+         
          1. 4.10.7.1.1 Hidden state
            2. 
+         
          2. 4.10.7.1.2 Text state and Search state
            3. 
+         
          3. 4.10.7.1.3 Telephone state
            4. 
+         
          4. 4.10.7.1.4 URL state
            5. 
+         
          5. 4.10.7.1.5 E-mail state
            6. 
+         
          6. 4.10.7.1.6 Password state
            7. 
+         
          7. 4.10.7.1.7 Date and Time state
            8. 
+         
          8. 4.10.7.1.8 Date state
            9. 
+         
          9. 4.10.7.1.9 Month state
            10. 
+         
          10. 4.10.7.1.10 Week state
            11. 
+         
          11. 4.10.7.1.11 Time state
            12. 
+         
          12. 4.10.7.1.12 Local Date and Time state
            13. 
+         
          13. 4.10.7.1.13 Number state
            14. 
+         
          14. 4.10.7.1.14 Range state
            15. 
+         
          15. 4.10.7.1.15 Color state
            16. 
+         
          16. 4.10.7.1.16 Checkbox state
            17. 
+         
          17. 4.10.7.1.17 Radio Button state
            18. 
+         
          18. 4.10.7.1.18 File Upload state
            19. 
+         
          19. 4.10.7.1.19 Submit Button state
            20. 
+         
          20. 4.10.7.1.20 Image Button state
            21. 
+         
          21. 4.10.7.1.21 Reset Button state
            22. 
+         
          22. 4.10.7.1.22 Button state
          2. 
+       
        2. 4.10.7.2 Common input element attributes
+        
            
+         
          1. 4.10.7.2.1 The autocomplete attribute
            2. 
+         
          2. 4.10.7.2.2 The list attribute
            3. 
+         
          3. 4.10.7.2.3 The readonly attribute
            4. 
+         
          4. 4.10.7.2.4 The size attribute
            5. 
+         
          5. 4.10.7.2.5 The required attribute
            6. 
+         
          6. 4.10.7.2.6 The multiple attribute
            7. 
+         
          7. 4.10.7.2.7 The maxlength attribute
            8. 
+         
          8. 4.10.7.2.8 The pattern attribute
            9. 
+         
          9. 4.10.7.2.9 The min and max attributes
            10. 
+         
          10. 4.10.7.2.10 The step attribute
            11. 
+         
          11. 4.10.7.2.11 The placeholder attribute
          3. 
+       
        3. 4.10.7.3 Common input element APIs
          4. 
+       
        4. 4.10.7.4 Common event behaviors
        8. 
+     
      8. 4.10.8 The button element
        9. 
+     
      9. 4.10.9 The select element
        10. 
+     
      10. 4.10.10 The datalist element
        11. 
+     
      11. 4.10.11 The optgroup element
        12. 
+     
      12. 4.10.12 The option element
        13. 
+     
      13. 4.10.13 The textarea element
        14. 
+     
      14. 4.10.14 The keygen element
        15. 
+     
      15. 4.10.15 The output element
        16. 
+     
      16. 4.10.16 The progress element
        17. 
+     
      17. 4.10.17 The meter element
        18. 
+     
      18. 4.10.18 Association of controls and forms
        19. 
+     
      19. 4.10.19 Attributes common to form controls
+      
          
+       
        1. 4.10.19.1 Naming form controls
          2. 
+       
        2. 4.10.19.2 Enabling and disabling form controls
          3. 
+       
        3. 4.10.19.3 A form control's value
          4. 
+       
        4. 4.10.19.4 Autofocusing a form control
          5. 
+       
        5. 4.10.19.5 Limiting user input length
          6. 
+       
        6. 4.10.19.6 Form submission
        20. 
+     
      20. 4.10.20 Constraints
+      
          
+       
        1. 4.10.20.1 Definitions
          2. 
+       
        2. 4.10.20.2 Constraint validation
          3. 
+       
        3. 4.10.20.3 The constraint validation API
          4. 
+       
        4. 4.10.20.4 Security
        21. 
+     
      21. 4.10.21 Form submission
+      
          
+       
        1. 4.10.21.1 Introduction
          2. 
+       
        2. 4.10.21.2 Implicit submission
          3. 
+       
        3. 4.10.21.3 Form submission algorithm
          4. 
+       
        4. 4.10.21.4 URL-encoded form data
          5. 
+       
        5. 4.10.21.5 Multipart form data
          6. 
+       
        6. 4.10.21.6 Plain text form data
        22. 
+     
      22. 4.10.22 Resetting a form
        23. 
+     
      23. 4.10.23 Event dispatch
      11. 
+   
    11. 4.11 Interactive elements
+    
        
+     
      1. 4.11.1 The details element
        2. 
+     
      2. 4.11.2 The summary element
        3. 
+     
      3. 4.11.3 The command element
        4. 
+     
      4. 4.11.4 The menu element
+      
          
+       
        1. 4.11.4.1 Introduction
          2. 
+       
        2. 4.11.4.2 Building menus and toolbars
          3. 
+       
        3. 4.11.4.3 Context menus
          4. 
+       
        4. 4.11.4.4 Toolbars
        5. 
+     
      5. 4.11.5 Commands
+      
          
+       
        1. 4.11.5.1 Using the a element to define a command
          2. 
+       
        2. 4.11.5.2 Using the button element to define a command
          3. 
+       
        3. 4.11.5.3 Using the input element to define a command
          4. 
+       
        4. 4.11.5.4 Using the option element to define a command
          5. 
+       
        5. 4.11.5.5 Using the command element to define
+  a command
          6. 
+       
        6. 4.11.5.6 Using the accesskey attribute on a label element to define a command
          7. 
+       
        7. 4.11.5.7 Using the accesskey attribute on a legend element to define a command
          8. 
+       
        8. 4.11.5.8 Using the accesskey attribute to define a command on other elements
        6. 
+     
      6. 4.11.6 The device element
+      
          
+       
        1. 4.11.6.1 Stream API
          2. 
+       
        2. 4.11.6.2 Peer-to-peer connections
      12. 
+   
    12. 4.12 Links
+    
        
+     
      1. 4.12.1 Hyperlink elements
        2. 
+     
      2. 4.12.2 Following hyperlinks
+      
          
+       
        1. 4.12.2.1 Hyperlink auditing
        3. 
+     
      3. 4.12.3 Link types
+      
          
+       
        1. 4.12.3.1 Link type "alternate"
          2. 
+       
        2. 4.12.3.2 Link type "archives"
          3. 
+       
        3. 4.12.3.3 Link type "author"
          4. 
+       
        4. 4.12.3.4 Link type "bookmark"
          5. 
+       
        5. 4.12.3.5 Link type "external"
          6. 
+       
        6. 4.12.3.6 Link type "help"
          7. 
+       
        7. 4.12.3.7 Link type "icon"
          8. 
+       
        8. 4.12.3.8 Link type "license"
          9. 
+       
        9. 4.12.3.9 Link type "nofollow"
          10. 
+       
        10. 4.12.3.10 Link type "noreferrer"
          11. 
+       
        11. 4.12.3.11 Link type "pingback"
          12. 
+       
        12. 4.12.3.12 Link type "prefetch"
          13. 
+       
        13. 4.12.3.13 Link type "search"
          14. 
+       
        14. 4.12.3.14 Link type "stylesheet"
          15. 
+       
        15. 4.12.3.15 Link type "sidebar"
          16. 
+       
        16. 4.12.3.16 Link type "tag"
          17. 
+       
        17. 4.12.3.17 Hierarchical link types
+        
            
+         
          1. 4.12.3.17.1 Link type "index"
            2. 
+         
          2. 4.12.3.17.2 Link type "up"
          18. 
+       
        18. 4.12.3.18 Sequential link types
+        
            
+         
          1. 4.12.3.18.1 Link type "first"
            2. 
+         
          2. 4.12.3.18.2 Link type "last"
            3. 
+         
          3. 4.12.3.18.3 Link type "next"
            4. 
+         
          4. 4.12.3.18.4 Link type "prev"
          19. 
+       
        19. 4.12.3.19 Other link types
      13. 
+   
    13. 4.13 Common idioms without dedicated elements
+    
        
+     
      1. 4.13.1 Tag clouds
        2. 
+     
      2. 4.13.2 Conversations
        3. 
+     
      3. 4.13.3 Footnotes
      14. 
+   
    14. 4.14 Matching HTML elements using selectors
+    
        
+     
      1. 4.14.1 Case-sensitivity
        2. 
+     
      2. 4.14.2 Pseudo-classes
    5. 
+ 
  5. 5 Microdata
+  
      
+   
    1. 5.1 Introduction
+    
        
+     
      1. 5.1.1 Overview
        2. 
+     
      2. 5.1.2 The basic syntax
        3. 
+     
      3. 5.1.3 Typed items
        4. 
+     
      4. 5.1.4 Global identifiers for items
        5. 
+     
      5. 5.1.5 Selecting names when defining vocabularies
        6. 
+     
      6. 5.1.6 Using the microdata DOM API
      2. 
+   
    2. 5.2 Encoding microdata
+    
        
+     
      1. 5.2.1 The microdata model
        2. 
+     
      2. 5.2.2 Items
        3. 
+     
      3. 5.2.3 Names: the itemprop attribute
        4. 
+     
      4. 5.2.4 Values
        5. 
+     
      5. 5.2.5 Associating names with items
      3. 
+   
    3. 5.3 Microdata DOM API
      4. 
+   
    4. 5.4 Microdata vocabularies
+    
        
+     
      1. 5.4.1 vCard
+      
          
+       
        1. 5.4.1.1 Conversion to vCard
          2. 
+       
        2. 5.4.1.2 Examples
        2. 
+     
      2. 5.4.2 vEvent
+      
          
+       
        1. 5.4.2.1 Conversion to iCalendar
          2. 
+       
        2. 5.4.2.2 Examples
        3. 
+     
      3. 5.4.3 Licensing works
+      
          
+       
        1. 5.4.3.1 Conversion to RDF
          2. 
+       
        2. 5.4.3.2 Examples
      5. 
+   
    5. 5.5 Converting HTML to other formats
+    
        
+     
      1. 5.5.1 JSON
        2. 
+     
      2. 5.5.2 RDF
+      
          
+       
        1. 5.5.2.1 Examples
        3. 
+     
      3. 5.5.3 Atom
    6. 
+ 
  6. 6 Loading Web pages
+  
      
+   
    1. 6.1 Browsing contexts
+    
        
+     
      1. 6.1.1 Nested browsing contexts
+      
          
+       
        1. 6.1.1.1 Navigating nested browsing contexts in the DOM
        2. 
+     
      2. 6.1.2 Auxiliary browsing contexts
+      
          
+       
        1. 6.1.2.1 Navigating auxiliary browsing contexts in the DOM
        3. 
+     
      3. 6.1.3 Secondary browsing contexts
        4. 
+     
      4. 6.1.4 Security
        5. 
+     
      5. 6.1.5 Groupings of browsing contexts
        6. 
+     
      6. 6.1.6 Browsing context names
      2. 
+   
    2. 6.2 The Window object
+    
        
+     
      1. 6.2.1 Security
        2. 
+     
      2. 6.2.2 APIs for creating and navigating browsing contexts by name
        3. 
+     
      3. 6.2.3 Accessing other browsing contexts
        4. 
+     
      4. 6.2.4 Named access on the Window object
        5. 
+     
      5. 6.2.5 Garbage collection and browsing contexts
        6. 
+     
      6. 6.2.6 Browser interface elements
        7. 
+     
      7. 6.2.7 The WindowProxy object
      3. 
+   
    3. 6.3 Origin
+    
        
+     
      1. 6.3.1 Relaxing the same-origin restriction
      4. 
+   
    4. 6.4 Session history and navigation
+    
        
+     
      1. 6.4.1 The session history of browsing contexts
        2. 
+     
      2. 6.4.2 The History interface
        3. 
+     
      3. 6.4.3 The Location interface
+      
          
+       
        1. 6.4.3.1 Security
        4. 
+     
      4. 6.4.4 Implementation notes for session history
      5. 
+   
    5. 6.5 Browsing the Web
+    
        
+     
      1. 6.5.1 Navigating across documents
        2. 
+     
      2. 6.5.2 Page load processing model for HTML files
        3. 
+     
      3. 6.5.3 Page load processing model for XML files
        4. 
+     
      4. 6.5.4 Page load processing model for text files
        5. 
+     
      5. 6.5.5 Page load processing model for images
        6. 
+     
      6. 6.5.6 Page load processing model for content that uses plugins
        7. 
+     
      7. 6.5.7 Page load processing model for inline content that doesn't have a DOM
        8. 
+     
      8. 6.5.8 Navigating to a fragment identifier
        9. 
+     
      9. 6.5.9 History traversal
+      
          
+       
        1. 6.5.9.1 Event definitions
        10. 
+     
      10. 6.5.10 Unloading documents
+      
          
+       
        1. 6.5.10.1 Event definition
        11. 
+     
      11. 6.5.11 Aborting a document load
      6. 
+   
    6. 6.6 Offline Web applications
+    
        
+     
      1. 6.6.1 Introduction
+      
          
+       
        1. 6.6.1.1 Event summary
        2. 
+     
      2. 6.6.2 Application caches
        3. 
+     
      3. 6.6.3 The cache manifest syntax
+      
          
+       
        1. 6.6.3.1 A sample manifest
          2. 
+       
        2. 6.6.3.2 Writing cache manifests
          3. 
+       
        3. 6.6.3.3 Parsing cache manifests
        4. 
+     
      4. 6.6.4 Downloading or updating an application cache
        5. 
+     
      5. 6.6.5 The application cache selection algorithm
        6. 
+     
      6. 6.6.6 Changes to the networking model
        7. 
+     
      7. 6.6.7 Expiring application caches
        8. 
+     
      8. 6.6.8 Application cache API
        9. 
+     
      9. 6.6.9 Browser state
    7. 
+ 
  7. 7 Web application APIs
+  
      
+   
    1. 7.1 Scripting
+    
        
+     
      1. 7.1.1 Introduction
        2. 
+     
      2. 7.1.2 Enabling and disabling scripting
        3. 
+     
      3. 7.1.3 Processing model
+      
          
+       
        1. 7.1.3.1 Definitions
          2. 
+       
        2. 7.1.3.2 Calling scripts
          3. 
+       
        3. 7.1.3.3 Creating scripts
          4. 
+       
        4. 7.1.3.4 Killing scripts
        4. 
+     
      4. 7.1.4 Event loops
+      
          
+       
        1. 7.1.4.1 Definitions
          2. 
+       
        2. 7.1.4.2 Processing model
          3. 
+       
        3. 7.1.4.3 Generic task sources
        5. 
+     
      5. 7.1.5 The javascript: protocol
        6. 
+     
      6. 7.1.6 Events
+      
          
+       
        1. 7.1.6.1 Event handlers
          2. 
+       
        2. 7.1.6.2 Event handlers on elements, Document objects, and Window objects
          3. 
+       
        3. 7.1.6.3 Event firing
          4. 
+       
        4. 7.1.6.4 Events and the Window object
          5. 
+       
        5. 7.1.6.5 Runtime script errors
      2. 
+   
    2. 7.2 Timers
      3. 
+   
    3. 7.3 User prompts
+    
        
+     
      1. 7.3.1 Simple dialogs
        2. 
+     
      2. 7.3.2 Printing
        3. 
+     
      3. 7.3.3 Dialogs implemented using separate documents
      4. 
+   
    4. 7.4 System state and capabilities
+    
        
+     
      1. 7.4.1 Client identification
        2. 
+     
      2. 7.4.2 Custom scheme and content handlers
+      
          
+       
        1. 7.4.2.1 Security and privacy
          2. 
+       
        2. 7.4.2.2 Sample user interface
        3. 
+     
      3. 7.4.3 Manually releasing the storage mutex
    8. 
+ 
  8. 8 User interaction
+  
      
+   
    1. 8.1 The hidden attribute
      2. 
+   
    2. 8.2 Activation
      3. 
+   
    3. 8.3 Scrolling elements into view
      4. 
+   
    4. 8.4 Focus
+    
        
+     
      1. 8.4.1 Sequential focus navigation
        2. 
+     
      2. 8.4.2 Focus management
        3. 
+     
      3. 8.4.3 Document-level focus APIs
        4. 
+     
      4. 8.4.4 Element-level focus APIs
      5. 
+   
    5. 8.5 The accesskey attribute
      6. 
+   
    6. 8.6 The text selection APIs
+    
        
+     
      1. 8.6.1 APIs for the browsing context selection
        2. 
+     
      2. 8.6.2 APIs for the text field selections
      7. 
+   
    7. 8.7 The contenteditable attribute
+    
        
+     
      1. 8.7.1 User editing actions
        2. 
+     
      2. 8.7.2 Making entire documents editable
      8. 
+   
    8. 8.8 Spelling and grammar checking
      9. 
+   
    9. 8.9 Drag and drop
+    
        
+     
      1. 8.9.1 Introduction
        2. 
+     
      2. 8.9.2 The DragEvent and DataTransfer interfaces
        3. 
+     
      3. 8.9.3 Events fired during a drag-and-drop action
        4. 
+     
      4. 8.9.4 Drag-and-drop processing model
+      
          
+       
        1. 8.9.4.1 When the drag-and-drop operation starts or ends in another
+  document
          2. 
+       
        2. 8.9.4.2 When the drag-and-drop operation starts or ends in another
+  application
        5. 
+     
      5. 8.9.5 The draggable attribute
        6. 
+     
      6. 8.9.6 Security risks in the drag-and-drop model
      10. 
+   
    10. 8.10 Undo history
+    
        
+     
      1. 8.10.1 Definitions
        2. 
+     
      2. 8.10.2 The UndoManager interface
        3. 
+     
      3. 8.10.3 Undo: moving back in the undo transaction history
        4. 
+     
      4. 8.10.4 Redo: moving forward in the undo transaction history
        5. 
+     
      5. 8.10.5 The UndoManagerEvent interface and the undo and redo events
        6. 
+     
      6. 8.10.6 Implementation notes
      11. 
+   
    11. 8.11 Editing APIs
    9. 
+ 
  9. 9 Communication
+  
      
+   
    1. 9.1 Event definitions
      2. 
+   
    2. 9.2 Cross-document messaging
+    
        
+     
      1. 9.2.1 Introduction
        2. 
+     
      2. 9.2.2 Security
+      
          
+       
        1. 9.2.2.1 Authors
          2. 
+       
        2. 9.2.2.2 User agents
        3. 
+     
      3. 9.2.3 Posting messages
      3. 
+   
    3. 9.3 Channel messaging
+    
        
+     
      1. 9.3.1 Introduction
        2. 
+     
      2. 9.3.2 Message channels
        3. 
+     
      3. 9.3.3 Message ports
+      
          
+       
        1. 9.3.3.1 Ports and garbage collection
    10. 
+ 
  10. 10 The HTML syntax
+  
      
+   
    1. 10.1 Writing HTML documents
+    
        
+     
      1. 10.1.1 The DOCTYPE
        2. 
+     
      2. 10.1.2 Elements
+      
          
+       
        1. 10.1.2.1 Start tags
          2. 
+       
        2. 10.1.2.2 End tags
          3. 
+       
        3. 10.1.2.3 Attributes
          4. 
+       
        4. 10.1.2.4 Optional tags
          5. 
+       
        5. 10.1.2.5 Restrictions on content models
          6. 
+       
        6. 10.1.2.6 Restrictions on the contents of raw text and RCDATA elements
        3. 
+     
      3. 10.1.3 Text
+      
          
+       
        1. 10.1.3.1 Newlines
        4. 
+     
      4. 10.1.4 Character references
        5. 
+     
      5. 10.1.5 CDATA sections
        6. 
+     
      6. 10.1.6 Comments
      2. 
+   
    2. 10.2 Parsing HTML documents
+    
        
+     
      1. 10.2.1 Overview of the parsing model
        2. 
+     
      2. 10.2.2 The input stream
+      
          
+       
        1. 10.2.2.1 Determining the character encoding
          2. 
+       
        2. 10.2.2.2 Character encodings
          3. 
+       
        3. 10.2.2.3 Preprocessing the input stream
          4. 
+       
        4. 10.2.2.4 Changing the encoding while parsing
        3. 
+     
      3. 10.2.3 Parse state
+      
          
+       
        1. 10.2.3.1 The insertion mode
          2. 
+       
        2. 10.2.3.2 The stack of open elements
          3. 
+       
        3. 10.2.3.3 The list of active formatting elements
          4. 
+       
        4. 10.2.3.4 The element pointers
          5. 
+       
        5. 10.2.3.5 Other parsing state flags
        4. 
+     
      4. 10.2.4 Tokenization
+      
          
+       
        1. 10.2.4.1 Data state
          2. 
+       
        2. 10.2.4.2 Character reference in data state
          3. 
+       
        3. 10.2.4.3 RCDATA state
          4. 
+       
        4. 10.2.4.4 Character reference in RCDATA state
          5. 
+       
        5. 10.2.4.5 RAWTEXT state
          6. 
+       
        6. 10.2.4.6 Script data state
          7. 
+       
        7. 10.2.4.7 PLAINTEXT state
          8. 
+       
        8. 10.2.4.8 Tag open state
          9. 
+       
        9. 10.2.4.9 End tag open state
          10. 
+       
        10. 10.2.4.10 Tag name state
          11. 
+       
        11. 10.2.4.11 RCDATA less-than sign state
          12. 
+       
        12. 10.2.4.12 RCDATA end tag open state
          13. 
+       
        13. 10.2.4.13 RCDATA end tag name state
          14. 
+       
        14. 10.2.4.14 RAWTEXT less-than sign state
          15. 
+       
        15. 10.2.4.15 RAWTEXT end tag open state
          16. 
+       
        16. 10.2.4.16 RAWTEXT end tag name state
          17. 
+       
        17. 10.2.4.17 Script data less-than sign state
          18. 
+       
        18. 10.2.4.18 Script data end tag open state
          19. 
+       
        19. 10.2.4.19 Script data end tag name state
          20. 
+       
        20. 10.2.4.20 Script data escape start state
          21. 
+       
        21. 10.2.4.21 Script data escape start dash state
          22. 
+       
        22. 10.2.4.22 Script data escaped state
          23. 
+       
        23. 10.2.4.23 Script data escaped dash state
          24. 
+       
        24. 10.2.4.24 Script data escaped dash dash state
          25. 
+       
        25. 10.2.4.25 Script data escaped less-than sign state
          26. 
+       
        26. 10.2.4.26 Script data escaped end tag open state
          27. 
+       
        27. 10.2.4.27 Script data escaped end tag name state
          28. 
+       
        28. 10.2.4.28 Script data double escape start state
          29. 
+       
        29. 10.2.4.29 Script data double escaped state
          30. 
+       
        30. 10.2.4.30 Script data double escaped dash state
          31. 
+       
        31. 10.2.4.31 Script data double escaped dash dash state
          32. 
+       
        32. 10.2.4.32 Script data double escaped less-than sign state
          33. 
+       
        33. 10.2.4.33 Script data double escape end state
          34. 
+       
        34. 10.2.4.34 Before attribute name state
          35. 
+       
        35. 10.2.4.35 Attribute name state
          36. 
+       
        36. 10.2.4.36 After attribute name state
          37. 
+       
        37. 10.2.4.37 Before attribute value state
          38. 
+       
        38. 10.2.4.38 Attribute value (double-quoted) state
          39. 
+       
        39. 10.2.4.39 Attribute value (single-quoted) state
          40. 
+       
        40. 10.2.4.40 Attribute value (unquoted) state
          41. 
+       
        41. 10.2.4.41 Character reference in attribute value state
          42. 
+       
        42. 10.2.4.42 After attribute value (quoted) state
          43. 
+       
        43. 10.2.4.43 Self-closing start tag state
          44. 
+       
        44. 10.2.4.44 Bogus comment state
          45. 
+       
        45. 10.2.4.45 Markup declaration open state
          46. 
+       
        46. 10.2.4.46 Comment start state
          47. 
+       
        47. 10.2.4.47 Comment start dash state
          48. 
+       
        48. 10.2.4.48 Comment state
          49. 
+       
        49. 10.2.4.49 Comment end dash state
          50. 
+       
        50. 10.2.4.50 Comment end state
          51. 
+       
        51. 10.2.4.51 Comment end bang state
          52. 
+       
        52. 10.2.4.52 Comment end space state
          53. 
+       
        53. 10.2.4.53 DOCTYPE state
          54. 
+       
        54. 10.2.4.54 Before DOCTYPE name state
          55. 
+       
        55. 10.2.4.55 DOCTYPE name state
          56. 
+       
        56. 10.2.4.56 After DOCTYPE name state
          57. 
+       
        57. 10.2.4.57 After DOCTYPE public keyword state
          58. 
+       
        58. 10.2.4.58 Before DOCTYPE public identifier state
          59. 
+       
        59. 10.2.4.59 DOCTYPE public identifier (double-quoted) state
          60. 
+       
        60. 10.2.4.60 DOCTYPE public identifier (single-quoted) state
          61. 
+       
        61. 10.2.4.61 After DOCTYPE public identifier state
          62. 
+       
        62. 10.2.4.62 Between DOCTYPE public and system identifiers state
          63. 
+       
        63. 10.2.4.63 After DOCTYPE system keyword state
          64. 
+       
        64. 10.2.4.64 Before DOCTYPE system identifier state
          65. 
+       
        65. 10.2.4.65 DOCTYPE system identifier (double-quoted) state
          66. 
+       
        66. 10.2.4.66 DOCTYPE system identifier (single-quoted) state
          67. 
+       
        67. 10.2.4.67 After DOCTYPE system identifier state
          68. 
+       
        68. 10.2.4.68 Bogus DOCTYPE state
          69. 
+       
        69. 10.2.4.69 CDATA section state
          70. 
+       
        70. 10.2.4.70 Tokenizing character references
        5. 
+     
      5. 10.2.5 Tree construction
+      
          
+       
        1. 10.2.5.1 Creating and inserting elements
          2. 
+       
        2. 10.2.5.2 Closing elements that have implied end tags
          3. 
+       
        3. 10.2.5.3 Foster parenting
          4. 
+       
        4. 10.2.5.4 The "initial" insertion mode
          5. 
+       
        5. 10.2.5.5 The "before html" insertion mode
          6. 
+       
        6. 10.2.5.6 The "before head" insertion mode
          7. 
+       
        7. 10.2.5.7 The "in head" insertion mode
          8. 
+       
        8. 10.2.5.8 The "in head noscript" insertion mode
          9. 
+       
        9. 10.2.5.9 The "after head" insertion mode
          10. 
+       
        10. 10.2.5.10 The "in body" insertion mode
          11. 
+       
        11. 10.2.5.11 The "text" insertion mode
          12. 
+       
        12. 10.2.5.12 The "in table" insertion mode
          13. 
+       
        13. 10.2.5.13 The "in table text" insertion mode
          14. 
+       
        14. 10.2.5.14 The "in caption" insertion mode
          15. 
+       
        15. 10.2.5.15 The "in column group" insertion mode
          16. 
+       
        16. 10.2.5.16 The "in table body" insertion mode
          17. 
+       
        17. 10.2.5.17 The "in row" insertion mode
          18. 
+       
        18. 10.2.5.18 The "in cell" insertion mode
          19. 
+       
        19. 10.2.5.19 The "in select" insertion mode
          20. 
+       
        20. 10.2.5.20 The "in select in table" insertion mode
          21. 
+       
        21. 10.2.5.21 The "in foreign content" insertion mode
          22. 
+       
        22. 10.2.5.22 The "after body" insertion mode
          23. 
+       
        23. 10.2.5.23 The "in frameset" insertion mode
          24. 
+       
        24. 10.2.5.24 The "after frameset" insertion mode
          25. 
+       
        25. 10.2.5.25 The "after after body" insertion mode
          26. 
+       
        26. 10.2.5.26 The "after after frameset" insertion mode
        6. 
+     
      6. 10.2.6 The end
        7. 
+     
      7. 10.2.7 Coercing an HTML DOM into an infoset
        8. 
+     
      8. 10.2.8 An introduction to error handling and strange cases in the parser
+      
          
+       
        1. 10.2.8.1 Misnested tags: <b><i></b></i>
          2. 
+       
        2. 10.2.8.2 Misnested tags: <b><p></b></p>
          3. 
+       
        3. 10.2.8.3 Unexpected markup in tables
          4. 
+       
        4. 10.2.8.4 Scripts that modify the page as it is being parsed
      3. 
+   
    3. 10.3 Serializing HTML fragments
      4. 
+   
    4. 10.4 Parsing HTML fragments
      5. 
+   
    5. 10.5 Named character references
    11. 
+ 
  11. 11 The XHTML syntax
+  
      
+   
    1. 11.1 Writing XHTML documents
      2. 
+   
    2. 11.2 Parsing XHTML documents
      3. 
+   
    3. 11.3 Serializing XHTML fragments
      4. 
+   
    4. 11.4 Parsing XHTML fragments
    12. 
+ 
  12. 12 Rendering
+  
      
+   
    1. 12.1 Introduction
      2. 
+   
    2. 12.2 The CSS user agent style sheet and presentational hints
+    
        
+     
      1. 12.2.1 Introduction
        2. 
+     
      2. 12.2.2 Display types
        3. 
+     
      3. 12.2.3 Margins and padding
        4. 
+     
      4. 12.2.4 Alignment
        5. 
+     
      5. 12.2.5 Fonts and colors
        6. 
+     
      6. 12.2.6 Punctuation and decorations
        7. 
+     
      7. 12.2.7 Resetting rules for inherited properties
        8. 
+     
      8. 12.2.8 The hr element
        9. 
+     
      9. 12.2.9 The fieldset element
      3. 
+   
    3. 12.3 Replaced elements
+    
        
+     
      1. 12.3.1 Embedded content
        2. 
+     
      2. 12.3.2 Timed tracks
        3. 
+     
      3. 12.3.3 Images
        4. 
+     
      4. 12.3.4 Attributes for embedded content and images
        5. 
+     
      5. 12.3.5 Image maps
        6. 
+     
      6. 12.3.6 Toolbars
      4. 
+   
    4. 12.4 Bindings
+    
        
+     
      1. 12.4.1 Introduction
        2. 
+     
      2. 12.4.2 The button element
        3. 
+     
      3. 12.4.3 The details element
        4. 
+     
      4. 12.4.4 The input element as a text entry widget
        5. 
+     
      5. 12.4.5 The input element as domain-specific widgets
        6. 
+     
      6. 12.4.6 The input element as a range control
        7. 
+     
      7. 12.4.7 The input element as a color well
        8. 
+     
      8. 12.4.8 The input element as a check box and radio button widgets
        9. 
+     
      9. 12.4.9 The input element as a file upload control
        10. 
+     
      10. 12.4.10 The input element as a button
        11. 
+     
      11. 12.4.11 The marquee element
        12. 
+     
      12. 12.4.12 The meter element
        13. 
+     
      13. 12.4.13 The progress element
        14. 
+     
      14. 12.4.14 The select element
        15. 
+     
      15. 12.4.15 The textarea element
        16. 
+     
      16. 12.4.16 The keygen element
        17. 
+     
      17. 12.4.17 The time element
      5. 
+   
    5. 12.5 Frames and framesets
      6. 
+   
    6. 12.6 Interactive media
+    
        
+     
      1. 12.6.1 Links, forms, and navigation
        2. 
+     
      2. 12.6.2 The title attribute
        3. 
+     
      3. 12.6.3 Editing hosts
      7. 
+   
    7. 12.7 Print media
    13. 
+ 
  13. 13 Obsolete features
+  
      
+   
    1. 13.1 Obsolete but conforming features
+    
        
+     
      1. 13.1.1 Warnings for obsolete but conforming features
      2. 
+   
    2. 13.2 Non-conforming features
      3. 
+   
    3. 13.3 Requirements for implementations
+    
        
+     
      1. 13.3.1 The applet element
        2. 
+     
      2. 13.3.2 The marquee element
        3. 
+     
      3. 13.3.3 Frames
        4. 
+     
      4. 13.3.4 Other elements, attributes and APIs
    14. 
+ 
  14. 14 IANA considerations
+  
      
+   
    1. 14.1 text/html
      2. 
+   
    2. 14.2 text/html-sandboxed
      3. 
+   
    3. 14.3 application/xhtml+xml
      4. 
+   
    4. 14.4 text/cache-manifest
      5. 
+   
    5. 14.5 text/ping
      6. 
+   
    6. 14.6 text/srt
      7. 
+   
    7. 14.7 application/microdata+json
      8. 
+   
    8. 14.8 Ping-From
      9. 
+   
    9. 14.9 Ping-To
    15. 
+ 
  15. Index
+  
      
+   
    1. Elements
      2. 
+   
    2. Element content categories
      3. 
+   
    3. Attributes
      4. 
+   
    4. Interfaces
      5. 
+   
    5. Events
    16. 
+ 
  16. References
    17. 
+ 
  17. Acknowledgements

+
+  
1 Introduction

+
+
+
+  
1.1 Is this HTML5?

+
+  
This section is non-normative.

+
+
+
+  
In short: Yes.

+
+  
In more length: "HTML5" has at various times been used to refer
+  to a wide variety of technologies, some of which originated in this
+  document, and some of which have only ever been tangentially
+  related.

+
+  
This specification actually now defines the next generation of
+  HTML after HTML5. HTML5 reached Last Call at the WHATWG in October
+  2009, and shortly after we started working on some experimental new
+  features that are not as stable as the rest of the
+  specification. The stability of sections is annotated in the
+  margin.

+
+  
The W3C has also been working on HTML in conjunction with the
+  WHATWG; at the W3C, this document has been split into several parts,
+  and the occasional informative paragraph or example has been removed
+  for technical reasons. For all intents and purposes, however, the
+  W3C HTML specifications and this specification are equivalent (and
+  they are in fact all generated from the same source document).

+
+  
Features that are considered part of the next generation of HTML
+  beyond HTML5 currently consist of only:

+
+  
Features that are part of HTML5 (and this specification) but that
+  are either currently, or have been in the past, published as
+  separate specifications:

+
+  
Features that are not currently in this document that were in the
+  past considered part of HTML5, or that were never part of HTML5 but
+  have been referred to as part of HTML5 in the media, include:

+
+  
1.2 Background

+
+  
This section is non-normative.

+
+  
The World Wide Web's markup language has always been HTML. HTML
+  was primarily designed as a language for semantically describing
+  scientific documents, although its general design and adaptations
+  over the years have enabled it to be used to describe a number of
+  other types of documents.

+
+  
The main area that has not been adequately addressed by HTML is a
+  vague subject referred to as Web Applications. This specification
+  attempts to rectify this, while at the same time updating the HTML
+  specifications to address issues raised in the past few years.

+
+
+  
1.3 Audience

+
+  
This section is non-normative.

+
+  
This specification is intended for authors of documents and
+  scripts that use the features defined in this specification, implementors of tools that operate on pages that use
+  the features defined in this specification, and individuals wishing
+  to establish the correctness of documents or implementations with
+  respect to the requirements of this specification.

+
+  
This document is probably not suited to readers who do not
+  already have at least a passing familiarity with Web technologies,
+  as in places it sacrifices clarity for precision, and brevity for
+  completeness. More approachable tutorials and authoring guides can
+  provide a gentler introduction to the topic.

+
+  
In particular, familiarity with the basics of DOM Core and DOM
+  Events is necessary for a complete understanding of some of the more
+  technical parts of this specification. An understanding of Web IDL,
+  HTTP, XML, Unicode, character encodings, JavaScript, and CSS will
+  also be helpful in places but is not essential.

+
+
+  
1.4 Scope

+
+  
This section is non-normative.

+
+  
This specification is limited to providing a semantic-level
+  markup language and associated semantic-level scripting APIs for
+  authoring accessible pages on the Web ranging from static documents
+  to dynamic applications.

+
+  
The scope of this specification does not include providing
+  mechanisms for media-specific customization of presentation
+  (although default rendering rules for Web browsers are included at
+  the end of this specification, and several mechanisms for hooking
+  into CSS are provided as part of the language).

+
+  
The scope of this specification is not to describe an entire
+  operating system. In particular, hardware configuration software,
+  image manipulation tools, and applications that users would be
+  expected to use with high-end workstations on a daily basis are out
+  of scope. In terms of applications, this specification is targeted
+  specifically at applications that would be expected to be used by
+  users on an occasional basis, or regularly but from disparate
+  locations, with low CPU requirements. For instance online purchasing
+  systems, searching systems, games (especially multiplayer online
+  games), public telephone books or address books, communications
+  software (e-mail clients, instant messaging clients, discussion
+  software), document editing software, etc.

+
+
+  
1.5 History

+
+  
This section is non-normative.

+
+  
For its first five years (1990-1995), HTML went through a number
+  of revisions and experienced a number of extensions, primarily
+  hosted first at CERN, and then at the IETF.

+
+  
With the creation of the W3C, HTML's development changed venue
+  again. A first abortive attempt at extending HTML in 1995 known as
+  HTML 3.0 then made way to a more pragmatic approach known as HTML
+  3.2, which was completed in 1997. HTML4 followed, reaching
+  completion in 1998.

+
+  
At this time, the W3C membership decided to stop evolving HTML
+  and instead begin work on an XML-based equivalent, called
+  XHTML. This effort started with a reformulation of HTML4 in XML,
+  known as XHTML 1.0, which added no new features except the new
+  serialization, and which was completed in 2000. After XHTML 1.0, the
+  W3C's focus turned to making it easier for other working groups to
+  extend XHTML, under the banner of XHTML Modularization. In parallel
+  with this, the W3C also worked on a new language that was not
+  compatible with the earlier HTML and XHTML languages, calling it
+  XHTML2.

+
+  
Around the time that HTML's evolution was stopped in 1998, parts
+  of the API for HTML developed by browser vendors were specified and
+  published under the name DOM Level 1 (in 1998) and DOM Level 2 Core
+  and DOM Level 2 HTML (starting in 2000 and culminating in
+  2003). These efforts then petered out, with some DOM Level 3
+  specifications published in 2004 but the working group being closed
+  before all the Level 3 drafts were completed.

+
+  
In 2003, the publication of XForms, a technology which was
+  positioned as the next generation of Web forms, sparked a renewed
+  interest in evolving HTML itself, rather than finding replacements
+  for it. This interest was borne from the realization that XML's
+  deployment as a Web technology was limited to entirely new
+  technologies (like RSS and later Atom), rather than as a replacement
+  for existing deployed technologies (like HTML).

+
+  
A proof of concept to show that it was possible to extend HTML4's
+  forms to provide many of the features that XForms 1.0 introduced,
+  without requiring browsers to implement rendering engines that were
+  incompatible with existing HTML Web pages, was the first result of
+  this renewed interest. At this early stage, while the draft was
+  already publicly available, and input was already being solicited
+  from all sources, the specification was only under Opera Software's
+  copyright.

+
+  
The idea that HTML's evolution should be reopened was tested at a
+  W3C workshop in 2004, where some of the principles that underlie the
+  HTML5 work (described below), as well as the aforementioned early
+  draft proposal covering just forms-related features, were presented
+  to the W3C jointly by Mozilla and Opera. The proposal was rejected
+  on the grounds that the proposal conflicted with the previously
+  chosen direction for the Web's evolution; the W3C staff and
+  membership voted to continue developing XML-based replacements
+  instead.

+
+  
Shortly thereafter, Apple, Mozilla, and Opera jointly announced
+  their intent to continue working on the effort under the umbrella of
+  a new venue called the WHATWG. A public mailing list was created,
+  and the draft was moved to the WHATWG site. The copyright was
+  subsequently amended to be jointly owned by all three vendors, and
+  to allow reuse of the specification.

+
+  
The WHATWG was based on several core principles, in particular
+  that technologies need to be backwards compatible, that
+  specifications and implementations need to match even if this means
+  changing the specification rather than the implementations, and that
+  specifications need to be detailed enough that implementations can
+  achieve complete interoperability without reverse-engineering each
+  other.

+
+  
The latter requirement in particular required that the scope of
+  the HTML5 specification include what had previously been specified
+  in three separate documents: HTML4, XHTML1, and DOM2 HTML. It also
+  meant including significantly more detail than had previously been
+  considered the norm.

+
+  
In 2006, the W3C indicated an interest to participate in the
+  development of HTML5 after all, and in 2007 formed a working group
+  chartered to work with the WHATWG on the development of the HTML5
+  specification. Apple, Mozilla, and Opera allowed the W3C to publish
+  the specification under the W3C copyright, while keeping a version
+  with the less restrictive license on the WHATWG site.

+
+  
Since then, both groups have been working together.

+
+  
A separate document has been published by the W3C HTML working
+  group to document the differences between this specification and the
+  language described in the HTML4 specification. [HTMLDIFF]

+
+
+
+
+  
1.6 Design notes

+
+  
This section is non-normative.

+
+  
It must be admitted that many aspects of HTML appear at first
+  glance to be nonsensical and inconsistent.

+
+  
HTML, its supporting DOM APIs, as well as many of its supporting
+  technologies, have been developed over a period of several decades
+  by a wide array of people with different priorities who, in many
+  cases, did not know of each other's existence.

+
+  
Features have thus arisen from many sources, and have not always
+  been designed in especially consistent ways. Furthermore, because of
+  the unique characteristics of the Web, implementation bugs have
+  often become de-facto, and now de-jure, standards, as content is
+  often unintentionally written in ways that rely on them before they
+  can be fixed.

+
+  
Despite all this, efforts have been made to adhere to certain
+  design goals. These are described in the next few subsections.

+
+
+  
1.6.1 Serializability of script execution

+
+  
This section is non-normative.

+
+  
To avoid exposing Web authors to the complexities of
+  multithreading, the HTML and DOM APIs are designed such that no
+  script can ever detect the simultaneous execution of other
+  scripts. Even with workers, the intent
+  is that the behavior of implementations can be thought of as
+  completely serializing the execution of all scripts in all browsing contexts.

+
+  
The navigator.yieldForStorageUpdates()
+  method, in this model, is equivalent to allowing other scripts to
+  run while the calling script is blocked.

+
+
+  
1.6.2 Compliance with other specifications

+
+  
This section is non-normative.

+
+  
This specification interacts with and relies on a wide variety of
+  other specifications. In certain circumstances, unfortunately,
+  conflicting needs have led to this specification violating the
+  requirements of these other specifications. Whenever this has
+  occurred, the transgressions have each been noted as a "willful
+  violation", and the reason for the violation has been
+  noted.

+
+
+
+
+  
1.7 HTML vs XHTML

+
+  
This section is non-normative.

+
+  
This specification defines an abstract language for describing
+  documents and applications, and some APIs for interacting with
+  in-memory representations of resources that use this language.

+
+  
The in-memory representation is known as "DOM HTML", or "the DOM"
+  for short. This specification defines version 5 of DOM HTML, known
+  as "DOM5 HTML".

+
+  
There are various concrete syntaxes that can be used to transmit
+  resources that use this abstract language, two of which are defined
+  in this specification.

+
+  
The first such concrete syntax is the HTML syntax. This is the
+  format suggested for most authors. It is compatible with most legacy
+  Web browsers. If a document is transmitted with an HTML MIME
+  type, such as text/html, then it will be
+  processed as an HTML document by Web browsers.
+
+  This specification defines the latest HTML syntax, known simply as
+  "HTML".
+  
+
+  

+
+  
The second concrete syntax is the XHTML syntax, which is an
+  application of XML. When a document is transmitted with an XML
+  MIME type, such as application/xhtml+xml, then
+  it is treated as an XML document by Web browsers, to be parsed by an
+  XML processor. Authors are reminded that the processing for XML and
+  HTML differs; in particular, even minor syntax errors will prevent a
+  document labeled as XML from being rendered fully, whereas they
+  would be ignored in the HTML syntax.
+
+  This specification defines the latest XHTML syntax, known simply as
+  "XHTML".
+  
+
+  

+
+  
The DOM, the HTML syntax, and XML cannot all represent the same
+  content. For example, namespaces cannot be represented using the
+  HTML syntax, but they are supported in the DOM and in XML.
+  Similarly, documents that use the noscript feature can
+  be represented using the HTML syntax, but cannot be represented with
+  the DOM or in XML. Comments that contain the string "-->" can be represented in the DOM but not in the
+  HTML syntax or in XML.

+
+
+  
1.8 Structure of this specification

+
+  
This section is non-normative.

+
+  
This specification is divided into the following major
+  sections:

+
+  
Common infrastructure

+
+   
The conformance classes, algorithms, definitions, and the
+   common underpinnings of the rest of the specification.

+
+
+   
Semantics, structure, and APIs of HTML documents

+
+   
Documents are built from elements. These elements form a tree
+   using the DOM. This section defines the features of this DOM, as
+   well as introducing the features common to all elements, and the
+   concepts used in defining elements.

+
+
+   
The elements of HTML

+
+   
Each element has a predefined meaning, which is explained in
+   this section. Rules for authors on how to use the element, along with user agent requirements for how to handle
+   each element, are also given.

+
+
+   
Microdata

+
+   
This specification introduces a mechanism for adding
+   machine-readable annotations to documents, so that tools can
+   extract trees of name/value pairs from the document. This section
+   describes this mechanism and some algorithms
+   that can be used to convert HTML documents into other
+   formats.
+
+   This section also defines some Microdata vocabularies for contact
+   information, calendar events, and licensing works.
+
+   

+
+
+   
Loading Web pages

+
+   
HTML documents do not exist in a vacuum — this section
+   defines many of the features that affect environments that deal
+   with multiple pages.

+
+   
Web application APIs

+
+   
This section introduces basic features for scripting of
+   applications in HTML.

+
+   
User interaction

+
+   
HTML documents can provide a number of mechanisms for users to
+   interact with and modify content, which are described in this
+   section.

+
+
+
+
+   
The communication APIs

+
+   
This section describes some mechanisms that applications
+   written in HTML can use to communicate with other applications from
+   different domains running on the same client.
+   

+
+
+
+   
The HTML syntax

+   
The XHTML syntax

+
+   
All of these features would be for naught if they couldn't be
+   represented in a serialized form and sent to other people, and so
+   these sections define the syntaxes of HTML, along with rules for
+   how to parse content using those syntaxes.

+
+
+  
There are also some appendices, defining rendering rules for Web browsers and listing
+  obsolete features and IANA
+  considerations.

+
+
+
+  
1.8.1 How to read this specification

+
+  
This specification should be read like all other specifications.
+  First, it should be read cover-to-cover, multiple times. Then, it
+  should be read backwards at least once. Then it should be read by
+  picking random sections from the contents list and following all the
+  cross-references.

+
+
+
+  
1.8.2 Typographic conventions

+
+  
This is a definition, requirement, or explanation.

+
+  
This is a note.

+
+  
This is an example.

+
+  
This is an open issue.

+
+  
This is a warning.

+
+  
interface Example {
+  // this is an IDL definition
+};

+
+  
variable = object . method( [ optionalArgument ] )

+
+   

+
+    
This is a note to authors describing the usage of an interface.

+
+   

+
+  
/* this is a CSS fragment */

+
+  
The defining instance of a term is marked up like this. Uses of that term are marked up like
+  this or like this.

+
+  
The defining instance of an element, attribute, or API is marked
+  up like this. References to
+  that element, attribute, or API are marked up like this.

+
+  
Other code fragments are marked up like
+  this.

+
+  
Variables are marked up like this.

+
+  
This is an implementation requirement.

+
+
+
+  
1.9 A quick introduction to HTML

+
+  
This section is non-normative.

+
+  
A basic HTML document looks like this:

+
+  
<!DOCTYPE html>
+<html>
+ <head>
+  <title>Sample page</title>
+ </head>
+ <body>
+  <h1>Sample page</h1>
+  <p>This is a <a href="demo.html">simple</a> sample.</p>
+  <!-- this is a comment -->
+ </body>
+</html>

+
+  
HTML documents consist of a tree of elements and text. Each
+  element is denoted in the source by a start tag, such as "<body>", and an end
+  tag, such as "</body>". (Certain
+  start tags and end tags can in certain cases be omitted and are implied by other
+  tags.)

+
+  
Tags have to be nested such that elements are all completely
+  within each other, without overlapping:

+
+  
<p>This is <em>very <strong>wrong</em>!</strong></p>

+  
<p>This <em>is <strong>correct</strong>.</em></p>

+
+  
This specification defines a set of elements that can be used in
+  HTML, along with rules about the ways in which the elements can be
+  nested.

+
+  
Elements can have attributes, which control how the elements
+  work. In the example below, there is a hyperlink,
+  formed using the a element and its href attribute:

+
+  
<a href="demo.html">simple</a>

+
+  
Attributes are placed
+  inside the start tag, and consist of a name and a value, separated by an "=" character. The attribute value can remain unquoted if it doesn't contain spaces or any of
+  " ' ` = <
+  or >. Otherwise, it has to be quoted using
+  either single or double quotes. The value, along with the "=" character, can be omitted altogether if the value
+  is the empty string.

+
+  
<!-- empty attributes -->
+<input name=address disabled>
+<input name=address disabled="">
+
+<!-- attributes with a value -->
+<input name=address maxlength=200>
+<input name=address maxlength='200'>
+<input name=address maxlength="200">

+
+  
HTML user agents (e.g. Web browsers) then parse this
+  markup, turning it into a DOM (Document Object Model) tree. A DOM
+  tree is an in-memory representation of a document.

+
+  
DOM trees contain several kinds of nodes, in particular a DOCTYPE
+  node, elements, text nodes, and comment nodes.

+
+  
The markup snippet at the top of
+  this section would be turned into the following DOM tree:

+
+  
  • DOCTYPE: html
  • html
    • head
      • #text: ⏎␣␣
      • title
        • #text: Sample page
      • #text: ⏎␣
    • #text: ⏎␣
    • body
      • #text: ⏎␣␣
      • h1
        • #text: Sample page
      • #text: ⏎␣␣
      • p
        • #text: This is a 
        • a href="demo.html"
          • #text: simple
        • #text:  sample.
      • #text: ⏎␣␣
      • #comment:  this is a comment 
      • #text: ⏎␣⏎
The root element of this tree is the
+  html element, which is the element always found at the
+  root of HTML documents. It contains two elements, head
+  and body, as well as a text node between them.

+
+  
There are many more text nodes in the DOM tree than one would
+  initially expect, because the source contains a number of spaces
+  (represented here by "␣") and line breaks ("⏎") that
+  all end up as text nodes in the DOM.

+
+  
The head element contains a title
+  element, which itself contains a text node with the text "Sample
+  page". Similarly, the body element contains an
+  h1 element, a p element, and a
+  comment.

+
+  
This DOM tree can be manipulated from scripts in the
+  page. Scripts (typically in JavaScript) are small programs that can
+  be embedded using the script element or using
+  event handler content attributes. For example, here is
+  a form with a script that sets the value of the form's
+  output element to say "Hello World":

+
+  
<form name="main">
+ Result: <output name="result"></output>
+ <script>
+  document.forms.main.elements.result.value = 'Hello World';
+ </script>
+</form>

+
+  
Each element in the DOM tree is represented by an object, and
+  these objects have APIs so that they can be manipulated. For
+  instance, a link (e.g. the a element in the tree above)
+  can have its "href"
+  attribute changed in several ways:

+
+  
var a = document.links[0]; // obtain the first link in the document
+a.href = 'sample.html'; // change the destination URL of the link
+a.protocol = 'https'; // change just the scheme part of the URL
+a.setAttribute('href', 'http://example.com/'); // change the content attribute directly

+
+  
Since DOM trees are used as the way to represent HTML documents
+  when they are processed and presented by implementations (especially
+  interactive implementations like Web browsers), this specification
+  is mostly phrased in terms of DOM trees, instead of the markup
+  described above.

+
+  
HTML documents represent a media-independent description of
+  interactive content. HTML documents might be rendered to a screen,
+  or through a speech synthesizer, or on a braille display. To
+  influence exactly how such rendering takes place, authors can use a
+  styling language such as CSS.

+
+  
In the following example, the page has been made yellow-on-blue
+  using CSS.

+
+  
<!DOCTYPE html>
+<html>
+ <head>
+  <title>Sample styled page</title>
+  <style>
+   body { background: navy; color: yellow; }
+  </style>
+ </head>
+ <body>
+  <h1>Sample styled page</h1>
+  <p>This page is just a demo.</p>
+ </body>
+</html>

+
+  
For more details on how to use HTML, authors are encouraged to
+  consult tutorials and guides. Some of the examples included in this
+  specification might also be of use, but the novice author is
+  cautioned that this specification, by necessity, defines the
+  language with a level of detail that might be difficult to
+  understand at first.

+
+
+  
1.10 Conformance requirements for authors

+
+  
This section is non-normative.

+
+  
Unlike previous versions of the HTML specification, this
+  specification defines in some detail the required processing for
+  invalid documents as well as valid documents.
 
+
+  
However, even though the processing of invalid content is in most
+  cases well-defined, conformance requirements for documents are still
+  important: in practice, interoperability (the situation in which all
+  implementations process particular content in a reliable and
+  identical or equivalent way) is not the only goal of document
+  conformance requirements. This section details some of the more
+  common reasons for still distinguishing between a conforming
+  document and one with errors.

+
+
+  
1.10.1 Presentational markup

+
+  
This section is non-normative.

+
+  
The majority of presentational features from previous versions of
+  HTML are no longer allowed. Presentational markup in general has
+  been found to have a number of problems:

+
+  
The use of presentational elements leads to poorer accessibility

+
+   

+
+    
While it is possible to use presentational markup in a way that
+    provides users of assistive technologies (ATs) with an acceptable
+    experience (e.g. using ARIA), doing so is significantly more
+    difficult than doing so when using semantically-appropriate
+    markup. Furthermore, even using such techniques doesn't help make
+    pages accessible for non-AT non-graphical users, such as users of
+    text-mode browsers.

+
+    
Using media-independent markup, on the other hand, provides an
+    easy way for documents to be authored in such a way that they work
+    for more users (e.g. text browsers).

+
+   

+
+
+   
Higher cost of maintenance

+
+   

+
+    
It is significantly easier to maintain a site written in such a
+    way that the markup is style-independent. For example, changing
+    the color of a site that uses <font color="">
+    throughout requires changes across the entire site, whereas a
+    similar change to a site based on CSS can be done by changing a
+    single file.

+
+   

+
+
+   
Higher document sizes

+
+   

+
+    
Presentational markup tends to be much more redundant, and thus
+    results in larger document sizes.

+
+   

+
+  
For those reasons, presentational markup has been removed from
+  HTML in this version. This change should not come as a surprise;
+  HTML4 deprecated presentational markup many years ago and provided a
+  mode (HTML4 Transitional) to help authors move away from
+  presentational markup; later, XHTML 1.1 went further and obsoleted
+  those features altogether.

+
+  
The only remaining presentational markup features in HTML are the
+  style attribute and the
+  style element. Use of the style attribute is somewhat discouraged in
+  production environments, but it can be useful for rapid prototyping
+  (where its rules can be directly moved into a separate style sheet
+  later) and for providing specific styles in unusual cases where a
+  separate style sheet would be inconvenient. Similarly, the
+  style element can be useful in syndication or for
+  page-specific styles, but in general an external style sheet is
+  likely to be more convenient when the styles apply to multiple
+  pages.

+
+  
It is also worth noting that four elements that were previously
+  presentational have been redefined in this specification to be
+  media-independent: b, i, hr,
+  and small.

+
+
+  
1.10.2 Syntax errors

+
+  
This section is non-normative.

+
+  
The syntax of HTML is constrained to avoid a wide variety of
+  problems.

+
+  
Unintuitive error-handling behavior

+
+   

+
+    
Certain invalid syntax constructs, when parsed, result in DOM
+    trees that are highly unintuitive.

+
+    

+
+     
For example, the following markup fragment results in a DOM
+     with an hr element that is an earlier
+     sibling of the corresponding table element:

+
+     
<table><hr>...

+
+    

+
+   

+
+
+   
Errors with optional error recovery

+
+   

+
+    
To allow user agents to be used in controlled environments
+    without having to implement the more bizarre and convoluted error
+    handling rules, user agents are permitted to fail whenever
+    encountering a parse error.

+
+   

+
+
+   
Errors where the error-handling behavior is not compatible with streaming user agents

+
+   

+
+    
Some error-handling behavior, such as the behavior for the
+    <table><hr>... example mentioned
+    above, are incompatible with streaming user agents. To avoid
+    interoperability problems with such user agents, any syntax
+    resulting in such behavior is considered invalid.

+
+   

+
+
+   
Errors that can result in infoset coercion

+
+   

+
+    
When a user agent based on XML is connected to an HTML parser,
+    it is possible that certain invariants that XML enforces, such as
+    comments never containing two consecutive hyphens, will be
+    violated by an HTML file. Handling this can require that the
+    parser coerce the HTML DOM into an XML-compatible infoset. Most
+    syntax constructs that require such handling are considered
+    invalid.

+
+   

+
+
+   
Errors that result in disproportionally poor performance

+
+   

+
+    
Certain syntax constructs can result in disproportionally poor
+    performance. To discourage the use of such constructs, they are
+    typically made non-conforming.

+
+    

+
+     
For example, the following markup results in poor performance
+     when hitting the highlighted end tag, since all the open elements
+     are examined first to see if they match the close tag:

+
+     
<p><em><span><span><span>...<span><span><span></em>

+
+    

+
+   

+
+
+   
Errors involving fragile syntax constructs

+
+   

+
+    
There are syntax constructs that, for historical reasons, are
+    relatively fragile. To help reduce the number of users who
+    accidentally run into such problems, they are made
+    non-conforming.

+
+    

+
+     
For example, the parsing of certain named character references
+     in attributes happens even with the closing semicolon being
+     omitted. It is safe to include an ampersand followed by letters
+     that do not form a named character reference, but if the letters
+     are changed to a string that does form a named character
+     reference, they will be interpreted as that character instead.

+
+     
In this fragment, the attribute's value is "?hello=1&world=2":

+
+     
<a href="?hello=1&world=2">Demo</a>

+
+     
In the following fragment, however, the attribute's value is
+     actually "?original=1©=2",
+     not the intended "?original=1&copy=2":

+
+     
<a href="?original=1&copy=2">Compare</a>

+
+     
To avoid this problem, all named character references are
+     required to end with a semicolon, and uses of named character
+     references without a semicolon are flagged as errors.

+
+     
Thus, the correct way to express the above cases is as
+     follows:

+
+     
<a href="?hello=1&world=2">Demo</a> <!-- &world is ok, since it's not a named character reference -->

+     
<a href="?original=1&amp;copy=2">Compare</a> <!-- the & has to be escaped, since &copy is a named character reference -->

+
+    

+
+   

+
+
+   
Errors involving known interoperability problems in legacy user agents

+
+   

+
+    
Certain syntax constructs are known to cause especially subtle
+    or serious problems in legacy user agents, and are therefore
+    marked as non-conforming to help authors avoid them.

+
+    

+
+     
For example, this is why the U+0060 GRAVE ACCENT character (`)
+     is not allowed in unquoted attributes. In certain legacy user
+     agents,  it is sometimes treated as a quote
+     character.

+
+    

+
+    

+
+     
Another example of this is the DOCTYPE, which is required to
+     trigger no-quirks mode, because the behavior of
+     legacy user agents in quirks mode is often largely
+     undocumented.

+
+    

+
+   

+
+
+   
Errors that risk exposing authors to security attacks

+
+   

+
+    
Certain restrictions exist purely to avoid known security
+    problems.

+
+    

+
+     
For example, the restriction on using UTF-7 exists purely to
+     avoid authors falling prey to a known cross-site-scripting attack
+     using UTF-7.

+
+    

+
+   

+
+
+   
Cases where the author's intent is unclear

+
+   

+
+    
Markup where the author's intent is very unclear is often made
+    non-conforming. Correcting these errors early makes later
+    maintenance easier.

+
+    

+
+     
For example, it is unclear whether the author intended the
+     following to be an h1 heading or an h2
+     heading:

+
+     
<h1>Contact details</h2>

+
+    

+
+   

+
+
+   
Cases that are likely to be typos

+
+   

+
+    
When a user makes a simple typo, it is helpful if the error can
+    be caught early, as this can save the author a lot of debugging
+    time. This specification therefore usually considers it an error
+    to use element names, attribute names, and so forth, that do not
+    match the names defined in this specification.

+
+    

+
+     
For example, if the author typed <capton>
+     instead of <caption>, this would be flagged as an
+     error and the author could correct the typo immediately.

+
+    

+
+   

+
+
+   
Errors that could interfere with new syntax in the future

+
+   

+
+    
In order to allow the language syntax to be extended in the
+    future, certain otherwise harmless features are disallowed.

+
+    

+
+     
For example, "attributes" in end tags are ignored currently,
+     but they are invalid, in case a future change to the language
+     makes use of that syntax feature without conflicting with
+     already-deployed (and valid!) content.

+
+    

+
+   

+
+
+  
Some authors find it helpful to be in the practice of always
+  quoting all attributes and always including all optional tags,
+  preferring the consistency derived from such custom over the minor
+  benefits of terseness afforded by making use of the flexibility of
+  the HTML syntax. To aid such authors, conformance checkers can
+  provide modes of operation wherein such conventions are
+  enforced.

+
+
+
+  
1.10.3 Restrictions on content models and on attribute values

+
+  
This section is non-normative.

+
+  
Beyond the syntax of the language, this specification also places
+  restrictions on how elements and attributes can be specified. These
+  restrictions are present for similar reasons:

+
+  
Errors involving content with dubious semantics

+
+   

+
+    
To avoid misuse of elements with defined meanings, content
+    models are defined that restrict how elements can be nested when
+    such nestings would be of dubious value.

+
+    
For example, this specification disallows
+    nesting a section element inside a kbd
+    element, since it is highly unlikely for an author to indicate
+    that an entire section should be keyed in.

+
+   

+
+
+   
Errors that involve a conflict in expressed semantics

+
+   

+
+    
Similarly, to draw the author's attention to mistakes in the
+    use of elements, clear contradictions in the semantics expressed
+    are also considered conformance errors.

+
+    

+
+     
In the fragments below, for example, the semantics are
+     nonsensical: a row cannot simultaneously be a cell, nor can a
+     radio button be a progress bar.

+
+     
<tr role="cell">

+     
<input type=radio role=progressbar>

+
+    

+
+    
Another example is the restrictions on the
+    content models of the ul element, which only allows
+    li element children. Lists by definition consist just
+    of zero or more list items, so if a ul element
+    contains something other than an li element, it's not
+    clear what was meant.

+
+   

+
+
+   
Cases where the default styles are likely to lead to confusion

+
+   

+
+    
Certain elements have default styles or behaviors that make
+    certain combinations likely to lead to confusion. Where these have
+    equivalent alternatives without this problem, the confusing
+    combinations are disallowed.

+
+    
For example, div elements are
+    rendered as block boxes, and span elements as inline
+    boxes. Putting a block box in an inline box is unnecessarily
+    confusing; since either nesting just div elements, or
+    nesting just span elements, or nesting
+    span elements inside div elements all
+    serve the same purpose as nesting a div element in a
+    span element, but only the latter involves a block
+    box in an inline box, the latter combination is disallowed.

+
+    
Another example would be the way
+    interactive content cannot be nested. For example, a
+    button element cannot contain a textarea
+    element. This is because the default behavior of such nesting
+    interactive elements would be highly confusing to users. Instead
+    of nesting these elements, they can be placed side by side.

+
+   

+
+
+   
Errors that indicate a likely misunderstanding of the specification

+
+   

+
+    
Sometimes, something is disallowed because allowing it would
+    likely cause author confusion.

+
+    
For example, setting the disabled attribute to the value
+    "false" is disallowed, because despite the
+    appearance of meaning that the element is enabled, it in fact
+    means that the element is disabled (what matters for
+    implementations is the presence of the attribute, not its
+    value).

+
+   

+
+
+   
Errors involving limits that have been imposed merely to simplify the language

+
+   

+
+    
Some conformance errors simplify the language that authors need
+    to learn.

+
+    
For example, the area element's
+    shape attribute, despite
+    accepting both circ and circle values in
+    practice as synonyms, disallows the use of the circ value, so as to
+    simplify tutorials and other learning aids. There would be no
+    benefit to allowing both, but it would cause extra confusion when
+    teaching the language.

+
+   

+
+
+   
Errors that involve peculiarities of the parser

+
+   

+
+    
Certain elements are parsed in somewhat eccentric ways
+    (typically for historical reasons), and their content model
+    restrictions are intended to avoid exposing the author to these
+    issues.

+
+    

+
+     
For example, a form element isn't allowed inside
+     phrasing content, because when parsed as HTML, a
+     form element's start tag will imply a p
+     element's end tag. Thus, the following markup results in two
+     paragraphs, not one:

+
+     
<p>Welcome. <form><label>Name:</label> <input></form>

+
+     
It is parsed exactly like the following:

+
+     
<p>Welcome. </p><form><label>Name:</label> <input></form>

+
+    

+
+   

+
+
+   
Errors that would likely result in scripts failing in hard-to-debug ways

+
+   

+
+    
Some errors are intended to help prevent script problems that
+    would be hard to debug.

+
+    
This is why, for instance, it is non-conforming
+    to have two id attributes with the
+    same value. Duplicate IDs lead to the wrong element being
+    selected, with sometimes disastrous effects whose cause is hard to
+    determine.

+
+   

+
+
+   
Errors that waste authoring time

+
+   

+
+    
Some constructs are disallowed because historically they have
+    been the cause of a lot of wasted authoring time, and by
+    encouraging authors to avoid making them, authors can save time in
+    future efforts.

+
+    
For example, a script element's
+    src attribute causes the
+    element's contents to be ignored. However, this isn't obvious,
+    especially if the element's contents appear to be executable
+    script — which can lead to authors spending a lot of time
+    trying to debug the inline script without realising that it is not
+    executing. To reduce this problem, this specification makes it
+    non-conforming to have executable script in a script
+    element when the src
+    attribute is present. This means that authors who are validating
+    their documents are less likely to waste time with this kind of
+    mistake.

+
+   

+
+
+   
Errors that involve areas that affect authors migrating to and from XHTML

+
+   

+
+    
Some authors like to write files that can be interpreted as
+    both XML and HTML with similar results. Though this practice is
+    discouraged in general due to the myriad of subtle complications
+    involved (especially when involving scripting, styling, or any
+    kind of automated serialization), this specification has a few
+    restrictions intended to at least somewhat mitigate the
+    difficulties. This makes it easier for authors to use this as a
+    transitionary step when migrating between HTML and XHTML.

+
+    
For example, there are somewhat complicated
+    rules surrounding the lang and
+    xml:lang attributes intended
+    to keep the two synchronized.

+
+    
Another example would be the restrictions on
+    the values of xmlns attributes in the HTML
+    serialization, which are intended to ensure that elements in
+    conforming documents end up in the same namespaces whether
+    processed as HTML or XML.

+
+   

+
+
+   
Errors that involve areas reserved for future expansion

+
+   

+
+    
As with the restrictions on the syntax intended to allow for
+    new syntax in future revisions of the language, some restrictions
+    on the content models of elements and values of attributes are
+    intended to allow for future expansion of the HTML vocabulary.

+
+    
For example, limiting the values of the target attribute that start
+    with an U+005F LOW LINE character (_) to only specific predefined
+    values allows new predefined values to be introduced at a future
+    time without conflicting with author-defined values.

+
+   

+
+
+   
Errors that indicate a mis-use of other specifications

+
+   

+
+    
Certain restrictions are intended to support the restrictions
+    made by other specifications.

+
+    
For example, requiring that attributes that
+    take media queries use only valid media queries
+    reinforces the importance of following the conformance rules of
+    that specification.

+
+   

+
+  

+
+  
This section is non-normative.

+
+  
The following documents might be of interest to readers of this
+  specification.

+
+  
Character Model for the World Wide Web 1.0: Fundamentals [CHARMOD]

+
+   
This Architectural Specification provides
+   authors of specifications, software developers, and content
+   developers with a common reference for interoperable text
+   manipulation on the World Wide Web, building on the Universal
+   Character Set, defined jointly by the Unicode Standard and ISO/IEC
+   10646. Topics addressed include use of the terms 'character',
+   'encoding' and 'string', a reference processing model, choice and
+   identification of character encodings, character escaping, and
+   string indexing.

+
+   
Unicode Security Considerations [UTR36]

+
+   
Because Unicode contains such a large number of
+   characters and incorporates the varied writing systems of the
+   world, incorrect usage can expose programs or systems to possible
+   security attacks. This is especially important as more and more
+   products are internationalized. This document describes some of the
+   security considerations that programmers, system analysts,
+   standards developers, and users should take into account, and
+   provides specific recommendations to reduce the risk of
+   problems.

+
+   
Web Content Accessibility Guidelines (WCAG) 2.0 [WCAG]

+
+   
Web Content Accessibility Guidelines (WCAG) 2.0
+   covers a wide range of recommendations for making Web content more
+   accessible. Following these guidelines will make content accessible
+   to a wider range of people with disabilities, including blindness
+   and low vision, deafness and hearing loss, learning disabilities,
+   cognitive limitations, limited movement, speech disabilities,
+   photosensitivity and combinations of these. Following these
+   guidelines will also often make your Web content more usable to
+   users in general.

+
+   
Authoring Tool Accessibility Guidelines (ATAG) 2.0 [ATAG]

+
+   
This specification provides
+   guidelines for designing Web content authoring tools that are more
+   accessible for people with disabilities. An authoring tool that
+   conforms to these guidelines will promote accessibility by
+   providing an accessible user interface to authors with disabilities
+   as well as by enabling, supporting, and promoting the production of
+   accessible Web content by all authors.

+
+   
User Agent Accessibility Guidelines (UAAG) 2.0 [UAAG]

+
+   
This document provides guidelines
+   for designing user agents that lower barriers to Web accessibility
+   for people with disabilities. User agents include browsers and
+   other types of software that retrieve and render Web content. A
+   user agent that conforms to these guidelines will promote
+   accessibility through its own user interface and through other
+   internal facilities, including its ability to communicate with
+   other technologies (especially assistive
+   technologies). Furthermore, all users, not just users with
+   disabilities, should find conforming user agents to be more
+   usable.

+
+  
2 Common infrastructure

+
+  
2.1 Terminology

+
+  
This specification refers to both HTML and XML attributes and IDL
+  attributes, often in the same context. When it is not clear which is
+  being referred to, they are referred to as content
+  attributes for HTML and XML attributes, and IDL
+  attributes for those defined on IDL interfaces. Similarly, the
+  term "properties" is used for both JavaScript object properties and
+  CSS properties. When these are ambiguous they are qualified as object properties and CSS
+  properties respectively.

+
+  
Generally, when the specification states that a feature applies
+  to the HTML syntax or the XHTML syntax, it
+  also includes the other. When a feature specifically only applies to
+  one of the two languages, it is called out by explicitly stating
+  that it does not apply to the other format, as in "for HTML,
+  ... (this does not apply to XHTML)".

+
+  
This specification uses the term document to
+  refer to any use of HTML, ranging from short static documents to
+  long essays or reports with rich multimedia, as well as to
+  fully-fledged interactive applications.

+
+  
For simplicity, terms such as shown, displayed, and visible might
+  sometimes be used when referring to the way a document is rendered
+  to the user. These terms are not meant to imply a visual medium;
+  they must be considered to apply to other media in equivalent
+  ways.

+
+  

+
+  
When an algorithm B says to return to another algorithm A, it
+  implies that A called B. Upon returning to A, the implementation
+  must continue from where it left off in calling B.

+
+  

+
+
+  
2.1.1 Resources

+
+  
The specification uses the term supported
+  when referring to whether a user agent has an implementation capable
+  of decoding the semantics of an external resource. A format or type
+  is said to be supported if the implementation can process an
+  external resource of that format or type without critical aspects of
+  the resource being ignored. Whether a specific resource is
+  supported can depend on what features of the resource's
+  format are in use.

+
+  
For example, a PNG image would be considered to
+  be in a supported format if its pixel data could be decoded and
+  rendered, even if, unbeknownst to the implementation, the image also
+  contained animation data.

+
+  
A MPEG4 video file would not be considered to be
+  in a supported format if the compression format used was not
+  supported, even if the implementation could determine the dimensions
+  of the movie from the file's metadata.

+
+  
What some specifications, in particular the HTTP and URI
+  specifications, refer to as a representation is referred to
+  in this specification as a resource. [HTTP] [RFC3986]

+
+  
The term MIME type is used to refer to what is
+  sometimes called an Internet media type in protocol
+  literature. The term media type in this specification is used
+  to refer to the type of media intended for presentation, as used by
+  the CSS specifications. [RFC2046] [MQ]

+
+  
A string is a valid MIME type if it matches the media-type rule defined in section 3.7 "Media Types"
+  of RFC 2616. In particular, a valid MIME type may
+  include MIME type parameters. [HTTP]

+
+  
A string is a valid MIME type with no parameters if it
+  matches the media-type rule defined in section
+  3.7 "Media Types" of RFC 2616, but does not contain any U+003B
+  SEMICOLON characters (;). In other words, if it consists only of a
+  type and subtype, with no MIME Type parameters. [HTTP]

+
+  
The term HTML MIME type is used to refer to the MIME types text/html and
+  text/html-sandboxed.

+
+  
A resource's critical subresources are those that the
+  resource needs to have available to be correctly processed. Which
+  resources are considered critical or not is defined by the
+  specification that defines the resource's format. For CSS resources,
+  only @import rules introduce critical
+  subresources; other resources, e.g. fonts or backgrounds, are
+  not.

+
+
+  
2.1.2 XML

+
+  
To ease migration from HTML to XHTML, UAs
+  conforming to this specification will place elements in HTML in the
+  http://www.w3.org/1999/xhtml namespace, at least for
+  the purposes of the DOM and CSS. The term "HTML
+  elements", when used in this specification, refers to any
+  element in that namespace, and thus refers to both HTML and XHTML
+  elements.

+
+  
Except where otherwise stated, all elements defined or mentioned
+  in this specification are in the
+  http://www.w3.org/1999/xhtml namespace, and all
+  attributes defined or mentioned in this specification have no
+  namespace.

+
+  
Attribute names are said to be XML-compatible if they
+  match the Name production defined in XML, they contain no
+  U+003A COLON characters (:), and their first three characters are
+  not an ASCII case-insensitive match for the string
+  "xml". [XML]

+
+  
The term XML MIME type is used to refer to the MIME types text/xml,
+  application/xml, and any MIME
+  type whose subtype ends with the four characters "+xml". [RFC3023]

+
+
+  
2.1.3 DOM trees

+
+  
The term root element, when not explicitly qualified
+  as referring to the document's root element, means the furthest
+  ancestor element node of whatever node is being discussed, or the
+  node itself if it has no ancestors. When the node is a part of the
+  document, then the node's root element is indeed the
+  document's root element; however, if the node is not currently part
+  of the document tree, the root element will be an orphaned node.

+
+  
When an element's root element is the root element
+  of a Document, it is said to be in a
+  Document. An element is said to have been inserted into a
+  document when its root element changes and is now
+  the document's root element. Analogously, an element is
+  said to have been removed from a document when its root
+  element changes from being the document's root
+  element to being another element.

+
+  
A node's home subtree is the subtree rooted at that
+  node's root element. When a node is in a
+  Document, its home subtree is that
+  Document's tree.

+
+  
The Document of a Node (such as an
+  element) is the Document that the Node's
+  ownerDocument IDL attribute returns. When a
+  Node is in a Document then
+  that Document is always the Node's
+  Document, and the Node's ownerDocument IDL attribute thus always returns that
+  Document.

+
+  
The term tree order means a pre-order, depth-first
+  traversal of DOM nodes involved (through the parentNode/childNodes relationship).

+
+  
When it is stated that some element or attribute is ignored, or treated as some other value, or
+  handled as if it was something else, this refers only to the
+  processing of the node after it is in the DOM. A
+  user agent must not mutate the DOM in such situations.

+
+  
The term text node refers to any Text
+  node, including CDATASection nodes; specifically, any
+  Node with node type TEXT_NODE (3)
+  or CDATA_SECTION_NODE (4). [DOMCORE]

+
+  
A content attribute is said to change value
+  only if its new value is different than its previous value; setting
+  an attribute to a value it already has does not change it.

+
+
+  
2.1.4 Scripting

+
+  
The construction "a Foo object", where
+  Foo is actually an interface, is sometimes used instead
+  of the more accurate "an object implementing the interface
+  Foo".

+
+  
An IDL attribute is said to be getting when
+  its value is being retrieved (e.g. by author script), and is said to
+  be setting when a new value is assigned to
+  it.

+
+  
If a DOM object is said to be live, then the
+  attributes and methods on that object must
+  operate on the actual underlying data, not a snapshot of the
+  data.

+
+  
The terms fire and dispatch are used interchangeably in the context of
+  events, as in the DOM Events specifications. The term trusted event is used as
+  defined by the DOM Events specification.  [DOMEVENTS]

+
+
+  
2.1.5 Plugins

+
+  
The term plugin refers to a user-agent defined set of
+  content handlers used by the user agent that can take part in the
+  user agent's rendering of a Document object, but that
+  neither act as child browsing
+  contexts of the Document nor introduce any
+  Node objects to the Document's DOM.

+
+  
Typically such content handlers are provided by third parties,
+  though a user agent can also designate built-in content handlers as
+  plugins.

+
+  
A user agent must not consider the types text/plain
+  and application/octet-stream as having a registered
+  plugin.
 
+
+  
One example of a plugin would be a PDF viewer
+  that is instantiated in a browsing context when the
+  user navigates to a PDF file. This would count as a plugin
+  regardless of whether the party that implemented the PDF viewer
+  component was the same as that which implemented the user agent
+  itself. However, a PDF viewer application that launches separate
+  from the user agent (as opposed to using the same interface) is not
+  a plugin by this definition.

+
+  
This specification does not define a mechanism for
+  interacting with plugins, as it is expected to be user-agent- and
+  platform-specific. Some UAs might opt to support a plugin mechanism
+  such as the Netscape Plugin API; others might use remote content
+  converters or have built-in support for certain types. [NPAPI]

+
+  
Browsers should take extreme care when
+  interacting with external content intended for plugins. When third-party software is run with
+  the same privileges as the user agent itself, vulnerabilities in the
+  third-party software become as dangerous as those in the user
+  agent.

+
+
+  
2.1.6 Character encodings

+
+  
The preferred MIME name of a character encoding is the
+  name or alias labeled as "preferred MIME name" in the IANA
+  Character Sets registry, if there is one, or the
+  encoding's name, if none of the aliases are so labeled. [IANACHARSET]

+
+  
An ASCII-compatible character encoding is a
+  single-byte or variable-length encoding in which the bytes 0x09,
+  0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A,
+  and 0x61 - 0x7A, ignoring bytes that
+  are the second and later bytes of multibyte sequences, all
+  correspond to single-byte sequences that map to the same Unicode
+  characters as those bytes in ANSI_X3.4-1968 (US-ASCII). [RFC1345]

+
+  
This includes such encodings as Shift_JIS,
+  HZ-GB-2312, and variants of ISO-2022, even though it is possible in
+  these encodings for bytes like 0x70 to be part of longer sequences
+  that are unrelated to their interpretation as ASCII. It excludes
+  such encodings as UTF-7, UTF-16, GSM03.38, and EBCDIC variants.

+
+  
+
+  
The term Unicode character is used to mean a
+  Unicode scalar value (i.e. any Unicode code point
+  that is not a surrogate code point). [UNICODE]

+
+
+
+
+
+
+
+  
2.2 Conformance requirements

+
+
+
+  
All diagrams, examples, and notes in this specification are
+  non-normative, as are all sections explicitly marked non-normative.
+  Everything else in this specification is normative.

+
+  
The key words "MUST", "MUST NOT", "REQUIRED",  "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
+  "OPTIONAL" in the normative parts of this document are to be
+  interpreted as described in RFC2119. For readability, these words do
+  not appear in all uppercase letters in this specification. [RFC2119]

+
+  
Requirements phrased in the imperative as part of
+  algorithms (such as "strip any leading space characters" or "return
+  false and abort these steps") are to be interpreted with the meaning
+  of the key word ("must", "should", "may", etc) used in introducing
+  the algorithm.

+
+  
This specification describes the conformance criteria for user agents (relevant to implementors) and
+  documents (relevant to authors and authoring tool
+  implementors).

+
+  
Conforming documents are those that comply with all
+  the conformance criteria for documents. For readability, some of
+  these conformance requirements are phrased as conformance
+  requirements on authors; such requirements are implicitly
+  requirements on documents: by definition, all documents are assumed
+  to have had an author. (In some cases, that author may itself be a
+  user agent — such user agents are subject to additional rules,
+  as explained below.)

+
+  
For example, if a requirement states that
+  "authors must not use the foobar element", it
+  would imply that documents are not allowed to contain elements named
+  foobar.

+
+  

+
+
+
+  
User agents fall into several (overlapping) categories with
+  different conformance requirements.

+
+  
Web browsers and other interactive user agents

+
+   

+
+    
Web browsers that support the XHTML syntax must
+    process elements and attributes from the HTML
+    namespace found in XML documents as described in this
+    specification, so that users can interact with them, unless the
+    semantics of those elements have been overridden by other
+    specifications.

+
+    
A conforming XHTML processor would, upon
+    finding an XHTML script element in an XML document,
+    execute the script contained in that element. However, if the
+    element is found within a transformation expressed in XSLT
+    (assuming the user agent also supports XSLT), then the processor
+    would instead treat the script element as an opaque
+    element that forms part of the transform.

+
+    
Web browsers that support the HTML syntax must
+    process documents labeled with an HTML MIME type as
+    described in this specification, so that users can interact with
+    them.

+
+    
User agents that support scripting must also be conforming
+    implementations of the IDL fragments in this specification, as
+    described in the Web IDL specification. [WEBIDL]

+
+    
Unless explicitly stated, specifications that
+    override the semantics of HTML elements do not override the
+    requirements on DOM objects representing those elements. For
+    example, the script element in the example above
+    would still implement the HTMLScriptElement
+    interface.

+
+   

+
+   
Non-interactive presentation user agents

+
+   

+
+    
User agents that process HTML and XHTML documents purely to
+    render non-interactive versions of them must comply to the same
+    conformance criteria as Web browsers, except that they are exempt
+    from requirements regarding user interaction.

+
+    
Typical examples of non-interactive presentation
+    user agents are printers (static UAs) and overhead displays
+    (dynamic UAs). It is expected that most static non-interactive
+    presentation user agents will also opt to lack scripting support.

+
+    
A non-interactive but dynamic presentation UA
+    would still execute scripts, allowing forms to be dynamically
+    submitted, and so forth. However, since the concept of "focus" is
+    irrelevant when the user cannot interact with the document, the UA
+    would not need to support any of the focus-related DOM APIs.

+
+   

+
+   
User agents with no scripting support

+
+   

+
+    
Implementations that do not support scripting (or which have
+    their scripting features disabled entirely) are exempt from
+    supporting the events and DOM interfaces mentioned in this
+    specification. For the parts of this specification that are
+    defined in terms of an events model or in terms of the DOM, such
+    user agents must still act as if events and the DOM were
+    supported.

+
+    
Scripting can form an integral part of an
+    application. Web browsers that do not support scripting, or that
+    have scripting disabled, might be unable to fully convey the
+    author's intent.

+
+   

+
+   
Conformance checkers

+
+   

+
+    
Conformance checkers must verify that a document conforms to
+    the applicable conformance criteria described in this
+    specification. Automated conformance checkers are exempt from
+    detecting errors that require interpretation of the author's
+    intent (for example, while a document is non-conforming if the
+    content of a blockquote element is not a quote,
+    conformance checkers running without the input of human judgement
+    do not have to check that blockquote elements only
+    contain quoted material).

+
+    
Conformance checkers must check that the input document
+    conforms when parsed without a browsing context
+    (meaning that no scripts are run, and that the parser's
+    scripting flag is disabled), and should also check
+    that the input document conforms when parsed with a browsing
+    context in which scripts execute, and that the scripts
+    never cause non-conforming states to occur other than transiently
+    during script execution itself. (This is only a "SHOULD" and not a
+    "MUST" requirement because it has been proven to be impossible. [COMPUTABLE])

+
+    
The term "HTML validator" can be used to refer to a
+    conformance checker that itself conforms to the applicable
+    requirements of this specification.

+    
+
+    

+
+     
XML DTDs cannot express all the conformance requirements of
+     this specification. Therefore, a validating XML processor and a
+     DTD cannot constitute a conformance checker. Also, since neither
+     of the two authoring formats defined in this specification are
+     applications of SGML, a validating SGML system cannot constitute
+     a conformance checker either.

+
+     
To put it another way, there are three types of conformance
+     criteria:

+
+     
  1. Criteria that can be expressed in a DTD.
    2. 
+
+      
  2. Criteria that cannot be expressed by a DTD, but can still be
+      checked by a machine.
    3. 
+
+      
  3. Criteria that can only be checked by a human.
    4. 
+
+     
A conformance checker must check for the first two. A simple
+     DTD-based validator only checks for the first class of errors and
+     is therefore not a conforming conformance checker according to
+     this specification.

+
+    

+   

+
+   
Data mining tools

+
+   

+
+    
Applications and tools that process HTML and XHTML documents
+    for reasons other than to either render the documents or check
+    them for conformance should act in accordance with the semantics
+    of the documents that they process.

+
+    
A tool that generates document outlines but increases the nesting
+    level for each paragraph and does not increase the nesting level
+    for each section would not be conforming.

+
+   

+
+   
Authoring tools and markup generators

+
+   

+
+    
Authoring tools and markup generators must generate
+    conforming documents. Conformance criteria that apply
+    to authors also apply to authoring tools, where appropriate.

+
+    
Authoring tools are exempt from the strict requirements of
+    using elements only for their specified purpose, but only to the
+    extent that authoring tools are not yet able to determine author
+    intent. However, authoring tools must not automatically misuse
+    elements or encourage their users to do so.

+
+    
For example, it is not conforming to use an
+    address element for arbitrary contact information;
+    that element can only be used for marking up contact information
+    for the author of the document or section. However, since an
+    authoring tool is likely unable to determine the difference, an
+    authoring tool is exempt from that requirement. This does not
+    mean, though, that authoring tools can use address
+    elements for any block of italics text (for instance); it just
+    means that the authoring tool doesn't have to verify that when the
+    user uses a tool for inserting contact information for a section,
+    that the user really is doing that and not inserting something
+    else instead.

+
+    
In terms of conformance checking, an editor has to
+    output documents that conform to the same extent that a
+    conformance checker will verify.

+
+    
When an authoring tool is used to edit a non-conforming
+    document, it may preserve the conformance errors in sections of
+    the document that were not edited during the editing session
+    (i.e. an editing tool is allowed to round-trip erroneous
+    content). However, an authoring tool must not claim that the
+    output is conformant if errors have been so preserved.

+
+    
Authoring tools are expected to come in two broad varieties:
+    tools that work from structure or semantic data, and tools that
+    work on a What-You-See-Is-What-You-Get media-specific editing
+    basis (WYSIWYG).

+
+    
The former is the preferred mechanism for tools that author
+    HTML, since the structure in the source information can be used to
+    make informed choices regarding which HTML elements and attributes
+    are most appropriate.

+
+    
However, WYSIWYG tools are legitimate. WYSIWYG tools should use
+    elements they know are appropriate, and should not use elements
+    that they do not know to be appropriate. This might in certain
+    extreme cases mean limiting the use of flow elements to just a few
+    elements, like div, b, i,
+    and span and making liberal use of the style attribute.

+
+    
All authoring tools, whether WYSIWYG or not, should make a best
+    effort attempt at enabling users to create well-structured,
+    semantically rich, media-independent content.

+
+   

+
+  
Some conformance requirements are phrased as requirements on
+  elements, attributes, methods or objects. Such requirements fall
+  into two categories: those describing content model restrictions,
+  and those describing implementation behavior. Those in the former
+  category are requirements on documents and authoring tools. Those in
+  the second category are requirements on user agents. Similarly, some
+  conformance requirements are phrased as requirements on authors;
+  such requirements are to be interpreted as conformance requirements
+  on the documents that authors produce. (In other words, this
+  specification does not distinguish between conformance criteria on
+  authors and conformance criteria on documents.)

+
+  
Conformance requirements phrased as algorithms or specific steps
+  may be implemented in any manner, so long as the end result is
+  equivalent. (In particular, the algorithms defined in this
+  specification are intended to be easy to follow, and not intended to
+  be performant.)

+
+  
User agents may impose
+  implementation-specific limits on otherwise unconstrained inputs,
+  e.g. to prevent denial of service attacks, to guard against running
+  out of memory, or to work around platform-specific limitations.

+
+  

+
+
+
+  
There is no implied relationship between
+  document conformance requirements and implementation conformance
+  requirements. User agents are not free to handle non-conformant
+  documents as they please; the processing model described in this
+  specification applies to implementations regardless of the
+  conformity of the input documents.

+
+  
For compatibility with existing content and prior specifications,
+  this specification describes two authoring formats: one based on XML
+  (referred to as the XHTML syntax), and one using a custom format inspired by SGML (referred to as
+  the HTML syntax). Implementations
+  may support only one of these two formats, although supporting both
+  is encouraged.

+
+  
The language in this
+  specification assumes that the user agent expands all entity
+  references, and therefore does not include entity reference nodes in
+  the DOM. If user agents do include entity reference nodes in the
+  DOM, then user agents must handle them as if they were fully
+  expanded when implementing this specification. For example, if a
+  requirement talks about an element's child text nodes, then any text
+  nodes that are children of an entity reference that is a child of
+  that element would be used as well. Entity references to unknown
+  entities must be treated as if they contained just an empty text
+  node for the purposes of the algorithms defined in this
+  specification.

+
+
+  

+
+  
2.2.1 Dependencies

+
+  
This specification relies on several other underlying
+  specifications.

+
+  
XML

+
+   

+
+    
Implementations that support the XHTML syntax must
+    support some version of XML, as well as its corresponding
+    namespaces specification, because that syntax uses an XML
+    serialization with namespaces. [XML] [XMLNS]

+
+   

+
+   
DOM

+
+   

+
+    
The Document Object Model (DOM) is a representation — a
+    model — of a document and its content. The DOM is not just
+    an API; the conformance criteria of HTML implementations are
+    defined, in this specification, in terms of operations on the DOM.
+    [DOMCORE]

+
+    
Implementations must support some version of DOM Core and DOM
+    Events, because this specification is defined in terms of the DOM,
+    and some of the features are defined as extensions to the DOM Core
+    interfaces. [DOMCORE] [DOMEVENTS]

+
+    
In particular, the following features are defined in the DOM
+    Core specification: [DOMCORE]

+
+    
  • Attr interface
    • 
+     
  • CDATASection interface
    • 
+     
  • Comment interface
    • 
+     
  • DOMImplementation interface
    • 
+     
  • Document interface
    • 
+     
  • DocumentFragment interface
    • 
+     
  • DocumentType interface
    • 
+     
  • DOMException interface
    • 
+     
  • Element interface
    • 
+     
  • Node interface
    • 
+     
  • NodeList interface
    • 
+     
  • ProcessingInstruction interface
    • 
+     
  • Text interface
    • 
+
+     
  • createDocument() method
    • 
+     
  • getElementById() method
    • 
+     
  • insertBefore() method
    • 
+
+     
  • childNodes attribute 
    • 
+     
  • localName attribute 
    • 
+     
  • parentNode attribute 
    • 
+     
  • tagName attribute 
    • 
+     
  • textContent attribute 
    • 
+
+    
The following features are defined in the DOM Events
+    specification: [DOMEVENTS]

+
+    
  • Event interface
    • 
+     
  • EventTarget interface
    • 
+     
  • UIEvent interface
    • 
+
+     
  • click event
    • 
+     
  • DOMActivate event
    • 
+
+     
  • target attribute
    • 
+
+    
The following features are defined in the DOM
+    Range specification: [DOMRANGE]

+
+    
  • Range interface
    • 
+
+     
  • deleteContents() method 
    • 
+     
  • selectNodeContents() method 
    • 
+     
  • setEnd() method 
    • 
+     
  • setStart() method 
    • 
+
+     
  • collapsed attribute 
    • 
+     
  • endContainer attribute 
    • 
+     
  • endOffset attribute 
    • 
+     
  • startContainer attribute 
    • 
+     
  • startOffset attribute 
    • 
+
+    

+
+   
Web IDL

+
+   

+
+    
The IDL fragments in this specification must be interpreted as
+    required for conforming IDL fragments, as described in the Web IDL
+    specification. [WEBIDL]

+
+    
Except where otherwise specified, if an IDL
+    attribute that is a floating point number type (float) is assigned an Infinity or Not-a-Number
+    (NaN) value, a NOT_SUPPORTED_ERR exception must be
+    raised.

+
+    
Except where otherwise specified, if a method with an argument
+    that is a floating point number type (float)
+    is passed an Infinity or Not-a-Number (NaN) value, a
+    NOT_SUPPORTED_ERR exception must be raised.

+
+   

+
+   
JavaScript

+
+   

+
+    
Some parts of the language described by this specification only
+    support JavaScript as the underlying scripting language. [ECMA262]

+
+    
The term "JavaScript" is used to refer to ECMA262,
+    rather than the official term ECMAScript, since the term
+    JavaScript is more widely known. Similarly, the MIME
+    type used to refer to JavaScript in this specification is
+    text/javascript, since that is the most
+    commonly used type, despite it
+    being an officially obsoleted type according to RFC
+    4329. [RFC4329]

+
+   

+
+   
Media Queries

+
+   

+
+    
Implementations must support some version of the Media Queries
+    language. [MQ]

+
+   

+
+   
URIs, IRIs, IDNA

+
+   

+
+    
Implementations must support the semantics of URLs defined in the URI and IRI specifications,
+    as well as the semantics of IDNA domain names defined in the
+    Internationalizing Domain Names in Applications
+    (IDNA) specification. [RFC3986]
+    [RFC3987] [RFC3490]
+
+   

+
+  
This specification does not require support of any
+  particular network protocol, style sheet language, scripting
+  language, or any of the DOM specifications beyond those described
+  above. However, the language described by this specification is
+  biased towards CSS as the styling language, JavaScript as the
+  scripting language, and HTTP as the network protocol, and several
+  features assume that those languages and protocols are in use.

+
+  
This specification might have certain additional
+  requirements on character encodings, image formats, audio formats,
+  and video formats in the respective sections.

+
+  

+
+
+
+  
2.2.2 Extensibility

+
+  
HTML has a wide number of extensibility mechanisms that can be
+  used for adding semantics in a safe manner:

+
+  
  • Authors can use the class
+   attribute to extend elements, effectively creating their own
+   elements, while using the most applicable existing "real" HTML
+   element, so that browsers and other tools that don't know of the
+   extension can still support it somewhat well. This is the tack used
+   by Microformats, for example.
    • 
+
+   
  • Authors can include data for inline client-side scripts or
+   server-side site-wide scripts to process using the data-*="" attributes. These are
+   guaranteed to never be touched by browsers, and allow scripts to
+   include data on HTML elements that scripts can then look for and
+   process.
    • 
+
+   
  • Authors can use the <meta name=""
+   content=""> mechanism to include page-wide metadata by
+   registering extensions to the
+   predefined set of metadata names.
    • 
+
+   
  • Authors can use the rel="" mechanism to annotate
+   links with specific meanings by registering  extensions to the predefined set of
+   link types. This is also used by Microformats.
    • 
+
+   
  • Authors can embed raw data using the <script type=""> mechanism with a custom
+   type, for further handling by a inline or server-side scripts.
    • 
+
+   
  • Authors can create plugins and
+   invoke them using the embed element. This is how Flash
+   works.
    • 
+
+   
  • Authors can extend APIs using the JavaScript prototyping
+   mechanism. This is widely used by script libraries, for
+   instance.
    • 
+
+   
  • Authors can use the microdata feature (the item="" and itemprop="" attributes) to embed
+   nested name-value pairs of data to be shared with other
+   applications and sites.
    • 
+
+  

+
+  
Vendor-specific proprietary user agent extensions to this
+  specification are strongly discouraged. Documents must not use such
+  extensions, as doing so reduces interoperability and fragments the
+  user base, allowing only users of specific user agents to access the
+  content in question.

+
+  
If such extensions are nonetheless needed, e.g. for experimental
+  purposes, then vendors are strongly urged to use one of the
+  following extension mechanisms:

+
+  
For markup-level features that can be limited to the XML
+  serialization and need not be supported in the HTML serialization,
+  vendors should use the namespace mechanism to define custom
+  namespaces in which the non-standard elements and attributes are
+  supported.

+
+  
For markup-level features that are intended for use with
+  the HTML syntax, extensions should be limited to new
+  attributes of the form "_vendor-feature", where
+  vendor is a short string that identifies the
+  vendor responsible for the extension, and feature is the name of the feature. New element names
+  should not be created. Using attributes for such extensions
+  exclusively allows extensions from multiple vendors to co-exist on
+  the same element, which would not be possible with elements. Using
+  the "_vendor-feature" form allows extensions to be made
+  without risk of conflicting with future additions to the
+  specification.

+
+  

+
+   
For instance, a browser named "FerretBrowser" could use "ferret"
+   as a vendor prefix, while a browser named "Mellblom Browser" could
+   use "mb". If both of these browsers invented extensions that turned
+   elements into scratch-and-sniff areas, an author experimenting with
+   these features could write:

+
+   
<p>This smells of lemons!
+<span _ferret-smellovision _ferret-smellcode="LEM01"
+      _mb-outputsmell _mb-smell="lemon juice"></span></p>

+
+  

+
+  
Attribute names starting with a U+005F LOW LINE character (_) are
+  reserved for user agent use and are guaranteed to never be formally
+  added to the HTML language.

+
+  
Pages that use such attributes are by definition
+  non-conforming.

+
+  
For DOM extensions, e.g. new methods and IDL attributes, the new
+  members should be prefixed by vendor-specific strings to prevent
+  clashes with future versions of this specification.

+
+  
All extensions must be defined so that the use of extensions
+  neither contradicts nor causes the non-conformance of functionality
+  defined in the specification.
 
+
+  

+
+   
For example, while strongly discouraged from doing so, an
+   implementation "Foo Browser" could add a new IDL attribute "fooTypeTime" to a control's DOM interface that
+   returned the time it took the user to select the current value of a
+   control (say). On the other hand, defining a new control that
+   appears in a form's elements
+   array would be in violation of the above requirement, as it would
+   violate the definition of elements given in this
+   specification.

+
+  

+
+  
When vendor-neutral extensions to this specification are needed,
+  either this specification can be updated accordingly, or an
+  extension specification can be written that overrides the
+  requirements in this specification. When someone applying this
+  specification to their activities decides that they will recognize
+  the requirements of such an extension specification, it becomes an
+  applicable
+  specification for the purposes of conformance requirements in
+  this specification.

+  
+
+  
User agents must treat elements and attributes that they do not
+  understand as semantically neutral; leaving them in the DOM (for DOM
+  processors), and styling them according to CSS (for CSS processors),
+  but not inferring any meaning from them.

+
+  
When support for a feature is disabled (e.g. as an emergency
+  measure to mitigate a security problem, or to aid in development, or
+  for performance reasons), user agents must act as if they had no
+  support for the feature whatsoever, and as if the feature was not
+  mentioned in this specification. For example, if a particular
+  feature is accessed via an attribute in a Web IDL interface, the
+  attribute itself would be omitted from the objects that implement
+  that interface — leaving the attribute on the object but
+  making it return null or throw an exception is insufficient.

+
+  

+
+
+
+  
2.3 Case-sensitivity and string comparison

+
+  
Comparing two strings in a case-sensitive manner means
+  comparing them exactly, code point for code point.

+
+  
Comparing two strings in an ASCII case-insensitive
+  manner means comparing them exactly, code point for code point, except
+  that the characters in the range U+0041 to U+005A (i.e. LATIN
+  CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding
+  characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A
+  to LATIN SMALL LETTER Z) are considered to also match.

+
+  
Comparing two strings in a compatibility caseless
+  manner means using the Unicode compatibility caseless match
+  operation to compare the two strings. [UNICODE]

+
+
+  

+
+  
Converting a string to
+  ASCII uppercase means replacing all characters in the range
+  U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z)
+  with the corresponding characters in the range U+0041 to U+005A
+  (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).

+
+  
Converting a string to
+  ASCII lowercase means replacing all characters in the range
+  U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL
+  LETTER Z) with the corresponding characters in the range U+0061
+  to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).

+
+  

+
+
+  
A string pattern is a prefix match
+  for a string s when pattern
+  is not longer than s and truncating s to pattern's length leaves the
+  two strings as matches of each other.

+
+
+  
2.4 Common microsyntaxes

+
+  
There are various places in HTML that accept particular data
+  types, such as dates or numbers. This section describes what the
+  conformance criteria for content in those formats is, and how to
+  parse them.

+
+  

+
+  
Implementors are strongly urged to carefully examine
+  any third-party libraries they might consider using to implement the
+  parsing of syntaxes described below. For example, date libraries are
+  likely to implement error handling behavior that differs from what
+  is required in this specification, since error-handling behavior is
+  often not defined in specifications that describe date syntaxes
+  similar to those used in this specification, and thus
+  implementations tend to vary greatly in how they handle errors.

+
+  

+
+
+  

+
+  
2.4.1 Common parser idioms

+
+  
The space characters, for the
+  purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER
+  TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and
+  U+000D CARRIAGE RETURN (CR).

+
+  
The White_Space characters are
+  those that have the Unicode property "White_Space" in the Unicode
+  PropList.txt data file. [UNICODE]

+
+  
This should not be confused with the "White_Space"
+  value (abbreviated "WS") of the "Bidi_Class" property in the Unicode.txt data file.

+
+  
The alphanumeric ASCII characters are those in the
+  ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN
+  CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, U+0061 LATIN
+  SMALL LETTER A to U+007A LATIN SMALL LETTER Z.

+
+  
Some of the micro-parsers described below follow the pattern of
+  having an input variable that holds the string
+  being parsed, and having a position variable
+  pointing at the next character to parse in input.

+
+  
For parsers based on this pattern, a step that requires the user
+  agent to collect a sequence of characters means that the
+  following algorithm must be run, with characters
+  being the set of characters that can be collected:

+
+  
  1. Let input and position be the same variables as those of the same
+   name in the algorithm that invoked these steps.
    2. 
+
+   
  2. Let result be the empty string.
    3. 
+
+   
  3. While position doesn't point past the
+   end of input and the character at position is one of the characters, append that character to the end of result and advance position to
+   the next character in input.
    4. 
+
+   
  4. Return result.
    5. 
+
+  
The step skip whitespace means that the user agent
+  must collect a sequence of characters that are space characters. The step skip
+  White_Space characters means that the user agent must
+  collect a sequence of characters that are
+  White_Space characters. In both cases, the collected
+  characters are not used. [UNICODE]

+
+  
When a user agent is to strip line breaks from a
+  string, the user agent must remove any U+000A LINE FEED (LF) and
+  U+000D CARRIAGE RETURN (CR) characters from that string.

+
+  
When a user agent is to strip leading and trailing
+  whitespace from a string, the user agent must remove all space characters that are at the
+  start or end of the string.

+
+  
The code-point length of a string is the number of
+  Unicode code points in that string.

+
+  

+
+
+
+  
2.4.2 Boolean attributes

+
+  
A number of attributes are boolean
+  attributes. The presence of a boolean attribute on an element
+  represents the true value, and the absence of the attribute
+  represents the false value.

+
+  
If the attribute is present, its value must either be the empty
+  string or a value that is an ASCII case-insensitive
+  match for the attribute's canonical name, with no leading or
+  trailing whitespace.

+
+  
The values "true" and "false" are not allowed on
+  boolean attributes. To represent a false value, the attribute has to
+  be omitted altogether.

+
+
+
+  
2.4.3 Keywords and enumerated attributes

+
+  
Some attributes are defined as taking one of a finite set of
+  keywords. Such attributes are called enumerated attributes. The keywords are each
+  defined to map to a particular state (several keywords
+  might map to the same state, in which case some of the keywords are
+  synonyms of each other; additionally, some of the keywords can be
+  said to be non-conforming, and are only in the specification for
+  historical reasons). In addition, two default states can be
+  given. The first is the invalid value default, the second
+  is the missing value default.

+
+  
If an enumerated attribute is specified, the attribute's value
+  must be an ASCII case-insensitive match for one of the
+  given keywords that are not said to be non-conforming, with no
+  leading or trailing whitespace.

+
+  
When the attribute is specified, if its value is an ASCII
+  case-insensitive match for one of the given keywords then
+  that keyword's state is the state that the attribute represents. If
+  the attribute value matches none of the given keywords, but the
+  attribute has an invalid value default, then the attribute
+  represents that state. Otherwise, if the attribute value matches
+  none of the keywords but there is a missing value default
+  state defined, then that is the state represented by the
+  attribute. Otherwise, there is no default, and invalid values must
+  be ignored.

+
+  
When the attribute is not specified, if there is a
+  missing value default state defined, then that is the state
+  represented by the (missing) attribute. Otherwise, the absence of
+  the attribute means that there is no state represented.

+
+  
The empty string can be a valid keyword.

+
+
+  
2.4.4 Numbers

+
+  
2.4.4.1 Non-negative integers

+
+  
A string is a valid non-negative integer if it
+  consists of one or more characters in the range U+0030 DIGIT ZERO
+  (0) to U+0039 DIGIT NINE (9).

+
+  
A valid non-negative integer represents the number
+  that is represented in base ten by that string of digits.

+
+  

+
+  
The rules for parsing non-negative integers are as
+  given in the following algorithm. When invoked, the steps must be
+  followed in the order given, aborting at the first step that returns
+  a value. This algorithm will return either zero, a positive integer,
+  or an error. Leading spaces are ignored. Trailing spaces and any
+  trailing garbage characters are ignored.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Skip whitespace.
    4. 
+
+   
  4. If position is past the end of input, return an error.
    5. 
+
+   
  5. If the character indicated by position
+   is a U+002B PLUS SIGN character (+), advance position to the next character. (The "+" is ignored, but it is not conforming.)
    6. 
+
+   
  6. If position is past the end of input, return an error.
    7. 
+
+   
  7. If the character indicated by position
+   is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
+   return an error.
    8. 
+
+   
+
+   
  8. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
+   resulting sequence as a base-ten integer. Let value be that integer.
    9. 
+
+   
  9. Return value.
    10. 
+
+  

+
+
+  
2.4.4.2 Signed integers

+
+  
A string is a valid integer if it consists of one or
+  more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+  NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS character
+  (-).

+
+  
A valid integer without a U+002D HYPHEN-MINUS (-)
+  prefix represents the number that is represented in base ten by that
+  string of digits. A valid integer with a
+  U+002D HYPHEN-MINUS (-) prefix represents the number represented in
+  base ten by the string of digits that follows the U+002D
+  HYPHEN-MINUS, subtracted from zero.

+
+  

+
+  
The rules for parsing integers are similar to the
+  rules for
+  non-negative integers, and are as given in the following
+  algorithm. When invoked, the steps must be followed in the order
+  given, aborting at the first step that returns a value. This
+  algorithm will return either an integer or an error. Leading spaces
+  are ignored. Trailing spaces and trailing garbage characters are
+  ignored.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Let sign have the value
+   "positive".
    4. 
+
+   
  4. Skip whitespace.
    5. 
+
+   
  5. If position is past the end of input, return an error.
    6. 
+
+   
  6. 
+
+    
    If the character indicated by position (the
+    first character) is a U+002D HYPHEN-MINUS character (-):
    
+
+    
    1. Let sign be "negative".
      2. 
+
+     
    2. Advance position to the next
+     character.
      3. 
+
+     
    3. If position is past the end of input, return an error.
      4. 
+
+    
    Otherwise, if the character indicated by position (the first character) is a U+002B PLUS
+    SIGN character (+):
    
+
+    
    1. Advance position to the next
+     character. (The "+" is ignored, but it is
+     not conforming.)
      2. 
+
+     
    2. If position is past the end of input, return an error.
      3. 
+
+    
    7. 
+
+   
  7. If the character indicated by position
+   is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
+   return an error.
    8. 
+
+   
+
+   
  8. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
+   resulting sequence as a base-ten integer. Let value be that integer.
    9. 
+
+   
  9. If sign is "positive", return value, otherwise return the result of subtracting
+   value from zero.
    10. 
+
+  

+
+
+  
2.4.4.3 Real numbers

+
+  
A string is a valid floating point number if it
+  consists of:

+
+  
  1. Optionally, a U+002D HYPHEN-MINUS character (-).
    2. 
+
+   
  2. A series of one or more characters in the range U+0030 DIGIT
+   ZERO (0) to U+0039 DIGIT NINE (9).
    3. 
+
+   
  3. Optionally:
+
+    
    1. A single U+002E FULL STOP character (.).
      2. 
+
+     
    2. A series of one or more characters in the range U+0030 DIGIT
+     ZERO (0) to U+0039 DIGIT NINE (9).
      3. 
+
+    
    4. 
+
+   
  4. Optionally:
+
+    
    1. Either a U+0065 LATIN SMALL LETTER E character (e) or a
+     U+0045 LATIN CAPITAL LETTER E character (E).
      2. 
+
+     
    2. Optionally, a U+002D HYPHEN-MINUS character (-) or U+002B
+     PLUS SIGN character (+).
      3. 
+
+     
    3. A series of one or more characters in the range U+0030 DIGIT
+     ZERO (0) to U+0039 DIGIT NINE (9).
      4. 
+
+    
    5. 
+
+  
A valid floating point number represents the number
+  obtained by multiplying the significand by ten raised to the power
+  of the exponent, where the significand is the first number,
+  interpreted as base ten (including the decimal point and the number
+  after the decimal point, if any, and interpreting the significand as
+  a negative number if the whole string starts with a U+002D
+  HYPHEN-MINUS character (-) and the number is not zero), and where
+  the exponent is the number after the E, if any (interpreted as a
+  negative number if there is a U+002D HYPHEN-MINUS character (-)
+  between the E and the number and the number is not zero, or else
+  ignoring a U+002B PLUS SIGN character (+) between the E and the
+  number if there is one). If there is no E, then the exponent is
+  treated as zero.

+
+  
The Infinity and Not-a-Number (NaN) values are not
+  valid floating point
+  numbers.

+
+  

+
+  
The best representation of the number n as a floating point number is the string
+  obtained from applying the JavaScript operator ToString to n. The JavaScript operator ToString is not uniquely
+  determined. When there are multiple possible strings that could be
+  obtained from the JavaScript operator ToString for a particular
+  value, the user agent must always return the same string for that
+  value (though it may differ from the value used by other user
+  agents).

+
+  
The rules for parsing floating point number values are
+  as given in the following algorithm. This algorithm must be aborted
+  at the first step that returns something. This algorithm will return
+  either a number or an error. Leading spaces are ignored. Trailing
+  spaces and garbage characters are ignored.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Let value have the value 1.
    4. 
+
+   
  4. Let divisor have the value 1.
    5. 
+
+   
  5. Let exponent have the value 1.
    6. 
+
+   
  6. Skip whitespace.
    7. 
+
+   
  7. If position is past the end of input, return an error.
    8. 
+
+   
  8. 
+
+    
    If the character indicated by position is a
+    U+002D HYPHEN-MINUS character (-):
    
+
+    
    1. Change value and divisor to −1.
      2. 
+
+     
    2. Advance position to the next
+     character.
      3. 
+
+     
    3. If position is past the end of input, return an error.
      4. 
+
+    
    9. 
+
+   
  9. If the character indicated by position
+   is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
+   return an error.
    10. 
+
+   
+
+   
  10. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
+   resulting sequence as a base-ten integer. Multiply value by that integer.
    11. 
+
+   
  11. If position is past the end of input, jump to the step labeled
+   conversion.
    12. 
+
+   
  12. If the character indicated by position
+   is a U+002E FULL STOP (.), run these substeps:
    
+
+    
    1. Advance position to the next
+     character.
      2. 
+
+     
    2. If position is past the end of input, or if the character indicated by position is not one of U+0030 DIGIT ZERO (0) to
+     U+0039 DIGIT NINE (9), then jump to the step labeled
+     conversion.
      3. 
+
+     
    3. Fraction loop: Multiply divisor
+     by ten.
      4. 
+
+     
    4. Add the value of the character indicated by position, interpreted as a base-ten digit (0..9)
+     and divided by divisor, to value.
      5. 
+
+     
    5. Advance position to the next
+     character.
      6. 
+
+     
    6. If position is past the end of input, then jump to the step labeled
+     conversion.
      7. 
+
+     
    7. If the character indicated by position
+     is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), jump
+     back to the step labeled fraction loop in these
+     substeps.
      8. 
+
+    
    13. 
+
+   
  13. If the character indicated by position
+   is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN
+   CAPITAL LETTER E character (E), run these substeps:
    
+
+    
    1. Advance position to the next
+     character.
      2. 
+
+     
    2. If position is past the end of input, then jump to the step labeled
+     conversion.
      3. 
+
+     
    3. 
+
+      
      If the character indicated by position is
+      a U+002D HYPHEN-MINUS character (-):
      
+
+      
      1. Change exponent to −1.
        2. 
+
+       
      2. Advance position to the next
+       character.
        3. 
+
+       
      3. If position is past the end of input, then jump to the step labeled
+       conversion.
        4. 
+
+      
      Otherwise, if the character indicated by position is a U+002B PLUS SIGN character (+):
      
+
+      
      1. Advance position to the next
+       character.
        2. 
+
+       
      2. If position is past the end of input, then jump to the step labeled
+       conversion.
        3. 
+
+      
      4. 
+
+     
    4. If the character indicated by position
+     is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9),
+     then jump to the step labeled conversion.
      5. 
+
+     
    5. Collect a sequence of characters in the range
+     U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
+     resulting sequence as a base-ten integer. Multiply exponent by that integer.
      6. 
+
+     
    6. Multiply value by ten raised to the
+     exponentth power.
      7. 
+
+    
    14. 
+
+   
  14. Conversion: Let S be the set of
+   finite IEEE 754 single-precision floating point values except
+   −0, but with two special values added: 2128 and −2128.
    15. 
+
+   
  15. Let rounded-value be the number in S that is closest to value,
+   selecting the number with an even significand if there are two
+   equally close values. (The two special values 2128 and −2128 are
+   considered to have even significands for this purpose.)
    16. 
+
+   
  16. If rounded-value is 2128 or −2128, return an
+   error.
    17. 
+
+   
  17. Return rounded-value.
    18. 
+
+  

+
+
+

+  
2.4.4.4 Percentages and lengths

+
+  
The rules for parsing dimension values are as given in
+  the following algorithm. When invoked, the steps must be followed in
+  the order given, aborting at the first step that returns a
+  value. This algorithm will return either a number greater than or
+  equal to 1.0, or an error; if a number is returned, then it is
+  further categorized as either a percentage or a length.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Skip whitespace.
    4. 
+
+   
  4. If position is past the end of input, return an error.
    5. 
+
+   
  5. If the character indicated by position
+   is a U+002B PLUS SIGN character (+), advance position to the next character.
    6. 
+
+   
  6. Collect a sequence of characters that are
+   U+0030 DIGIT ZERO (0) characters, and discard them.
    7. 
+
+   
  7. If position is past the end of input, return an error.
    8. 
+
+   
  8. If the character indicated by position
+   is not one of U+0031 DIGIT ONE (1) to U+0039 DIGIT NINE (9), then
+   return an error.
    9. 
+
+   
+
+   
  9. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
+   resulting sequence as a base-ten integer. Let value be that number.
    10. 
+
+   
  10. If position is past the end of input, return value as a
+   length.
    11. 
+
+   
  11. 
+
+    
    If the character indicated by position is a
+    U+002E FULL STOP character (.):
    
+
+    
    1. Advance position to the next
+     character.
      2. 
+
+     
    2. If position is past the end of input, or if the character indicated by position is not one of U+0030 DIGIT ZERO (0) to
+     U+0039 DIGIT NINE (9), then return value as a
+     length.
      3. 
+
+     
    3. Let divisor have the value 1.
      4. 
+
+     
    4. Fraction loop: Multiply divisor
+     by ten.
      5. 
+
+     
    5. Add the value of the character indicated by position, interpreted as a base-ten digit (0..9)
+     and divided by divisor, to value.
      6. 
+
+     
    6. Advance position to the next
+     character.
      7. 
+
+     
    7. If position is past the end of input, then return value as a
+     length.
      8. 
+
+     
    8. If the character indicated by position
+     is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), return
+     to the step labeled fraction loop in these
+     substeps.
      9. 
+
+    
    12. 
+
+   
  12. If position is past the end of input, return value as a
+   length.
    13. 
+
+   
  13. If the character indicated by position
+   is a U+0025 PERCENT SIGN character (%), return value as a percentage.
    14. 
+
+   
  14. Return value as a length.
    15. 
+
+  

+
+
+  
2.4.4.5 Lists of integers

+
+  
A valid list of integers is a number of valid integers separated by U+002C
+  COMMA characters, with no other characters (e.g. no space characters). In addition, there
+  might be restrictions on the number of integers that can be given,
+  or on the range of values allowed.

+
+  

+
+  
The rules for parsing a list of integers are as
+  follows:

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Let numbers be an initially empty list
+   of integers. This list will be the result of this
+   algorithm.
    4. 
+
+   
  4. If there is a character in the string input at position position, and
+   it is either a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON
+   character, then advance position to the next
+   character in input, or to beyond the end of the
+   string if there are no more characters.
    5. 
+
+   
  5. If position points to beyond the end of
+   input, return numbers and
+   abort.
    6. 
+
+   
  6. If the character in the string input at
+   position position is a U+0020 SPACE, U+002C
+   COMMA, or U+003B SEMICOLON character, then return to step 4.
    7. 
+
+   
  7. Let negated be false.
    8. 
+   
  8. Let value be 0.
    9. 
+
+   
  9. Let started be false. This variable is
+   set to true when the parser sees a number or a U+002D HYPHEN-MINUS
+   character (-).
    10. 
+
+   
  10. Let got number be false. This variable
+   is set to true when the parser sees a number.
    11. 
+
+   
  11. Let finished be false. This variable is
+   set to true to switch parser into a mode where it ignores
+   characters until the next separator.
    12. 
+
+   
  12. Let bogus be false.
    13. 
+
+   
  13. Parser: If the character in the string input at position position
+   is:
    
+
+    
    A U+002D HYPHEN-MINUS character
    
+
+     
    
+
+      
    Follow these substeps:
    
+
+      
    1. If got number is true, let finished be true.
      2. 
+
+       
    2. If finished is true, skip to the next
+       step in the overall set of steps.
      3. 
+
+       
    3. If started is true, let negated be false.
      4. 
+
+       
    4. Otherwise, if started is false and if bogus is false, let negated
+       be true.
      5. 
+
+       
    5. Let started be true.
      6. 
+
+      
    
+
+
+     
    A character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+     NINE (9)
    
+
+     
    
+
+      
    Follow these substeps:
    
+
+      
    1. If finished is true, skip to the next
+       step in the overall set of steps.
      2. 
+
+       
    2. Multiply value by ten.
      3. 
+
+       
    3. Add the value of the digit, interpreted in base ten, to
+       value.
      4. 
+
+       
    4. Let started be true.
      5. 
+
+       
    5. Let got number be true.
      6. 
+
+      
    
+
+
+     
    A U+0020 SPACE character
    
+     
    A U+002C COMMA character
    
+     
    A U+003B SEMICOLON character
    
+
+     
    
+
+      
    Follow these substeps:
    
+
+      
    1. If got number is false, return the numbers list and abort. This happens if an entry
+       in the list has no digits, as in "1,2,x,4".
      2. 
+
+       
    2. If negated is true, then negate value.
      3. 
+
+       
    3. Append value to the numbers list.
      4. 
+
+       
    4. Jump to step 4 in the overall set of steps.
      5. 
+
+      
    
+
+
+     
+     
    A character in the range U+0001 to U+001F,  U+0021 to U+002B,  U+002D to U+002F,  U+003A,  U+003C to U+0040,  U+005B to U+0060,  U+007b to U+007F
+        (i.e. any other non-alphabetic ASCII character)
    
+
+ 
+
+     
    
+
+      
    Follow these substeps:
    
+
+      
    1. If got number is true, let finished be true.
      2. 
+
+       
    2. If finished is true, skip to the next
+       step in the overall set of steps.
      3. 
+
+       
    3. Let negated be false.
      4. 
+
+      
    
+
+
+     
    Any other character
    
+     
+
+     
    
+
+      
    Follow these substeps:
    
+
+      
    1. If finished is true, skip to the next
+       step in the overall set of steps.
      2. 
+
+       
    2. Let negated be false.
      3. 
+
+       
    3. Let bogus be true.
      4. 
+
+       
    4. If started is true, then return the
+       numbers list, and abort. (The value in value is not appended to the list first; it is
+       dropped.)
      5. 
+
+      
    
+
+    
    14. 
+
+   
  14. Advance position to the next character
+   in input, or to beyond the end of the string if
+   there are no more characters.
    15. 
+
+   
  15. If position points to a character (and
+   not to beyond the end of input), jump to the
+   big Parser step above.
    16. 
+
+   
  16. If negated is true, then negate value.
    17. 
+
+   
  17. If got number is true, then append value to the numbers list.
    18. 
+
+   
  18. Return the numbers list and
+   abort.
    19. 
+
+  

+
+
+  

+
+  
2.4.4.6 Lists of dimensions

+
+  
+
+  
The rules for parsing a list of dimensions are as
+  follows. These rules return a list of zero or more pairs consisting
+  of a number and a unit, the unit being one of percentage,
+  relative, and absolute.

+
+  
  1. Let raw input be the string being
+   parsed.
    2. 
+
+   
  2. If the last character in raw input is a
+   U+002C COMMA character (,), then remove that character from raw input.
    3. 
+
+   
  3. Split the string raw input on commas. Let raw
+   tokens be the resulting list of tokens.
    4. 
+
+   
  4. Let result be an empty list of
+   number/unit pairs.
    5. 
+
+   
  5. 
+
+    
    For each token in raw tokens, run the
+    following substeps:
    
+
+    
    1. Let input be the token.
      2. 
+
+     
    2. Let position be a pointer into input, initially pointing at the start of the
+     string.
      3. 
+
+     
    3. Let value be the number 0.
      4. 
+
+     
    4. Let unit be absolute.
      5. 
+
+     
    5. If position is past the end of input, set unit to
+     relative and jump to the last substep.
      6. 
+
+     
    6. If the character at position is a
+     character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
+     (9), collect a sequence of characters in the range
+     U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), interpret the
+     resulting sequence as an integer in base ten, and increment value by that integer.
      7. 
+
+     
    7. 
+
+      
      If the character at position is a U+002E
+      FULL STOP character (.), run these substeps:
      
+
+      
      1. Collect a sequence of characters consisting
+       of space characters and
+       characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+       NINE (9). Let s be the resulting
+       sequence.
        2. 
+
+       
      2. Remove all space
+       characters in s.
        3. 
+
+       
      3. 
+
+        
        If s is not the empty string, run these
+        subsubsteps:
        
+
+        
        1. Let length be the number of
+         characters in s (after the spaces were
+         removed).
          2. 
+
+         
        2. Let fraction be the result of
+         interpreting s as a base-ten integer, and
+         then dividing that number by 10length.
          3. 
+
+         
        3. Increment value by fraction.
          4. 
+
+        
        4. 
+
+      
      8. 
+
+     
    8. Skip whitespace.
      9. 
+
+     
    9. 
+
+      
      If the character at position is a U+0025
+      PERCENT SIGN character (%), then set unit to
+      percentage.
      
+
+      
      Otherwise, if the character at position
+      is a U+002A ASTERISK character (*), then set unit to relative.
      
+
+     
      10. 
+
+     
+
+     
    10. Add an entry to result consisting of
+     the number given by value and the unit given
+     by unit.
      11. 
+
+    
    6. 
+
+   
  6. Return the list result.
    7. 
+
+  

+
+
+  
2.4.5 Dates and times

+
+  
In the algorithms below, the number of days in month month of year year is:
+  31 if month is 1, 3, 5, 7, 8, 10, or
+  12; 30 if month is 4, 6, 9, or 11;
+  29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and
+  28 otherwise. This takes into account leap years in the
+  Gregorian calendar. [GREGORIAN]

+
+  
The digits in the date
+  and time syntaxes defined in this section must be characters in the
+  range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), used to
+  express numbers in base ten.

+
+  

+
+  
While the formats described here are intended to be
+  subsets of the corresponding ISO8601 formats, this specification
+  defines parsing rules in much more detail than ISO8601.
+  Implementors are therefore encouraged to carefully examine any date
+  parsing libraries before using them to implement the parsing rules
+  described below; ISO8601 libraries might not parse dates and times
+  in exactly the same manner. [ISO8601]

+
+  

+
+
+  
2.4.5.1 Months

+
+  
A month consists of a specific
+  proleptic Gregorian date with no time-zone information and no date
+  information beyond a year and a month. [GREGORIAN]

+
+  
A string is a valid month string representing a year
+  year and month month if it
+  consists of the following components in the given order:

+
+  
  1. Four or more digits, representing year, where year > 0
    2. 
+
+   
  2. A U+002D HYPHEN-MINUS character (-)
    3. 
+
+   
  3. Two digits,
+   representing the month month, in the range
+   1 ≤ month ≤ 12
    4. 
+
+  

+
+  
The rules to parse a month string are as follows. This
+  will return either a year and month, or nothing. If at any point the
+  algorithm says that it "fails", this means that it is aborted at
+  that point and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Parse a month component to obtain year and month. If this returns
+   nothing, then fail.
    
+
+   
  4. If position is not beyond the
+   end of input, then fail.
    5. 
+
+   
  5. Return year and month.
    6. 
+
+  
The rules to parse a month component, given an input string and a position, are
+  as follows. This will return either a year and a month, or
+  nothing. If at any point the algorithm says that it "fails", this
+  means that it is aborted at that point and returns nothing.

+
+  
  1. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not at least four characters long, then
+   fail. Otherwise, interpret the resulting sequence as a base-ten
+   integer. Let that number be the year.
    2. 
+
+   
  2. If year is not a number greater than
+   zero, then fail.
    3. 
+
+   
  3. If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character,
+   then fail. Otherwise, move position forwards
+   one character.
    4. 
+
+   
  4. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not exactly two characters long, then fail. Otherwise,
+   interpret the resulting sequence as a base-ten integer. Let that
+   number be the month.
    5. 
+
+   
  5. If month is not a number in the range
+   1 ≤ month ≤ 12, then
+   fail.
    6. 
+
+   
  6. Return year and month.
    7. 
+
+  

+
+
+  
2.4.5.2 Dates

+
+  
A date consists of a specific
+  proleptic Gregorian date with no time-zone information, consisting
+  of a year, a month, and a day. [GREGORIAN]

+
+  
A string is a valid date string representing a year
+  year, month month, and day
+  day if it consists of the following components
+  in the given order:

+
+  
  1. A valid month string, representing year and month
    2. 
+
+   
  2. A U+002D HYPHEN-MINUS character (-)
    3. 
+
+   
  3. Two digits,
+   representing day, in the range
+   1 ≤ day ≤ maxday where maxday is the number of days
+   in the month month and year year
    4. 
+
+  

+
+  
The rules to parse a date string are as follows. This
+  will return either a date, or nothing. If at any point the algorithm
+  says that it "fails", this means that it is aborted at that point
+  and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
    
+
+   
  4. If position is not beyond the
+   end of input, then fail.
    5. 
+
+   
  5. Let date be the date with year year, month month, and day day.
    6. 
+
+   
  6. Return date.
    7. 
+
+  
The rules to parse a date component, given an input string and a position, are
+  as follows. This will return either a year, a month, and a day, or
+  nothing. If at any point the algorithm says that it "fails", this
+  means that it is aborted at that point and returns nothing.

+
+  
  1. Parse a month component to obtain year and month. If this returns
+   nothing, then fail.
    2. 
+
+   
  2. Let maxday be the number of days
+   in month month of year year.
    3. 
+
+   
  3. If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character,
+   then fail. Otherwise, move position forwards
+   one character.
    4. 
+
+   
  4. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not exactly two characters long, then fail. Otherwise,
+   interpret the resulting sequence as a base-ten integer. Let that
+   number be the day.
    5. 
+
+   
  5. If day is not a number in the range
+   1 ≤ day ≤ maxday, then fail.
    6. 
+
+   
  6. Return year, month,
+   and day.
    7. 
+
+  

+
+
+  
2.4.5.3 Times

+
+  
A time consists of a specific
+  time with no time-zone information, consisting of an hour, a minute,
+  a second, and a fraction of a second.

+
+  
A string is a valid time string representing an hour
+  hour, a minute minute, and a
+  second second if it consists of the following
+  components in the given order:

+
+  
  1. Two digits,
+   representing hour, in the range
+   0 ≤ hour ≤ 23
    2. 
+
+   
  2. A U+003A COLON character (:)
    3. 
+
+   
  3. Two digits,
+   representing minute, in the range
+   0 ≤ minute ≤ 59
    4. 
+
+   
  4. Optionally (required if second is
+   non-zero):
+
+    
    1. A U+003A COLON character (:)
      2. 
+
+     
    2. Two digits,
+     representing the integer part of second, in
+     the range 0 ≤ s ≤ 59
      3. 
+
+     
    3. Optionally (required if second is not an
+     integer):
+
+      
      1. A 002E FULL STOP character (.)
        2. 
+
+       
      2. One or more digits, representing the
+       fractional part of second
        3. 
+
+      
      4. 
+
+    
    5. 
+
+  
The second component cannot be
+  60 or 61; leap seconds cannot be represented.

+
+  

+
+  
The rules to parse a time string are as follows. This
+  will return either a time, or nothing. If at any point the algorithm
+  says that it "fails", this means that it is aborted at that point
+  and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
    
+
+   
  4. If position is not beyond the
+   end of input, then fail.
    5. 
+
+   
  5. Let time be the time with hour hour, minute minute, and second
+   second.
    6. 
+
+   
  6. Return time.
    7. 
+
+  
The rules to parse a time component, given an input string and a position, are
+  as follows. This will return either an hour, a minute, and a second,
+  or nothing. If at any point the algorithm says that it "fails", this
+  means that it is aborted at that point and returns nothing.

+
+  
  1. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not exactly two characters long, then fail. Otherwise,
+   interpret the resulting sequence as a base-ten integer. Let that
+   number be the hour.
    2. 
+
+   
  2. If hour is not a number in the range
+   0 ≤ hour ≤ 23, then
+   fail.
    3. 
+
+   
  3. If position is beyond the end of input or if the character at position is not a U+003A COLON character, then
+   fail. Otherwise, move position forwards one
+   character.
    4. 
+
+   
  4. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not exactly two characters long, then fail. Otherwise,
+   interpret the resulting sequence as a base-ten integer. Let that
+   number be the minute.
    5. 
+
+   
  5. If minute is not a number in the range
+   0 ≤ minute ≤ 59, then
+   fail.
    6. 
+
+   
  6. Let second be a string with the value
+   "0".
    7. 
+
+   
  7. 
+
+    
    If position is not beyond the end of
+    input and the character at position is a U+003A COLON, then run these
+    substeps:
    
+
+    
    1. Advance position to the next character
+     in input.
      2. 
+
+     
    2. If position is beyond the end of input, or at the last character in input, or if the next two characters in
+     input starting at position are not two characters both in the range
+     U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
+     fail.
      3. 
+
+     
    3. Collect a sequence of characters that are
+     either characters in the range U+0030 DIGIT ZERO (0) to U+0039
+     DIGIT NINE (9) or U+002E FULL STOP characters. If the collected
+     sequence has more than one U+002E FULL STOP characters, or if the
+     last character in the sequence is a U+002E FULL STOP character,
+     then fail. Otherwise, let the collected string be second instead of its previous value.
      4. 
+
+    
    8. 
+
+   
  8. Interpret second as a base-ten number
+   (possibly with a fractional part). Let second
+   be that number instead of the string version.
    9. 
+
+   
  9. If second is not a number in the range
+   0 ≤ second < 60, then
+   fail.
    10. 
+
+   
  10. Return hour, minute,
+   and second.
    11. 
+
+  

+
+
+  
2.4.5.4 Local dates and times

+
+  
A local date and time
+  consists of a specific proleptic Gregorian date, consisting of a
+  year, a month, and a day, and a time, consisting of an hour, a
+  minute, a second, and a fraction of a second, but expressed without
+  a time zone. [GREGORIAN]

+
+  
A string is a valid local date and time string
+  representing a date and time if it consists of the following
+  components in the given order:

+
+  
  1. A valid date string representing the date.
    2. 
+
+   
  2. A U+0054 LATIN CAPITAL LETTER T character (T).
    3. 
+
+   
  3. A valid time string representing the time.
    4. 
+
+  

+
+  
The rules to parse a local date and time string are as
+  follows. This will return either a date and time, or nothing. If at
+  any point the algorithm says that it "fails", this means that it is
+  aborted at that point and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
    
+
+   
  4. If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T
+   character (T) then fail. Otherwise, move position forwards one character.
    5. 
+
+   
  5. Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
    
+
+   
  6. If position is not beyond the
+   end of input, then fail.
    7. 
+
+   
  7. Let date be the date with year year, month month, and day day.
    8. 
+
+   
  8. Let time be the time with hour hour, minute minute, and second
+   second.
    9. 
+
+   
  9. Return date and time.
    10. 
+
+  

+
+
+
+  
2.4.5.5 Global dates and times

+
+  
A global date and time
+  consists of a specific proleptic Gregorian date, consisting of a
+  year, a month, and a day, and a time, consisting of an hour, a
+  minute, a second, and a fraction of a second, expressed with a
+  time-zone offset, consisting of a signed number of hours and
+  minutes. [GREGORIAN]

+
+  
A string is a valid global date and time string
+  representing a date, time, and a time-zone offset if it consists of
+  the following components in the given order:

+
+  
  1. A valid date string representing the date
    2. 
+
+   
  2. A U+0054 LATIN CAPITAL LETTER T character (T)
    3. 
+
+   
  3. A valid time string representing the time
    4. 
+
+   
  4. Either:
+
+    
    • A U+005A LATIN CAPITAL LETTER Z character (Z), allowed only
+     if the time zone is UTC
      • 
+
+     
    • Or:
+
+      
      1. Either a U+002B PLUS SIGN character (+) or a U+002D
+       HYPHEN-MINUS character (-), representing the sign of the
+       time-zone offset
        2. 
+
+       
      2. Two digits,
+       representing the hours component hour of
+       the time-zone offset, in the range 0 ≤ hour ≤ 23
        3. 
+
+       
      3. A U+003A COLON character (:)
        4. 
+
+       
      4. Two digits,
+       representing the minutes component minute
+       of the time-zone offset, in the range 0 ≤ minute ≤ 59
        5. 
+
+      
      • 
+
+    
    5. 
+
+  
This format allows for time-zone offsets from -23:59
+  to +23:59. In practice, however, the range of offsets of actual time
+  zones is -12:00 to +14:00, and the minutes component of offsets of
+  actual time zones is always either 00, 30, or 45.

+
+  

+
+   
The following are some examples of dates written as valid global date and
+   time strings.

+
+   
"0037-12-13T00:00Z"

+
+    
Midnight UTC on the birthday of Nero (the Roman Emperor). See
+    below for further discussion on which date this actually
+    corresponds to.

+
+    
"1979-10-14T12:00:00.001-04:00"

+
+    
One millisecond after noon on October 14th 1979, in the time
+    zone in use on the east coast of the USA during daylight saving
+    time.

+
+    
"8592-01-01T02:09+02:09"

+
+    
Midnight UTC on the 1st of January, 8592. The time zone
+    associated with that time is two hours and nine minutes ahead of
+    UTC, which is not currently a real time zone, but is nonetheless
+    allowed.

+
+   
Several things are notable about these dates:

+
+   
  • Years with fewer than four digits have to be
+    zero-padded. The date "37-12-13" would not be a valid date.
    • 
+
+    
  • To unambiguously identify a moment in time prior to the
+    introduction of the Gregorian calendar, the date has to be first
+    converted to the Gregorian calendar from the calendar in use at
+    the time (e.g. from the Julian calendar). The date of Nero's birth
+    is the 15th of December 37, in the Julian Calendar, which is the
+    13th of December 37 in the proleptic Gregorian Calendar.
    •  
+
+    
  • The time and time-zone offset components are not optional.
    • 
+
+    
  • Dates before the year one can't be represented as a datetime
+    in this version of HTML.
    • 
+
+    
  • Time-zone offsets differ based on daylight savings time.
    • 
+
+   

+
+  

+
+  
The best representation of the global date and time
+  string datetime is the valid global
+  date and time string representing datetime with the last character of the string not
+  being a U+005A LATIN CAPITAL LETTER Z character (Z), even if the
+  time zone is UTC, and with a U+002D HYPHEN-MINUS character (-)
+  representing the sign of the time-zone offset when the time zone is
+  UTC.

+
+  
The rules to parse a global date and time string are
+  as follows. This will return either a time in UTC, with associated
+  time-zone offset information for round tripping or display purposes,
+  or nothing. If at any point the algorithm says that it "fails", this
+  means that it is aborted at that point and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
    
+
+   
  4. If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T
+   character (T) then fail. Otherwise, move position forwards one character.
    5. 
+
+   
  5. Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
    
+
+   
  6. If position is beyond the end of input, then fail.
    7. 
+
+   
  7. Parse a time-zone offset component to obtain
+   timezonehours and timezoneminutes. If this returns
+   nothing, then fail.
    
+
+   
  8. If position is not beyond the
+   end of input, then fail.
    9. 
+
+   
  9. Let time be the moment in time at year
+   year, month month, day day, hours hour, minute minute, second second,
+   subtracting timezonehours
+   hours and timezoneminutes
+   minutes. That moment in time is a moment in the UTC
+   time zone.
    10. 
+
+   
  10. Let timezone be timezonehours hours and timezoneminutes minutes from
+   UTC.
    11. 
+
+   
  11. Return time and timezone.
    12. 
+
+  
The rules to parse a time-zone offset component, given
+  an input string and a position, are as follows. This will return either
+  time-zone hours and time-zone minutes, or nothing. If at any point
+  the algorithm says that it "fails", this means that it is aborted at
+  that point and returns nothing.

+
+  
  1. 
+
+    
    If the character at position is a U+005A
+    LATIN CAPITAL LETTER Z character (Z), then:
    
+
+    
    1. Let timezonehours
+     be 0.
      2. 
+
+     
    2. Let timezoneminutes be 0.
      3. 
+
+     
    3. Advance position to the next character
+     in input.
      4. 
+
+    
    Otherwise, if the character at position is
+    either a U+002B PLUS SIGN (+) or a U+002D HYPHEN-MINUS (-),
+    then:
    
+
+    
    1. If the character at position is a
+     U+002B PLUS SIGN (+), let sign be
+     "positive". Otherwise, it's a U+002D HYPHEN-MINUS (-); let sign be "negative".
      2. 
+
+     
    2. Advance position to the next character
+     in input.
      3. 
+
+     
    3. Collect a sequence of characters in the range
+     U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+     sequence is not exactly two characters long, then
+     fail. Otherwise, interpret the resulting sequence as a base-ten
+     integer. Let that number be the timezonehours.
      4. 
+
+     
    4. If timezonehours is
+     not a number in the range 0 ≤ timezonehours ≤ 23, then fail.
      5. 
+
+     
    5. If sign is "negative", then negate timezonehours.
      6. 
+
+     
    6. If position is beyond the end of input or if the character at position is not a U+003A COLON character, then
+     fail. Otherwise, move position forwards one
+     character.
      7. 
+
+     
    7. Collect a sequence of characters in the range
+     U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+     sequence is not exactly two characters long, then
+     fail. Otherwise, interpret the resulting sequence as a base-ten
+     integer. Let that number be the timezoneminutes.
      8. 
+
+     
    8. If timezoneminutes is
+     not a number in the range 0 ≤ timezoneminutes ≤ 59, then fail.
      9. 
+
+     
    9. If sign is "negative", then negate timezoneminutes.
      10. 
+
+    
    Otherwise, fail.
    
+
+   
    2. 
+
+   
  2. Return timezonehours
+   and timezoneminutes.
    3. 
+
+  

+
+
+  
2.4.5.6 Weeks

+
+  
A week consists of a week-year
+  number and a week number representing a seven-day period starting on
+  a Monday. Each week-year in this calendaring system has either 52 or
+  53 such seven-day periods, as defined below. The seven-day period
+  starting on the Gregorian date Monday December 29th 1969
+  (1969-12-29) is defined as week number 1 in week-year
+  1970. Consecutive weeks are numbered sequentially. The week before
+  the number 1 week in a week-year is the last week in the previous
+  week-year, and vice versa. [GREGORIAN]

+
+  
A week-year with a number year has 53 weeks
+  if it corresponds to either a year year in the
+  proleptic Gregorian calendar that has a Thursday as its first day
+  (January 1st), or a year year in the proleptic
+  Gregorian calendar that has a Wednesday as its first day (January
+  1st) and where year is a number divisible by
+  400, or a number divisible by 4 but not by 100. All other week-years
+  have 52 weeks.

+
+  
The week number of the last day of a week-year with 53
+  weeks is 53; the week number of the last day of a week-year with 52
+  weeks is 52.

+
+  
The week-year number of a particular day can be
+  different than the number of the year that contains that day in the
+  proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of
+  the Gregorian year y.

+
+  
A string is a valid week string representing a
+  week-year year and week week
+  if it consists of the following components in the given order:

+
+  
  1. Four or more digits, representing year, where year > 0
    2. 
+
+   
  2. A U+002D HYPHEN-MINUS character (-)
    3. 
+
+   
  3. A U+0057 LATIN CAPITAL LETTER W character (W)
    4. 
+
+   
  4. Two digits,
+   representing the week week, in the range
+   1 ≤ week ≤ maxweek, where maxweek is the
+   week number of the last day of week-year year
    5. 
+
+  

+
+  
The rules to parse a week string are as follows. This
+  will return either a week-year number and week number, or
+  nothing. If at any point the algorithm says that it "fails", this
+  means that it is aborted at that point and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not at least four characters long, then
+   fail. Otherwise, interpret the resulting sequence as a base-ten
+   integer. Let that number be the year.
    4. 
+
+   
  4. If year is not a number greater than
+   zero, then fail.
    5. 
+
+   
  5. If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character,
+   then fail. Otherwise, move position forwards
+   one character.
    6. 
+
+   
  6. If position is beyond the end of input or if the character at position is not a U+0057 LATIN CAPITAL LETTER W
+   character (W), then fail. Otherwise, move position forwards one character.
    7. 
+
+   
  7. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
+   sequence is not exactly two characters long, then fail. Otherwise,
+   interpret the resulting sequence as a base-ten integer. Let that
+   number be the week.
    8. 
+
+   
  8. Let maxweek be the week number of
+   the last day of year year.
    9. 
+
+   
  9. If week is not a number in the range
+   1 ≤ week ≤ maxweek, then fail.
    10. 
+
+   
  10. If position is not beyond the
+   end of input, then fail.
    11. 
+
+   
  11. Return the week-year number year and the
+   week number week.
    12. 
+
+  

+
+
+  
2.4.5.7 Vaguer moments in time

+
+  
A string is a valid date or time string if it is also
+  one of the following:

+
+  
A string is a valid date or time string in content if
+  it consists of zero or more White_Space characters,
+  followed by a valid date or time string, followed by
+  zero or more further White_Space characters.

+
+  
A string is a valid date string with optional time if
+  it is also one of the following:

+
+  
A string is a valid date string in content with optional
+  time if it consists of zero or more White_Space
+  characters, followed by a valid date string with optional
+  time, followed by zero or more further
+  White_Space characters.

+
+  

+
+  
The rules to parse a date or time string are as
+  follows. The algorithm is invoked with a flag indicating if the
+  in attribute variant or the in content variant is to
+  be used. The algorithm will return either a date, a time, a global date and time, or nothing. If
+  at any point the algorithm says that it "fails", this means that it
+  is aborted at that point and returns nothing.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. For the in content variant: skip White_Space
+   characters.
    4. 
+
+   
  4. Set start position to the same position
+   as position.
    5. 
+
+   
  5. Set the date present and time present flags to true.
    6. 
+
+   
  6. Parse a date component to obtain year, month, and day. If this fails, then set the date
+   present flag to false.
    
+
+   
  7. 
+
+    
    If date present is true, and position is not beyond the end of input, and the character at position is a U+0054 LATIN CAPITAL LETTER T
+    character (T), then advance position to the
+    next character in input.
    
+
+    
    Otherwise, if date present is true, and
+    either position is beyond the end of input or the character at position is not a U+0054 LATIN CAPITAL LETTER T
+    character (T), then set time present to
+    false.
    
+
+    
    Otherwise, if date present is false, set
+    position back to the same position as start position.
    
+
+   
    8. 
+
+   
  8. If the time present flag is true, then
+   parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
    9. 
+
+   
  9. If the date present and time present flags are both true, but position is beyond the end of input, then fail.
    10. 
+
+   
  10. If the date present and time present flags are both true, parse a
+   time-zone offset component to obtain timezonehours and timezoneminutes. If this returns
+   nothing, then fail.
    
+
+   
  11. For the in content variant: skip White_Space
+   characters.
    12. 
+
+   
  12. If position is not beyond the
+   end of input, then fail.
    13. 
+
+   
  13. 
+
+    
    If the date present flag is true and the
+    time present flag is false, then let date be the date with year year, month month, and day day, and return date.
    
+
+    
    Otherwise, if the time present flag is true
+    and the date present flag is false, then let
+    time be the time with hour hour, minute minute, and second
+    second, and return time.
    
+
+    
    Otherwise, let time be the moment in time
+    at year year, month month,
+    day day, hours hour,
+    minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes, that moment in time being a
+    moment in the UTC time zone; let timezone be
+    timezonehours hours and
+    timezoneminutes minutes
+    from UTC; and return time and timezone.
    
+
+   
    14. 
+
+  

+
+
+  
2.4.6 Colors

+
+  
A simple color consists of three 8-bit numbers in the
+  range 0..255, representing the red, green, and blue components of
+  the color respectively, in the sRGB color space. [SRGB]

+
+  
A string is a valid simple color if it is exactly
+  seven characters long, and the first character is a U+0023 NUMBER
+  SIGN character (#), and the remaining six characters are all in the
+  range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN
+  CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN
+  SMALL LETTER A to U+0066 LATIN SMALL LETTER F, with the first two
+  digits representing the red component, the middle two digits
+  representing the green component, and the last two digits
+  representing the blue component, in hexadecimal.

+
+  
A string is a valid lowercase simple color if it is a
+  valid simple color and doesn't use any characters in
+  the range U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL
+  LETTER F.

+
+  

+
+  
The rules for parsing simple color values are as given
+  in the following algorithm. When invoked, the steps must be followed
+  in the order given, aborting at the first step that returns a
+  value. This algorithm will return either a simple color
+  or an error.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. If input is not exactly seven characters
+   long, then return an error.
    3. 
+
+   
  3. If the first character in input is not a
+   U+0023 NUMBER SIGN character (#), then return an error.
    4. 
+
+   
  4. If the last six characters of input are
+   not all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
+   (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER
+   F, U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, then
+   return an error.
    5. 
+
+   
  5. Let result be a simple
+   color.
    
+
+   
  6. Interpret the second and third characters as a hexadecimal
+   number and let the result be the red component of result.
    
+
+   
  7. Interpret the fourth and fifth characters as a hexadecimal
+   number and let the result be the green component of result.
    
+
+   
  8. Interpret the sixth and seventh characters as a hexadecimal
+   number and let the result be the blue component of result.
    
+
+   
  9. Return result.
    
+
+  
The rules for serializing simple color values given a
+  simple color are as given in the following
+  algorithm:

+
+  
  1. Let result be a string consisting of a
+   single U+0023 NUMBER SIGN character (#).
    2. 
+
+   
  2. Convert the red, green, and blue components in turn to
+   two-digit hexadecimal numbers using the digits U+0030 DIGIT ZERO
+   (0) to U+0039 DIGIT NINE (9) and U+0061 LATIN SMALL LETTER A
+   to U+0066 LATIN SMALL LETTER F, zero-padding if necessary, and
+   append these numbers to result, in the order
+   red, green, blue.
    
+
+   
  3. Return result, which will be a
+   valid lowercase simple color.
    4. 
+
+  
Some obsolete legacy attributes parse colors in a more
+  complicated manner, using the rules for parsing a legacy color
+  value, which are given in the following algorithm. When
+  invoked, the steps must be followed in the order given, aborting at
+  the first step that returns a value. This algorithm will return
+  either a simple color or an error.

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. If input is the empty string, then
+   return an error.
    3. 
+
+   
  3. If input is an ASCII
+   case-insensitive match for the string "transparent", then return an error.
    4. 
+
+   
  4. If input is an ASCII
+   case-insensitive match for one of the keywords listed in the
+   SVG color
+   keywords or CSS2 System
+   Colors sections of the CSS3 Color specification, then return
+   the simple color corresponding to that keyword. [CSSCOLOR]
    5. 
+
+   
  5. 
+
+    
    If input is four characters long, and the
+    first character in input is a U+0023 NUMBER
+    SIGN character (#), and the last three characters of input are all in the range U+0030 DIGIT ZERO (0)
+    to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046
+    LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A to U+0066
+    LATIN SMALL LETTER F, then run these substeps:
    
+
+    
    1. Let result be a simple
+     color.
      
+
+     
    2. Interpret the second character of input as a hexadecimal digit; let the red
+     component of result be the resulting number
+     multiplied by 17.
      
+
+     
    3. Interpret the third character of input
+     as a hexadecimal digit; let the green component of result be the resulting number multiplied by
+     17.
      
+
+     
    4. Interpret the fourth character of input as a hexadecimal digit; let the blue
+     component of result be the resulting number
+     multiplied by 17.
      
+
+     
    5. Return result.
      
+
+    
    6. 
+
+   
  6. Replace any characters in input that
+   have a Unicode code point greater than U+FFFF (i.e. any characters
+   that are not in the basic multilingual plane) with the
+   two-character string "00".
    7. 
+
+   
  7. If input is longer than 128 characters,
+   truncate input, leaving only the first 128
+   characters.
    8. 
+
+   
  8. If the first character in input is a
+   U+0023 NUMBER SIGN character (#), remove it.
    9. 
+
+   
  9. Replace any character in input that is
+   not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9),
+   U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, and
+   U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F with the
+   character U+0030 DIGIT ZERO (0).
    10. 
+
+   
  10. While input's length is zero or not a
+   multiple of three, append a U+0030 DIGIT ZERO (0) character to input.
    11. 
+
+   
  11. Split input into three strings of equal
+   length, to obtain three components. Let length
+   be the length of those components (one third the length of input).
    12. 
+
+   
  12. If length is greater than 8, then remove
+   the leading length-8
+   characters in each component, and let length be
+   8.
    13. 
+
+   
  13. While length is greater than two and the
+   first character in each component is a U+0030 DIGIT ZERO (0)
+   character, remove that character and reduce length by one.
    14. 
+
+   
  14. If length is still greater than
+   two, truncate each component, leaving only the first two
+   characters in each.
    15. 
+
+   
  15. Let result be a simple
+   color.
    
+
+   
  16. Interpret the first component as a hexadecimal number; let
+   the red component of result be the resulting
+   number.
    17. 
+
+   
  17. Interpret the second component as a hexadecimal number; let
+   the green component of result be the resulting
+   number.
    18. 
+
+   
  18. Interpret the third component as a hexadecimal number; let
+   the blue component of result be the resulting
+   number.
    19. 
+
+   
  19. Return result.
    
+
+  

+
+  
The 2D graphics
+  context has a separate color syntax that also handles
+  opacity.

+
+  
+
+
+  
2.4.7 Space-separated tokens

+
+  
A set of space-separated tokens is a string containing
+  zero or more words separated by one or more space characters, where words consist of any
+  string of one or more characters, none of which are space characters.

+
+  
A string containing a set of space-separated tokens
+  may have leading or trailing space
+  characters.

+
+  
An unordered set of unique space-separated tokens is a
+  set of space-separated tokens where none of the words
+  are duplicated.

+
+  
An ordered set of unique space-separated tokens is a
+  set of space-separated tokens where none of the words
+  are duplicated but where the order of the tokens is meaningful.

+
+  
Sets of
+  space-separated tokens sometimes have a defined set of
+  allowed values. When a set of allowed values is defined, the tokens
+  must all be from that list of allowed values; other values are
+  non-conforming. If no such set of allowed values is provided, then
+  all values are conforming.

+
+  

+
+  
When a user agent has to split a string on spaces, it
+  must use the following algorithm:

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Let tokens be a list of tokens,
+   initially empty.
    4. 
+
+   
  4. Skip whitespace
    5. 
+
+   
  5. While position is not past the end of
+   input:
    
+
+    
    1. Collect a sequence of characters that are not
+     space characters.
      2. 
+
+     
    2. Add the string collected in the previous step to tokens.
      3. 
+
+     
    3. Skip whitespace
      4. 
+
+    
    6. 
+
+   
  6. Return tokens.
    7. 
+
+  
When a user agent has to remove a token from a string,
+  it must use the following algorithm:

+
+  
  1. Let input be the string being
+   modified.
    2. 
+
+   
  2. Let token be the token being removed. It
+   will not contain any space
+   characters.
    3. 
+
+   
  3. Let output be the output string,
+   initially empty.
    4. 
+
+   
  4. Let position be a pointer into input, initially pointing at the start of the
+   string.
    5. 
+
+   
  5. Loop: If position is beyond the
+   end of input, abort these steps.
    6. 
+
+   
  6. If the character at position is a
+   space character:
    
+
+    
    1. Append the character at position to
+     the end of output.
      2. 
+
+     
    2. Advance position so it points at the
+     next character in input.
      3. 
+
+     
    3. Return to the step labeled loop.
      4. 
+
+    
    7. 
+
+   
  7. Otherwise, the character at position is
+   the first character of a token. Collect a sequence of
+   characters that are not space
+   characters, and let that be s.
    8. 
+
+   
  8. If s is exactly equal to token, then:
    
+
+    
    1. Skip whitespace (in input).
      2. 
+
+     
    2. Remove any space
+     characters currently at the end of output.
      3. 
+
+     
    3. If position is not past the end of
+     input, and output is not
+     the empty string, append a single U+0020 SPACE character at the
+     end of output.
      4. 
+
+    
    9. 
+
+   
  9. Otherwise, append s to the end of output.
    10. 
+
+   
  10. Return to the step labeled loop.
    11. 
+
+  
This causes any occurrences of the token to be
+  removed from the string, and any spaces that were surrounding the
+  token to be collapsed to a single space, except at the start and end
+  of the string, where such spaces are removed.

+
+  

+
+
+
+  
2.4.8 Comma-separated tokens

+
+  
A set of comma-separated tokens is a string containing
+  zero or more tokens each separated from the next by a single U+002C
+  COMMA character (,), where tokens consist of any string of zero or
+  more characters, neither beginning nor ending with space characters, nor containing any
+  U+002C COMMA characters (,), and optionally surrounded by space characters.

+
+  
For instance, the string " a ,b,,d d " consists of four
+  tokens: "a", "b", the empty string, and "d d". Leading and
+  trailing whitespace around each token doesn't count as part of the
+  token, and the empty string can be a token.

+
+  
Sets of
+  comma-separated tokens sometimes have further restrictions on
+  what consists a valid token. When such restrictions are defined, the
+  tokens must all fit within those restrictions; other values are
+  non-conforming. If no such restrictions are specified, then all
+  values are conforming.

+
+  

+
+  
When a user agent has to split a string on commas, it
+  must use the following algorithm:

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Let tokens be a list of tokens,
+   initially empty.
    4. 
+
+   
  4. Token: If position is past the
+   end of input, jump to the last step.
    5. 
+
+   
  5. Collect a sequence of characters that are not
+   U+002C COMMA characters (,). Let s be the resulting sequence (which might be the
+   empty string).
    6. 
+
+   
  6. Remove any leading or trailing sequence of space characters from s.
    7. 
+
+   
  7. Add s to tokens.
    8. 
+
+   
  8. If position is not past the end of input, then the character at position is a U+002C COMMA character (,); advance
+   position past that character.
    9. 
+
+   
  9. Jump back to the step labeled token.
    10. 
+
+   
  10. Return tokens.
    11. 
+
+  

+
+
+
+
+  
2.4.9 References

+
+  
A valid hash-name reference to an element of type type is a string consisting of a U+0023 NUMBER SIGN
+  character (#) followed by a string which exactly matches the value
+  of the name attribute of an element with type
+  type in the document.

+
+  

+
+  
The rules for parsing a hash-name reference to an
+  element of type type are as follows:

+
+  
  1. If the string being parsed does not contain a U+0023 NUMBER
+   SIGN character, or if the first such character in the string is the
+   last character in the string, then return null and abort these
+   steps.
    2. 
+
+   
  2. Let s be the string from the character
+   immediately after the first U+0023 NUMBER SIGN character in the
+   string being parsed up to the end of that string.
    3. 
+
+   
  3. Return the first element of type type
+   that has an id attribute whose value
+   is a case-sensitive match for s or
+   a name attribute whose value is a
+   compatibility caseless match for s.
    4. 
+
+   
+
+  

+
+
+  
2.4.10 Media queries

+
+  
A string is a valid media query if it matches the
+  media_query_list production of the Media
+  Queries specification. [MQ]

+
+  
A string matches the environment of the user if it is
+  the empty string, a string consisting of only space characters, or is a media query that matches
+  the user's environment according to the definitions given in the
+  Media Queries specification. [MQ]

+
+
+
+
+  
2.5 URLs

+
+  
2.5.1 Terminology

+
+  
+
+  
A URL is a string used to identify a resource.

+
+  
A URL is a valid URL if at least one of
+  the following conditions holds:

+
+  
A string is a valid non-empty URL if it is a
+  valid URL but it is not the empty string.

+
+  
A string is a valid URL potentially surrounded by
+  spaces if, after stripping leading and trailing whitespace from
+  it, it is a valid URL.

+
+  
A string is a valid non-empty URL potentially surrounded by
+  spaces if, after stripping leading and trailing whitespace from
+  it, it is a valid non-empty URL.

+
+  

+
+  
To parse a URL url into its
+  component parts, the user agent must use the parse
+  an address algorithm defined by the IRI specification. [RFC3987]

+
+  
Parsing a URL can fail. If it does not, then it results in the
+  following components, again as defined by the IRI specification:

+
+  
  • <scheme>
    • 
+   
  • <host>
    • 
+   
  • <port>
    • 
+   
  • <hostport>
    • 
+   
  • <path>
    • 
+   
  • <query>
    • 
+   
  • <fragment>
    • 
+   
  • <host-specific>
    • 
+  
To resolve a URL to an absolute URL
+  relative to either another absolute URL or an element,
+  the user agent must use the following steps. Resolving a URL can
+  result in an error, in which case the URL is not resolvable.

+
+  
  1. Let url be the URL being
+   resolved.
    2. 
+
+   
  2. 
+
+    
    Let encoding be determined as follows:
    
+
+    
    If the URL had a character encoding defined when the URL was
+     created or defined
    
+
+     
    The URL character encoding is as defined.
    
+
+     
    If the URL came from a script (e.g. as an argument to a
+     method)
    
+
+     
    The URL character encoding is the script's URL character
+     encoding.
    
+
+     
    If the URL came from a DOM node (e.g. from an element)
    
+
+     
    The node has a Document, and the URL character
+     encoding is the document's character encoding.
    
+
+    
    3. 
+
+   
  3. If encoding is a UTF-16 encoding, then
+   change the value of encoding to UTF-8.
    4. 
+
+   
  4. 
+
+    
    If the algorithm was invoked with an absolute URL
+    to use as the base URL, let base be that
+    absolute URL.
    
+
+    
    Otherwise, let base be the base URI of
+    the element, as defined by the XML Base specification, with
+    the base URI of the document entity being defined as the
+    document base URL of the Document that
+    owns the element. [XMLBASE]
    
+
+    
    For the purposes of the XML Base specification, user agents
+    must act as if all Document objects represented XML
+    documents.
    
+
+    
    It is possible for xml:base attributes to be present
+    even in HTML fragments, as such attributes can be added
+    dynamically using script. (Such scripts would not be conforming,
+    however, as xml:base attributes
+    are not allowed in HTML documents.)
    
+
+    
    The document base URL of a Document
+    object is the absolute URL obtained by running these
+    substeps:
    
+
+    
    1. Let fallback base url be the
+     document's address.
      2. 
+
+     
    2. 
+
+      
+
+      
+
+      
      If fallback base url is
+      about:blank, and the Document's
+      browsing context has a creator browsing
+      context, then let fallback base url
+      be the document base URL of the creator
+      Document instead.
      
+
+     
      3. 
+
+     
    3. If there is no base element that is both a
+     child of the head element and has an
+     href attribute, then the
+     document base URL is fallback base
+     url.
      4. 
+
+     
    4. Otherwise, let url be the value of the
+     href attribute of the first
+     such element.
      5. 
+
+     
    5. Resolve url relative to fallback base
+     url (thus, the base href attribute isn't affected by
+     xml:base attributes).
      6. 
+
+     
    6. The document base URL is the result of the
+     previous step if it was successful; otherwise it is fallback base url.
      7. 
+
+    
    5. 
+
+   
  5. Return the result of applying the resolve
+   an address algorithm defined by the IRI specification to
+   resolve url relative to base using encoding encoding. [RFC3987]
    6. 
+
+  

+
+  
A URL is an absolute URL if resolving it results in the same output
+  regardless of what it is resolved relative to, and that output is
+  not a failure.

+
+  
An absolute URL is a hierarchical URL if,
+  when resolved and then parsed, there is a character immediately
+  after the <scheme> component
+  and it is a U+002F SOLIDUS character (/).

+
+  
An absolute URL is an authority-based URL
+  if, when resolved and then parsed, there are two characters
+  immediately after the <scheme>
+  component and they are both U+002F SOLIDUS characters (//).

+
+  
This specification defines the URL
+  about:legacy-compat as a reserved, though
+  unresolvable, about: URI, for use in DOCTYPEs in HTML
+  documents when needed for compatibility with XML tools. [ABOUT]

+
+  
This specification defines the URL
+  about:srcdoc as a reserved, though
+  unresolvable, about: URI, that is used as
+  the document's address of iframe srcdoc documents. [ABOUT]

+
+  
The term "URL" in this specification is used in a
+  manner distinct from the precise technical meaning it is given in
+  RFC 3986. Readers familiar with that RFC will find it easier to read
+  this specification if they pretend the term "URL" as used
+  herein is really called something else altogether. This is a
+  willful violation of RFC 3986. [RFC3986]

+
+
+  

+
+  
2.5.2 Dynamic changes to base URLs

+
+  
When an xml:base attribute
+  changes, the attribute's element, and all descendant elements, are
+  affected by a base URL change.

+
+  
When a document's document base URL changes, all
+  elements in that document are affected by a base URL
+  change.

+
+  
When an element is moved from one document to another, if the two
+  documents have different base
+  URLs, then that element and all its descendants are
+  affected by a base URL change.

+
+  
When an element is affected by a base URL change, it
+  must act as described in the following list:

+
+  
If the element is a hyperlink
+   element

+
+   

+
+    
If the absolute URL identified by the hyperlink is
+    being shown to the user, or if any data derived from that URL is
+    affecting the display, then the href attribute should be re-resolved relative to the element
+    and the UI updated appropriately.

+
+    
For example, the CSS :link/:visited pseudo-classes might have
+    been affected.

+
+
+    
If the hyperlink has a ping attribute and its absolute URL(s) are being shown to the
+    user, then the ping
+    attribute's tokens should be re-resolved relative to the element and the UI updated
+    appropriately.

+
+
+   

+
+   
If the element is a q, blockquote,
+   section, article, ins, or
+   del element with a cite
+   attribute

+
+   

+
+    
If the absolute URL identified by the cite attribute is being shown to the user, or if
+    any data derived from that URL is affecting the display, then the
+    URL should be re-resolved relative to the element and the UI updated
+    appropriately.

+
+   

+
+   
Otherwise

+
+   

+
+    
The element is not directly affected.

+
+    
Changing the base URL doesn't affect the image
+    displayed by img elements, although subsequent
+    accesses of the src IDL attribute
+    from script will return a new absolute URL that might
+    no longer correspond to the image being shown.

+
+   

+
+  

+
+
+
+  
2.5.3 Interfaces for URL manipulation

+
+  
An interface that has a complement of URL decomposition IDL
+  attributes will have seven attributes with the following
+  definitions:

+
+
           attribute DOMString protocol;
+           attribute DOMString host;
+           attribute DOMString hostname;
+           attribute DOMString port;
+           attribute DOMString pathname;
+           attribute DOMString search;
+           attribute DOMString hash;

+
+  
o . protocol [ = value ]

+   

+    
Returns the current scheme of the underlying URL.

+    
Can be set, to change the underlying URL's scheme.

+   

+
+   
o . host [ = value ]

+   

+    
Returns the current host and port (if it's not the default port) in the underlying URL.

+    
Can be set, to change the underlying URL's host and port.

+    
The host and the port are separated by a colon. The port part,
+    if omitted, will be assumed to be the current scheme's default
+    port.

+   

+
+   
o . hostname [ = value ]

+   

+    
Returns the current host in the underlying URL.

+    
Can be set, to change the underlying URL's host.

+   

+
+   
o . port [ = value ]

+   

+    
Returns the current port in the underlying URL.

+    
Can be set, to change the underlying URL's port.

+   

+
+   
o . pathname [ = value ]

+   

+    
Returns the current path in the underlying URL.

+    
Can be set, to change the underlying URL's path.

+   

+
+   
o . search [ = value ]

+   

+    
Returns the current query component in the underlying URL.

+    
Can be set, to change the underlying URL's query component.

+   

+
+   
o . hash [ = value ]

+   

+    
Returns the current fragment identifier in the underlying URL.

+    
Can be set, to change the underlying URL's fragment identifier.

+   

+
+  

+
+  
The attributes defined to be URL decomposition IDL attributes must
+  act as described for the attributes with the same corresponding
+  names in this section.

+
+  
In addition, an interface with a complement of URL decomposition IDL
+  attributes will define an input, which is a URL
+  that the attributes act on, and a common setter action, which is a
+  set of steps invoked when any of the attributes' setters are
+  invoked.

+
+  
The seven URL decomposition IDL attributes have similar
+  requirements.

+
+  
On getting, if the input
+  is an absolute URL that fulfills the condition given in
+  the "getter condition" column corresponding to the attribute in the
+  table below, the user agent must return the part of the input URL given in the "component"
+  column, with any prefixes specified in the "prefix" column
+  appropriately added to the start of the string and any suffixes
+  specified in the "suffix" column appropriately added to the end of
+  the string. Otherwise, the attribute must return the empty
+  string.

+
+  
On setting, the new value must first be mutated as described by
+  the "setter preprocessor" column, then mutated by %-escaping any
+  characters in the new value that are not valid in the relevant
+  component as given by the "component" column. Then, if the input is an absolute
+  URL and the resulting new value fulfills the condition given
+  in the "setter condition" column, the user agent must make a new
+  string output by replacing the component of the
+  URL given by the "component" column in the input URL with the new value;
+  otherwise, the user agent must let output be
+  equal to the input. Finally,
+  the user agent must invoke the common setter action with the
+  value of output.

+
+  
When replacing a component in the URL, if the component is part
+  of an optional group in the URL syntax consisting of a character
+  followed by the component, the component (including its prefix
+  character) must be included even if the new value is the empty
+  string.

+
+  
The previous paragraph applies in particular to the
+  ":" before a <port> component, the "?" before a <query> component, and the "#" before a <fragment> component.

+
+  
For the purposes of the above definitions, URLs must be parsed
+  using the URL parsing rules defined
+  in this specification.

+
+  
Attribute
+     Component
+     Getter Condition
+     Prefix
+     Suffix
+     Setter Preprocessor
+     Setter Condition
+   
protocol
+     <scheme>
+     —
+     —
+     U+003A COLON (:)
+     Remove all trailing U+003A COLON characters (:)
+     The new value is not the empty string
+    
host
+     <hostport>
+     input is an authority-based URL
+     —
+     —
+     —
+     The new value is not the empty string and input is an authority-based URL
+    
hostname
+     <host>
+     input is an authority-based URL
+     —
+     —
+     Remove all leading U+002F SOLIDUS characters (/)
+     The new value is not the empty string and input is an authority-based URL
+    
port
+     <port>
+     input is an authority-based URL, and contained a <port> component (possibly an empty one)
+     —
+     —
+     Remove all characters in the new value from the first that is not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), if any.
+         Remove any leading U+0030 DIGIT ZERO characters (0) in the new value.
+         If the resulting string is empty, set it to a single U+0030 DIGIT ZERO character (0).
+     input is an authority-based URL,
+         and the new value, when interpretted as a base-ten integer, is less than or equal to 65535
+    
pathname
+     <path>
+     input is a hierarchical URL
+     —
+     —
+     If it has no leading U+002F SOLIDUS character (/), prepend a U+002F SOLIDUS character (/) to the new value
+     input is hierarchical
+    
search
+     <query>
+     input is a hierarchical URL, and contained a <query> component (possibly an empty one)
+     U+003F QUESTION MARK (?)
+     —
+     Remove one leading U+003F QUESTION MARK character (?), if any
+     input is a hierarchical URL
+    
hash
+     <fragment>
+     input contained a non-empty <fragment> component
+     U+0023 NUMBER SIGN (#)
+     —
+     Remove one leading U+0023 NUMBER SIGN character (#), if any
+     —
+  

+
+  

+
+   
The table below demonstrates how the getter condition for search results in different results
+   depending on the exact original syntax of the URL:

+
+   
 Input URL
+       search value
+       Explanation
+    
 http://example.com/
+       empty string
+       No <query> component in input URL.
+     
 http://example.com/?
+       ?
+       There is a <query> component, but it is empty.
+           The question mark in the resulting value is the prefix.
+     
 http://example.com/?test
+       ?test
+       The <query> component has the value "test".
+     
 http://example.com/?test#
+       ?test
+       The (empty) <fragment> component is not part of the <query> component.
+   

+
+
+  

+
+  
2.6 Fetching resources

+
+  
When a user agent is to fetch a resource or
+  URL, optionally from an origin origin,
+  and optionally with a synchronous flag and/or a manual
+  redirect flag, the following steps must be run. (When a
+  URL is to be fetched, the URL identifies a resource to be
+  obtained.)

+
+  
+
+  
+
+  
  1. 
+
+    
    Generate the address of the resource from which Request-URIs
+    are obtained as required by HTTP for the Referer (sic) header from the
+    document's current address of the appropriate
+    Document as given by the following list. [HTTP]
    
+
+    
    When navigating
    
+
+     
    The active document of the source browsing
+     context.
    
+
+     
    When fetching resources for an element
    
+
+     
    The element's Document.
    
+
+     
    When fetching resources in response to a call to an API
    
+
+     
    The entry script's document.
    
+
+    
    Remove any <fragment>
+    component from the generated address of the resource from which
+    Request-URIs are obtained.
     
+
+    
    If the origin of the appropriate
+    Document is not a scheme/host/port tuple, then the
+    Referer (sic) header must be
+    omitted, regardless of its value.
    
+
+   
    2. 
+
+   
  2. If the algorithm was not invoked with the synchronous
+   flag, perform the remaining steps asynchronously.
    3. 
+
+   
  3. 
+
+    
    This is the main step.
    
+
+    
    If the resource is identified by an absolute URL,
+    and the resource is to be obtained using an idempotent action
+    (such as an HTTP GET or
+    equivalent), and it is already being downloaded for other
+    reasons (e.g. another invocation of this algorithm), and this
+    request would be identical to the previous one (e.g. same Accept and Origin headers), and the user agent is
+    configured such that it is to reuse the data from the existing
+    download instead of initiating a new one, then use the results of
+    the existing download instead of starting a new one.
    
+
+    
    Otherwise, at a time convenient to the user and the user agent,
+    download (or otherwise obtain) the resource, applying the
+    semantics of the relevant specifications (e.g. performing an HTTP
+    GET or POST operation, or reading the file from disk, dereferencing javascript: URLs,
+    etc).
    
+
+    
    For the purposes of the Referer (sic) header, use the
+    address of the resource from which Request-URIs are
+    obtained generated in the earlier step.
    
+
+    
    For the purposes of the Origin
+    header, if the fetching algorithm was
+    explicitly initiated from an origin, then the origin that initiated the HTTP request is origin. Otherwise, this is a request from
+    a "privacy-sensitive" context. [ORIGIN]
    
+
+    
    If the resource is identified by the URL
+    about:blank, then the resource is
+    immediately available and consists of the empty string, with no
+    metadata.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If there are cookies to be set, then the user agent must run
+    the following substeps:
    
+
+    
    1. Wait until ownership of the storage mutex can
+     be taken by this instance of the fetching algorithm.
      2. 
+
+     
    2. Take ownership of the storage mutex.
      3. 
+
+     
    3. Update the cookies. [COOKIES]
      4. 
+
+     
    4. Release the storage mutex so that it is once
+     again free.
      5. 
+
+    
    5. 
+
+   
  5. 
+
+    
    If the fetched resource is an HTTP redirect or equivalent,
+    then:
    
+
+    
    If the manual redirect flag is set
    
+
+     
    
+
+      
    Continue, using the fetched resource (the redirect) as the
+      result of the algorithm.
    
+
+     
    
+
+     
    Otherwise
    
+
+     
    
+
+      
    First, apply any relevant requirements for redirects (such as
+      showing any appropriate prompts). Then, redo main step,
+      but using the target of the redirect as the resource to fetch,
+      rather than the original resource.
    
+
+      
    The HTTP specification requires that 301, 302,
+      and 307 redirects, when applied to methods other than the safe
+      methods, not be followed without user confirmation. That would
+      be an appropriate prompt for the purposes of the requirement in
+      the paragraph above. [HTTP]
    
+
+     
    
+
+    
    6. 
+
+   
  6. 
+
+    
    If the algorithm was not invoked with the synchronous
+    flag: When the resource is available, or if there is an error
+    of some description, queue a task that uses the
+    resource as appropriate. If the resource can be processed
+    incrementally, as, for instance, with a progressively interlaced
+    JPEG or an HTML file, additional tasks may be queued to process
+    the data as it is downloaded. The task source for
+    these tasks is the
+    networking task source.
    
+
+    
    Otherwise, return the resource or error information to the
+    calling algorithm.
    
+
+   
    7. 
+
+  
If the user agent can determine the actual length of the resource
+  being fetched for an instance of this
+  algorithm, and if that length is finite, then that length is the
+  file's size. Otherwise, the
+  subject of the algorithm (that is, the resource being fetched) has
+  no known size. (For
+  example, the HTTP Content-Length header might
+  provide this information.)

+
+  
The user agent must also keep track of the number of bytes downloaded for
+  each instance of this algorithm. This number must exclude any
+  out-of-band metadata, such as HTTP headers.

+
+  
The application cache processing model
+  introduces some changes to the
+  networking model to handle the returning of cached
+  resources.

+
+  
The navigation
+  processing model handles redirects itself, overriding the
+  redirection handling that would be done by the fetching
+  algorithm.

+
+  
Whether the type
+  sniffing rules apply to the fetched resource depends on the
+  algorithm that invokes the rules — they are not always
+  applicable.

+
+
+  
2.6.1 Protocol concepts

+
+  
User agents can implement a variety of transfer protocols, but
+  this specification mostly defines behavior in terms of HTTP. [HTTP]

+
+  
The HTTP GET
+  method is equivalent to the default retrieval action of the
+  protocol. For example, RETR in FTP. Such actions are idempotent and
+  safe, in HTTP terms.

+
+  
The HTTP response
+  codes are equivalent to statuses in other protocols that have
+  the same basic meanings. For example, a "file not found" error is
+  equivalent to a 404 code, a server error is equivalent to a 5xx
+  code, and so on.

+
+  
The HTTP
+  headers are equivalent to fields in other protocols that have
+  the same basic meaning. For example, the HTTP authentication
+  headers are equivalent to the authentication aspects of the FTP
+  protocol.

+
+
+  
+
+  
Anything in this specification that refers to HTTP also applies
+  to HTTP-over-TLS, as represented by URLs
+  representing the https scheme.

+
+  
User agents should report certificate errors to
+  the user and must either refuse to download resources sent with
+  erroneous certificates or must act as if such resources were in fact
+  served with no encryption.

+
+  
User agents should warn the user that there is a potential
+  problem whenever the user visits a page that the user has previously
+  visited, if the page uses less secure encryption on the second
+  visit.

+
+  
Not doing so can result in users not noticing man-in-the-middle
+  attacks.

+
+  

+
+   
If a user connects to a server with a self-signed certificate,
+   the user agent could allow the connection but just act as if there
+   had been no encryption. If the user agent instead allowed the user
+   to override the problem and then displayed the page as if it was
+   fully and safely encrypted, the user could be easily tricked into
+   accepting man-in-the-middle connections.

+
+   
If a user connects to a server with full encryption, but the
+   page then refers to an external resource that has an expired
+   certificate, then the user agent will act as if the resource was
+   unavailable, possibly also reporting the problem to the user. If
+   the user agent instead allowed the resource to be used, then an
+   attacker could just look for "secure" sites that used resources
+   from a different host and only apply man-in-the-middle attacks to
+   that host, for example taking over scripts in the page.

+
+   
If a user bookmarks a site that uses a CA-signed certificate,
+   and then later revisits that site directly but the site has started
+   using a self-signed certificate, the user agent could warn the user
+   that a man-in-the-middle attack is likely underway, instead of
+   simply acting as if the page was not encrypted.

+
+  

+
+
+  
2.6.3 Determining the type of a resource

+
+  
The Content-Type metadata of a
+  resource must be obtained and interpreted in a manner consistent
+  with the requirements of the Content-Type Processing Model
+  specification. [MIMESNIFF]

+
+  
The sniffed type of a
+  resource must be found in a manner consistent with the
+  requirements given in the Content-Type Processing Model
+  specification for finding the sniffed-type of the relevant
+  sequence of octets. [MIMESNIFF]

+
+  
The rules for sniffing
+  images specifically and the rules for distingushing if a resource is text or
+  binary are also defined in the Content-Type Processing Model
+  specification. Both sets of rules return a MIME type as
+  their result. [MIMESNIFF]

+
+  
It is imperative that the rules in the
+  Content-Type Processing Model specification be followed
+  exactly. When a user agent uses different heuristics for content
+  type detection than the server expects, security problems can
+  occur. For more details, see the Content-Type Processing Model
+  specification. [MIMESNIFF]

+
+  
The algorithm for extracting an encoding from a
+  Content-Type, given a string s, is as
+  follows. It either returns an encoding or nothing.

+
+  
  1. Find the first seven characters in s
+   that are an ASCII case-insensitive match for the word
+   "charset".  If no such match is found, return
+   nothing.
    2. 
+
+   
  2. Skip any U+0009, U+000A, U+000C, U+000D, or U+0020
+   characters that immediately follow the word "charset" (there might not be any).
    3. 
+
+   
  3. If the next character is not a U+003D EQUALS SIGN ('='),
+   return nothing and abort these steps.
    4. 
+
+   
  4. Skip any U+0009, U+000A, U+000C, U+000D, or U+0020
+   characters that immediately follow the equals sign (there might not
+   be any).
    5. 
+
+   
  5. 
+
+    
    Process the next character as follows:
    
+
+    
    If it is a U+0022 QUOTATION MARK ('"') and there is a later U+0022 QUOTATION MARK ('"') in s
    
+     
    If it is a U+0027 APOSTROPHE ("'") and there is a later U+0027 APOSTROPHE ("'") in s
    
+     
    Return the encoding corresponding to the string between this character and the next earliest occurrence of this character.
    
+
+     
    If it is an unmatched U+0022 QUOTATION MARK ('"')
    
+     
    If it is an unmatched U+0027 APOSTROPHE ("'")
    
+     
    If there is no next character
    
+     
    Return nothing.
    
+
+     
    Otherwise
    
+     
    Return the encoding corresponding to the string from this
+     character to the first U+0009, U+000A, U+000C, U+000D, U+0020, or
+     U+003B character or the end of s, whichever
+     comes first.
    
+
+    
    6. 
+
+  
This requirement is a willful violation
+  of the HTTP specification, motivated by the need for backwards
+  compatibility with legacy content. [HTTP]

+
+  

+
+
+
+  
2.7 Common DOM interfaces

+
+  
2.7.1 Reflecting content attributes in IDL attributes

+
+  
Some IDL attributes are defined to reflect a
+  particular content attribute. This means that on getting, the IDL
+  attribute returns the current value of the content attribute, and on
+  setting, the IDL attribute changes the value of the content
+  attribute to the given value.

+
+
+
+  

+
+  
In general, on getting, if the content attribute is not present,
+  the IDL attribute must act as if the content attribute's value is
+  the empty string; and on setting, if the content attribute is not
+  present, it must first be added.

+
+  
If a reflecting IDL attribute is a DOMString
+  attribute whose content attribute is defined to contain a
+  URL, then on getting, the IDL attribute must resolve the value of the content
+  attribute relative to the element and return the resulting
+  absolute URL if that was successful, or the empty
+  string otherwise; and on setting, must set the content attribute to
+  the specified literal value. If the content attribute is absent, the
+  IDL attribute must return the default value, if the content
+  attribute has one, or else the empty string.

+
+  
If a reflecting IDL attribute is a DOMString
+  attribute whose content attribute is defined to contain one or more
+  URLs, then on getting, the IDL attribute
+  must split the content
+  attribute on spaces and return the concatenation of resolving each token URL to an
+  absolute URL relative to the element, with a single
+  U+0020 SPACE character between each URL, ignoring any tokens that
+  did not resolve successfully. If the content attribute is absent,
+  the IDL attribute must return the default value, if the content
+  attribute has one, or else the empty string. On setting, the IDL
+  attribute must set the content attribute to the specified literal
+  value.

+
+  
If a reflecting IDL attribute is a DOMString whose
+  content attribute is an enumerated attribute, and the
+  IDL attribute is limited to only known values, then, on
+  getting, the IDL attribute must return the conforming value
+  associated with the state the attribute is in (in its canonical
+  case), or the empty string if the attribute is in a state that has
+  no associated keyword value; and on setting, if the new value is an
+  ASCII case-insensitive match for one of the keywords
+  given for that attribute, then the content attribute must be set to
+  the conforming value associated with the state that the attribute
+  would be in if set to the given new value, otherwise, if the new
+  value is the empty string, then the content attribute must be
+  removed, otherwise, the content attribute must be set to the given
+  new value.

+
+  
If a reflecting IDL attribute is a DOMString but
+  doesn't fall into any of the above categories, then the getting and
+  setting must be done in a transparent, case-preserving manner.

+
+  
If a reflecting IDL attribute is a boolean
+  attribute, then on getting the IDL attribute must return true if the
+  content attribute is set, and false if it is absent. On setting, the
+  content attribute must be removed if the IDL attribute is set to
+  false, and must be set to the empty string if the IDL attribute is
+  set to true. (This corresponds to the rules for boolean content attributes.)

+
+  
If a reflecting IDL attribute is a signed integer type
+  (long) then, on getting, the content attribute must be
+  parsed according to the rules for parsing signed integers, and if that is
+  successful, and the value is in the range of the IDL attribute's
+  type, the resulting value must be returned. If, on the other hand,
+  it fails or returns an out of range value, or if the attribute is
+  absent, then the default value must be returned instead, or 0 if
+  there is no default value. On setting, the given value must be
+  converted to the shortest possible string representing the number as
+  a valid integer and then that string must be used as
+  the new content attribute value.

+
+  
If a reflecting IDL attribute is a signed integer type
+  (long) that is limited to only non-negative
+  numbers then, on getting, the content attribute must be parsed
+  according to the rules for parsing non-negative
+  integers, and if that is successful, and the value is in the
+  range of the IDL attribute's type, the resulting value must be
+  returned. If, on the other hand, it fails or returns an out of range
+  value, or if the attribute is absent, the default value must be
+  returned instead, or −1 if there is no default value. On
+  setting, if the value is negative, the user agent must fire an
+  INDEX_SIZE_ERR exception. Otherwise, the given value
+  must be converted to the shortest possible string representing the
+  number as a valid non-negative integer and then that
+  string must be used as the new content attribute value.

+
+  
If a reflecting IDL attribute is an unsigned integer
+  type (unsigned long) then, on getting, the content
+  attribute must be parsed according to the rules for parsing
+  non-negative integers, and if that is successful, and the
+  value is in the range of the IDL attribute's type, the resulting
+  value must be returned. If, on the other hand, it fails or returns
+  an out of range value, or if the attribute is absent, the default
+  value must be returned instead, or 0 if there is no default
+  value. On setting, the given value must be converted to the shortest
+  possible string representing the number as a valid
+  non-negative integer and then that string must be used as the
+  new content attribute value.

+
+  
If a reflecting IDL attribute is an unsigned integer type
+  (unsigned long) that is limited to only
+  non-negative numbers greater than zero, then the behavior is
+  similar to the previous case, but zero is not allowed. On getting,
+  the content attribute must first be parsed according to the
+  rules for parsing non-negative integers, and if that is
+  successful, and the value is in the range of the IDL attribute's
+  type, the resulting value must be returned. If, on the other hand,
+  it fails or returns an out of range value, or if the attribute is
+  absent, the default value must be returned instead, or 1 if there is
+  no default value. On setting, if the value is zero, the user agent
+  must fire an INDEX_SIZE_ERR exception. Otherwise, the
+  given value must be converted to the shortest possible string
+  representing the number as a valid non-negative integer
+  and then that string must be used as the new content attribute
+  value.

+
+  
If a reflecting IDL attribute is a floating point number type
+  (float), then, on getting, the content attribute must
+  be parsed according to the rules for parsing floating point
+  number values, and if that is successful, the resulting value
+  must be returned. If, on the other hand, it fails, or if the
+  attribute is absent, the default value must be returned instead, or
+  0.0 if there is no default value. On setting, the given value must
+  be converted to the best representation of the number as a
+  floating point number and then that string must be used as
+  the new content attribute value.

+
+  
The values Infinity and Not-a-Number (NaN) values
+  throw an exception on setting, as defined
+  earlier.

+
+  
If a reflecting IDL attribute is of the type
+  DOMTokenList or DOMSettableTokenList, then
+  on getting it must return a DOMTokenList or
+  DOMSettableTokenList object (as appropriate) whose
+  underlying string is the element's corresponding content
+  attribute. When the object mutates its underlying string, the
+  content attribute must itself be immediately mutated. When the
+  attribute is absent, then the string represented by the object is
+  the empty string; when the object mutates this empty string, the
+  user agent must add the corresponding content attribute, with its
+  value set to the value it would have been set to after mutating the
+  empty string. The same DOMTokenList or
+  DOMSettableTokenList object must be returned every time
+  for each attribute.

+
+  

+
+   
If an element with no attributes has its element.classList.remove()
+   method invoked, the underlying string won't be changed, since the
+   result of removing any token from the empty string is still the
+   empty string. However, if the element.classList.add() method is
+   then invoked, a class attribute
+   will be added to the element with the value of the token to be
+   added.

+
+  

+
+  
If a reflecting IDL attribute has the type
+  HTMLElement, or an interface that descends from
+  HTMLElement, then, on getting, it must run the
+  following algorithm (stopping at the first point where a value is
+  returned):

+
+  
  1. If the corresponding content attribute is absent, then the
+   IDL attribute must return null.
    2. 
+
+   
  2. Let candidate be the element that the document.getElementById() method
+   would find when called on the content attribute's document if it
+   was passed as its argument the current value of the corresponding
+   content attribute.
    3. 
+
+   
  3. If candidate is null, or if it is not
+   type-compatible with the IDL attribute, then the IDL attribute must
+   return null.
    4. 
+
+   
  4. Otherwise, it must return candidate.
    5. 
+
+  
On setting, if the given element has an id attribute, then the content attribute must
+  be set to the value of that id
+  attribute. Otherwise, the IDL attribute must be set to the empty
+  string.

+
+  

+
+
+  
2.7.2 Collections

+
+  
The HTMLCollection, HTMLAllCollection,
+  HTMLFormControlsCollection,
+  HTMLOptionsCollection, and
+  HTMLPropertiesCollection interfaces represent various
+  lists of DOM nodes. Collectively, objects implementing these
+  interfaces are called collections.

+
+  
When a collection is created, a
+  filter and a root are associated with the collection.

+
+  
For example, when the HTMLCollection
+  object for the document.images attribute is
+  created, it is associated with a filter that selects only
+  img elements, and rooted at the root of the
+  document.

+
+  
The collection then represents a
+  live view of the subtree rooted at the collection's
+  root, containing only nodes that match the given filter. The view is
+  linear. In the absence of specific requirements
+  to the contrary, the nodes within the collection must be sorted in
+  tree order.

+
+  

+
+  
The rows list is
+  not in tree order.

+
+  
An attribute that returns a collection must return the same
+  object every time it is retrieved.

+
+  

+
+
+  
2.7.2.1 HTMLCollection

+
+  
The HTMLCollection interface represents a generic
+  collection of elements.

+
+  
interface HTMLCollection {
+  readonly attribute unsigned long length;
+  caller getter object item(in unsigned long index); // only returns Element
+  caller getter object namedItem(in DOMString name); // only returns Element
+};

+
+  
collection . length

+   

+    
Returns the number of elements in the collection.

+   

+
+   
element = collection . item(index)

+   
collection[index]

+   
collection(index)

+   

+    
Returns the item with index index from the collection. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
element = collection . namedItem(name)

+   
collection[name]

+   
collection(name)

+   

+    
Returns the first item with ID or name name
+    from the collection.

+    
Returns null if no element with that ID or name could be found.

+    
Only a, applet, area,
+    embed, form, frame,
+    frameset, iframe, img, and
+    object elements can have a name for the purpose of
+    this method; their name is given by the value of their name attribute.

+   

+  

+
+  
The object's indices of the supported indexed
+  properties are the numbers in the range zero to one less than
+  the number of nodes represented by the collection. If
+  there are no such elements, then there are no supported
+  indexed properties.

+
+  
The length
+  attribute must return the number of nodes represented by the
+  collection.

+
+  
The item(index) method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
+  return null.

+
+  
The names of the supported named properties consist
+  of the values of the name attributes of each
+  a, applet, area,
+  embed, form, frame,
+  frameset, iframe, img, and
+  object element represented by the
+  collection with a name attribute, plus
+  the list of IDs that the elements represented by the
+  collection have.

+
+  
The namedItem(key) method must return the first node
+  in the collection that matches the following requirements:

+
+  
If no such elements are found, then the method must return
+  null.

+
+  

+
+
+  
2.7.2.2 HTMLAllCollection

+
+  
The HTMLAllCollection interface represents a generic
+  collection of elements just like
+  HTMLCollection, with the exception that its namedItem() method
+  returns an HTMLCollection object when there are
+  multiple matching elements.

+
+  
interface HTMLAllCollection : HTMLCollection {
+  // inherits length and item()
+  caller getter object namedItem(in DOMString name); // overrides inherited namedItem()
+  HTMLAllCollection tags(in DOMString tagName);
+};

+
+  
collection . length

+   

+    
Returns the number of elements in the collection.

+   

+
+   
element = collection . item(index)

+   
collection[index]

+   
collection(index)

+   

+    
Returns the item with index index from the collection. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
element = collection . namedItem(name)

+   
collection = collection . namedItem(name)

+   
collection[name]

+   
collection(name)

+   

+    
Returns the item with ID or name name from the collection.

+    
If there are multiple matching items, then an HTMLAllCollection object containing all those elements is returned.

+    
Returns null if no element with that ID or name could be found.

+    
Only a, applet, area,
+    embed, form, frame,
+    frameset, iframe, img, and
+    object elements can have a name for the purpose of
+    this method; their name is given by the value of their name attribute.

+   

+
+   
collection = collection . tags(tagName)

+   

+    
Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.

+   

+
+  

+
+  
The object's indices of the supported indexed
+  properties and names of the supported named
+  properties are as defined for HTMLCollection
+  objects.

+
+  
The namedItem(key) method must act according to the
+  following algorithm:

+
+  
  1. 
+
+    
    Let collection be an
+    HTMLAllCollection object rooted at the same node as
+    the HTMLAllCollection object on which the method was
+    invoked, whose filter matches only only elements that already
+    match the filter of the HTMLAllCollection object on
+    which the method was invoked and that are either:
    
+
+    
    2. 
+
+   
  2. If, at the time the method is called, there is exactly one node
+   in collection, then return that node and stop
+   the algorithm.
    3. 
+
+   
  3. Otherwise, if, at the time the method is called, collection is empty, return null and stop the
+   algorithm.
    4. 
+
+   
  4. Otherwise, return collection.
    5. 
+
+  
The tags(tagName) method must return an
+  HTMLAllCollection rooted at the same node as the
+  HTMLAllCollection object on which the method was
+  invoked, whose filter matches only HTML elements whose
+  local name is the tagName argument and that
+  already match the filter of the HTMLAllCollection
+  object on which the method was invoked. In HTML
+  documents, the argument must first be converted to
+  ASCII lowercase.

+
+  

+
+
+  
2.7.2.3 HTMLFormControlsCollection

+
+  
The HTMLFormControlsCollection interface represents
+  a collection of listed elements in form
+  and fieldset elements.

+
+  
interface HTMLFormControlsCollection : HTMLCollection {
+  // inherits length and item()
+  caller getter object namedItem(in DOMString name); // overrides inherited namedItem()
+};
+
+interface RadioNodeList : NodeList {
+          attribute DOMString value;
+};

+
+  
collection . length

+   

+    
Returns the number of elements in the collection.

+   

+
+   
element = collection . item(index)

+   
collection[index]

+   
collection(index)

+   

+    
Returns the item with index index from the collection. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
element = collection . namedItem(name)

+   
radioNodeList = collection . namedItem(name)

+   
collection[name]

+   
collection(name)

+   

+    
Returns the item with ID or name name from the collection.

+    
If there are multiple matching items, then a RadioNodeList object containing all those elements is returned.

+    
Returns null if no element with that ID or name could be found.

+   

+
+   
radioNodeList . value [ = value ]

+   

+    
Returns the value of the first checked radio button represented by the object.

+    
Can be set, to check the first radio button with the given value represented by the object.

+   

+
+  

+
+  
The object's indices of the supported indexed
+  properties are as defined for HTMLCollection
+  objects.

+
+  
The names of the supported named properties consist
+  of the values of all the id and name attributes of all the elements
+  represented by the collection.

+
+  
The namedItem(name) method must act according to the
+  following algorithm:

+
+  
  1. If, at the time the method is called, there is exactly one node
+   in the collection that has either an id attribute or a name attribute equal to name, then return that node and stop the
+   algorithm.
    2. 
+
+   
  2. Otherwise, if there are no nodes in the collection that have
+   either an id attribute or a name attribute equal to name, then return null and stop the algorithm.
    3. 
+
+   
  3. Otherwise, create a new RadioNodeList object
+   representing a live view of the
+   HTMLFormControlsCollection object, further filtered so
+   that the only nodes in the RadioNodeList object are
+   those that have either an id attribute
+   or a name attribute equal to name. The nodes in the RadioNodeList
+   object must be sorted in tree order.
    4. 
+
+   
  4. Return that RadioNodeList object.
    5. 
+
+  
Members of the RadioNodeList interface inherited
+  from the NodeList interface must behave as they would
+  on a NodeList object.

+
+  
The value
+  IDL attribute on the RadioNodeList object, on getting,
+  must return the value returned by running the following steps:

+
+  
  1. Let element be the first element in
+   tree order represented by the
+   RadioNodeList object that is an input
+   element whose type attribute
+   is in the Radio Button
+   state and whose checkedness
+   is true. Otherwise, let it be null.
    2. 
+
+   
  2. If element is null, or if it is an
+   element with no value
+   attribute, return the empty string.
    3. 
+
+   
  3. Otherwise, return the value of element's
+   value attribute.
    4. 
+
+  
On setting, the value IDL attribute must run
+  the following steps:

+
+  
  1. Let element be the first element in
+   tree order represented by the
+   RadioNodeList object that is an input
+   element whose type attribute
+   is in the Radio Button
+   state and whose value content
+   attribute is present and equal to the new value, if any. Otherwise,
+   let it be null.
    2. 
+
+   
  2. If element is not null, then set its
+   checkedness to true.
    
+
+  

+
+
+  
2.7.2.4 HTMLOptionsCollection

+
+  
The HTMLOptionsCollection interface represents a
+  list of option elements. It is always rooted on a
+  select element and has attributes and methods that
+  manipulate that element's descendants.

+
+  
interface HTMLOptionsCollection : HTMLCollection {
+  // inherits item()
+           attribute unsigned long length; // overrides inherited length
+  caller getter object namedItem(in DOMString name); // overrides inherited namedItem()
+  void add(in HTMLElement element, in optional HTMLElement before);
+  void add(in HTMLElement element, in long before);
+  void remove(in long index);
+};

+
+  
collection . length [ = value ]

+   

+    
Returns the number of elements in the collection.

+    
When set to a smaller number, truncates the number of option elements in the corresponding container.

+    
When set to a greater number, adds new blank option elements to that container.

+   

+
+   
element = collection . item(index)

+   
collection[index]

+   
collection(index)

+   

+    
Returns the item with index index from the collection. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
element = collection . namedItem(name)

+   
nodeList = collection . namedItem(name)

+   
collection[name]

+   
collection(name)

+   

+    
Returns the item with ID or name name from the collection.

+    
If there are multiple matching items, then a NodeList object containing all those elements is returned.

+    
Returns null if no element with that ID could be found.

+   

+
+   
collection . add(element [, before ] )

+   

+    
Inserts element before the node given by before.

+    
The before argument can be a number, in
+    which case element is inserted before the item
+    with that number, or an element from the collection, in which case
+    element is inserted before that element.

+    
If before is omitted, null, or a number out
+    of range, then element will be added at the
+    end of the list.

+    
This method will throw a HIERARCHY_REQUEST_ERR
+    exception if element is an ancestor of the
+    element into which it is to be inserted. If element is not an option or
+    optgroup element, then the method does nothing.

+   

+
+  

+
+  
The object's indices of the supported indexed
+  properties are as defined for HTMLCollection
+  objects.

+
+  
On getting, the length
+  attribute must return the number of nodes represented by the
+  collection.

+
+  
On setting, the behavior depends on whether the new value is
+  equal to, greater than, or less than the number of nodes
+  represented by the collection at that time. If the
+  number is the same, then setting the attribute must do nothing. If
+  the new value is greater, then n new
+  option elements with no attributes and no child nodes
+  must be appended to the select element on which the
+  HTMLOptionsCollection is rooted, where n is the difference between the two numbers (new
+  value minus old value). Mutation events must be fired as if a
+  DocumentFragment containing the new option
+  elements had been inserted.  If the new value is lower, then the
+  last n nodes in the collection must be removed
+  from their parent nodes, where n is the
+  difference between the two numbers (old value minus new value).

+
+  
Setting length never removes
+  or adds any optgroup elements, and never adds new
+  children to existing optgroup elements (though it can
+  remove children from them).

+
+  
The names of the supported named properties consist
+  of the values of all the id and name attributes of all the elements
+  represented by the collection.

+
+  
The namedItem(name) method must act according to the
+  following algorithm:

+
+  
  1. If, at the time the method is called, there is exactly one node
+   in the collection that has either an id attribute or a name attribute equal to name, then return that node and stop the
+   algorithm.
    2. 
+
+   
  2. Otherwise, if there are no nodes in the collection that have
+   either an id attribute or a name attribute equal to name, then return null and stop the algorithm.
    3. 
+
+   
+   
  3. Otherwise, create a new NodeList object
+   representing a live view of the
+   HTMLOptionsCollection object, further filtered so that
+   the only nodes in the NodeList object are those that
+   have either an id attribute or a name attribute equal to name. The nodes in the NodeList object
+   must be sorted in tree order.
    4. 
+
+   
  4. Return that NodeList object.
    5. 
+
+  
The add(element, before)
+  method must act according to the following algorithm:

+
+  
  1. If element is not an option
+   or optgroup element, then return and abort these
+   steps.
    2. 
+
+   
  2. If element is an ancestor of the
+   select element on which the
+   HTMLOptionsCollection is rooted, then throw a
+   HIERARCHY_REQUEST_ERR exception.
    3. 
+
+   
  3. If before is an element, but that
+   element isn't a descendant of the select element on
+   which the HTMLOptionsCollection is rooted, then throw
+   a NOT_FOUND_ERR exception.
    4. 
+
+   
  4. If element and before are the same element, then return and abort
+   these steps.
    5. 
+
+   
  5. If before is a node, then let reference be that node. Otherwise, if before is an integer, and there is a beforeth node in the collection, let reference be that node. Otherwise, let reference be null.
    6. 
+
+   
  6. If reference is not null, let parent be the parent node of reference. Otherwise, let parent
+   be the select element on which the
+   HTMLOptionsCollection is rooted.
    7. 
+
+   
  7. Act as if the DOM Core insertBefore() method was
+   invoked on the parent node, with element as the first argument and reference as the second argument.
    
+
+  
The remove(index) method must act according to
+  the following algorithm:

+
+  
  1. If the number of nodes represented by the
+   collection is zero, abort these steps.
    2. 
+
+   
  2. If index is not a number greater than or
+   equal to 0 and less than the number of nodes represented by
+   the collection, let element be the first
+   element in the collection. Otherwise, let element be the indexth element
+   in the collection.
    3. 
+
+   
  3. Remove element from its parent
+   node.
    4. 
+
+  

+
+
+  

+
+
+  
2.7.2.5 HTMLPropertiesCollection

+
+
+  
The HTMLPropertiesCollection interface represents a
+  collection of elements that add
+  name-value pairs to a particular item in the microdata
+  model.

+
+  
interface HTMLPropertiesCollection : HTMLCollection {
+  // inherits length and item()
+  caller getter PropertyNodeList namedItem(in DOMString name); // overrides inherited namedItem()
+  readonly attribute DOMStringList names;
+};
+
+typedef sequence<any> PropertyValueArray;
+
+interface PropertyNodeList : NodeList {
+  readonly attribute PropertyValueArray values;
+};

+
+  
collection . length

+   

+    
Returns the number of elements in the collection.

+   

+
+   
element = collection . item(index)

+   
collection[index]

+   
collection(index)

+   

+    
Returns the element with index index from the collection. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
propertyNodeList = collection . namedItem(name)

+   
collection[name]

+   
collection(name)

+   

+    
Returns a PropertyNodeList object containing any elements that add a property named name.

+   

+
+   
collection . names

+   

+    
Returns a DOMStringList with the property names of the elements in the collection.

+   

+
+   
propertyNodeList . values

+   

+    
Returns an array of the various values that the relevant elements have.

+   

+
+  

+
+  
The object's indices of the supported indexed
+  properties are as defined for HTMLCollection
+  objects.

+
+  
The names of the supported named properties consist
+  of the property names of all the elements
+  represented by the collection.

+
+  
The names
+  attribute must return a live DOMStringList
+  object giving the property names of all the elements
+  represented by the collection, listed in tree
+  order, but with duplicates removed, leaving only the first
+  occurrence of each name. The same object must be returned each
+  time.

+
+  
The namedItem(name) method must return a
+  PropertyNodeList object representing a
+  live view of the HTMLPropertiesCollection
+  object, further filtered so that the only nodes in the
+  PropertyNodeList object are those that have a property name equal to name. The nodes in the PropertyNodeList
+  object must be sorted in tree order, and the same
+  object must be returned each time a particular name is queried.

+
+  
Members of the PropertyNodeList interface inherited
+  from the NodeList interface must behave as they would
+  on a NodeList object.

+
+  
The values
+  IDL attribute on the PropertyNodeList object, on
+  getting, must return a newly constructed array whose values are the
+  values obtained from the itemValue DOM property of each of the
+  elements represented by the object, in tree order.

+
+  

+
+  

+
+
+
+  
2.7.3 DOMTokenList

+
+  
The DOMTokenList interface represents an interface
+  to an underlying string that consists of a set of
+  space-separated tokens.

+
+  
DOMTokenList objects are always
+  case-sensitive, even when the underlying string might
+  ordinarily be treated in a case-insensitive manner.

+
+  
interface DOMTokenList {
+  readonly attribute unsigned long length;
+  getter DOMString item(in unsigned long index);
+  boolean contains(in DOMString token);
+  void add(in DOMString token);
+  void remove(in DOMString token);
+  boolean toggle(in DOMString token);
+  stringifier DOMString ();
+};

+
+  
tokenlist . length

+   

+    
Returns the number of tokens in the string.

+   

+
+   
element = tokenlist . item(index)

+   
tokenlist[index]

+   

+    
Returns the token with index index. The tokens are returned in the order they are found in the underlying string.

+    
Returns null if index is out of range.

+   

+
+   
hastoken = tokenlist . contains(token)

+   

+    
Returns true if the token is present; false otherwise.

+    
Throws a SYNTAX_ERR exception if token is empty.

+    
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

+   

+
+   
tokenlist . add(token)

+   

+    
Adds token, unless it is already present.

+    
Throws a SYNTAX_ERR exception if token is empty.

+    
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

+   

+
+   
tokenlist . remove(token)

+   

+    
Removes token if it is present.

+    
Throws a SYNTAX_ERR exception if token is empty.

+    
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

+   

+
+   
hastoken = tokenlist . toggle(token)

+   

+    
Adds token if it is not present, or removes
+    it if it is. Returns true if token is now
+    present (it was added); returns false if it is not (it was
+    removed).

+    
Throws a SYNTAX_ERR exception if token is empty.

+    
Throws an INVALID_CHARACTER_ERR exception if token contains any spaces.

+   

+
+  

+
+  
The length
+  attribute must return the number of tokens that result from splitting the underlying string on
+  spaces. This is the length.

+
+  
The object's indices of the supported indexed
+  properties are the numbers in the range zero to length-1, unless the length is zero, in which case
+  there are no supported indexed properties.

+
+  
The item(index) method must split the underlying string on spaces,
+  preserving the order of the tokens as found in the underlying
+  string, and then return the indexth item in this
+  list. If index is equal to or greater than the
+  number of tokens, then the method must return null.

+
+  
For example, if the string is "a b
+  a c" then there are four tokens: the token with index 0 is
+  "a", the token with index 1 is "b", the token with index 2 is "a", and the token with index 3 is "c".

+
+  
The contains(token) method must run the following
+  algorithm:

+
+  
  1. If the token argument is the empty string,
+   then raise a SYNTAX_ERR exception and stop the
+   algorithm.
    2. 
+
+   
  2. If the token argument contains any space characters, then raise an
+   INVALID_CHARACTER_ERR exception and stop the
+   algorithm.
    3. 
+
+   
  3. Otherwise, split the
+   underlying string on spaces to get the list of tokens in the
+   object's underlying string.
    4. 
+
+   
  4. If the token indicated by token is a
+   case-sensitive match for one of the tokens in the
+   object's underlying string then return true and stop this
+   algorithm.
    5. 
+
+   
  5. Otherwise, return false.
    6. 
+
+  
The add(token) method must run the following
+  algorithm:

+
+  
  1. If the token argument is the empty string,
+   then raise a SYNTAX_ERR exception and stop the
+   algorithm.
    2. 
+
+   
  2. If the token argument contains any space characters, then raise an
+   INVALID_CHARACTER_ERR exception and stop the
+   algorithm.
    3. 
+
+   
  3. Otherwise, split the
+   underlying string on spaces to get the list of tokens in the
+   object's underlying string.
    4. 
+
+   
  4. If the given token is a
+   case-sensitive match for one of the tokens in the
+   DOMTokenList object's underlying string then stop the
+   algorithm.
    5. 
+
+   
  5. Otherwise, if the DOMTokenList object's underlying
+   string is not the empty string and the last character of that
+   string is not a space character, then append a U+0020
+   SPACE character to the end of that string.
    6. 
+
+   
  6. Append the value of token to the end of the
+   DOMTokenList object's underlying string.
    7. 
+
+  
The remove(token) method must run the following
+  algorithm:

+
+  
  1. If the token argument is the empty string,
+   then raise a SYNTAX_ERR exception and stop the
+   algorithm.
    2. 
+
+   
  2. If the token argument contains any space characters, then raise an
+   INVALID_CHARACTER_ERR exception and stop the
+   algorithm.
    3. 
+
+   
  3. Otherwise, remove
+   the given token from the underlying
+   string.
    4. 
+
+  
The toggle(token) method must run the following
+  algorithm:

+
+  
  1. If the token argument is the empty string,
+   then raise a SYNTAX_ERR exception and stop the
+   algorithm.
    2. 
+
+   
  2. If the token argument contains any space characters, then raise an
+   INVALID_CHARACTER_ERR exception and stop the
+   algorithm.
    3. 
+
+   
  3. Otherwise, split the
+   underlying string on spaces to get the list of tokens in the
+   object's underlying string.
    4. 
+
+   
  4. If the given token is a
+   case-sensitive match for one of the tokens in the
+   DOMTokenList object's underlying string then remove the given token from the underlying string and stop the
+   algorithm, returning false.
    5. 
+
+   
  5. Otherwise, if the DOMTokenList object's underlying
+   string is not the empty string and the last character of that
+   string is not a space character, then append a U+0020
+   SPACE character to the end of that string.
    6. 
+
+   
  6. Append the value of token to the end of the
+   DOMTokenList object's underlying string.
    7. 
+
+   
  7. Return true.
    8. 
+
+  
Objects implementing the DOMTokenList interface must
+  stringify to the object's
+  underlying string representation.

+
+  

+
+
+  
2.7.4 DOMSettableTokenList

+
+  
The DOMSettableTokenList interface is the same as the
+  DOMTokenList interface, except that it allows the
+  underlying string to be directly changed.

+
+  
interface DOMSettableTokenList : DOMTokenList {
+            attribute DOMString value;
+};

+
+  
tokenlist . value

+   

+    
Returns the underlying string.

+    
Can be set, to change the underlying string.

+   

+
+  

+
+  
An object implementing the DOMSettableTokenList
+  interface must act as defined for the DOMTokenList
+  interface, except for the value attribute defined
+  here.

+
+  
The value
+  attribute must return the underlying string on getting, and must
+  replace the underlying string with the new value on setting.

+
+  

+
+
+  

+
+  
2.7.5 Safe passing of structured data

+
+  
When a user agent is required to obtain a structured
+  clone of an object, it must run the following algorithm, which
+  either returns a separate object, or throws an exception.

+
+  
  1. Let input be the object being
+   cloned.
    2. 
+
+   
  2. Let memory be a list of objects,
+   initially empty. (This is used to catch cycles.)
    3. 
+
+   
  3. Let output be the object resulting from
+   calling the internal structured cloning algorithm with
+   input and memory.
    4. 
+
+   
  4. Return output.
    5. 
+
+  
The internal structured cloning algorithm is always
+  called with two arguments, input and memory, and its behavior depends on the type of input, as follows:

+
+  
If input is the undefined value

+
+   
Return the undefined value.

+
+   
If input is the null value

+
+   
Return the null value.

+
+   
If input is the false value

+
+   
Return the false value.

+
+   
If input is the true value

+
+   
Return the true value.

+
+   
If input is a Number object

+
+   
Return a newly constructed Number object with the same value as input.

+
+   
If input is a String object

+
+   
Return a newly constructed String object with the same value as input.

+
+   
If input is a Date object

+
+   
Return a newly constructed Date object with the same value as input.

+
+   
If input is a RegExp object

+
+   

+
+    
Return a newly constructed RegExp object with the same pattern and flags as input.

+
+    
The value of the lastIndex property is not copied.

+
+   

+
+   
If input is a ImageData object

+
+   
Return a newly constructed ImageData object
+   with the same width and
+   height as input, and with a newly constructed
+   CanvasPixelArray for its data attribute, with the same
+   length and pixel
+   values as the input's.

+
+   
If input is a File object

+
+   
Return a newly constructed File object corresponding to the same underlying data.

+
+   
If input is a Blob object

+
+   
Return a newly constructed Blob object corresponding to the same underlying data.

+
+   
If input is a FileList object

+
+   
Return a newly constructed FileList object containing a list of newly constructed File objects corresponding to the same underlying data as those in input, maintaining their relative order.

+
+   
If input is an Array object

+   
If input is an Object object

+
+   

+
+    
  1. If input is in memory, then throw a
+     NOT_SUPPORTED_ERR exception and abort the overall
+     structured clone algorithm.
    2. 
+
+     
  2. Otherwise, let new memory be a list
+     consisting of the items in memory with the
+     addition of input.
    3. 
+
+     
  3. Create a new object, output, of the
+     same type as input: either an Array or an
+     Object.
    4. 
+
+     
  4. 
+
+      
    For each enumerable property in input,
+      add a corresponding property to output
+      having the same name, and having a value created from invoking
+      the internal structured cloning algorithm
+      recursively with the value of the property as the "input" argument and new
+      memory as the "memory" argument. The
+      order of the properties in the input and
+      output objects must be the same.
    
+
+      
    This does not walk the prototype chain.
    
+
+     
    5. 
+
+     
  5. Return output.
    6. 
+
+    

+
+   
If input is another native object type (e.g. Error)

+   
If input is a host object (e.g. a DOM node)

+
+   
Throw a NOT_SUPPORTED_ERR exception and abort
+   the overall structured clone algorithm.

+
+  

+
+
+  
2.7.6 DOMStringMap

+
+  
The DOMStringMap interface represents a set of
+  name-value pairs. It exposes these using the scripting language's
+  native mechanisms for property access.

+
+  

+
+  
When a DOMStringMap object is instantiated, it is
+  associated with three algorithms, one for getting the list of
+  name-value pairs, one for setting names to certain values, and one
+  for deleting names.

+
+  
interface DOMStringMap {
+  getter DOMString (in DOMString name);
+  setter void (in DOMString name, in DOMString value);
+  creator void (in DOMString name, in DOMString value);
+  deleter void (in DOMString name);
+};

+
+  
The names of the supported named properties on a
+  DOMStringMap object at any instant are the names of
+  each pair returned from the algorithm for getting the list of
+  name-value pairs at that instant.

+
+  
When a DOMStringMap object is indexed to retrieve a
+  named property name, the value returned must be
+  the value component of the name-value pair whose name component is
+  name in the list returned by the algorithm for
+  getting the list of name-value pairs.

+
+  
When a DOMStringMap object is indexed to create or
+  modify a named property name with value value, the algorithm for setting names to certain
+  values must be run, passing name as the name and
+  the result of converting value to a
+  DOMString as the value.

+
+  
When a DOMStringMap object is indexed to delete a
+  named property named name, the algorithm for
+  deleting names must be run, passing name as the
+  name.

+
+  
The DOMStringMap interface definition
+  here is only intended for JavaScript environments. Other language
+  bindings will need to define how DOMStringMap is to be
+  implemented for those languages.

+
+  

+
+  

+
+   
The dataset attribute on
+   elements exposes the data-*
+   attributes on the element.

+
+   
Given the following fragment and elements with similar
+   constructions:

+
+   
<img class="tower" id="tower5" data-x="12" data-y="5"
+     data-ai="robotarget" data-hp="46" data-ability="flames"
+     src="towers/rocket.png alt="Rocket Tower">

+
+   
...one could imagine a function splashDamage() that takes some arguments, the first
+   of which is the element to process:

+
+   
function splashDamage(node, x, y, damage) {
+  if (node.classList.contains('tower') && // checking the 'class' attribute
+      node.dataset.x == x && // reading the 'data-x' attribute
+      node.dataset.y == y) { // reading the 'data-y' attribute
+    var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute
+    hp = hp - damage;
+    if (hp < 0) {
+      hp = 0;
+      node.dataset.ai = 'dead'; // setting the 'data-ai' attribute
+      delete node.dataset.ability; // removing the 'data-ability' attribute
+    }
+    node.dataset.hp = hp; // setting the 'data-hp' attribute
+  }
+}

+
+  

+
+
+  
2.7.7 DOM feature strings

+
+  
DOM3 Core defines mechanisms for checking for interface support,
+  and for obtaining implementations of interfaces, using feature
+  strings. [DOMCORE]

+
+  
Authors are strongly discouraged from using these, as they are
+  notoriously unreliable and imprecise. Authors are encouraged to rely
+  on explicit feature testing or the graceful degradation behavior
+  intrinsic to some of the features in this specification.

+
+  

+
+  
For historical reasons, user agents should return the true value
+  when the hasFeature(feature, version)
+  method of the DOMImplementation interface is invoked
+  with feature set to either "HTML" or "XHTML" and version set to either "1.0" or
+  "2.0".

+
+  

+
+
+  
2.7.8 Exceptions

+
+  
The following are DOMException codes. [DOMCORE]

+
+  
  1. INDEX_SIZE_ERR
    2. 
+   
  2. DOMSTRING_SIZE_ERR
    3. 
+   
  3. HIERARCHY_REQUEST_ERR
    4. 
+   
  4. WRONG_DOCUMENT_ERR
    5. 
+   
  5. INVALID_CHARACTER_ERR
    6. 
+   
  6. NO_DATA_ALLOWED_ERR
    7. 
+   
  7. NO_MODIFICATION_ALLOWED_ERR
    8. 
+   
  8. NOT_FOUND_ERR
    9. 
+   
  9. NOT_SUPPORTED_ERR
    10. 
+   
  10. INUSE_ATTRIBUTE_ERR
    11. 
+   
  11. INVALID_STATE_ERR
    12. 
+   
  12. SYNTAX_ERR
    13. 
+   
  13. INVALID_MODIFICATION_ERR
    14. 
+   
  14. NAMESPACE_ERR
    15. 
+   
  15. INVALID_ACCESS_ERR
    16. 
+   
  16. VALIDATION_ERR
    17. 
+   
  17. TYPE_MISMATCH_ERR
    18. 
+   
  18. SECURITY_ERR
    19.  
+   
  19. NETWORK_ERR
    20.  
+   
  20. ABORT_ERR
    21.  
+   
  21. URL_MISMATCH_ERR
    22.  
+   
  22. QUOTA_EXCEEDED_ERR
    23.  
+ 
+   
  23. PARSE_ERR
    24.  
+   
  24. SERIALIZE_ERR
    25.  
+  

+
+  
2.7.9 Garbage collection

+
+  
There is an implied strong reference from any IDL
+  attribute that returns a pre-existing object to that object.

+
+  

+
+   
For example, the document.location attribute means
+   that there is a strong reference from a Document
+   object to its Location object. Similarly, there is
+   always a strong reference from a Document to any
+   descendant nodes, and from any node to its owner
+   Document.

+
+  

+
+  

+
+
+  
2.8 Namespaces

+
+  
The HTML namespace is: http://www.w3.org/1999/xhtml

+
+  
The MathML namespace is: http://www.w3.org/1998/Math/MathML

+
+  
The SVG namespace is: http://www.w3.org/2000/svg

+
+  
The XLink namespace is: http://www.w3.org/1999/xlink

+
+  
The XML namespace is: http://www.w3.org/XML/1998/namespace

+
+  
The XMLNS namespace is: http://www.w3.org/2000/xmlns/

+
+  
Data mining tools and other user agents that perform operations
+  on content without running scripts, evaluating CSS or XPath
+  expressions, or otherwise exposing the resulting DOM to arbitrary
+  content, may "support namespaces" by just asserting that their DOM
+  node analogues are in certain namespaces, without actually exposing
+  the above strings.

+
+
+  
3 Semantics, structure, and APIs of HTML documents

+
+  
3.1 Documents

+
+  
Every XML and HTML document in an HTML UA is represented by a
+  Document object. [DOMCORE]

+
+  
The document's address is an absolute URL
+  that is set when the Document is created. The
+  document's current address is an absolute URL
+  that can change during the lifetime of the Document,
+  for example when the user navigates to
+  a fragment identifier on the
+  page or when the pushState() method is called
+  with a new URL. The document's
+  current address must be set to the document's
+  address when the Document is created.

+
+  
Interactive user agents typically expose the
+  document's current address in their user interface.

+
+  
When a Document is created by a script using the createDocument()
+  or createHTMLDocument()
+  APIs, the document's address is the same as the
+  document's address of the script's document.

+
+  
Document objects are assumed to be XML
+  documents unless they are flagged as being HTML
+  documents when they are created. Whether a document is an
+  HTML document or an XML document affects the behavior of
+  certain APIs and the case-sensitivity of some selectors.

+
+
+
+  
3.1.1 Documents in the DOM

+
+  
All Document objects (in user agents implementing
+  this specification) must also implement
+  the HTMLDocument interface, available using
+  binding-specific methods. (This is the case whether or not the
+  document in question is an HTML
+  document or indeed whether it contains any HTML
+  elements at all.) Document objects must also implement the document-level interface
+  of any other namespaces that the UA supports.

+
+  
For example, if an HTML implementation also
+  supports SVG, then the Document object implements both
+  HTMLDocument and SVGDocument.

+
+  
Because the HTMLDocument interface is
+  now obtained using binding-specific casting methods instead of
+  simply being the primary interface of the document object, it is no
+  longer defined as inheriting from Document.

+
+  
[OverrideBuiltins]
+interface HTMLDocument {
+  // resource metadata management
+  [PutForwards=href] readonly attribute Location location;
+  readonly attribute DOMString URL;
+           attribute DOMString domain;
+  readonly attribute DOMString referrer;
+           attribute DOMString cookie;
+  readonly attribute DOMString lastModified;
+  readonly attribute DOMString compatMode;
+           attribute DOMString charset;
+  readonly attribute DOMString characterSet;
+  readonly attribute DOMString defaultCharset;
+  readonly attribute DOMString readyState;
+
+  // DOM tree accessors
+  getter any (in DOMString name);
+           attribute DOMString title;
+           attribute DOMString dir;
+           attribute HTMLElement body;
+  readonly attribute HTMLHeadElement head;
+  readonly attribute HTMLCollection images;
+  readonly attribute HTMLCollection embeds;
+  readonly attribute HTMLCollection plugins;
+  readonly attribute HTMLCollection links;
+  readonly attribute HTMLCollection forms;
+  readonly attribute HTMLCollection scripts;
+  NodeList getElementsByName(in DOMString elementName);
+  NodeList getElementsByClassName(in DOMString classNames);
+  NodeList getItems(in optional DOMString typeNames); // microdata 
+
+  // dynamic markup insertion
+           attribute DOMString innerHTML;
+  HTMLDocument open(in optional DOMString type, in optional DOMString replace);
+  WindowProxy open(in DOMString url, in DOMString name, in DOMString features, in optional boolean replace);
+  void close();
+  void write(in DOMString... text);
+  void writeln(in DOMString... text);
+
+  // user interaction
+  readonly attribute WindowProxy defaultView;
+  Selection getSelection();
+  readonly attribute Element activeElement;
+  boolean hasFocus();
+           attribute DOMString designMode;
+  boolean execCommand(in DOMString commandId);
+  boolean execCommand(in DOMString commandId, in boolean showUI);
+  boolean execCommand(in DOMString commandId, in boolean showUI, in DOMString value);
+  boolean queryCommandEnabled(in DOMString commandId);
+  boolean queryCommandIndeterm(in DOMString commandId);
+  boolean queryCommandState(in DOMString commandId);
+  boolean queryCommandSupported(in DOMString commandId);
+  DOMString queryCommandValue(in DOMString commandId);
+  readonly attribute HTMLCollection commands;
+
+  // event handler IDL attributes
+           attribute Function onabort;
+           attribute Function onblur;
+           attribute Function oncanplay;
+           attribute Function oncanplaythrough;
+           attribute Function onchange;
+           attribute Function onclick;
+           attribute Function oncontextmenu;
+           attribute Function ondblclick;
+           attribute Function ondrag;
+           attribute Function ondragend;
+           attribute Function ondragenter;
+           attribute Function ondragleave;
+           attribute Function ondragover;
+           attribute Function ondragstart;
+           attribute Function ondrop;
+           attribute Function ondurationchange;
+           attribute Function onemptied;
+           attribute Function onended;
+           attribute Function onerror;
+           attribute Function onfocus;
+           attribute Function onformchange;
+           attribute Function onforminput;
+           attribute Function oninput;
+           attribute Function oninvalid;
+           attribute Function onkeydown;
+           attribute Function onkeypress;
+           attribute Function onkeyup;
+           attribute Function onload;
+           attribute Function onloadeddata;
+           attribute Function onloadedmetadata;
+           attribute Function onloadstart;
+           attribute Function onmousedown;
+           attribute Function onmousemove;
+           attribute Function onmouseout;
+           attribute Function onmouseover;
+           attribute Function onmouseup;
+           attribute Function onmousewheel;
+           attribute Function onpause;
+           attribute Function onplay;
+           attribute Function onplaying;
+           attribute Function onprogress;
+           attribute Function onratechange;
+           attribute Function onreadystatechange;
+           attribute Function onscroll;
+           attribute Function onseeked;
+           attribute Function onseeking;
+           attribute Function onselect;
+           attribute Function onshow;
+           attribute Function onstalled;
+           attribute Function onsubmit;
+           attribute Function onsuspend;
+           attribute Function ontimeupdate;
+           attribute Function onvolumechange;
+           attribute Function onwaiting;
+};
+Document implements HTMLDocument;

+
+  
Since the HTMLDocument interface holds methods and
+  attributes related to a number of disparate features, the members of
+  this interface are described in various different sections.

+
+
+  
3.1.2 Security

+
+  
User agents must raise a
+  SECURITY_ERR exception whenever any of the members of
+  an HTMLDocument object are accessed by scripts whose
+  effective script origin is not the same as the Document's effective
+  script origin.

+
+
+
+  
3.1.3 Resource metadata management

+
+  
document . URL

+   

+    
Returns the document's address.

+   

+
+   
document . referrer

+   

+    
Returns the
+    address of the Document from which the user
+    navigated to this one, unless it was blocked or there was no such
+    document, in which case it returns the empty string.

+    
The noreferrer link
+    type can be used to block the referrer.

+   

+
+  

+
+  
The URL
+  attribute must return the document's address.

+
+  
The referrer attribute
+  must return either the current address of the active document
+  of the source browsing context at the time the
+  navigation was started (that is, the page which navigated the browsing context
+  to the current document), with any <fragment> component removed; or
+  the empty string if there is no such originating page, or if the UA
+  has been configured not to report referrers in this case, or if the
+  navigation was initiated for a hyperlink with a noreferrer keyword.

+
+  

+
+  
In the case of HTTP, the referrer IDL attribute will
+  match the Referer (sic) header
+  that was sent when fetching the current
+  page.

+
+  
Typically user agents are configured to not report
+  referrers in the case where the referrer uses an encrypted protocol
+  and the current page does not (e.g. when navigating from an https: page to an http:
+  page).

+
+  
document . cookie [ = value ]

+   

+    
Returns the HTTP cookies that apply to the
+    Document. If there are no cookies or cookies can't be
+    applied to this resource, the empty string will be returned.

+    
Can be set, to add a new cookie to the element's set of HTTP
+    cookies.

+    
If the contents are sandboxed into a unique origin (in an
+    iframe with the sandbox attribute) or the
+    resource was labeled as text/html-sandboxed, a
+    SECURITY_ERR exception will be thrown on getting and
+    setting.

+   

+
+  

+
+  
The cookie
+  attribute represents the cookies of the resource from which the
+  Document was created.

+
+  
Some Document objects are cookie-free Document
+  objects. Any Document object created by the createDocument() or createHTMLDocument()
+  factory methods is a cookie-free Document
+  object. Any Document whose address does not use a server-based
+  naming authority is a cookie-free Document
+  object. Other specifications can also define
+  Document objects as being cookie-free Document
+  objects.

+
+  
On getting, if the document is a
+  cookie-free Document object, then the user
+  agent must return the empty string. Otherwise, if the
+  Document's origin is not a
+  scheme/host/port tuple, the user agent must raise a
+  SECURITY_ERR exception. Otherwise, the user agent must
+  first obtain the storage mutex and then return the
+  cookie-string for the document's address for a
+  "non-HTTP" API. [COOKIES]

+
+  
On setting, if the document is a cookie-free
+  Document object, then the user agent must do
+  nothing. Otherwise, if the Document's
+  origin is not a scheme/host/port tuple, the user agent
+  must raise a SECURITY_ERR exception. Otherwise, the
+  user agent must obtain the storage mutex and then act
+  as it would when receiving a set-cookie-string for
+  the document's address via a "non-HTTP" API, consisting
+  of the new value. [COOKIES]

+
+  
Since the cookie attribute is accessible
+  across frames, the path restrictions on cookies are only a tool to
+  help manage which cookies are sent to which parts of the site, and
+  are not in any way a security feature.

+
+  

+
+  
document . lastModified

+   

+    
Returns the date of the last modification to the document, as
+    reported by the server, in the form "MM/DD/YYYY hh:mm:ss", in the user's local
+    time zone.

+    
If the last modification date is not known, the current time is
+    returned instead.

+   

+
+  

+
+  
The lastModified
+  attribute, on getting, must return the date and time of the
+  Document's source file's last modification, in the
+  user's local time zone, in the following format:

+
+  
  1.  The month component of the date. 
    2. 
+
+   
  2.  A U+002F SOLIDUS character (/). 
    3. 
+
+   
  3.  The day component of the date. 
    4. 
+
+   
  4.  A U+002F SOLIDUS character (/). 
    5. 
+
+   
  5.  The year component of the date. 
    6. 
+
+   
  6.  A U+0020 SPACE character. 
    7. 
+
+   
  7.  The hours component of the time. 
    8. 
+
+   
  8.  A U+003A COLON character (:). 
    9. 
+
+   
  9.  The minutes component of the time. 
    10. 
+
+   
  10.  A U+003A COLON character (:). 
    11. 
+
+   
  11.  The seconds component of the time. 
    12. 
+
+  
All the numeric components above, other than the year, must be
+  given as two digits in the range U+0030 DIGIT ZERO (0) to U+0039
+  DIGIT NINE (9) representing the number in base ten, zero-padded if
+  necessary. The year must be given as the shortest possible string of
+  four or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
+  DIGIT NINE (9) representing the number in base ten, zero-padded if
+  necessary.

+
+  
The Document's source file's last modification date
+  and time must be derived from relevant features of the networking
+  protocols used, e.g. from the value of the HTTP Last-Modified header of the
+  document, or from metadata in the file system for local files. If
+  the last modification date and time are not known, the attribute
+  must return the current date and time in the above format.

+
+  

+
+  
document . compatMode

+   

+    
In a conforming document, returns the string "CSS1Compat". (In quirks mode
+    documents, returns the string "BackCompat",
+    but a conforming document can never trigger quirks
+    mode.)

+   

+
+  

+
+  
A Document is always set to one of three modes:
+  no-quirks mode, the default; quirks mode, used
+  typically for legacy documents; and limited-quirks mode,
+  also known as "almost standards" mode. The mode is only ever changed
+  from the default by the HTML parser, based on the
+  presence, absence, or value of the DOCTYPE string.

+
+  
The compatMode IDL
+  attribute must return the literal string "CSS1Compat" unless the document has been set to
+  quirks mode by the HTML parser, in which
+  case it must instead return the literal string "BackCompat".

+
+  

+
+  
document . charset [ = value ]

+   

+    
Returns the document's character encoding.

+    
Can be set, to dynamically change the document's
+    character encoding.

+    
New values that are not IANA-registered aliases supported by the user agent are ignored.

+   

+
+   
document . characterSet

+   

+    
Returns the document's character encoding.

+   

+
+   
document . defaultCharset

+   

+    
Returns what might be the user agent's default character
+    encoding. (The user agent might return another character encoding
+    altogether, e.g. to protect the user's privacy, or if the user
+    agent doesn't use a single default encoding.)

+   

+
+  

+
+  
Documents have an associated character encoding. When a Document
+  object is created, the document's character encoding
+  must be initialized to UTF-16. Various algorithms during page
+  loading affect this value, as does the charset setter. [IANACHARSET]

+
+  
The charset
+  IDL attribute must, on getting, return the preferred MIME
+  name of the document's character encoding. On
+  setting, if the new value is an IANA-registered alias for a
+  character encoding supported by the user agent, the document's
+  character encoding must be set to that character
+  encoding. (Otherwise, nothing happens.)

+
+  
The characterSet
+  IDL attribute must, on getting, return the preferred MIME
+  name of the document's character encoding.

+
+  
The defaultCharset
+  IDL attribute must, on getting, return the preferred MIME
+  name of a character encoding, possibly the user's default
+  encoding, or an encoding associated with the user's current
+  geographical location, or any arbitrary encoding name.

+
+  

+
+  
document . readyState

+   

+    
Returns "loading" while the Document is loading, and "complete" once it has loaded.

+    
The readystatechange event fires on the Document object when this value changes.

+   

+
+  

+
+  
Each document has a current document readiness. When a
+  Document object is created, it must have its
+  current document readiness set to the string "loading"
+  if the document is associated with an HTML parser or an
+  XML parser, or to the string "complete"
+  otherwise. Various algorithms during page loading affect this
+  value. When the value is set, the user agent must fire a
+  simple event named readystatechange at the
+  Document object.

+
+  
A Document is said to have an active
+  parser if it is associated with an HTML parser or
+  an XML parser that has not yet been stopped or aborted.

+
+  
The readyState IDL
+  attribute must, on getting, return the current document
+  readiness.

+
+  

+
+
+
+  
3.1.4 DOM tree accessors

+
+  
The html element of a document is the
+  document's root element, if there is one and it's an
+  html element, or null otherwise.

+
+  
document . head

+   

+    
Returns the head element.

+   

+
+  
The head element of a document is the
+  first head element that is a child of the
+  html element, if there is one, or null
+  otherwise.

+
+  

+
+  
The head
+  attribute, on getting, must return the head
+  element of the document (a head element or
+  null).

+
+  

+
+  
document . title [ = value ]

+   

+    
Returns the document's title, as given by the
+    title element.

+    
Can be set, to update the document's title. If there is no
+    head element,
+    the new value is ignored.

+    
In SVG documents, the SVGDocument interface's
+    title attribute takes
+    precedence.

+   

+
+  
The title element of a document is the
+  first title element in the document (in tree order), if
+  there is one, or null otherwise.

+
+  

+
+  
The title attribute must,
+  on getting, run the following algorithm:

+
+  
  1. If the root element is an svg
+   element in the "http://www.w3.org/2000/svg"
+   namespace, and the user agent supports SVG, then return the value
+   that would have been returned by the IDL attribute of the same name
+   on the SVGDocument interface. [SVG]
    2. 
+
+   
  2. Otherwise, let value be a concatenation
+   of the data of all the child text
+   nodes of the title element, in
+   tree order, or the empty string if the
+   title element is null.
    3. 
+
+   
  3. Replace any sequence of one or more consecutive space characters in value with a single U+0020 SPACE character.
    4. 
+
+   
  4. Remove any leading or trailing space characters in value.
    5. 
+
+   
  5. Return value.
    6. 
+
+  
On setting, the following algorithm must be run. Mutation events
+  must be fired as appropriate.

+
+  
  1. If the root element is an svg
+   element in the "http://www.w3.org/2000/svg"
+   namespace, and the user agent supports SVG, then the setter must
+   defer to the setter for the IDL attribute of the same name on the
+   SVGDocument interface (if it is readonly, then this
+   will raise an exception). Stop the algorithm here. [SVG]
    2. 
+
+   
  2. If the title element is null and
+   the head element is null, then the
+   attribute must do nothing. Stop the algorithm here.
    3. 
+
+   
  3. If the title element is null, then a
+   new title element must be created and appended to
+   the head element. Let element be that element. Otherwise, let element be the title
+   element.
    4. 
+
+   
  4. The children of element (if any) must all
+   be removed.
    5. 
+
+   
  5. A single Text node whose data is the new value
+   being assigned must be appended to element.
    6. 
+
+  
The title attribute on
+  the HTMLDocument interface should shadow the attribute
+  of the same name on the SVGDocument interface when the
+  user agent supports both HTML and SVG. [SVG]

+
+  

+
+  
document . body [ = value ]

+   

+    
Returns the body element.

+    
Can be set, to replace the body element.

+    
If the new value is not a body or frameset element, this will throw a HIERARCHY_REQUEST_ERR exception.

+   

+
+  
The body element of a document is the first child of
+  the html element that is either a
+  body element or a frameset element. If
+  there is no such element, it is null. If the body
+  element is null, then when the specification requires that events be
+  fired at "the body element", they must instead be fired at the
+  Document object.

+
+  

+
+  
The body
+  attribute, on getting, must return the body element of
+  the document (either a body element, a
+  frameset element, or null). On setting, the following
+  algorithm must be run:

+
+  
  1. If the new value is not a body or
+   frameset element, then raise a
+   HIERARCHY_REQUEST_ERR exception and abort these
+   steps.
    2. 
+
+   
  2. Otherwise, if the new value is the same as the body
+   element, do nothing. Abort these steps.
    3. 
+
+   
  3. Otherwise, if the body element is not null, then
+   replace that element with the new value in the DOM, as if the root
+   element's replaceChild() method had been
+   called with the new value and the
+   incumbent body element as its two arguments respectively,
+   then abort these steps.
    4. 
+
+   
  4. Otherwise, the body element is null. Append
+   the new value to the root element.
    5. 
+
+  

+
+  
document . images

+   

+    
Returns an HTMLCollection of the img elements in the Document.

+   

+
+   
document . embeds

+   
document . plugins

+   

+    
Return an HTMLCollection of the embed elements in the Document.

+   

+
+   
document . links

+   

+    
Returns an HTMLCollection of the a and area elements in the Document that have href attributes.

+   

+
+   
document . forms

+   

+    
Return an HTMLCollection of the form elements in the Document.

+   

+
+   
document . scripts

+   

+    
Return an HTMLCollection of the script elements in the Document.

+   

+
+  

+
+  
+
+  
The images
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  img elements.

+
+  
The embeds
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  embed elements.

+
+  
The plugins
+  attribute must return the same object as that returned by the embeds attribute.

+
+  
The links
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only a
+  elements with href
+  attributes and area elements with href attributes.

+
+  
The forms
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  form elements.

+
+  
The scripts
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  script elements.

+
+  

+
+  
collection = document . getElementsByName(name)

+   

+    
Returns a NodeList of elements in the
+    Document that have a name
+    attribute with the value name.

+   

+
+   
collection = document . getElementsByClassName(classes)

+   
collection = element . getElementsByClassName(classes)

+   

+    
Returns a NodeList of the elements in the object
+    on which the method was invoked (a Document or an
+    Element) that have all the classes given by classes.

+    
The classes argument is interpreted as a
+    space-separated list of classes.

+   

+
+  

+
+  
The getElementsByName(name) method takes a string name, and must return a live
+  NodeList containing all the HTML elements
+  in that document that have a name attribute
+  whose value is equal to the name argument (in a
+  case-sensitive manner), in tree order.
+  When the method is invoked on a Document object again
+  with the same argument, the user agent may return the same as the
+  object returned by the earlier call. In other cases, a new
+  NodeList object must be returned.

+
+  
The getElementsByClassName(classNames) method takes a string that
+  contains a set of space-separated tokens representing
+  classes. When called, the method must return a live
+  NodeList object containing all the elements in the
+  document, in tree order, that have all the classes
+  specified in that argument, having obtained the classes by splitting a string on
+  spaces. (Duplicates are ignored.) If there are no tokens
+  specified in the argument, then the method must return an empty
+  NodeList. If the document is in quirks
+  mode, then the comparisons for the classes must be done in an
+  ASCII case-insensitive manner, otherwise, the
+  comparisons must be done in a case-sensitive manner.
+  When the method is invoked on a Document object again
+  with the same argument, the user agent may return the same object as
+  the object returned by the earlier call. In other cases, a new
+  NodeList object must be returned.

+
+  
The getElementsByClassName(classNames) method on the
+  HTMLElement interface must return a live
+  NodeList with the nodes that the
+  HTMLDocument getElementsByClassName()
+  method would return when passed the same argument(s), excluding any
+  elements that are not descendants of the HTMLElement
+  object on which the method was invoked.
+  When the method is invoked on an HTMLElement object
+  again with the same argument, the user agent may return the same
+  object as the object returned by the earlier call. In other cases, a
+  new NodeList object must be returned.

+
+  

+
+  
HTML, SVG, and MathML elements define which classes they are in
+  by having an attribute with no namespace with the name class containing a space-separated list of classes
+  to which the element belongs. Other specifications may also allow
+  elements in their namespaces to be labeled as being in specific
+  classes.

+
+  

+
+   
Given the following XHTML fragment:

+
+   
<div id="example">
+ <p id="p1" class="aaa bbb"/>
+ <p id="p2" class="aaa ccc"/>
+ <p id="p3" class="bbb ccc"/>
+</div>

+
+   
A call to document.getElementById('example').getElementsByClassName('aaa')
+   would return a NodeList with the two paragraphs p1 and p2 in it.

+
+   
A call to getElementsByClassName('ccc bbb') would only
+   return one node, however, namely p3. A call
+   to document.getElementById('example').getElementsByClassName('bbb  ccc ')
+   would return the same thing.

+
+   
A call to getElementsByClassName('aaa,bbb') would return no
+   nodes; none of the elements above are in the "aaa,bbb" class.

+
+  

+
+
+
+  

+
+  
The HTMLDocument interface supports named properties. The names
+  of the supported named properties at any moment consist of
+  the values of the name content
+  attributes of all the applet, embed,
+  form, iframe, img, and
+  fallback-free object elements in the
+  Document that have name
+  content attributes, and the values of the id content attributes of all the
+  applet and fallback-free
+  object elements in the Document that have
+  id content attributes, and the values
+  of the id content attributes of all the
+  img elements in the Document that have
+  both name content attributes and
+  id content attributes.

+
+  
When the
+  HTMLDocument object is indexed for property
+  retrieval using a name name, then the user
+  agent must return the value obtained using the following steps:

+
+  
  1. 
+
+    
    Let elements be the list of named elements with
+    the name name in the Document.
+
+    
    There will be at least one such element, by
+    definition.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If elements has only one element, and that
+    element is an iframe element, then return the
+    WindowProxy object of the nested browsing
+    context represented by that iframe element,
+    and abort these steps.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Otherwise, if elements has only one
+    element, return that element and abort these steps.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Otherwise return an HTMLCollection rooted at the
+    Document node, whose filter matches only named elements with
+    the name name.
     
+
+   
    5. 
+
+  
+
+  
Named elements
+  with the name name, for the purposes of the
+  above algorithm, are those that are either:

+
+  
An object element is said to be
+  fallback-free if it has no object or
+  embed descendants.

+
+  

+
+  
The dir
+  attribute on the HTMLDocument interface is defined
+  along with the dir content
+  attribute.

+
+
+
+  
3.1.5 Creating documents

+
+  
XML documents can be created from script using the
+  createDocument()
+  method on the DOMImplementation interface.

+
+  
HTML documents can be created using the createHTMLDocument()
+  method:

+
+  
[Supplemental, NoInterfaceObject]
+interface DOMHTMLImplementation {
+  Document createHTMLDocument(in DOMString title);
+};
+DOMImplementation implements DOMHTMLImplementation;

+
+  
document = document . implementation . createHTMLDocument( title )

+   

+
+    
Returns a new Document, with a basic DOM already
+    constructed with an appropriate title element.

+
+   

+
+  

+
+  
The createHTMLDocument(title) method, when invoked, must run the
+  following steps:

+
+  
  1. Let doc be a newly created
+   Document object.
    2. 
+
+   
  2. Mark doc as being an HTML document.
    3. 
+
+   
  3. Create a DocumentType node with the name attribute set to the string "html", and the other attributes specific to
+   DocumentType objects set to the empty string, null,
+   and empty lists, as appropriate. Append the newly created node to
+   doc.
    4. 
+
+   
  4. Create an html element, and append it to doc.
    5. 
+
+   
  5. Create a head element, and append it to the
+   html element created in the previous step.
    
+
+   
  6. Create a title element, and append it to the
+   head element created in the previous step.
    
+
+   
  7. Create a Text node, and set its data attribute to the string given by the method's
+   argument (which could be the empty string). Append it to the
+   title element created in the previous step.
    
+
+   
  8. Create a body element, and append it to the
+   html element created in the earlier step.
    
+
+   
  9. Return doc.
    10. 
+
+  

+
+
+
+  
3.2 Elements

+
+  
3.2.1 Semantics

+
+  
Elements, attributes, and attribute values in HTML are defined
+  (by this specification) to have certain meanings (semantics). For
+  example, the ol element represents an ordered list, and
+  the lang attribute represents the
+  language of the content.

+
+  
Authors must not use elements, attributes, or attribute values
+  for purposes other than their appropriate intended semantic
+  purpose. Authors must not use elements, attributes, or attribute
+  values that are not permitted by this specification or other
+  applicable specifications.

+
+  

+   
For example, the following document is non-conforming, despite
+   being syntactically correct:

+
+   
<!DOCTYPE HTML>
+<html lang="en-GB">
+ <head> <title> Demonstration </title> </head>
+ <body>
+  <table>
+   <tr> <td> My favourite animal is the cat. </td> </tr>
+   <tr>
+    <td>
+     —<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>,
+     in an essay from 1992
+    </td>
+   </tr>
+  </table>
+ </body>
+</html>

+
+   
...because the data placed in the cells is clearly not tabular
+   data (and the cite element mis-used). A corrected
+   version of this document might be:

+
+   
<!DOCTYPE HTML>
+<html lang="en-GB">
+ <head> <title> Demonstration </title> </head>
+ <body>
+  <blockquote>
+   <p> My favourite animal is the cat. </p>
+  </blockquote>
+  <p>
+   —<a href="http://example.org/~ernest/">Ernest</a>,
+   in an essay from 1992
+  </p>
+ </body>
+</html>

+
+   
This next document fragment, intended to represent the heading
+   of a corporate site, is similarly non-conforming because the second
+   line is not intended to be a heading of a subsection, but merely a
+   subheading or subtitle (a subordinate heading for the same
+   section).

+
+   
<body>
+ <h1>ABC Company</h1>
+ <h2>Leading the way in widget design since 1432</h2>
+ ...

+
+   
The hgroup element is intended for these kinds of
+   situations:

+
+   
<body>
+ <hgroup>
+  <h1>ABC Company</h1>
+  <h2>Leading the way in widget design since 1432</h2>
+ </hgroup>
+ ...

+
+   
In the next example, there is a non-conforming attribute value
+   ("carpet") and a non-conforming attribute ("texture"), which
+   is not permitted by this specification:

+
+   
<label>Carpet: <input type="carpet" name="c" texture="deep pile"></label>

+
+   
Here would be an alternative and correct way to mark this up:

+
+   
<label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label>

+
+  

+
+  
Through scripting and using other mechanisms, the values of
+  attributes, text, and indeed the entire structure of the document
+  may change dynamically while a user agent is processing it. The
+  semantics of a document at an instant in time are those represented
+  by the state of the document at that instant in time, and the
+  semantics of a document can therefore change over time. User agents
+  must update their presentation of the
+  document as this occurs.

+
+  
HTML has a progress element that
+  describes a progress bar. If its "value" attribute is dynamically
+  updated by a script, the UA would update the rendering to show the
+  progress changing.

+
+
+
+  
3.2.2 Elements in the DOM

+
+  
The nodes representing HTML elements in the DOM
+  must implement, and expose to scripts, the
+  interfaces listed for them in the relevant sections of this
+  specification. This includes HTML elements in XML
+  documents, even when those documents are in another context
+  (e.g. inside an XSLT transform).

+
+  
Elements in the DOM represent
+  things; that is, they have intrinsic meaning, also known as
+  semantics.

+
+  
For example, an ol element
+  represents an ordered list.

+
+  
The basic interface, from which all the HTML
+  elements' interfaces inherit, and which
+  must be used by elements that have no additional
+  requirements, is the HTMLElement interface.

+
+  
interface HTMLElement : Element {
+  // DOM tree accessors
+  NodeList getElementsByClassName(in DOMString classNames);
+
+  // dynamic markup insertion
+           attribute DOMString innerHTML;
+           attribute DOMString outerHTML;
+  void insertAdjacentHTML(in DOMString position, in DOMString text);
+
+  // metadata attributes
+           attribute DOMString id;
+           attribute DOMString title;
+           attribute DOMString lang;
+           attribute DOMString dir;
+           attribute DOMString className;
+  readonly attribute DOMTokenList classList;
+  readonly attribute DOMStringMap dataset;
+
+  // microdata 
+           attribute boolean itemScope;
+           attribute DOMString itemType;
+           attribute DOMString itemId;
+  [PutForwards=value] readonly attribute DOMSettableTokenList itemRef;
+  [PutForwards=value] readonly attribute DOMSettableTokenList itemProp;
+  readonly attribute HTMLPropertiesCollection properties;
+           attribute any itemValue;
+
+  // user interaction
+           attribute boolean hidden;
+  void click();
+  void scrollIntoView();
+  void scrollIntoView(in boolean top);
+           attribute long tabIndex;
+  void focus();
+  void blur();
+           attribute DOMString accessKey;
+  readonly attribute DOMString accessKeyLabel;
+           attribute boolean draggable;
+           attribute DOMString contentEditable;
+  readonly attribute boolean isContentEditable;
+           attribute HTMLMenuElement contextMenu;
+           attribute DOMString spellcheck;
+
+  // command API
+  readonly attribute DOMString commandType;
+  readonly attribute DOMString label;
+  readonly attribute DOMString icon;
+  readonly attribute boolean disabled;
+  readonly attribute boolean checked;
+
+  // styling
+  readonly attribute CSSStyleDeclaration style;
+
+  // event handler IDL attributes
+           attribute Function onabort;
+           attribute Function onblur;
+           attribute Function oncanplay;
+           attribute Function oncanplaythrough;
+           attribute Function onchange;
+           attribute Function onclick;
+           attribute Function oncontextmenu;
+           attribute Function ondblclick;
+           attribute Function ondrag;
+           attribute Function ondragend;
+           attribute Function ondragenter;
+           attribute Function ondragleave;
+           attribute Function ondragover;
+           attribute Function ondragstart;
+           attribute Function ondrop;
+           attribute Function ondurationchange;
+           attribute Function onemptied;
+           attribute Function onended;
+           attribute Function onerror;
+           attribute Function onfocus;
+           attribute Function onformchange;
+           attribute Function onforminput;
+           attribute Function oninput;
+           attribute Function oninvalid;
+           attribute Function onkeydown;
+           attribute Function onkeypress;
+           attribute Function onkeyup;
+           attribute Function onload;
+           attribute Function onloadeddata;
+           attribute Function onloadedmetadata;
+           attribute Function onloadstart;
+           attribute Function onmousedown;
+           attribute Function onmousemove;
+           attribute Function onmouseout;
+           attribute Function onmouseover;
+           attribute Function onmouseup;
+           attribute Function onmousewheel;
+           attribute Function onpause;
+           attribute Function onplay;
+           attribute Function onplaying;
+           attribute Function onprogress;
+           attribute Function onratechange;
+           attribute Function onreadystatechange;
+           attribute Function onscroll;
+           attribute Function onseeked;
+           attribute Function onseeking;
+           attribute Function onselect;
+           attribute Function onshow;
+           attribute Function onstalled;
+           attribute Function onsubmit;
+           attribute Function onsuspend;
+           attribute Function ontimeupdate;
+           attribute Function onvolumechange;
+           attribute Function onwaiting;
+};
+
+interface HTMLUnknownElement : HTMLElement { };

+
+  
The HTMLElement interface holds methods and
+  attributes related to a number of disparate features, and the
+  members of this interface are therefore described in various
+  different sections of this specification.

+
+  

+
+  
The HTMLUnknownElement interface must be used for
+  HTML elements that are not defined by this
+  specification (or other applicable specifications).

+
+  

+
+
+
+  
3.2.3 Global attributes

+
+  
The following attributes are common to and may be specified on
+  all HTML elements (even those not
+  defined in this specification):

+
+  
The following event handler content attributes may
+  be specified on any HTML
+  element:

+
+  
The attributes marked with an asterisk have a
+  different meaning when specified on body elements as
+  those elements expose event handlers of the
+  Window object with the same names.

+
+  
While these attributes apply to all elements, they
+  are not useful on all elements. For example, only media elements will ever receive a volumechange event fired by
+  the user agent.

+
+  
Custom data attributes
+  (e.g. data-foldername or data-msgid) can be specified on any HTML element, to store custom data
+  specific to the page.

+
+  
In HTML documents, elements in the HTML
+  namespace may have an xmlns attribute
+  specified, if, and only if, it has the exact value
+  "http://www.w3.org/1999/xhtml". This does not apply to
+  XML documents.

+
+  
In HTML, the xmlns attribute
+  has absolutely no effect. It is basically a talisman. It is allowed
+  merely to make migration to and from XHTML mildly easier. When
+  parsed by an HTML parser, the attribute ends up in no
+  namespace, not the "http://www.w3.org/2000/xmlns/"
+  namespace like namespace declaration attributes in XML do.

+
+  
In XML, an xmlns attribute is
+  part of the namespace declaration mechanism, and an element cannot
+  actually have an xmlns attribute in no
+  namespace specified.

+
+  
To enable assistive technology products to expose a more
+  fine-grained interface than is otherwise possible with HTML elements
+  and attributes, a set of annotations for assistive technology
+  products can be specified (the ARIA role and aria-* attributes).

+
+
+  
3.2.3.1 The id attribute

+
+  
The id attribute specifies its
+  element's unique identifier (ID). The
+  value must be unique amongst all the IDs in the element's home
+  subtree and must contain at least one character. The value
+  must not contain any space
+  characters.

+
+  
+
+  
An element's unique
+  identifier can be used for a variety of purposes, most
+  notably as a way to link to specific parts of a document using
+  fragment identifiers, as a way to target an element when scripting,
+  and as a way to style a specific element from CSS.

+
+  

+
+  
If the value is not the empty string, user agents must associate
+  the element with the given value (exactly, including any space
+  characters) for the purposes of ID matching within the element's
+  home subtree (e.g. for selectors in CSS or for the
+  getElementById()
+  method in the DOM).

+
+  
Identifiers are opaque strings. Particular meanings should not be
+  derived from the value of the id
+  attribute.

+
+  
This specification doesn't preclude an element having multiple
+  IDs, if other mechanisms (e.g. DOM Core methods) can set an
+  element's ID in a way that doesn't conflict with the id attribute.

+
+  
The id IDL attribute must
+  reflect the id content
+  attribute.

+
+  

+
+
+  
3.2.3.2 The title attribute

+
+  
The title attribute
+  represents advisory information for the element, such
+  as would be appropriate for a tooltip. On a link, this could be the
+  title or a description of the target resource; on an image, it could
+  be the image credit or a description of the image; on a paragraph,
+  it could be a footnote or commentary on the text; on a citation, it
+  could be further information about the source; and so forth. The
+  value is text.

+
+  
If this attribute is omitted from an element, then it implies
+  that the title attribute of the
+  nearest ancestor HTML element
+  with a title attribute set is also
+  relevant to this element. Setting the attribute overrides this,
+  explicitly stating that the advisory information of any ancestors is
+  not relevant to this element. Setting the attribute to the empty
+  string indicates that the element has no advisory information.

+
+  
If the title attribute's value
+  contains U+000A LINE FEED (LF) characters, the content is split into
+  multiple lines. Each U+000A LINE FEED (LF) character represents a
+  line break.

+
+  

+
+   
Caution is advised with respect to the use of newlines in title attributes.

+
+   
For instance, the following snippet actually defines an
+   abbreviation's expansion with a line break in it:

+
+   
<p>My logs show that there was some interest in <abbr title="Hypertext
+Transport Protocol">HTTP</abbr> today.</p>

+
+  

+
+  
Some elements, such as link, abbr, and
+  input, define additional semantics for the title attribute beyond the semantics
+  described above.

+
+  

+
+  
The title IDL attribute
+  must reflect the title
+  content attribute.

+
+  

+
+
+
+  
3.2.3.3 The lang and xml:lang attributes

+
+  
The lang attribute (in
+  no namespace) specifies the primary language for the element's
+  contents and for any of the element's attributes that contain
+  text. Its value must be a valid BCP 47 language tag, or the empty
+  string. Setting the attribute to the empty string indicates that the
+  primary language is unknown. [BCP47]

+
+  
The lang
+  attribute in the XML namespace is defined in XML. [XML]

+
+  
If these attributes are omitted from an element, then the
+  language of this element is the same as the language of its parent
+  element, if any.

+
+  
The lang attribute in no namespace
+  may be used on any HTML
+  element.

+
+  
The lang
+  attribute in the XML namespace may be used on
+  HTML elements in XML documents, as well as
+  elements in other namespaces if the relevant specifications allow it
+  (in particular, MathML and SVG allow lang attributes in the
+  XML namespace to be specified on their
+  elements). If both the lang attribute
+  in no namespace and the lang attribute in the XML
+  namespace are specified on the same element, they must
+  have exactly the same value when compared in an ASCII
+  case-insensitive manner.

+
+  
Authors must not use the lang attribute in the XML
+  namespace on HTML elements in HTML
+  documents. To ease migration to and from XHTML, authors may
+  specify an attribute in no namespace with no prefix and with the
+  literal localname "xml:lang" on HTML
+  elements in HTML documents, but such attributes
+  must only be specified if a lang
+  attribute in no namespace is also specified, and both attributes
+  must have the same value when compared in an ASCII
+  case-insensitive manner.

+
+  
The attribute in no namespace with no prefix and
+  with the literal localname "xml:lang" has no
+  effect on language processing.

+
+  

+
+  
To determine the language of a node, user agents must
+  look at the nearest ancestor element (including the element itself
+  if the node is an element) that has a lang attribute in the
+  XML namespace set or is an HTML element and has a lang in no namespace attribute set. That
+  attribute specifies the language of the node (regardless of its
+  value).

+
+  
If both the lang attribute in no
+  namespace and the lang attribute in the XML
+  namespace are set on an element, user agents must use
+  the lang attribute
+  in the XML namespace, and the lang attribute in no namespace must be
+  ignored for the purposes of determining
+  the element's language.

+
+  
If none of the node's ancestors, including the root
+  element, have either attribute set, but there is a
+  pragma-set default language set, then that is the
+  language of the node. If there is no pragma-set default
+  language set, then language information from a higher-level
+  protocol (such as HTTP), if any, must be used as the final fallback
+  language instead. In the absence of any such language information,
+  and in cases where the higher-level protocol reports multiple
+  languages, the language of the node is unknown, and the
+  corresponding language tag is the empty string.

+
+  
If the resulting value is not a recognized language tag, then it
+  must be treated as an unknown language having the given language
+  tag, distinct from all other languages. For the purposes of
+  round-tripping or communicating with other services that expect
+  language tags, user agents should pass unknown language tags
+  through unmodified.

+
+  
Thus, for instance, an element with lang="xyzzy" would be matched by the selector :lang(xyzzy) (e.g. in CSS), but it would not be
+  matched by :lang(abcde), even though both are
+  equally invalid. Similarly, if a Web browser and screen reader
+  working in unison communicated about the language of the element,
+  the browser would tell the screen reader that the language was
+  "xyzzy", even if it knew it was invalid, just in case the screen
+  reader actually supported a language with that tag after all.

+
+  
If the resulting value is the empty string, then it must be
+  interpreted as meaning that the language of the node is explicitly
+  unknown.

+
+  
User agents may use the element's language to determine proper
+  processing or rendering (e.g. in the selection of appropriate
+  fonts or pronunciations, or for dictionary selection). 

+
+  
The lang IDL attribute
+  must reflect the lang
+  content attribute in no namespace.

+
+  

+
+
+
+  
3.2.3.4 The xml:base
+  attribute (XML only)

+
+  
The xml:base attribute is
+  defined in XML Base. [XMLBASE]

+
+  
The xml:base attribute may be
+  used on elements of XML documents. Authors must not
+  use the xml:base attribute in
+  HTML documents.

+
+
+  
3.2.3.5 The dir attribute

+
+  
The dir attribute specifies the
+  element's text directionality. The attribute is an enumerated
+  attribute with the keyword ltr mapping
+  to the state ltr, and the keyword rtl
+  mapping to the state rtl. The attribute has no invalid
+  value default and no missing value default.

+
+  

+
+  
The processing of this attribute is primarily performed by the
+  presentation layer. For example, the rendering section in this
+  specification defines a mapping from this attribute to the CSS
+  'direction' and 'unicode-bidi' properties, and CSS defines rendering
+  in terms of those properties.

+
+  

+
+  
The directionality of an element, which is used in
+  particular by the canvas element's text rendering API,
+  is either 'ltr' or 'rtl'. If the user agent supports CSS and the
+  'direction' property on this element has a computed value of either
+  'ltr' or 'rtl', then that is the directionality of the
+  element. Otherwise, if the element is being rendered,
+  then the directionality of the element is the
+  directionality used by the presentation layer, potentially
+  determined from the value of the dir
+  attribute on the element. Otherwise, if the element's dir attribute has the state ltr, the
+  element's directionality is 'ltr' (left-to-right); if the attribute
+  has the state rtl, the element's directionality is 'rtl'
+  (right-to-left); and otherwise, the element's directionality is the
+  same as its parent element, or 'ltr' if there is no parent
+  element.

+
+  
document . dir [ = value ]

+   

+    
Returns the html element's dir attribute's value, if any.

+    
Can be set, to either "ltr" or "rtl", to replace the html element's dir attribute's value.

+    
If there is no html element, returns the empty string and ignores new values.

+   

+
+  

+
+  
The dir IDL attribute on
+  an element must reflect the dir content attribute of that element,
+  limited to only known values.

+
+  
The dir IDL
+  attribute on HTMLDocument objects must
+  reflect the dir content
+  attribute of the html element, if any,
+  limited to only known values. If there is no such
+  element, then the attribute must return the empty string and do
+  nothing on setting.

+
+  

+
+  
Authors are strongly encouraged to use the dir attribute to indicate text direction
+  rather than using CSS, since that way their documents will continue
+  to render correctly even in the absence of CSS (e.g. as interpreted
+  by search engines).

+
+
+  
3.2.3.6 The class attribute

+
+  
Every HTML element may have a
+  class attribute specified.

+
+  
The attribute, if specified, must have a value that is a
+  set of space-separated tokens representing the various
+  classes that the element belongs to.

+
+  

+
+  
The classes that an HTML
+  element has assigned to it consists of all the classes
+  returned when the value of the class
+  attribute is split on
+  spaces. (Duplicates are ignored.)

+
+  

+
+  
Assigning classes to an element affects class
+  matching in selectors in CSS, the getElementsByClassName()
+  method in the DOM, and other such features.

+
+  
There are no additional restrictions on the tokens authors can
+  use in the class attribute, but
+  authors are encouraged to use values that describe the nature of the
+  content, rather than values that describe the desired presentation
+  of the content.

+
+  

+
+  
The className and
+  classList IDL
+  attributes must both reflect the class content attribute.

+
+  

+
+
+
+  
3.2.3.7 The style attribute

+
+  
All HTML elements may have the style content attribute set. This is a
+  CSS styling attribute as defined by the CSS Styling
+  Attribute Syntax specification. [CSSATTR]

+
+  

+
+  
In user agents that support CSS, the attribute's value must be
+  parsed when the attribute is added or has its value changed, according
+  to the rules given for CSS styling attributes. [CSSATTR]

+
+  

+
+  
Documents that use style
+  attributes on any of their elements must still be comprehensible and
+  usable if those attributes were removed.

+
+  
In particular, using the style attribute to hide and show content,
+  or to convey meaning that is otherwise not included in the document,
+  is non-conforming. (To hide and show content, use the hidden attribute.)

+
+  
element . style

+   

+    
Returns a CSSStyleDeclaration object for the element's style attribute.

+   

+
+  

+
+  
The style IDL attribute
+  must return a CSSStyleDeclaration whose value
+  represents the declarations specified in the attribute, if
+  present. Mutating the CSSStyleDeclaration object must
+  create a style attribute on the
+  element (if there isn't one already) and then change its value to be
+  a value representing the serialized form of the
+  CSSStyleDeclaration object. The same object must be
+  returned each time. [CSSOM]

+
+  

+
+  

+
+   
In the following example, the words that refer to colors are
+   marked up using the span element and the style attribute to make those words show
+   up in the relevant colors in visual media.

+
+   
<p>My sweat suit is <span style="color: green; background:
+transparent">green</span> and my eyes are <span style="color: blue;
+background: transparent">blue</span>.</p>

+
+  

+
+
+
+  
3.2.3.8 Embedding custom non-visible data

+
+  
A custom data attribute is an attribute in no
+  namespace whose name starts with the string "data-", has at least one
+  character after the hyphen, is XML-compatible, and
+  contains no characters in the range U+0041 to U+005A (LATIN CAPITAL
+  LETTER A to LATIN CAPITAL LETTER Z).

+
+  
All attributes on HTML elements in
+  HTML documents get ASCII-lowercased automatically, so
+  the restriction on ASCII uppercase letters doesn't affect such
+  documents.

+
+  
Custom data attributes
+  are intended to store custom data private to the page or
+  application, for which there are no more appropriate attributes or
+  elements.

+
+  
These attributes are not intended for use by software that is
+  independent of the site that uses the attributes.

+
+  

+
+   
For instance, a site about music could annotate list items
+   representing tracks in an album with custom data attributes
+   containing the length of each track. This information could then be
+   used by the site itself to allow the user to sort the list by track
+   length, or to filter the list for tracks of certain lengths.

+
+   
<ol>
+ <li data-length="2m11s">Beyond The Sea</li>
+ ...
+</ol>

+
+   
It would be inappropriate, however, for the user to use generic
+   software not associated with that music site to search for tracks
+   of a certain length by looking at this data.

+
+   
This is because these attributes are intended for use by the
+   site's own scripts, and are not a generic extension mechanism for
+   publicly-usable metadata.

+
+  

+
+  
Every HTML element may have
+  any number of custom data
+  attributes specified, with any value.

+
+  
element . dataset

+   

+
+    
Returns a DOMStringMap object for the element's data-* attributes.

+
+    
Hyphenated names become camel-cased. For example, data-foo-bar="" becomes element.dataset.fooBar.

+
+   

+
+  

+
+  
The dataset IDL
+  attribute provides convenient accessors for all the data-* attributes on an element. On
+  getting, the dataset IDL attribute
+  must return a DOMStringMap object, associated with the
+  following algorithms, which expose these attributes on their
+  element:

+
+  
The algorithm for getting the list of name-value pairs

+
+   

+    
  1. Let list be an empty list of name-value
+     pairs.
    2. 
+
+     
  2. For each content attribute on the element whose first five
+     characters are the string "data-" and whose
+     remaining characters (if any) do not include any characters in
+     the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN
+     CAPITAL LETTER Z), add a name-value pair to list whose name is the attribute's name with the
+     first five characters removed and whose value is the attribute's
+     value.
    3. 
+
+     
  3. For each name on the list, for each U+002D HYPHEN-MINUS
+     character (-) in the name that is followed by a character in the
+     range U+0061 to U+007A (U+0061 LATIN SMALL LETTER A to U+007A
+     LATIN SMALL LETTER Z), remove the U+002D HYPHEN-MINUS character
+     (-) and replace the character that followed it by the same
+     character converted to ASCII uppercase.
    4. 
+
+     
  4. Return list.
    5. 
+
+    

+
+   
The algorithm for setting names to certain values

+
+   

+    
  1. Let name be the name passed to the
+     algorithm.
    2. 
+
+     
  2. Let value be the value passed to the
+     algorithm.
    3. 
+
+     
  3. If name contains a U+002D HYPHEN-MINUS
+     character (-) followed by a character in the range U+0061 to
+     U+007A (U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
+     Z), throw a SYNTAX_ERR exception and abort these
+     steps.
    4. 
+
+     
  4. For each character in the range U+0041 to U+005A (U+0041
+     LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z) in name, insert a U+002D HYPHEN-MINUS character (-)
+     before the character and replace the character with the same
+     character converted to ASCII lowercase.
    5. 
+
+     
  5. Insert the string data- at the front of
+     name.
    6. 
+
+     
  6. Set the value of the attribute with the name name, to the value value,
+     replacing any previous value if the attribute already existed. If
+     setAttribute() would have raised an
+     exception when setting an attribute with the name name, then this must raise the same
+     exception.
    7. 
+
+    

+
+   
The algorithm for deleting names

+
+   

+    
  1. Let name be the name passed to the
+     algorithm.
    2. 
+
+     
  2. If name contains a U+002D HYPHEN-MINUS
+     character (-) followed by a character in the range U+0061 to
+     U+007A (U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
+     Z), throw a SYNTAX_ERR exception and abort these
+     steps.
    3. 
+
+     
  3. For each character in the range U+0041 to U+005A (U+0041
+     LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z) in name, insert a U+002D HYPHEN-MINUS character (-)
+     before the character and replace the character with the same
+     character converted to ASCII lowercase.
    4. 
+
+     
  4. Insert the string data- at the front of
+     name.
    5. 
+
+     
  5. Remove the attribute with the name name,
+     if such an attribute exists. Do nothing otherwise.
    6. 
+
+    

+
+  
The same object must be returned each time.

+
+  

+
+  

+
+   
If a Web page wanted an element to represent a space ship,
+   e.g. as part of a game, it would have to use the class attribute along with data-* attributes:

+
+   
<div class="spaceship" data-ship-id="92432"
+     data-weapons="laser 2" data-shields="50%"
+     data-x="30" data-y="10" data-z="90">
+ <button class="fire"
+         onclick="spaceships[this.parentNode.dataset.shipId].fire()">
+  Fire
+ </button>
+</div>

+
+   
Notice how the hyphenated attribute name becomes capitalized in
+   the API.

+
+  

+
+  
Authors should carefully design such extensions so that when the
+  attributes are ignored and any associated CSS dropped, the page is
+  still usable.

+
+  

+
+  
User agents must not derive any implementation behavior from
+  these attributes or values. Specifications intended for user agents
+  must not define these attributes to have any meaningful values.

+
+  

+
+  
JavaScript libraries may use the custom data attributes, as they are considered to
+  be part of the page on which they are used. Authors of libraries
+  that are reused by many authors are encouraged to include their name
+  in the attribute names, to reduce the risk of clashes.

+
+  

+
+   
For example, a library called "DoQuery" could use attribute
+   names like data-doquery-range, and a library
+   called "jJo" could use attributes names like data-jjo-range.

+
+  

+
+
+  
3.2.4 Element definitions

+
+  
Each element in this specification has a definition that includes
+  the following information:

+
+  
Categories

+
+   
A list of categories to
+   which the element belongs. These are used when defining the
+   content models for each element.

+
+
+   
Contexts in which this element may be used

+
+   
A non-normative description of where the element can
+   be used. This information is redundant with the content models of
+   elements that allow this one as a child, and is provided only as a
+   convenience.

+
+
+   
Content model

+
+   
A normative description of what content must be included as
+   children and descendants of the element.

+
+
+   
Content attributes

+
+   
A normative list of attributes that may be specified on the
+   element (except where otherwise disallowed).

+
+
+   
DOM interface

+
+   
A normative definition of a DOM interface that such elements
+   must implement.

+
+  
This is then followed by a description of what the element
+  represents, along with any additional normative
+  conformance criteria that may apply to authors and implementations. Examples are sometimes
+  also included.

+
+
+  
3.2.4.1 Attributes

+
+  
Except where otherwise specified, attributes
+  on HTML elements may have any string value, including
+  the empty string. Except where explicitly stated, there is no
+  restriction on what text can be specified in such attributes.

+
+
+
+  
3.2.5 Content models

+
+  
Each element defined in this specification has a content model: a
+  description of the element's expected contents. An HTML element must have contents that match the
+  requirements described in the element's content model.

+
+  
As noted in the conformance and terminology
+  sections, for the purposes of determining if an element matches its
+  content model or not, CDATASection nodes in the DOM are treated as
+  equivalent to Text nodes, and entity reference nodes are treated as if
+  they were expanded in place.

+
+  
The space characters are
+  always allowed between elements. User agents represent these
+  characters between elements in the source markup as text nodes in
+  the DOM. Empty text nodes and text nodes consisting of just sequences of
+  those characters are considered inter-element
+  whitespace.

+
+  
Inter-element whitespace, comment nodes, and
+  processing instruction nodes must be ignored when establishing
+  whether an element's contents match the element's content model or
+  not, and must be ignored when following algorithms that define
+  document and element semantics.

+
+  
An element A is said to be preceded or
+  followed by a second element B if A and B have the same parent node
+  and there are no other element nodes or text nodes (other than
+  inter-element whitespace) between them.

+
+  
Authors must not use HTML elements anywhere except
+  where they are explicitly allowed, as defined for each element, or
+  as explicitly required by other specifications. For XML compound
+  documents, these contexts could be inside elements from other
+  namespaces, if those elements are defined as providing the relevant
+  contexts.

+
+  

+   
For example, the Atom specification defines a content element. When its type attribute has the value xhtml, the Atom specification requires that it
+   contain a single HTML div element. Thus, a
+   div element is allowed in that context, even though
+   this is not explicitly normatively stated by this specification. [ATOM]

+  

+
+  
In addition, HTML elements may be orphan nodes
+  (i.e. without a parent node).

+
+  

+
+   
For example, creating a td element and storing it
+   in a global variable in a script is conforming, even though
+   td elements are otherwise only supposed to be used
+   inside tr elements.

+
+   
var data = {
+  name: "Banana",
+  cell: document.createElement('td'),
+};

+
+  

+
+
+  
3.2.5.1 Kinds of content

+
+  
Each element in HTML falls into zero or more categories that group elements with similar
+  characteristics together. The following broad categories are used in
+  this specification:

+
+  
Some elements also fall into other categories, which
+  are defined in other parts of this specification.

+
+  
These categories are related as follows:

+
+  
Sectioning content, heading content, phrasing content, and
+  embedded content are all types of flow content. Embedded content is
+  also a type of phrasing content.

+
+  
In addition, certain elements are categorized as form-associated elements and
+  further subcategorized to define their role in various form-related
+  processing models.

+
+  
Some elements have unique requirements and do not fit into any
+  particular category.

+
+
+  
3.2.5.1.1 Metadata content

+
+  
Metadata content is content that sets up the
+  presentation or behavior of the rest of the content, or that sets
+  up the relationship of the document with other documents, or that
+  conveys other "out of band" information.

+
+  
+  
Elements from other namespaces whose semantics are primarily
+  metadata-related (e.g. RDF) are also metadata
+  content.

+
+  

+
+   
Thus, in the XML serialization, one can use RDF, like this:

+
+   
<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
+ <head>
+  <title>Hedral's Home Page</title>
+  <r:RDF>
+   <Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#"
+           r:about="http://hedral.example.com/#">
+    <fullName>Cat Hedral</fullName>
+    <mailbox r:resource="mailto:hedral@damowmow.com"/>
+    <personalTitle>Sir</personalTitle>
+   </Person>
+  </r:RDF>
+ </head>
+ <body>
+  <h1>My home page</h1>
+  <p>I like playing with string, I guess. Sister says squirrels are fun
+  too so sometimes I follow her to play with them.</p>
+ </body>
+</html>

+
+   
This isn't possible in the HTML serialization, however.

+
+  

+
+
+  
3.2.5.1.2 Flow content

+
+  
Most elements that are used in the body of documents and
+  applications are categorized as flow content.

+
+  
+  
As a general rule, elements whose content model allows any
+  flow content should have either at least one descendant
+  text node that is not inter-element
+  whitespace, or at least one descendant element node that is
+  embedded content. For the purposes of this requirement,
+  del elements and their descendants must not be counted
+  as contributing to the ancestors of the del
+  element.

+
+  
This requirement is not a hard requirement, however, as there are
+  many cases where an element can be empty legitimately, for example
+  when it is used as a placeholder which will later be filled in by a
+  script, or when the element is part of a template and would on most
+  pages be filled in but on some pages is not relevant.

+
+
+  
3.2.5.1.3 Sectioning content

+
+  
Sectioning content is content that defines the scope
+  of headings and footers.

+
+  
+  
Each sectioning content element potentially has a
+  heading and an outline. See the section on
+  headings and sections for further details.

+
+  
There are also certain elements that are sectioning roots. These are distinct
+  from sectioning content, but they can also have an
+  outline.

+
+
+  
3.2.5.1.4 Heading content

+
+  
Heading content defines the header of a section
+  (whether explicitly marked up using sectioning content
+  elements, or implied by the heading content itself).

+
+  
+  
3.2.5.1.5 Phrasing content

+
+  
Phrasing content is the text of the document, as well
+  as elements that mark up that text at the intra-paragraph
+  level. Runs of phrasing content form paragraphs.

+
+  
+  
As a general rule, elements whose content model allows any
+  phrasing content should have either at least one
+  descendant text node that is not inter-element
+  whitespace, or at least one descendant element node that is
+  embedded content. For the purposes of this requirement,
+  nodes that are descendants of del elements must not be
+  counted as contributing to the ancestors of the del
+  element.

+
+  
Most elements that are categorized as phrasing
+  content can only contain elements that are themselves categorized as
+  phrasing content, not any flow content.

+
+  
Text, in the context of content
+  models, means text nodes. Text is sometimes used as a content
+  model on its own, but is also phrasing content, and can
+  be inter-element whitespace (if the text nodes are empty or contain just space characters).

+
+
+  
3.2.5.1.6 Embedded content

+
+  
Embedded content is content that imports another
+  resource into the document, or content from another vocabulary that
+  is inserted into the document.

+
+  
+  
Elements that are from namespaces other than the HTML
+  namespace and that convey content but not metadata, are
+  embedded content for the purposes of the content models
+  defined in this specification. (For example, MathML, or SVG.)

+
+  
Some embedded content elements can have fallback
+  content: content that is to be used when the external resource
+  cannot be used (e.g. because it is of an unsupported format). The
+  element definitions state what the fallback is, if any.

+
+
+  
3.2.5.1.7 Interactive content

+
+
+
+  
Interactive content is content that is specifically
+  intended for user interaction.

+
+  
+  
Certain elements in HTML have an activation
+  behavior, which means that the user can activate them. This
+  triggers a sequence of events dependent on the activation mechanism,
+  and normally culminating in a click
+  event followed by a DOMActivate event, as described below.

+
+  

+
+  
The user agent should allow the user to manually trigger elements
+  that have an activation behavior, for instance using
+  keyboard or voice input, or through mouse clicks. When the user
+  triggers an element with a defined activation behavior
+  in a manner other than clicking it, the default action of the
+  interaction event must be to run synthetic click activation
+  steps on the element.
 
+
+  
When a user agent is to run synthetic click activation
+  steps on an element, the user agent must run pre-click
+  activation steps on the element, then fire a click event at the element. The
+  default action of this click event
+  must be to run post-click activation steps on the
+  element. If the event is canceled, the user agent must run
+  canceled activation steps on the element instead.

+
+  
Given an element target, the nearest
+  activatable element is the element returned by the following
+  algorithm:

+
+  
  1. If target has a defined activation
+   behavior, then return target and abort
+   these steps.
    2. 
+
+   
  2. If target has a parent element, then set
+   target to that parent element and return to the
+   first step.
    3. 
+
+   
  3. Otherwise, there is no nearest activatable
+   element.
    4. 
+
+  
When a pointing device is clicked, the user agent must run these
+  steps:

+
+  
  1. Let e be the nearest
+   activatable element of the element designated by the user,
+   if any.
    2. 
+
+   
  2. If there is an element e, run
+   pre-click activation steps on it.
    3. 
+
+   
  3. 
+
+    
    Dispatch the required click
+    event.
     
+
+    
    If there is an element e, then the default
+    action of the click event must be
+    to run post-click activation steps on element e.
    
+
+    
    If there is an element e but the event is
+    canceled, the user agent must run canceled activation
+    steps on element e.
    
+
+   
    4. 
+
+  
The above doesn't happen for arbitrary synthetic
+  events dispatched by author script. However, the click() method can be used to make it
+  happen programmatically.

+
+  
When a user agent is to run pre-click activation steps
+  on an element, it must run the pre-click activation steps
+  defined for that element, if any.

+
+  
When a user agent is to run post-click activation
+  steps on an element, the user agent must fire a simple
+  event named DOMActivate that is cancelable at
+  that element. The default action of this event must be to run
+  final activation steps on that element. If the event is
+  canceled, the user agent must run canceled activation
+  steps on the element instead.

+
+  
When a user agent is to run canceled activation steps
+  on an element, it must run the canceled activation steps
+  defined for that element, if any.

+
+  
When a user agent is to run final activation steps on
+  an element, it must run the activation behavior defined
+  for that element. Activation behaviors can refer to the click and DOMActivate events that were fired
+  by the steps above leading up to this point.

+
+  

+
+
+  
3.2.5.2 Transparent content models

+
+  
Some elements are described as transparent; they have
+  "transparent" in the description of their content model.

+
+  
When a content model includes a part that is "transparent", those
+  parts must not contain content that would not be conformant if all
+  transparent elements in the tree were replaced, in their parent
+  element, by the children in the "transparent" part of their content
+  model, retaining order.

+
+  

+
+   
Consider the following markup fragment:

+
+   
<p>Hello <a href="world.html"><em>wonderful</em> world</a>!</p>

+
+   
Its DOM looks like the following:

+
+   
  • p
    • #text: Hello 
    • a href="world.html"
      • em
        • #text: wonderful
      • #text:  world
    • #text: !
The content model of the a element is
+   transparent. To see if its contents are conforming,
+   therefore, the element is replaced by its contents:

+
+   
  • p
    • #text: Hello 
    • em
      • #text: wonderful
    • #text:  world
    • #text: !
Since that is conforming, the contents of the a are
+   conforming in the original fragment.

+
+  

+
+  
When a transparent element has no parent, then the part of its
+  content model that is "transparent" must instead be treated as
+  accepting any flow content.

+
+
+  
3.2.5.3 Paragraphs

+
+  
The term paragraph as defined in this
+  section is distinct from (though related to) the p
+  element defined later. The paragraph concept defined
+  here is used to describe how to interpret documents.

+
+  
A paragraph is typically a run of phrasing
+  content that forms a block of text with one or more sentences
+  that discuss a particular topic, as in typography, but can also be
+  used for more general thematic grouping. For instance, an address is
+  also a paragraph, as is a part of a form, a byline, or a stanza in a
+  poem.

+
+  

+
+   
In the following example, there are two paragraphs in a
+   section. There is also a heading, which contains phrasing content
+   that is not a paragraph. Note how the comments and
+   inter-element whitespace do not form paragraphs.

+
+   
<section>
+  <h1>Example of paragraphs</h1>
+  This is the <em>first</em> paragraph in this example.
+  <p>This is the second.</p>
+  <!-- This is not a paragraph. -->
+</section>

+
+  

+
+  
Paragraphs in flow content are defined relative to
+  what the document looks like without the a,
+  ins, del, and map elements
+  complicating matters, since those elements, with their hybrid
+  content models, can straddle paragraph boundaries, as shown in the
+  first two examples below.

+
+  
Generally, having elements straddle paragraph
+  boundaries is best avoided. Maintaining such markup can be
+  difficult.

+
+  

+
+   
The following example takes the markup from the earlier example
+   and puts ins and del elements around some
+   of the markup to show that the text was changed (though in this
+   case, the changes admittedly don't make much sense). Notice how
+   this example has exactly the same paragraphs as the previous one,
+   despite the ins and del elements —
+   the ins element straddles the heading and the first
+   paragraph, and the del element straddles the boundary
+   between the two paragraphs.

+
+   
<section>
+  <ins><h1>Example of paragraphs</h1>
+  This is the <em>first</em> paragraph in</ins> this example<del>.
+  <p>This is the second.</p></del>
+  <!-- This is not a paragraph. -->
+</section>

+
+  

+
+  

+
+  
Let view be a view of the DOM that replaces
+  all a, ins, del, and
+  map elements in the document with their contents. Then,
+  in view, for each run of sibling phrasing
+  content nodes uninterrupted by other types of content, in an
+  element that accepts content other than phrasing
+  content as well as phrasing content, let first be the first node of the run, and let last be the last node of the run. For each such run
+  that consists of at least one node that is neither embedded
+  content nor inter-element whitespace, a
+  paragraph exists in the original DOM from immediately before first to immediately after last. (Paragraphs can thus span across
+  a, ins, del, and
+  map elements.)

+
+  
Conformance checkers may warn authors of cases where they have
+  paragraphs that overlap each other (this can happen with
+  object, video, audio, and
+  canvas elements, and indirectly through elements in
+  other namespaces that allow HTML to be further embedded therein,
+  like svg or math).
 
+
+  

+
+  
A paragraph is also formed explicitly by
+  p elements.

+
+  
The p element can be used to wrap
+  individual paragraphs when there would otherwise not be any content
+  other than phrasing content to separate the paragraphs from each
+  other.

+
+  

+
+   
In the following example, the link spans half of the first
+   paragraph, all of the heading separating the two paragraphs, and
+   half of the second paragraph. It straddles the paragraphs and the
+   heading.

+
+   
<aside>
+ Welcome!
+ <a href="about.html">
+  This is home of...
+  <h1>The Falcons!</h1>
+  The Lockheed Martin multirole jet fighter aircraft!
+ </a>
+ This page discusses the F-16 Fighting Falcon's innermost secrets.
+</aside>

+
+   
Here is another way of marking this up, this time showing the
+   paragraphs explicitly, and splitting the one link element into
+   three:

+
+   
<aside>
+ <p>Welcome! <a href="about.html">This is home of...</a></p>
+ <h1><a href="about.html">The Falcons!</a></h1>
+ <p><a href="about.html">The Lockheed Martin multirole jet
+ fighter aircraft!</a> This page discusses the F-16 Fighting
+ Falcon's innermost secrets.</p>
+</aside>

+
+  

+
+  

+
+   
+
+   
It is possible for paragraphs to overlap when using certain
+   elements that define fallback content. For example, in the
+   following section:

+
+   
<section>
+ <h1>My Cats</h1>
+ You can play with my cat simulator.
+ <object data="cats.sim">
+  To see the cat simulator, use one of the following links:
+  <ul>
+   <li><a href="cats.sim">Download simulator file</a>
+   <li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a>
+  </ul>
+  Alternatively, upgrade to the Mellblom Browser.
+ </object>
+ I'm quite proud of it.
+</section>

+
+   
There are five paragraphs:

+
+   
  1. The paragraph that says "You can play with my cat
+    simulator. object I'm quite proud of it.", where
+    object is the object element.
    2. 
+
+    
  2. The paragraph that says "To see the cat simulator, use one of
+    the following links:".
    3. 
+
+    
  3. The paragraph that says "Download simulator file".
    4. 
+
+    
  4. The paragraph that says "Use online simulator".
    5. 
+
+    
  5. The paragraph that says "Alternatively, upgrade to the Mellblom Browser.".
    6. 
+
+   
The first paragraph is overlapped by the other four. A user
+   agent that supports the "cats.sim" resource will only show the
+   first one, but a user agent that shows the fallback will
+   confusingly show the first sentence of the first paragraph as
+   if it was in the same paragraph as the second one, and will show
+   the last paragraph as if it was at the start of the second sentence
+   of the first paragraph.

+
+   
To avoid this confusion, explicit p elements can be
+   used.

+
+  

+
+
+
+  
3.2.6 Annotations for assistive technology products (ARIA)

+
+  
Authors may use the ARIA role
+  and aria-* attributes on HTML
+  elements, in accordance with the requirements described in
+  the ARIA specifications, except where these conflict with the
+  strong native semantics described below. These
+  exceptions are intended to prevent authors from making assistive
+  technology products report nonsensical states that do not represent
+  the actual state of the document. [ARIA]

+
+  

+
+  
User agents are required to implement ARIA semantics on all
+  HTML elements, as defined in the ARIA
+  specifications. The implicit ARIA semantics defined
+  below must be recognized by implementations. [ARIAIMPL]

+
+  

+
+  
The following table defines the strong native
+  semantics and corresponding implicit
+  ARIA semantics that apply to HTML
+  elements. Each language feature (element or attribute) in a
+  cell in the first column implies the ARIA semantics (role, states,
+  and/or properties) given in the cell in the second column of the
+  same row. Authors must not set the ARIA role and aria-* attributes in a manner that
+  conflicts with the semantics described in the following table. When multiple rows apply to an element, the role from
+  the last row to define a role must be applied, and the states and
+  properties from all the rows must be combined.

+
+  
Language feature
+     Strong native semantics and implied ARIA semantics
+
+   
a element that represents a hyperlink
+     link role
+
+    
area element that represents a hyperlink
+     link role
+
+    
button element
+     button role
+
+    
datalist element
+     listbox role, with the aria-multiselectable property set to "false"
+
+    
h1 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
h2 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
h3 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
h4 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
h5 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
h6 element that does not have an hgroup ancestor
+     heading role, with the aria-level property set to the element's outline depth
+
+    
hgroup element
+     heading role, with the aria-level property set to the element's outline depth
+
+    
hr element
+     separator role
+
+    
img element whose alt attribute's value is empty
+     presentation role
+
+    
input element with a type attribute in the Button state
+     button role
+
+    
input element with a type attribute in the Checkbox state
+     checkbox role, with the aria-checked state set to "mixed" if the element's indeterminate IDL attribute is true, or "true" if the element's checkedness is true, or "false" otherwise
+
+    
input element with a type attribute in the Color state
+     No role
+
+    
input element with a type attribute in the Date state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Date and Time state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Local Date and Time state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the E-mail state with no suggestions source element
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the File Upload state
+     button role
+
+    
input element with a type attribute in the Hidden state
+     No role
+
+    
input element with a type attribute in the Image Button state
+     button role
+
+    
input element with a type attribute in the Month state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Number state
+     spinbutton role, with the aria-readonly state set to "true" if the element has a readonly attribute, the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and, if the result of applying the rules for parsing floating point number values to the element's value is a number, with the aria-valuenow property set to that number
+
+    
input element with a type attribute in the Password state
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Radio Button state
+     radio role, with the aria-checked state set to "true" if the element's checkedness is true, or "false" otherwise
+
+    
input element with a type attribute in the Range state
+     slider role, with the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and the aria-valuenow property set to the result of applying the rules for parsing floating point number values to the element's value, if that that results in a number, or the default value otherwise
+
+    
input element with a type attribute in the Reset Button state
+     button role
+
+    
input element with a type attribute in the Search state with no suggestions source element
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Submit Button state
+     button role
+
+    
input element with a type attribute in the Telephone state with no suggestions source element
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Text state with no suggestions source element
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Text, Search, Telephone, URL, or E-mail states with a suggestions source element
+     combobox role, with the aria-owns property set to the same value as the list attribute, and the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Time state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the URL state with no suggestions source element
+     textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
input element with a type attribute in the Week state
+     No role, with the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
link element that represents a hyperlink
+     link role
+
+    
menu element with a type attribute in the context menu state
+     No role
+
+    
menu element with a type attribute in the list state
+     menu role
+
+    
menu element with a type attribute in the toolbar state
+     toolbar role
+
+    
nav element
+     navigation role
+
+    
option element that is in a list of options or that represents a suggestion in a datalist element
+     option role, with the aria-selected state set to "true" if the element's selectedness is true, or "false" otherwise.
+
+    
progress element
+     progressbar role, with, if the progress bar is determinate, the aria-valuemax property set to the maximum value of the progress bar, the aria-valuemin property set to zero, and the aria-valuenow property set to the current value of the progress bar
+
+    
select element with a multiple attribute
+     listbox role, with the aria-multiselectable property set to "true"
+
+    
select element with no multiple attribute
+     listbox role, with the aria-multiselectable property set to "false"
+
+    
td element
+     gridcell role, with the aria-labelledby property set to the value of the headers attribute, if any
+
+    
textarea element
+     textbox role, with the aria-multiline property set to "true", and the aria-readonly state set to "true" if the element has a readonly attribute
+
+    
th element that is neither a column header nor a row header
+     gridcell role, with the aria-labelledby property set to the value of the headers attribute, if any
+
+    
th element that is a column header
+     columnheader role, with the aria-labelledby property set to the value of the headers attribute, if any
+
+    
th element that is a row header
+     rowheader role, with the aria-labelledby property set to the value of the headers attribute, if any
+
+    
tr element
+     row role
+
+    
An element that defines a command, whose Type facet is "checkbox", and that is a descendant of a menu element whose type attribute in the list state
+     menuitemcheckbox role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
+
+    
An element that defines a command, whose Type facet is "command", and that is a descendant of a menu element whose type attribute in the list state
+     menuitem role
+
+    
An element that defines a command, whose Type facet is "radio", and that is a descendant of a menu element whose type attribute in the list state
+     menuitemradio role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
+
+    
Elements that are disabled
+     The aria-disabled state set to "true"
+
+    
Elements that are required
+     The aria-required state set to "true"
+
+  
Some HTML elements have native semantics that can be
+  overridden. The following table lists these elements and their implicit ARIA semantics,
+  along with the restrictions that apply to those elements. Each
+  language feature (element or attribute) in a cell in the first
+  column implies, unless otherwise overriden, the ARIA semantic (role,
+  state, or property) given in the cell in the second column of the
+  same row, but this semantic may be overridden under the conditions
+  listed in the cell in the third column of that row.

+
+  
Language feature
+     Default implied ARIA semantic
+     Restrictions
+
+   
address element
+     No role
+     If specified, role must be contentinfo (ARIA restricts usage of this role to one per page)
+
+    
article element
+     article role
+     Role must be either article, document, application, or main (ARIA restricts usage of this role to one per page)
+
+    
aside element
+     note role
+     Role must be either note, complementary, or search
+
+    
footer element
+     No role
+     If specified, role must be contentinfo (ARIA restricts usage of this role to one per page)
+
+    
header element
+     No role
+     If specified, role must be banner (ARIA restricts usage of this role to one per page)
+
+    
li element whose parent is an ol or ul element
+     listitem role
+     Role must be either listitem or treeitem
+
+    
ol element
+     list role
+     Role must be either list, tree, or directory
+
+    
output element
+     status role
+     No restrictions
+
+    
section element
+     region role
+     Role must be either region, document, application, contentinfo (ARIA restricts usage of this role to one per page), main (ARIA restricts usage of this role to one per page), search, alert, dialog, alertdialog, status, or log
+
+    
table element
+     grid role
+     Role must be either grid or treegrid
+
+    
ul element
+     list role
+     Role must be either list or tree, or directory
+
+    
The body element
+     document role
+     Role must be either document or application
+
+  

+
+  
User agents may apply different defaults than those described in
+  this section in order to expose the semantics of HTML
+  elements in a manner more fine-grained than possible with the
+  above definitions.

+
+  
Conformance checkers are encouraged to phrase errors such that
+  authors are encouraged to use more appropriate elements rather than
+  remove accessibility annotations. For example, if an a
+  element is marked as having the button role, a conformance
+  checker could say "Either a button element or an
+  input element is required when using the button role" rather than "The
+  button role cannot be
+  used with a elements".

+
+  

+
+
+  
3.3 APIs in HTML documents

+
+  
For HTML documents, and for HTML
+  elements in HTML documents, certain APIs defined
+  in DOM Core become case-insensitive or case-changing, as sometimes
+  defined in DOM Core, and as summarized or
+  required below. [DOMCORE]

+
+  
This does not apply to XML documents or to elements
+  that are not in the HTML namespace despite being in
+  HTML documents.

+
+  
Element.tagName and Node.nodeName

+
+   

+
+    
These attributes must return element
+    names converted to ASCII uppercase, regardless of the case
+    with which they were created.

+
+   

+
+
+   
Document.createElement()

+
+   

+
+    
The canonical form of HTML markup is all-lowercase; thus, this
+    method will lowercase
+    the argument before creating the requisite element. Also, the element created must be in the HTML
+    namespace.

+
+    
This doesn't apply to Document.createElementNS(). Thus, it is possible,
+    by passing this last method a tag name in the wrong case, to
+    create an element that appears to have the same tag name as that
+    of an element defined in this specification when its tagName attribute is examined, but that
+    doesn't support the corresponding interfaces. The "real" element
+    name (unaffected by case conversions) can be obtained from the
+    localName attribute.

+
+   

+
+
+   
Element.setAttribute()

+   
Element.setAttributeNode()

+
+   

+
+    
Attribute names are converted to ASCII lowercase.

+
+    

+
+     
Specifically: when an attribute is set on an HTML element using Element.setAttribute(), the name argument must be
+     converted to ASCII lowercase before the element is
+     affected; and when an Attr node is set on an HTML element using Element.setAttributeNode(), it must have its name
+     converted to ASCII lowercase before the element is
+     affected.

+
+    

+
+    
This doesn't apply to Element.setAttributeNS() and Element.setAttributeNodeNS().

+
+   

+
+
+   
Element.getAttribute()

+   
Element.getAttributeNode()

+
+   

+
+    
Attribute names are converted to ASCII lowercase.

+
+    

+
+     
Specifically: When the Element.getAttribute() method or the Element.getAttributeNode() method is invoked on
+     an HTML element, the name
+     argument must be converted to ASCII lowercase before the
+     element's attributes are examined.

+
+    

+
+    
This doesn't apply to Element.getAttributeNS() and Element.getAttributeNodeNS().

+
+   

+
+
+   
Document.getElementsByTagName()

+   
Element.getElementsByTagName()

+
+   

+
+    
HTML elements match by lower-casing the argument before
+    comparison, elements from other namespaces are treated as in XML
+    (case-sensitively).

+
+    

+
+    
Specifically, these methods (but not their namespaced
+    counterparts) must compare the given argument in a
+    case-sensitive manner, but when looking at HTML elements, the argument must
+    first be converted to ASCII lowercase.

+
+    

+
+    
Thus, in an HTML
+    document with nodes in multiple namespaces, these methods
+    will effectively be both case-sensitive and case-insensitive at
+    the same time.

+
+   

+
+
+  

+
+  
3.4 Interactions with XPath and XSLT

+
+  
Implementations of XPath 1.0 that
+  operate on HTML documents parsed or created in the manners described
+  in this specification (e.g. as part of the document.evaluate() API) must act as if the
+  following edit was applied to the XPath 1.0 specification.

+
+  
First, remove this paragraph:

+
+  

+
+   
A QName in the
+   node test is expanded into an expanded-name
+   using the namespace declarations from the expression context.  This
+   is the same way expansion is done for element type names in start
+   and end-tags except that the default namespace declared with xmlns is not used: if the QName does
+   not have a prefix, then the namespace URI is null (this is the same
+   way attribute names are expanded).  It is an error if the QName has a
+   prefix for which there is no namespace declaration in the
+   expression context.

+
+  

+
+  
Then, insert in its place the following:

+
+  

+
+   
A QName in the node test is expanded into an expanded-name using
+   the namespace declarations from the expression context. If the
+   QName has a prefix, then there must be a namespace
+   declaration for this prefix in the expression context, and the
+   corresponding namespace
+   URI is the one that is associated with this prefix.  It is an error
+   if the QName has a prefix for which there is no namespace
+   declaration in the expression context. 

+
+   
If the QName has no prefix and the principal node type of the
+   axis is element, then the default element namespace is
+   used. Otherwise if the QName has no prefix, the namespace URI is
+   null. The default element namespace is a member of the context for
+   the XPath expression. The value of the default element namespace
+   when executing an XPath expression through the DOM3 XPath API is
+   determined in the following way:

+
+   
  1. If the context node is from an HTML DOM, the default element
+    namespace is "http://www.w3.org/1999/xhtml".
    2. 
+
+    
  2. Otherwise, the default element namespace URI is null.
    3. 
+
+   
This is equivalent to adding the default element
+   namespace feature of XPath 2.0 to XPath 1.0, and using the HTML
+   namespace as the default element namespace for HTML documents. It
+   is motivated by the desire to have implementations be compatible
+   with legacy HTML content while still supporting the changes that
+   this specification introduces to HTML regarding the namespace used
+   for HTML elements, and by the desire to use XPath 1.0 rather than
+   XPath 2.0.

+
+  

+
+  
This change is a willful violation of
+  the XPath 1.0 specification, motivated by desire to have
+  implementations be compatible with legacy content while still
+  supporting the changes that this specification introduces to HTML
+  regarding which namespace is used for HTML elements. [XPATH10]
 
+
+  
XSLT 1.0 processors outputting
+  to a DOM when the output method is "html" (either explicitly or via
+  the defaulting rule in XSLT 1.0) are affected as follows:

+
+  
If the transformation program outputs an element in no namespace,
+  the processor must, prior to constructing the corresponding DOM
+  element node, change the namespace of the element to the HTML
+  namespace, ASCII-lowercase the element's local name, and
+  ASCII-lowercase
+  the names of any non-namespaced attributes on the element.

+
+  
This requirement is a willful violation
+  of the XSLT 1.0 specification, required because this specification
+  changes the namespaces and case-sensitivity rules of HTML in a
+  manner that would otherwise be incompatible with DOM-based XSLT
+  transformations. (Processors that serialize the output are
+  unaffected.) [XSLT10]
 
+
+  

+
+
+
+  
3.5 Dynamic markup insertion

+
+  
APIs for dynamically inserting markup into the
+  document interact with the parser, and thus their behavior varies
+  depending on whether they are used with HTML documents
+  (and the HTML parser) or XHTML in XML
+  documents (and the XML parser).

+
+
+
+  
3.5.1 Opening the input stream

+
+  
The open()
+  method comes in several variants with different numbers of
+  arguments.

+
+  
document = document . open( [ type [, replace ] ] )

+
+   

+
+    
Causes the Document to be replaced in-place, as if
+    it was a new Document object, but reusing the
+    previous object, which is then returned.

+
+    
If the type argument is omitted or has the
+    value "text/html", then the resulting
+    Document has an HTML parser associated with it, which
+    can be given data to parse using document.write(). Otherwise, all
+    content passed to document.write() will be parsed
+    as plain text.

+
+    
If the replace argument is present and has
+    the value "replace", the existing entries in
+    the session history for the Document object are
+    removed.

+
+    
The method has no effect if the Document is still
+    being parsed.

+
+    
Throws an INVALID_STATE_ERR exception if the
+    Document is an XML
+    document.

+
+   

+
+   
window = document . open( url, name, features [, replace ] )

+
+   

+
+    
Works like the window.open()
+    method.

+
+   

+
+  

+
+  
When called with two or fewer arguments, the method must act as
+  follows:

+
+  
  1. If the Document object is not flagged as an HTML document, throw an
+   INVALID_STATE_ERR exception and abort these
+   steps.
    2. 
+
+   
  2. Let type be the value of the first
+   argument, if there is one, or "text/html"
+   otherwise.
    3. 
+
+   
  3. Let replace be true if there is a second
+   argument and it is an ASCII case-insensitive match for
+   the value "replace", and false otherwise.
    4. 
+
+   
  4. 
+
+    
    If the document has an active parser that isn't a
+    script-created parser, and the insertion
+    point associated with that parser's input
+    stream is not undefined (that is, it does point to
+    somewhere in the input stream), then the method does
+    nothing. Abort these steps and return the Document
+    object on which the method was invoked.
    
+
+    
    This basically causes document.open() to be ignored
+    when it's called in an inline script found during the parsing of
+    data sent over the network, while still letting it have an effect
+    when called asynchronously or on a document that is itself being
+    spoon-fed using these APIs.
    
+
+   
    5. 
+
+   
  5. Release the storage mutex.
    6. 
+
+   
  6. Prompt to
+   unload the Document object. If the user
+   refused to allow the document to be unloaded, then
+   these steps must be aborted.
    7. 
+
+   
  7. Unload the
+   Document object, with the recycle
+   parameter set to true.
    8. 
+
+   
  8. If the document has an active parser, then
+   abort that
+   parser.
    9. 
+
+   
  9. Unregister all event listeners registered on the
+   Document node and its descendants.
    
+
+   
  10. Remove any tasks
+   associated with the Document in any task
+   source.
    11.  
+
+   
  11. Remove all child nodes of the document, without firing any
+   mutation events.
    12.  
+
+   
  12. Replace the Document's singleton objects with
+   new instances of those objects. (This includes in particular the
+   Window, Location, History,
+   ApplicationCache, UndoManager,
+   Navigator, and Selection objects, the
+   various BarProp objects, the two Storage
+   objects, and the various HTMLCollection objects. It
+   also includes all the Web IDL prototypes in the JavaScript binding,
+   including the Document object's prototype.)
    13. 
+
+   
+   
+
+   
  13. Change the document's character encoding to
+   UTF-16.
    14. 
+
+   
  14. Change the document's address to the
+   entry script's document's address.
    15. 
+
+   
  15. Create a new HTML parser and associate it with
+   the document. This is a script-created parser (meaning
+   that it can be closed by the document.open() and document.close() methods, and
+   that the tokenizer will wait for an explicit call to document.close() before emitting
+   an end-of-file token). The encoding confidence is
+   irrelevant.
    16. 
+
+   
  16. 
+
+    
+
+    
    If the type string contains a U+003B
+    SEMICOLON character (;), remove the first such character and all
+    characters from it up to the end of the string.
    
+
+    
    Strip all leading and trailing space characters from type.
    
+
+    
    If type is not now an ASCII
+    case-insensitive match for the string
+    "text/html", then act as if the tokenizer had emitted
+    a start tag token with the tag name "pre", then switch the
+    HTML parser's tokenizer to the PLAINTEXT
+    state.
    
+
+    
+
+   
    17. 
+
+   
  17. 
+
+    
    Remove all the entries in the browsing context's
+    session history after the current
+    entry. If the current entry is the last entry
+    in the session history, then no entries are removed.
    
+
+    
    This doesn't necessarily
+    have to affect the user agent's user interface.
    
+
+   
    18. 
+
+   
  18. Remove any tasks queued by
+   the history traversal task source.
    19. 
+
+   
  19. Remove any earlier entries that share the same
+   Document.
    20. 
+
+   
  20. If replace is false, then add a new
+   entry, just before the last entry, and associate with the new entry
+   the text that was parsed by the previous parser associated with the
+   Document object, as well as the state of the document
+   at the start of these steps. (This allows the user to step
+   backwards in the session history to see the page before it was
+   blown away by the document.open() call.)
    21. 
+
+   
  21. Finally, set the insertion point to point at
+   just before the end of the input stream (which at this
+   point will be empty).
    22. 
+
+   
  22. Return the Document on which the method was
+   invoked.
    23. 
+
+  
When called with three or more arguments, the open() method on the
+  HTMLDocument object must call the open() method on the Window
+  object of the HTMLDocument object, with the same
+  arguments as the original call to the open() method, and return whatever
+  that method returned. If the HTMLDocument object has no
+  Window object, then the method must raise an
+  INVALID_ACCESS_ERR exception.

+
+  

+
+
+
+  
3.5.2 Closing the input stream

+
+  
document . close()

+
+   

+
+    
Closes the input stream that was opened by the document.open() method.

+
+    
Throws an INVALID_STATE_ERR exception if the
+    Document is an XML
+    document.

+
+   

+
+  

+
+  
The close()
+  method must run the following steps:

+
+  
  1. If the Document object is not flagged as an
+   HTML document, throw an
+   INVALID_STATE_ERR exception and abort these
+   steps.
    2. 
+
+   
  2. If there is no script-created parser associated
+   with the document, then abort these steps.
    3. 
+
+   
  3. Insert an explicit "EOF" character at the end
+   of the parser's input stream.
    4. 
+
+   
  4. If there is a pending parsing-blocking script,
+   then abort these steps.
    5. 
+
+   
  5. Run the tokenizer, processing resulting tokens as they are
+   emitted, and stopping when the tokenizer reaches the explicit
+   "EOF" character or spins
+   the event loop.
    6. 
+
+  

+
+
+
+  
3.5.3 document.write()

+
+  
document . write(text...)

+
+   

+
+    
Adds the given string(s) to the Document's input
+    stream. If necessary, calls the open() method implicitly
+    first.

+
+    
This method throws an INVALID_STATE_ERR exception
+    when invoked on XML documents.

+
+    
Unless called from the body of a script element
+    while the document is being parsed, or called on a script-created
+    document, calling this method will clear the current page first,
+    as if document.open() had
+    been called.

+
+   

+
+  

+
+  
The document.write(...)
+  method must act as follows:

+
+  
  1. 
+
+    
    If the method was invoked on an XML
+    document, throw an INVALID_STATE_ERR
+    exception and abort these steps.
    
+
+    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the insertion point is undefined, the open() method must be called
+    (with no arguments) on the document
+    object. If the user refused to allow the document to be
+    unloaded, then these steps must be aborted. Otherwise, the
+    insertion point will point at just before the end of
+    the (empty) input stream.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    The string consisting of the concatenation of all the arguments
+    to the method must be inserted into the input stream
+    just before the insertion point.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If there is a pending parsing-blocking script, then the
+    method must now return without further processing of the
+    input stream.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Otherwise, the tokenizer must process the characters that were
+    inserted, one at a time, processing resulting tokens as they are
+    emitted, and stopping when the tokenizer reaches the insertion
+    point or when the processing of the tokenizer is aborted by the
+    tree construction stage (this can happen if a script
+    end tag token is emitted by the tokenizer).
+
+    
    If the document.write() method was
+    called from script executing inline (i.e. executing because the
+    parser parsed a set of script tags), then this is a
+    reentrant invocation of the
+    parser.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Finally, the method must return.
    
+
+   
    7. 
+
+  

+
+
+  
3.5.4 document.writeln()

+
+  
document . writeln(text...)

+
+   

+
+    
Adds the given string(s) to the Document's input
+    stream, followed by a newline character. If necessary, calls the
+    open() method implicitly
+    first.

+
+    
This method throws an INVALID_STATE_ERR exception
+    when invoked on XML documents.

+
+   

+
+  

+
+  
The document.writeln(...)
+  method, when invoked, must act as if the document.write() method had been
+  invoked with the same argument(s), plus an extra argument consisting
+  of a string containing a single line feed character (U+000A).

+
+  

+
+
+
+  
3.5.5 innerHTML

+
+  
The innerHTML IDL
+  attribute represents the markup of the node's contents.

+
+  
document . innerHTML [ = value ]

+
+   

+
+    
Returns a fragment of HTML or XML that represents the
+    Document.

+
+    
Can be set, to replace the Document's contents
+    with the result of parsing the given string.

+
+    
In the case of XML documents, will throw an
+    INVALID_STATE_ERR if the Document cannot
+    be serialized to XML, and a SYNTAX_ERR if the given
+    string is not well-formed.

+
+   

+
+   
element . innerHTML [ = value ]

+
+   

+
+    
Returns a fragment of HTML or XML that represents the element's
+    contents.

+
+    
Can be set, to replace the contents of the element with nodes
+    parsed from the given string.

+
+    
In the case of XML documents, will throw an
+    INVALID_STATE_ERR if the element cannot be serialized
+    to XML, and a SYNTAX_ERR if the given string is not
+    well-formed.

+
+   

+
+  

+
+  
On getting, if the node's document is an HTML document, then the attribute must return the
+  result of running the HTML fragment serialization
+  algorithm on the node; otherwise, the node's document is an
+  XML document, and the attribute
+  must return the result of running the XML fragment
+  serialization algorithm on the node instead (this might raise
+  an exception instead of returning a string).

+
+  
On setting, the following steps must be run:

+
+  
  1. 
+
+    
    If the node's document is an HTML
+    document: Invoke the HTML fragment parsing
+    algorithm.
    
+
+    
    If the node's document is an XML
+    document: Invoke the XML fragment parsing
+    algorithm.
    
+
+    
    In either case, the algorithm must be invoked with the string
+    being assigned into the innerHTML attribute as the input. If the node is an Element
+    node, then, in addition, that element must be passed as the context element.
    
+
+    
    If this raises an exception, then abort these steps.
    
+
+    
    Otherwise, let new children be the nodes
+    returned.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the attribute is being set on a Document node,
+    and that document has an active parser, then abort
+    that parser.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Remove the child nodes of the node whose innerHTML attribute is being set,
+    firing appropriate mutation events.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If the attribute is being set on a Document
+    node, let target document be that
+    Document node. Otherwise, the attribute is being
+    set on an Element node; let target
+    document be the ownerDocument of
+    that Element.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Set the ownerDocument of all the nodes in
+    new children to the target
+    document.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Append all the new children nodes to the
+    node whose innerHTML attribute
+    is being set, preserving their order, and firing mutation events
+    as if a DocumentFragment containing the new children had been inserted.
    
+
+   
    7. 
+
+  

+
+
+
+  
3.5.6 outerHTML

+
+  
The outerHTML IDL
+  attribute represents the markup of the element and its contents.

+
+  
element . outerHTML [ = value ]

+
+   

+
+    
Returns a fragment of HTML or XML that represents the element
+    and its contents.

+
+    
Can be set, to replace the element with nodes parsed from the
+    given string.

+
+    
In the case of XML documents, will throw an
+    INVALID_STATE_ERR if the element cannot be serialized
+    to XML, and a SYNTAX_ERR if the given string is not
+    well-formed.

+
+    
Throws a NO_MODIFICATION_ALLOWED_ERR exception if
+    the parent of the element is the Document
+    node.

+
+   

+
+  

+
+  
On getting, if the node's document is an HTML document, then the attribute must return the
+  result of running the HTML fragment serialization
+  algorithm on a fictional node whose only child is the node on
+  which the attribute was invoked; otherwise, the node's document is
+  an XML document, and the
+  attribute must return the result of running the XML fragment
+  serialization algorithm on that fictional node instead (this
+  might raise an exception instead of returning a string).

+
+  
On setting, the following steps must be run:

+
+  
  1. 
+
+    
    Let target be the element whose outerHTML attribute is being
+    set.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If target has no parent node, then abort
+    these steps. There would be no way to obtain a reference to the
+    nodes created even if the remaining steps were run.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If target's parent node is a
+    Document object, throw a
+    NO_MODIFICATION_ALLOWED_ERR exception and abort these
+    steps.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Let parent be target's
+    parent node, unless that is a DocumentFragment node,
+    in which case let parent be an arbitrary
+    body element.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If target's document is an HTML document: Invoke the HTML
+    fragment parsing algorithm.
    
+
+    
    If target's document is an XML document: Invoke the XML fragment
+    parsing algorithm.
    
+
+    
    In either case, the algorithm must be invoked with the string
+    being assigned into the outerHTML attribute as the input, and parent as the context element.
    
+
+    
    If this raises an exception, then abort these steps.
    
+
+    
    Otherwise, let new children be the nodes
+    returned.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Set the ownerDocument of all the nodes in
+    new children to target's
+    document.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Remove target from its parent node, firing
+    mutation events as appropriate, and then insert in its place all
+    the new children nodes, preserving their
+    order, and again firing mutation events as if a
+    DocumentFragment containing the new
+    children had been inserted.
    
+
+   
    8. 
+
+  

+
+
+
+  
3.5.7 insertAdjacentHTML()

+
+  
element . insertAdjacentHTML(position, text)

+
+   

+
+    
Parses the given string text as HTML or XML
+    and inserts the resulting nodes into the tree in the position
+    given by the position argument, as
+    follows:

+
+    
"beforebegin"

+     
Before the element itself.

+     
"afterbegin"

+     
Just inside the element, before its first child.

+     
"beforeend"

+     
Just inside the element, after its last child.

+     
"afterend"

+     
After the element itself.

+    
Throws a SYNTAX_ERR exception if the arguments
+    have invalid values (e.g., in the case of XML
+    documents, if the given string is not well-formed).

+
+    
Throws a NO_MODIFICATION_ALLOWED_ERR exception if
+    the given position isn't possible (e.g. inserting elements after
+    the root element of a Document).

+
+   

+
+  

+
+  
The insertAdjacentHTML(position, text)
+  method, when invoked, must run the following algorithm:

+
+  
  1. 
+
+    
    Let position and text
+    be the method's first and second arguments, respectively.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Let target be the element on which the
+    method was invoked.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Use the first matching item from this list:
    
+
+    
    If position is an ASCII
+     case-insensitive match for the string "beforebegin"
    
+     
    If position is an ASCII
+     case-insensitive match for the string "afterend"
    
+
+     
    
+
+      
    If target has no parent node, then abort
+      these steps.
    
+
+      
    If target's parent node is a
+      Document object, then throw a
+      NO_MODIFICATION_ALLOWED_ERR exception and abort
+      these steps.
+
+      
    Otherwise, let context be the parent node
+      of target.
    
+
+     
    
+
+     
    If position is an ASCII
+     case-insensitive match for the string "afterbegin"
    
+     
    If position is an ASCII
+     case-insensitive match for the string "beforeend"
    
+
+     
    
+
+      
    Let context be the same as target.
    
+
+     
    
+
+     
    Otherwise
    
+
+     
    
+
+      
    Throw a SYNTAX_ERR exception.
    
+
+     
    
+
+    
    4. 
+
+   
  4. 
+
+    
    If target's document is an HTML document: Invoke the HTML
+    fragment parsing algorithm.
    
+
+    
    If target's document is an XML document: Invoke the XML fragment
+    parsing algorithm.
    
+
+    
    In either case, the algorithm must be invoked with text as the input, and the
+    element selected in by the previous step as the context element.
    
+
+    
    If this raises an exception, then abort these steps.
    
+
+    
    Otherwise, let new children be the nodes
+    returned.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Set the ownerDocument of all the nodes in
+    new children to target's
+    document.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Use the first matching item from this list:
    
+
+    
    If position is an ASCII
+     case-insensitive match for the string "beforebegin"
    
+
+     
    
+
+      
    Insert all the new children nodes
+      immediately before target.
    
+
+     
    
+
+     
    If position is an ASCII
+     case-insensitive match for the string "afterbegin"
    
+
+     
    
+
+      
    Insert all the new children nodes before
+      the first child of target, if there is
+      one. If there is no such child, append them all to target.
    
+
+     
    
+
+     
    If position is an ASCII
+     case-insensitive match for the string "beforeend"
    
+
+     
    
+
+      
    Append all the new children nodes to target.
    
+
+     
    
+
+     
    If position is an ASCII
+     case-insensitive match for the string "afterend"
    
+
+     
    
+
+      
    Insert all the new children nodes
+      immediately after target.
    
+
+     
    
+
+    
    The new children nodes must be inserted in
+    a manner that preserves their order and fires mutation events as
+    if a DocumentFragment containing the new children had been inserted.
    
+
+   
    7. 
+
+  

+
+
+
+  
4 The elements of HTML

+
+  
4.1 The root element

+
+  
4.1.1 The html element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the root element of a document.

+   
Wherever a subdocument fragment is allowed in a compound document.

+   
Content model:

+   
A head element followed by a body element.

+   
Content attributes:

+   
Global attributes

+   
manifest

+   
DOM interface:

+   

+    
interface HTMLHtmlElement : HTMLElement {};

+   

+  
The html element represents the root of
+  an HTML document.

+
+  
The manifest
+  attribute gives the address of the document's application
+  cache manifest, if there is
+  one. If the attribute is present, the attribute's value must be a
+  valid non-empty URL potentially surrounded by
+  spaces.

+
+  
The manifest attribute
+  only has an effect during
+  the early stages of document load. Changing the attribute
+  dynamically thus has no effect (and thus, no DOM API is provided for
+  this attribute).

+
+  
For the purposes of application cache selection,
+  later base elements cannot affect the resolving of relative URLs in manifest attributes, as the
+  attributes are processed before those elements are seen.

+
+  
The window.applicationCache IDL
+  attribute provides scripted access to the offline application
+  cache mechanism.

+
+  

+
+   
The html element in the following example declares
+   that the document's language is English.

+
+   
<!DOCTYPE html>
+<html lang="en">
+<head>
+<title>Swapping Songs</title>
+</head>
+<body>
+<h1>Swapping Songs</h1>
+<p>Tonight I swapped some of the songs I wrote with some friends, who
+gave me some of the songs they wrote. I love sharing my music.</p>
+</body>
+</html>

+
+  

+
+
+
+
+  
4.2 Document metadata

+
+  
4.2.1 The head element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the first element in an html element.

+   
Content model:

+   
If the document is an iframe srcdoc document or if title information is available from a higher-level protocol: Zero or more elements of metadata content.

+   
Otherwise: One or more elements of metadata content, of which exactly one is a title element.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLHeadElement : HTMLElement {};

+   

+  
The head element represents a
+  collection of metadata for the Document.

+
+  

+
+   
The collection of metadata in a head element can be
+   large or small. Here is an example of a very short one:

+
+   
<!doctype html>
+<html>
+ <head>
+  <title>A document with a short head</title>
+ </head>
+ <body>
+ ...

+
+   
Here is an example of a longer one:

+
+   
<!DOCTYPE HTML>
+<HTML>
+ <HEAD>
+  <META CHARSET="UTF-8">
+  <BASE HREF="http://www.example.com/">
+  <TITLE>An application with a long head</TITLE>
+  <LINK REL="STYLESHEET" HREF="default.css">
+  <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text">
+  <SCRIPT SRC="support.js"></SCRIPT>
+  <META NAME="APPLICATION-NAME" CONTENT="Long headed application">
+ </HEAD>
+ <BODY>
+ ...

+
+  

+
+  
The title element is a required child
+  in most situations, but when a higher-level protocol provides title
+  information, e.g. in the Subject line of an e-mail when HTML is used
+  as an e-mail authoring format, the title element can be
+  omitted.

+
+
+
+  
4.2.2 The title element

+
+  
Categories

+   
Metadata content.

+   
Contexts in which this element may be used:

+   
In a head element containing no other title elements.

+   
Content model:

+   
Text.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLTitleElement : HTMLElement {
+           attribute DOMString text;
+};

+   

+  
The title element represents the
+  document's title or name. Authors should use titles that identify
+  their documents even when they are used out of context, for example
+  in a user's history or bookmarks, or in search results. The
+  document's title is often different from its first heading, since the
+  first heading does not have to stand alone when taken out of
+  context.

+
+  
There must be no more than one title element per
+  document.

+
+  
title . text [ = value ]

+
+   

+
+    
Returns the contents of the element, ignoring child nodes that
+    aren't text nodes.

+
+    
Can be set, to replace the element's children with the given
+    value.

+
+   

+
+  

+
+  
The IDL attribute text must return a
+  concatenation of the contents of all the text nodes that are direct children of the
+  title element (ignoring any other nodes such as
+  comments or elements), in tree order. On setting, it must act the
+  same way as the textContent IDL attribute.

+
+  

+
+  

+
+   
Here are some examples of appropriate titles, contrasted with
+   the top-level headings that might be used on those same pages.

+
+   
  <title>Introduction to The Mating Rituals of Bees</title>
+    ...
+  <h1>Introduction</h1>
+  <p>This companion guide to the highly successful
+  <cite>Introduction to Medieval Bee-Keeping</cite> book is...

+
+   
The next page might be a part of the same site. Note how the
+   title describes the subject matter unambiguously, while the first
+   heading assumes the reader knows what the context is and therefore
+   won't wonder if the dances are Salsa or Waltz:

+
+   
  <title>Dances used during bee mating rituals</title>
+    ...
+  <h1>The Dances</h1>

+
+  

+
+  
The string to use as the document's title is given by the document.title IDL
+  attribute. User agents should use the document's
+  title when referring to the document in their user
+  interface.

+
+
+  
4.2.3 The base element

+
+  
Categories

+   
Metadata content.

+   
Contexts in which this element may be used:

+   
In a head element containing no other base elements.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
href

+   
target

+   
DOM interface:

+   

+
interface HTMLBaseElement : HTMLElement {
+           attribute DOMString href;
+           attribute DOMString target;
+};

+   

+  
The base element allows authors to specify the
+  document base URL for the purposes of resolving relative URLs, and the name
+  of the default browsing context for the purposes of
+  following hyperlinks. The element does not represent any content beyond this
+  information.

+
+  
There must be no more than one base element per
+  document.

+
+  
A base element must have either an href attribute, a target attribute, or both.

+
+  
The href content
+  attribute, if specified, must contain a valid URL potentially
+  surrounded by spaces.

+
+  
A base element, if it has an href attribute, must come before any
+  other elements in the tree that have attributes defined as taking
+  URLs, except the html element
+  (its manifest attribute
+  isn't affected by base elements).

+
+  

+
+  
If there are multiple base elements
+  with href attributes, all but the
+  first are ignored.

+
+  

+
+  
The target
+  attribute, if specified, must contain a valid browsing context
+  name or keyword, which specifies which browsing
+  context is to be used as the default when hyperlinks and forms in the Document cause navigation.

+
+  
A base element, if it has a target attribute, must come before
+  any elements in the tree that represent hyperlinks.

+
+  

+
+  
If there are multiple base elements
+  with target attributes, all but
+  the first are ignored.

+
+  
The href and target IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  

+
+  

+
+   
In this example, a base element is used to set the
+   document base URL:

+
+   
<!DOCTYPE html>
+<html>
+    <head>
+        <title>This is an example for the &lt;base&gt; element</title>
+        <base href="http://www.example.com/news/index.html">
+    </head>
+    <body>
+        <p>Visit the <a href="archives.html">archives</a>.</p>
+    </body>
+</html>

+
+   
The link in the above example would be a link to "http://www.example.com/news/archives.html".

+
+  

+
+
+
+
+  
+
+  
Categories

+   
Metadata content.

+
+   
If the itemprop attribute is present: flow content.

+   
If the itemprop attribute is present: phrasing content.

+
+   
Contexts in which this element may be used:

+   
Where metadata content is expected.

+   
In a noscript element that is a child of a head element.

+
+   
If the itemprop attribute is present: where phrasing content is expected.

+
+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
href

+   
rel

+   
media

+   
hreflang

+   
type

+   
sizes

+   
Also, the title attribute has special semantics on this element.

+   
DOM interface:

+   

+
interface HTMLLinkElement : HTMLElement {
+           attribute boolean disabled;
+           attribute DOMString href;
+           attribute DOMString rel;
+  readonly attribute DOMTokenList relList;
+           attribute DOMString media;
+           attribute DOMString hreflang;
+           attribute DOMString type;
+  [PutForwards=value] readonly attribute DOMSettableTokenList sizes;
+};
+HTMLLinkElement implements LinkStyle;

+   

+  
The link element allows authors to link their
+  document to other resources.

+
+  
The destination of the link(s) is given by the href attribute, which must
+  be present and must contain a valid non-empty URL potentially
+  surrounded by spaces. If the href attribute is absent, then the
+  element does not define a link.

+
+
+  
A link element must have either a rel attribute, or an itemprop attribute, or both.

+
+  
The types of link indicated (the relationships) are given by the
+  value of the rel
+  attribute, which, if present, must have a value that is a set
+  of space-separated tokens. The allowed
+  values and their meanings are defined in a later section. If the rel attribute
+  is absent, or if none of the values used are allowed according to
+  the definitions in this specification, then the element does not
+  define a link.

+
+  
Two categories of links can be created using the
+  link element. Links
+  to external resources are links to resources that are to be
+  used to augment the current document, and hyperlink links are links to
+  other documents. The link types
+  section defines whether a particular link type is an external
+  resource or a hyperlink. One element can create multiple links (of
+  which some might be external resource links and some might be
+  hyperlinks); exactly which and how many links are created depends on
+  the keywords given in the rel
+  attribute. User agents must process the links on a per-link basis,
+  not a per-element basis.

+
+  
Each link is handled separately. For instance, if
+  there are two link elements with rel="stylesheet", they each count as a separate
+  external resource, and each is affected by its own attributes
+  independently.

+
+  
The exact behavior for links to external resources depends on the
+  exact relationship, as defined for the relevant link type. Some of
+  the attributes control whether or not the external resource is to be
+  applied (as defined below).

+
+  

+
+  
For external resources that are represented in the
+  DOM (for example, style sheets), the DOM representation must be made
+  available even if the resource is not applied. To obtain the resource, the user
+  agent must run the following steps:

+
+  
  1. If the href attribute's
+   value is the empty string, then abort these steps.
    2. 
+
+   
  2. Resolve the
+   URL given by the href attribute, relative to the
+   element.
    3. 
+
+   
  3. If the previous step fails, then abort these steps.
    4. 
+
+   
  4. Fetch the resulting absolute
+   URL.
    5.  
+
+  
User agents may opt to only try to obtain such resources when
+  they are needed, instead of pro-actively fetching all the external resources that are
+  not applied.

+
+  
The semantics of the protocol used (e.g. HTTP) must be followed
+  when fetching external resources. (For example, redirects will be
+  followed and 404 responses will cause the external resource to not
+  be applied.)

+
+  
+  
Once the attempts to obtain the resource and its critical
+  subresources are complete, the user agent must, if the loads
+  were successful, queue a task to fire a simple
+  event named load at the
+  link element, or, if the resource or one of its
+  critical subresources failed to completely load for any
+  reason (e.g. DNS error, HTTP 404 response, a connection being
+  prematurely closed, unsupported Content-Type), queue a
+  task to fire a simple event named error at the link
+  element. Non-network errors in processing the resource or its
+  subresources (e.g. CSS parse errors, PNG decoding errors) are not
+  failures for the purposes of this paragraph.

+
+  
The task source for these tasks is the DOM manipulation task
+  source.

+
+  
The element must delay the load event of the
+  element's document until all the attempts to obtain the resource and
+  its critical subresources are complete. (Resources that
+  the user agent has not yet attempted to obtain, e.g. because it is
+  waiting for the resource to be needed, do not delay the load
+  event.)

+
+  
Interactive user agents may provide users with a
+  means to follow the
+  hyperlinks created using the link element,
+  somewhere within their user interface. The exact interface is not
+  defined by this specification, but it could include the following
+  information (obtained from the element's attributes, again as
+  defined below), in some form or another (possibly simplified), for
+  each hyperlink created with each link element in the
+  document:

+
+  
  • The relationship between this document and the resource (given
+   by the rel attribute)
    • 
+
+   
  • The title of the resource (given by the title attribute).
    • 
+
+   
  • The address of the resource (given by the href attribute).
    • 
+
+   
  • The language of the resource (given by the hreflang attribute).
    • 
+
+   
  • The optimum media for the resource (given by the media attribute).
    • 
+
+  
User agents could also include other information, such as the
+  type of the resource (as given by the type attribute).

+
+  

+
+  
Hyperlinks created with the link
+  element and its rel attribute
+  apply to the whole page. This contrasts with the rel attribute of a
+  and area elements, which indicates the type of a link
+  whose context is given by the link's location within the
+  document.

+
+  
The media
+  attribute says which media the resource applies to. The value must
+  be a valid media query.

+
+  

+
+  
If the link is a hyperlink
+  then the media attribute is
+  purely advisory, and describes for which media the document in
+  question was designed.

+
+  
However, if the link is an external resource link,
+  then the media attribute is
+  prescriptive. The user agent must apply the external resource when
+  the media attribute's value
+  matches the environment and the other relevant
+  conditions apply, and must not apply it otherwise.

+
+  
The external resource might have further
+  restrictions defined within that limit its applicability. For
+  example, a CSS style sheet might have some @media blocks. This specification does not override
+  such further restrictions or requirements.

+
+  

+
+  
The default, if the media attribute is omitted, is "all", meaning that by default links apply to all
+  media.

+
+  
The hreflang
+  attribute on the link element has the same semantics as
+  the hreflang
+  attribute on hyperlink elements.

+
+  
The type attribute
+  gives the MIME type of the linked resource. It is
+  purely advisory.  The value must be a valid MIME
+  type.

+
+  
For external resource
+  links, the type attribute
+  is used as a hint to user agents so that they can avoid fetching
+  resources they do not support. If the attribute
+  is present, then the user agent must assume that the resource is of
+  the given type (even if that is not a valid MIME type,
+  e.g. the empty string). If the attribute is omitted, but the
+  external resource link type has a default type defined, then the
+  user agent must assume that the resource is of that type. If the UA
+  does not support the given MIME type for the given link
+  relationship, then the UA should not obtain the resource; if the UA
+  does support the given MIME type for the given link
+  relationship, then the UA should obtain the resource. If the
+  attribute is omitted, and the external resource link type does not
+  have a default type defined, but the user agent would obtain the resource if the type
+  was known and supported, then the user agent should obtain the resource under the
+  assumption that it will be supported.

+
+  

+
+  
User agents must not consider the type attribute authoritative —
+  upon fetching the resource, user agents must not use the type attribute to determine its actual
+  type. Only the actual type (as defined in the next paragraph) is
+  used to determine whether to apply the resource, not the
+  aforementioned assumed type.

+
+  
+
+  
The stylesheet
+  link type defines rules for processing the resource's Content-Type metadata.

+
+  
Once the user agent has established the type of the resource, the
+  user agent must apply the resource if it is of a supported type and
+  the other relevant conditions apply, and must ignore the resource
+  otherwise.

+
+  

+
+   
If a document contains style sheet links labeled as follows:

+
+   
<link rel="stylesheet" href="A" type="text/plain">
+<link rel="stylesheet" href="B" type="text/css">
+<link rel="stylesheet" href="C">

+
+   
...then a compliant UA that supported only CSS style sheets
+   would fetch the B and C files, and skip the A file (since
+   text/plain is not the MIME type for CSS style
+   sheets).

+
+   
For files B and C, it would then check the actual types returned
+   by the server. For those that are sent as text/css, it
+   would apply the styles, but for those labeled as
+   text/plain, or any other type, it would not.

+
+   
If one of the two files was returned without a
+   Content-Type metadata, or with a syntactically
+   incorrect type like Content-Type: "null", then the default type
+   for stylesheet links would kick
+   in. Since that default type is text/css, the
+   style sheet would nonetheless be applied.

+
+  

+
+  

+
+  
The title
+  attribute gives the title of the link. With one exception, it is
+  purely advisory. The value is text. The exception is for style sheet
+  links, where the title
+  attribute defines alternative style sheet sets.

+
+  
The title
+  attribute on link elements differs from the global
+  title attribute of most other
+  elements in that a link without a title does not inherit the title
+  of the parent element: it merely has no title.

+
+  
The sizes attribute is used
+  with the icon link type. The attribute
+  must not be specified on link elements that do not have
+  a rel attribute that specifies
+  the icon keyword.

+
+  

+
+  
Some versions of HTTP defined a Link:
+  header, to be processed like a series of link elements.
+  If supported, for the purposes of ordering links defined by HTTP
+  headers must be assumed to come before any links in the document, in
+  the order that they were given in the HTTP entity header. (URIs in
+  these headers are to be processed and resolved according to the
+  rules given in HTTP; the rules of this specification don't
+  apply.) [HTTP] [WEBLINK]
 
+
+  
The IDL attributes href, rel, media, hreflang, and type, and sizes each must
+  reflect the respective content attributes of the same
+  name.

+
+  
The IDL attribute relList must reflect the rel content attribute.

+
+  

+
+  
The IDL attribute disabled only applies
+  to style sheet links. When the link element defines a
+  style sheet link, then the disabled attribute behaves as
+  defined for the alternative
+  style sheets DOM. For all other link elements it
+  always return false and does nothing on setting.
 
+
+  
The LinkStyle interface is also implemented by
+  this element; the styling processing model defines
+  how. [CSSOM]

+
+  

+
+   
Here, a set of link elements provide some style
+   sheets:

+
+   
<!-- a persistent style sheet -->
+<link rel="stylesheet" href="default.css">
+
+<!-- the preferred alternate style sheet -->
+<link rel="stylesheet" href="green.css" title="Green styles">
+
+<!-- some alternate style sheets -->
+<link rel="alternate stylesheet" href="contrast.css" title="High contrast">
+<link rel="alternate stylesheet" href="big.css" title="Big fonts">
+<link rel="alternate stylesheet" href="wide.css" title="Wide screen">

+
+  

+
+  

+
+   
The following example shows how you can specify versions of the
+   page that use alternative formats, are aimed at other languages,
+   and that are intended for other media:

+
+   
<link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
+<link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
+<link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
+<link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
+<link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
+<link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF">

+
+  

+
+
+
+
+
+  
4.2.5 The meta element

+
+  
Categories

+   
Metadata content.

+
+   
If the itemprop attribute is present: flow content.

+   
If the itemprop attribute is present: phrasing content.

+
+   
Contexts in which this element may be used:

+   
If the charset attribute is present, or if the element's http-equiv attribute is in the Encoding declaration state: in a head element.

+   
If the http-equiv attribute is present but not in the Encoding declaration state: in a head element.

+   
If the http-equiv attribute is present but not in the Encoding declaration state: in a noscript element that is a child of a head element.

+   
If the name attribute is present: where metadata content is expected.

+
+   
If the itemprop attribute is present: where metadata content is expected.

+   
If the itemprop attribute is present: where phrasing content is expected.

+
+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
name

+   
http-equiv

+   
content

+   
charset

+   
DOM interface:

+   

+
interface HTMLMetaElement : HTMLElement {
+           attribute DOMString name;
+           attribute DOMString httpEquiv;
+           attribute DOMString content;
+};

+   

+  
The meta element represents various
+  kinds of metadata that cannot be expressed using the
+  title, base, link,
+  style, and script elements.

+
+  
The meta element can represent document-level
+  metadata with the name
+  attribute, pragma directives with the http-equiv attribute, and the
+  file's character encoding declaration when an HTML
+  document is serialized to string form (e.g. for transmission over
+  the network or for disk storage) with the charset attribute.

+
+
+  
Exactly one of the name,
+  http-equiv, charset, and itemprop attributes must be
+  specified.

+
+  
If either name, http-equiv, or itemprop is specified, then the content attribute must also be
+  specified. Otherwise, it must be omitted.

+
+  
The charset
+  attribute specifies the character encoding used by the
+  document. This is a character encoding declaration. If
+  the attribute is present in an XML
+  document, its value must be an ASCII
+  case-insensitive match for the string "UTF-8" (and the document is therefore forced to use
+  UTF-8 as its encoding).

+
+  
The charset
+  attribute on the meta element has no effect in XML
+  documents, and is only allowed in order to facilitate migration to
+  and from XHTML.

+
+  
There must not be more than one meta element with a
+  charset attribute per
+  document.

+
+  
The content
+  attribute gives the value of the document metadata or pragma
+  directive when the element is used for those purposes. The allowed
+  values depend on the exact context, as described in subsequent
+  sections of this specification.

+
+  
If a meta element has a name attribute, it sets
+  document metadata. Document metadata is expressed in terms of
+  name/value pairs, the name
+  attribute on the meta element giving the name, and the
+  content attribute on the same
+  element giving the value. The name specifies what aspect of metadata
+  is being set; valid names and the meaning of their values are
+  described in the following sections. If a meta element
+  has no content attribute,
+  then the value part of the metadata name/value pair is the empty
+  string.

+
+  

+
+  
The name and content IDL attributes
+  must reflect the respective content attributes of the
+  same name. The IDL attribute httpEquiv must
+  reflect the content attribute http-equiv.

+
+  

+
+
+  
4.2.5.1 Standard metadata names

+
+  
This specification defines a few names for the name attribute of the
+  meta element.

+
+  
Names are case-insensitive, and must be compared
+  in an ASCII case-insensitive manner.

+
+  
application-name

+
+   
The value must be a short free-form string giving the name
+   of the Web application that the page represents. If the page is not
+   a Web application, the application-name metadata name
+   must not be used. There must not be more than one meta
+   element with its name attribute
+   set to the value application-name per
+   document. User agents may use the application
+   name in UI in preference to the page's title, since
+   the title might include status messages and the like relevant to
+   the status of the page at a particular moment in time instead of
+   just being the name of the application.

+
+   
author

+
+   
The value must be a free-form string giving the name of one
+   of the page's authors.

+
+   
description

+
+   
The value must be a free-form string that describes the
+   page. The value must be appropriate for use in a directory of
+   pages, e.g. in a search engine. There must not be more than one
+   meta element with its name attribute set to the value description per document.

+
+   
generator

+
+   

+
+    
The value must be a free-form string that identifies one of the
+    software packages used to generate the document. This value must
+    not be used on hand-authored pages.

+
+    

+
+     
Here is what a tool called "Frontweaver" could include in its
+     output, in the page's head element, to identify
+     itself as the tool used to generate the page:

+
+     
<meta name=generator content="Frontweaver 8.2">

+
+    

+
+   

+
+   
keywords

+
+   

+
+    
The value must be a set of comma-separated tokens,
+    each of which is a keyword relevant to the page.

+
+    

+
+     
This page about typefaces on British motorways uses a
+     meta element to specify some keywords that users
+     might use to look for the page:

+
+     
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Typefaces on UK motorways</title>
+  <meta name="keywords" content="british,type face,font,fonts,highway,highways">
+ </head>
+ <body>
+  ...

+
+    

+
+    
Many search engines do not consider such keywords,
+    because this feature has historically been used unreliably and
+    even misleadingly as a way to spam search engine results in a way
+    that is not helpful for users.

+
+    

+
+    
To obtain the list of keywords that the author has specified as
+    applicable to the page, the user agent must run the following
+    steps:

+
+    
  1. Let keywords be an empty
+     list.
    2. 
+
+     
  2. 
+
+      
    For each meta element with a name attribute and a content attribute and whose
+      name attribute's value is
+      keywords, run the following
+      substeps:
    
+
+      
    1. Split the value
+       of the element's content
+       attribute on commas.
      2. 
+
+       
    2. Add the resulting tokens, if any, to keywords.
      3. 
+
+      
    3. 
+
+     
  3. Remove any duplicates from keywords.
    4. 
+
+     
  4. Return keywords. This is the list of
+     keywords that the author has specified as applicable to the
+     page.
    5. 
+
+    
User agents should not use this information when there is
+    insufficient confidence in the reliability of the value.

+
+    
For instance, it would be reasonable for a
+    content management system to use the keyword information of pages
+    within the system to populate the index of a site-specific search
+    engine, but a large-scale content aggregator that used this
+    information would likely find that certain users would try to game
+    its ranking mechanism through the use of inappropriate
+    keywords.

+
+    

+
+   

+
+  
4.2.5.2 Other metadata names

+
+  
Extensions to the predefined
+  set of metadata names may be registered in the WHATWG Wiki
+  MetaExtensions page. [WHATWGWIKI]

+
+  
Anyone is free to edit the WHATWG Wiki MetaExtensions page at any
+  time to add a type. These new names must be specified with the
+  following information:

+
+  
Keyword

+
+   
The actual name being defined. The name should not be
+   confusingly similar to any other defined name (e.g. differing only
+   in case).

+
+
+   
Brief description

+
+   
A short non-normative description of what the metadata
+   name's meaning is, including the format the value is required to be
+   in.

+
+
+   
Specification

+
+   
A link to a more detailed description of the metadata name's
+   semantics and requirements. It could be another page on the Wiki,
+   or a link to an external page.

+
+
+   
Synonyms

+
+   
A list of other names that have exactly the same processing
+   requirements. Authors should not use the names defined to be
+   synonyms, they are only intended to allow user agents to support
+   legacy content. Anyone may remove synonyms that are not used in
+   practice; only names that need to be processed as synonyms for
+   compatibility with legacy content are to be registered in this
+   way.

+
+
+   
Status

+
+   

+
+    
One of the following:

+
+    
Proposed

+
+     
The name has not received wide peer review and
+     approval. Someone has proposed it and is, or soon will be, using
+     it.

+
+     
Ratified

+
+     
The name has received wide peer review and approval. It has a
+     specification that unambiguously defines how to handle pages that
+     use the name, including when they use it in incorrect ways.

+
+     
Discontinued

+
+     
The metadata name has received wide peer review and it has
+     been found wanting. Existing pages are using this metadata name,
+     but new pages should avoid it. The "brief description" and
+     "specification" entries will give details of what authors should
+     use instead, if anything.

+
+    
If a metadata name is found to be redundant with existing
+    values, it should be removed and listed as a synonym for the
+    existing value.

+
+    
If a metadata name is registered in the "proposed" state for a
+    period of a month or more without being used or specified, then it
+    may be removed from the registry.

+
+    
If a metadata name is added with the "proposed" status and
+    found to be redundant with existing values, it should be removed
+    and listed as a synonym for the existing value. If a metadata name
+    is added with the "proposed" status and found to be harmful, then
+    it should be changed to "discontinued" status.

+
+    
Anyone can change the status at any time, but should only do so
+    in accordance with the definitions above.

+
+   

+
+  

+
+  
Conformance checkers must use the information given on the WHATWG
+  Wiki MetaExtensions page to establish if a value is allowed or not:
+  values defined in this specification or marked as "proposed" or
+  "ratified" must be accepted, whereas values marked as "discontinued"
+  or not listed in either this specification or on the aforementioned
+  page must be rejected as invalid. Conformance checkers may cache
+  this information (e.g. for performance reasons or to avoid the use
+  of unreliable network connectivity).

+
+  
When an author uses a new metadata name not defined by either
+  this specification or the Wiki page, conformance checkers should
+  offer to add the value to the Wiki, with the details described
+  above, with the "proposed" status.

+
+  

+
+  
Metadata names whose values are to be URLs must not be proposed or accepted. Links must
+  be represented using the link element, not the
+  meta element.

+
+
+
+  
4.2.5.3 Pragma directives

+
+  
When the http-equiv attribute
+  is specified on a meta element, the element is a pragma
+  directive.

+
+  
The http-equiv
+  attribute is an enumerated attribute. The following
+  table lists the keywords defined for this attribute. The states
+  given in the first cell of the rows with keywords give the states to
+  which those keywords map. 

+
+
+
+  
State
+     Keywords
+     Notes
+   
Content Language
+     content-language
+     Conformance checkers will include a warning
+    
Encoding declaration
+     content-type
+     
+
+    
Default style
+     default-style
+     
+    
Refresh
+     refresh
+     
+  

+
+  
When a meta element is inserted into the document, if its
+  http-equiv attribute is
+  present and represents one of the above states, then the user agent
+  must run the algorithm appropriate for that state, as described in
+  the following list:

+
+  

+
+  
Content language state (http-equiv="content-language")
+
+   

+
+    
This pragma sets the pragma-set default
+    language. Until the pragma is successfully processed, there
+    is no pragma-set default language.

+
+    
Conformance checkers will include a warning if
+    this pragma is used. Authors are encouraged to use the lang attribute instead.

+
+    

+
+    
  1. If another meta element with an http-equiv attribute in the
+     Content
+     Language state has already been successfully processed
+     (i.e. when it was inserted the user agent processed it and
+     reached the last step of this list of steps), then abort these
+     steps.
    2. 
+
+     
  2. If the meta element has no content attribute, or if that
+     attribute's value is the empty string, then abort these
+     steps.
    3. 
+
+     
  3. If the element's content attribute contains a
+     U+002C COMMA character (,) then abort these steps.
    4. 
+
+     
  4. Let input be the value of the
+     element's content
+     attribute.
    5. 
+
+     
  5. Let position point at the first
+     character of input.
    6. 
+
+     
  6. Skip whitespace.
    7. 
+
+     
  7. Collect a
+     sequence of characters that are not space characters.
    8. 
+
+     
  8. Let the pragma-set default language be the
+     string that resulted from the previous step.
    9. 
+
+    

+
+    
For meta elements with an http-equiv attribute in the
+    Content
+    Language state, the content attribute must have a
+    value consisting of a valid BCP 47 language tag. [BCP47]

+
+    
This pragma is not exactly equivalent to the HTTP
+    Content-Language header, for instance it only
+    supports one language. [HTTP]

+
+   

+
+   
Encoding declaration state (http-equiv="content-type")
+
+   

+
+    
The Encoding
+    declaration state is just an alternative form of setting
+    the charset attribute: it is a
+    character encoding declaration. This state's user agent requirements are all handled
+    by the parsing section of the specification.

+
+    
For meta elements with an http-equiv attribute in the
+    Encoding
+    declaration state, the content attribute must have a
+    value that is an ASCII case-insensitive match for a
+    string that consists of: the literal string "text/html;", optionally followed by any number of
+    space characters, followed by
+    the literal string "charset=", followed by
+    the character encoding name of the character encoding
+    declaration.

+
+    
If the document contains a meta element with an
+    http-equiv attribute in
+    the Encoding
+    declaration state, then the document must not contain a
+    meta element with the charset attribute present.

+
+    
The Encoding
+    declaration state may be used in HTML
+    documents, but elements with an http-equiv attribute in that
+    state must not be used in XML documents.

+
+   

+
+   
Default style state (http-equiv="default-style")
+
+   

+
+    
This pragma sets the name of the default alternative style sheet
+    set.

+
+    

+
+    
  1. If the meta element has no content attribute, or if that
+     attribute's value is the empty string, then abort these
+     steps.
    2. 
+
+     
  2. Set the preferred style sheet set to the
+     value of the element's content attribute. [CSSOM]
    3. 
+
+    

+
+   

+
+   
Refresh state (http-equiv="refresh")
+
+   

+
+    
This pragma acts as timed redirect.

+
+    

+
+    
  1. If another meta element with an http-equiv attribute in the
+     Refresh state
+     has already been successfully processed (i.e. when it was
+     inserted the user agent processed it and reached the last step of
+     this list of steps), then abort these steps.
    2. 
+
+     
  2. If the meta element has no content attribute, or if that
+     attribute's value is the empty string, then abort these
+     steps.
    3. 
+
+     
  3. Let input be the value of the
+     element's content
+     attribute.
    4. 
+
+     
  4. Let position point at the first
+     character of input.
    5. 
+
+     
  5. Skip whitespace.
    6. 
+
+     
  6. Collect a
+     sequence of characters in the range U+0030 DIGIT ZERO (0)
+     to U+0039 DIGIT NINE (9), and parse the resulting string using
+     the rules for parsing non-negative integers. If the
+     sequence of characters collected is the empty string, then no
+     number will have been parsed; abort these steps. Otherwise, let
+     time be the parsed number.
    7. 
+
+     
  7. Collect a
+     sequence of characters in the range U+0030 DIGIT ZERO (0) to
+     U+0039 DIGIT NINE (9) and U+002E FULL STOP (.). Ignore any collected
+     characters.
    8. 
+
+     
  8. Skip whitespace.
    9. 
+
+     
  9. Let url be the address of the current
+     page.
    10. 
+
+     
  10. If the character in input pointed to
+     by position is a U+003B SEMICOLON (";"), then advance position to
+     the next character. Otherwise, jump to the last step.
    11. 
+
+     
  11. Skip whitespace.
    12. 
+
+     
  12. If the character in input pointed to
+     by position is a U+0055 LATIN CAPITAL LETTER
+     U character (U) or a U+0075 LATIN SMALL LETTER U character (u),
+     then advance position to the next
+     character. Otherwise, jump to the last step.
    13. 
+
+     
  13. If the character in input pointed to
+     by position is a U+0052 LATIN CAPITAL LETTER
+     R character (R) or a U+0072 LATIN SMALL LETTER R character (r),
+     then advance position to the next
+     character. Otherwise, jump to the last step.
    14. 
+
+     
  14. If the character in input pointed to
+     by position is s U+004C LATIN CAPITAL LETTER
+     L character (L) or a U+006C LATIN SMALL LETTER L character (l),
+     then advance position to the next
+     character. Otherwise, jump to the last step.
    15. 
+
+     
  15. Skip whitespace.
    16. 
+
+     
  16. If the character in input pointed to
+     by position is a U+003D EQUALS SIGN ("="), then advance position to
+     the next character. Otherwise, jump to the last step.
    17. 
+
+     
  17. Skip whitespace.
    18. 
+
+     
  18. If the character in input pointed to
+     by position is either a U+0027 APOSTROPHE
+     character (') or U+0022 QUOTATION MARK character ("), then let
+     quote be that character, and advance position to the next character. Otherwise, let
+     quote be the empty string.
    19. 
+
+     
  19. Let url be equal to the substring of
+     input from the character at position to the end of the string.
    20. 
+
+     
  20. If quote is not the empty string, and
+     there is a character in url equal to quote, then truncate url at
+     that character, so that it and all subsequent characters are
+     removed.
    
+
+     
  21. Strip any trailing space
+     characters from the end of url.
    22. 
+
+     
  22. Strip any U+0009 CHARACTER TABULATION, U+000A LINE FEED
+     (LF), and U+000D CARRIAGE RETURN (CR) characters from url.
    23. 
+
+     
  23. Resolve the url value to an absolute URL,
+     relative to the meta element. If this fails, abort
+     these steps.
    24. 
+
+     
  24. 
+
+      
    Perform one or more of the following steps:
    
+
+      
    In addition, the user agent may, as with anything, inform the
+      user of any and all aspects of its operation, including the
+      state of any timers, the destinations of any timed redirects,
+      and so forth.
    
+
+     
    25. 
+
+    

+
+    
For meta elements with an http-equiv attribute in the
+    Refresh state,
+    the content attribute must
+    have a value consisting either of:

+
+    
  •  just a valid non-negative integer, or
    • 
+
+     
  •  a valid non-negative integer, followed by a
+     U+003B SEMICOLON character (;), followed by one or more space characters, followed by
+     either a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075
+     LATIN SMALL LETTER U character (u), a U+0052 LATIN CAPITAL LETTER
+     R character (R) or a U+0072 LATIN SMALL LETTER R character (r), a
+     U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN
+     SMALL LETTER L character (l), a U+003D EQUALS SIGN character (=),
+     and then a valid URL.
    • 
+
+    
In the former case, the integer represents a number of seconds
+    before the page is to be reloaded; in the latter case the integer
+    represents a number of seconds before the page is to be replaced
+    by the page at the given URL.

+
+    

+
+     
A news organization's front page could include the following
+     markup in the page's head element, to ensure that
+     the page automatically reloads from the server every five
+     minutes:

+
+     
<meta http-equiv="Refresh" content="300">

+
+    

+
+    

+
+     
A sequence of pages could be used as an automated slide show
+     by making each page refresh to the next page in the sequence,
+     using markup such as the following:

+
+     
<meta http-equiv="Refresh" content="20; URL=page4.html">

+
+    

+
+   

+
+  
There must not be more than one meta element with
+  any particular state in the document at a time.

+
+
+  
4.2.5.4 Other pragma directives

+
+  
Extensions to the
+  predefined set of pragma directives may, under certain
+  conditions, be registered in the WHATWG Wiki
+  PragmaExtensions page. [WHATWGWIKI]

+
+  
Such extensions must use a name that is identical to an HTTP
+  header registered in the Permanent Message Header Field Registry,
+  and must have behavior identical to that described for the HTTP
+  header. [IANAPERMHEADERS]

+
+  
Pragma directives corresponding to headers describing metadata,
+  or not requiring specific user agent processing, must not be
+  registered; instead, use metadata names. Pragma
+  directives corresponding to headers that affect the HTTP processing
+  model (e.g. caching) must not be registered, as they would result in
+  HTTP-level behavior being different for user agents that implement
+  HTML than for user agents that do not.

+
+  
Anyone is free to edit the WHATWG Wiki PragmaExtensions page at
+  any time to add a pragma directive satisfying these conditions. Such
+  registrations must specify the following information:

+
+  
Keyword

+
+   
The actual name being defined. The name must match a
+   previously-registered HTTP name with the same
+   requirements.

+
+
+   
Brief description

+
+   
A short non-normative description of the purpose of the
+   pragma directive.

+
+
+   
Specification

+
+   
A link to the specification defining the corresponding HTTP
+   header.

+
+  

+
+  
Conformance checkers must use the information given on the WHATWG
+  Wiki PragmaExtensions page to establish if a value is allowed or
+  not: values defined in this specification or listed on the
+  aforementioned page must be accepted, whereas values not listed in
+  either this specification or on the aforementioned page must be
+  rejected as invalid. Conformance checkers may cache this information
+  (e.g. for performance reasons or to avoid the use of unreliable
+  network connectivity).

+
+  

+
+
+
+
+  
4.2.5.5 Specifying the document's character encoding

+
+  
+
+  
A character encoding declaration is a mechanism by
+  which the character encoding used to store or transmit a document is
+  specified.

+
+  
The following restrictions apply to character encoding
+  declarations:

+
+  
  • The character encoding name given must be the name of the
+   character encoding used to serialize the file.
    • 
+
+   
  • The value must be a valid character encoding name, and must be
+   an ASCII case-insensitive match for the
+   preferred MIME name for that encoding. [IANACHARSET]
    • 
+
+   
  • The character encoding declaration must be serialized without
+   the use of character references
+   or character escapes of any kind.
    • 
+
+   
  • The element containing the character encoding
+   declaration must be serialized completely within the first 512
+   bytes of the document.
    • 
+
+   
  • There can only be one character encoding declaration in the
+   document.
    •  
+
+  
If an HTML document does not
+  start with a BOM, and if its encoding is not explicitly given by
+  Content-Type metadata, and the
+  document is not an iframe srcdoc document, then the
+  character encoding used must be an ASCII-compatible character
+  encoding, and, in addition, if that encoding isn't US-ASCII
+  itself, then the encoding must be specified using a
+  meta element with a charset attribute or a
+  meta element with an http-equiv attribute in the
+  Encoding declaration
+  state.

+
+  
If the document is an iframe srcdoc document, the
+  document must not have a character encoding
+  declaration. (In this case, the source is already decoded,
+  since it is part of the document that contained the
+  iframe.)

+
+  
If an HTML document contains
+  a meta element with a charset attribute or a
+  meta element with an http-equiv attribute in the
+  Encoding declaration
+  state, then the character encoding used must be an
+  ASCII-compatible character encoding.

+
+  
Authors are encouraged to use UTF-8. Conformance checkers may
+  advise authors against using legacy encodings.

+
+  

+
+  
Authoring tools should default to using UTF-8 for newly-created
+  documents.

+
+  

+
+  
Encodings in which a series of bytes in the range 0x20 to 0x7E
+  can encode characters other than the corresponding characters in the
+  range U+0020 to U+007E represent a potential security vulnerability:
+  a user agent that does not support the encoding (or does not support
+  the label used to declare the encoding, or does not use the same
+  mechanism to detect the encoding of unlabelled content as another
+  user agent) might end up interpreting technically benign plain text
+  content as HTML tags and JavaScript. For example, this applies to
+  encodings in which the bytes corresponding to "<script>" in ASCII can encode a different
+  string. Authors should not use such encodings, which are known to
+  include JIS_C6226-1983,
+  JIS_X0212-1990, HZ-GB-2312, JOHAB  (Windows code
+  page 1361), encodings based on ISO-2022, and encodings based on EBCDIC. Furthermore, authors must not
+  use the CESU-8, UTF-7, BOCU-1 and SCSU encodings, which also fall
+  into this category, because these encodings were never intended for
+  use for Web content.
+  [RFC1345]
+  [RFC1842]
+  [RFC1468]
+  [RFC2237]
+  [RFC1554]
+  [RFC1922]
+  [RFC1557]
+  [CESU8]
+  [UTF7]
+  [BOCU1]
+  [SCSU]
+  
+  

+
+  
Authors should not use UTF-32, as the encoding detection
+  algorithms described in this specification intentionally do not
+  distinguish it from UTF-16. [UNICODE]

+
+  
Using non-UTF-8 encodings can have unexpected
+  results on form submission and URL encodings, which use the
+  document's character encoding by default.

+
+  
In XHTML, the XML declaration should be used for inline character
+  encoding information, if necessary.

+
+  

+
+   
In HTML, to declare that the character encoding is UTF-8, the
+   author could include the following markup near the top of the
+   document (in the head element):

+
+   
<meta charset="utf-8">

+
+   
In XML, the XML declaration would be used instead, at the very
+   top of the markup:

+
+   
<?xml version="1.0" encoding="utf-8"?>

+
+  

+
+
+  
4.2.6 The style element

+
+  
Categories

+   
Metadata content.

+   
If the scoped attribute is present: flow content.

+   
Contexts in which this element may be used:

+   
If the scoped attribute is absent: where metadata content is expected.

+   
If the scoped attribute is absent: in a noscript element that is a child of a head element.

+   
If the scoped attribute is present: where flow content is expected, but before any other flow content other than other style elements and inter-element whitespace.

+   
Content model:

+   
Depends on the value of the type attribute, but must match requirements described in prose below.

+   
Content attributes:

+   
Global attributes

+   
media

+   
type

+   
scoped

+   
Also, the title attribute has special semantics on this element.

+   
DOM interface:

+   

+
interface HTMLStyleElement : HTMLElement {
+           attribute boolean disabled;
+           attribute DOMString media;
+           attribute DOMString type;
+           attribute boolean scoped;
+};
+HTMLStyleElement implements LinkStyle;

+   

+  
The style element allows authors to embed style
+  information in their documents. The style element is
+  one of several inputs to the styling processing
+  model. The element does not represent content for the user.

+
+  
The type
+  attribute gives the styling language. If the attribute is present,
+  its value must be a valid MIME type that designates a
+  styling language. The charset parameter must
+  not be specified. The default, which is used if the attribute is
+  absent, is "text/css". [RFC2318]

+
+  

+
+  
+  
When examining types to determine if they support the language,
+  user agents must not ignore unknown MIME parameters — types
+  with unknown parameters must be assumed to be unsupported. The charset parameter must be treated as an unknown
+  parameter for the purpose of comparing MIME
+  types here.

+
+  

+
+  
The media
+  attribute says which media the styles apply to. The value must be a
+  valid media query.  The user agent
+  must apply the styles when the media attribute's value
+  matches the environment and the other relevant
+  conditions apply, and must not apply them otherwise.

+
+  

+
+  
The styles might be further limited in scope,
+  e.g. in CSS with the use of @media
+  blocks. This specification does not override such further
+  restrictions or requirements.

+
+  

+
+  
The default, if the media attribute is omitted, is
+  "all", meaning that by default styles apply to
+  all media.

+
+  
The scoped
+  attribute is a boolean attribute. If set, it indicates
+  that the styles are intended just for the subtree rooted at the
+  style element's parent element, as opposed to the whole
+  Document.

+
+  

+
+  
If the scoped attribute is
+  present, then the user agent must apply the specified style
+  information only to the style element's parent element
+  (if any), and that element's child nodes. Otherwise, the specified
+  styles must, if applied, be applied to the entire document.

+
+  

+
+  
The title attribute on
+  style elements defines alternative style sheet
+  sets. If the style element has no title attribute, then it has no
+  title; the title attribute of
+  ancestors does not apply to the style element. [CSSOM]

+
+  
The title
+  attribute on style elements, like the title attribute on link
+  elements, differs from the global title attribute in that a
+  style block without a title does not inherit the title
+  of the parent element: it merely has no title.

+
+  
The textContent of a style element must
+  match the style production in the following
+  ABNF, the character set for which is Unicode. [ABNF]

+
+  
style         = no-c-start *( c-start no-c-end c-end no-c-start )
+no-c-start    = <any string that doesn't contain a substring that matches c-start >
+c-start       = "<!--"
+no-c-end      = <any string that doesn't contain a substring that matches c-end >
+c-end         = "-->"

+
+  
+
+  

+
+  
All descendant elements must be processed, according to their
+  semantics, before the style element itself is
+  evaluated. For styling languages that consist of pure text, user
+  agents must evaluate style elements by passing the
+  concatenation of the contents of all the text nodes that are direct children of the
+  style element (not any other nodes such as comments or
+  elements), in tree order, to the style system. For
+  XML-based styling languages, user agents must pass all the child
+  nodes of the style element to the style system.

+
+  
All URLs found by the styling language's
+  processor must be resolved,
+  relative to the element (or as defined by the styling language),
+  when the processor is invoked.

+
+  
+  
Once the attempts to obtain the style sheet's critical
+  subresources, if any, are complete, or, if the style sheet
+  has no critical subresources, once the style sheet has
+  been parsed and processed, the user agent must, if the loads were
+  successful or there were none, queue a task to
+  fire a simple event named load at the style element,
+  or, if one of the style sheet's critical subresources
+  failed to completely load for any reason (e.g. DNS error, HTTP 404
+  response, a connection being prematurely closed, unsupported
+  Content-Type), queue a task to fire a simple
+  event named error at the
+  style element. Non-network errors in processing the
+  style sheet or its subresources (e.g. CSS parse errors, PNG decoding
+  errors) are not failures for the purposes of this paragraph.

+
+  
The task source for these tasks is the DOM manipulation task
+  source.

+
+  
The element must delay the load event of the
+  element's document until all the attempts to obtain the style
+  sheet's critical subresources, if any, are
+  complete.

+
+  

+
+  
This specification does not specify a style system,
+  but CSS is expected to be supported by most Web browsers. [CSS]

+
+  

+
+  
The media, type and scoped IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  

+
+  
The disabled
+  IDL attribute behaves as defined for the alternative style sheets
+  DOM.

+
+  
The LinkStyle interface is also implemented by
+  this element; the styling processing model defines
+  how. [CSSOM]

+
+  

+
+   
The following document has its emphasis styled as bright red
+   text rather than italics text, while leaving titles of works and
+   Latin words in their default italics. It shows how using
+   appropriate elements enables easier restyling of documents.

+
+   
<!DOCTYPE html>
+<html lang="en-US">
+ <head>
+  <title>My favorite book</title>
+  <style>
+   body { color: black; background: white; }
+   em { font-style: normal; color: red; }
+  </style>
+ </head>
+ <body>
+  <p>My <em>favorite</em> book of all time has <em>got</em> to be
+  <cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks
+  about the <i lang="la">Felis Catus</i> in modern human society.</p>
+ </body>
+</html>

+
+  

+
+
+
+
+  
4.2.7 Styling

+
+  
The link and style elements can provide
+  styling information for the user agent to use when rendering the
+  document. The DOM Styling specification specifies what styling
+  information is to be used by the user agent and how it is to be
+  used. [CSSOM]

+
+  
The style and link elements implement
+  the LinkStyle interface. [CSSOM]

+
+  

+
+  
For style elements, if the user agent does not
+  support the specified styling language, then the sheet attribute of the element's
+  LinkStyle interface must return null. Similarly,
+  link elements that do not represent external resource links that contribute to
+  the styling processing model (i.e. that do not have a stylesheet keyword in their rel attribute), and link
+  elements whose specified resource has not yet been fetched, or is
+  not in a supported styling language, must have their
+  LinkStyle interface's sheet attribute return null.

+
+  
Otherwise, the LinkStyle interface's sheet attribute must return a
+  StyleSheet object with the following properties: [CSSOM]

+
+  
The style sheet type

+
+   
The style sheet type must be the same as the style's specified
+   type. For style elements, this is the same as the
+   type content attribute's
+   value, or text/css if that is omitted. For
+   link elements, this is the Content-Type metadata of the specified
+   resource.

+
+   
The style sheet location

+
+   
For link elements, the location must be the
+   result of resolving the
+   URL given by the element's href content attribute, relative to
+   the element, or the empty string if that fails. For
+   style elements, there is no location.
 
+
+   
The style sheet media

+
+   
The media must be the same as the value of the element's
+   media content attribute, or the empty string,
+   if the attribute is omitted.

+
+   
The style sheet title

+
+   
The title must be the same as the value of the element's
+   title content attribute, if the
+   attribute is present and has a non-empty value. If the attribute is
+   absent or its value is the empty string, then the style sheet does
+   not have a title (it is the empty string). The title is used for
+   defining alternative style sheet sets.

+
+   
The style sheet alternate flag

+
+   
For link elements, true if the link is an
+   alternative stylesheet. In all other cases, false.

+
+
+
+  
The same object must be returned each time.

+
+  
The disabled IDL
+  attribute on link and style elements must
+  return false and do nothing on setting, if the sheet attribute of their
+  LinkStyle interface is null. Otherwise, it must return
+  the value of the StyleSheet interface's disabled attribute on
+  getting, and forward the new value to that same attribute on
+  setting.

+
+  
+
+  
The rules for handling alternative
+  style sheets are defined in the CSS object model specification. [CSSOM]

+
+  
Style sheets, whether added by a link element, a
+  style element, an <?xml-stylesheet> PI,
+  an HTTP Link: header, or some other
+  mechanism, have a style sheet ready flag, which is
+  initially unset.

+
+  
When a style sheet is ready to be applied, its style sheet
+  ready flag must be set. If the style sheet referenced no
+  other resources (e.g. it was an internal style sheet given by a
+  style element with no @import
+  rules), then the style rules must be synchronously made available to
+  script; otherwise, the style rules must only be made available to
+  script once the event loop reaches its "update the
+  rendering" step.

+
+  
A style sheet in the context of the Document of an
+  HTML parser or XML parser is said to be
+  a style sheet blocking scripts if the element was created
+  by that Document's parser, and the element is either a
+  style element or a link element that was
+  an external resource link that
+  contributes to the styling processing model when the element
+  was created by the parser, and the element's style sheet was enabled
+  when the element was created by the parser, and the element's
+  style sheet ready flag is not yet set, and, the last
+  time the event loop reached step 1, the element was
+  in that Document,
+  and the user agent hasn't given up on that particular style sheet
+  yet. A user agent may give up on a style sheet at any time.

+
+  

+
+
+
+  
4.3 Scripting

+
+  
Scripts allow authors to add interactivity to their documents.

+
+  
Authors are encouraged to use declarative alternatives to
+  scripting where possible, as declarative mechanisms are often more
+  maintainable, and many users disable scripting.

+
+  

+   
For example, instead of using script to show or hide a section
+   to show more details, the details element could be
+   used.

+  

+
+  
Authors are also encouraged to make their applications degrade
+  gracefully in the absence of scripting support.

+
+  

+   
For example, if an author provides a link in a table header to
+   dynamically resort the table, the link could also be made to
+   function without scripts by requesting the sorted table from the
+   server.

+  

+
+
+  
4.3.1 The script element

+
+  
Categories

+   
Metadata content.

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where metadata content is expected.

+   
Where phrasing content is expected.

+   
Content model:

+   
If there is no src
+   attribute, depends on the value of the type attribute, but must match
+   script content restrictions.

+   
If there is a src
+   attribute, the element must be either empty or contain only
+   script documentation that also matches script
+   content restrictions.

+   
Content attributes:

+   
Global attributes

+   
src

+   
async

+   
defer

+   
type

+   
charset

+   
DOM interface:

+   

+
interface HTMLScriptElement : HTMLElement {
+           attribute DOMString src;
+           attribute boolean async;
+           attribute boolean defer;
+           attribute DOMString type;
+           attribute DOMString charset;
+           attribute DOMString text;
+};

+   

+  
The script element allows authors to include dynamic
+  script and data blocks in their documents. The element does not
+  represent content for the user.

+
+  
When used to include dynamic scripts, the scripts may either be
+  embedded inline or may be imported from an external file using the
+  src attribute. If the language
+  is not that described by "text/javascript",
+  then the type attribute must
+  be present, as described below.

+
+  
When used to include data blocks (as opposed to scripts), the
+  data must be embedded inline, the format of the data must be given
+  using the type attribute, and
+  the src attribute must not be
+  specified.

+
+  
The type
+  attribute gives the language of the script or format of the data. If
+  the attribute is present, its value must be a valid MIME
+  type. The charset parameter must not be
+  specified. The default, which is used if the attribute is absent,
+  is "text/javascript".

+
+  
The src
+  attribute, if specified, gives the address of the external script
+  resource to use. The value of the attribute must be a valid
+  non-empty URL potentially surrounded by spaces identifying a
+  script resource of the type given by the type attribute, if the attribute is
+  present, or of the type "text/javascript", if
+  the attribute is absent. A resource is a script resource of a given
+  type if that type identifies a scripting language and the resource
+  conforms with the requirements of that language's specification.

+
+  
The charset
+  attribute gives the character encoding of the external script
+  resource. The attribute must not be specified if the src attribute is not present. If the
+  attribute is set, its value must be a valid character encoding name,
+  must be an ASCII case-insensitive match for the
+  preferred MIME name for that encoding, and must match
+  the encoding given in the charset parameter of
+  the Content-Type metadata of the
+  external file, if any. [IANACHARSET]

+
+  
The async and
+  defer attributes
+  are boolean attributes that
+  indicate how the script should be executed. The defer and async attributes must not be
+  specified if the src attribute
+  is not present.

+
+  
There are three possible modes that can be selected using these
+  attributes. If the async
+  attribute is present, then the script will be executed
+  asynchronously, as soon as it is available. If the async attribute is not present but
+  the defer attribute is
+  present, then the script is executed when the page has finished
+  parsing. If neither attribute is present, then the script is
+  fetched and executed immediately, before the user agent continues
+  parsing the page.

+
+  
The exact processing details for these attributes
+  are, for mostly historical reasons, somewhat non-trivial, involving
+  a number of aspects of HTML. The implementation requirements are
+  therefore by necessity scattered throughout the specification. The
+  algorithms below (in this section) describe the core of this
+  processing, but these algorithms reference and are referenced by the
+  parsing rules for script start
+  and end tags in HTML, in foreign content, and in XML, the rules for the document.write() method, the
+  handling of scripting, etc.

+
+  
The defer attribute may be
+  specified even if the async
+  attribute is specified, to cause legacy Web browsers that only
+  support defer (and not async) to fall back to the defer behavior instead of the
+  synchronous blocking behavior that is the default.

+
+  
Changing the src, type, charset, async, and defer attributes dynamically has no
+  direct effect; these attribute are only used at specific times
+  described below.
 
+
+  

+
+  
A script element has several associated pieces of
+  state.

+
+  
The first is a flag indicating whether or not the script block
+  has been "already started". Initially,
+  script elements must have this flag unset (script
+  blocks, when created, are not "already started"). When a
+  script element is cloned, the "already started" flag,
+  if set, must be propagated to the clone when it is created.

+
+  
The second is a flag indicating whether the element was
+  "parser-inserted". Initially, script
+  elements must have this flag unset. It is set by the HTML
+  parser and the XML parser on script
+  elements they insert and affects the processing of those
+  elements.

+
+  
The third is a flag indicating whether or not the script block is
+  "ready to be parser-executed". Initially,
+  script elements must have this flag unset (script
+  blocks, when created, are not "ready to be parser-executed"). This
+  flag is used only for elements that are also
+  "parser-inserted", to let the parser know when to
+  execute the script.

+
+  
The fourth and fifth pieces of state are the script
+  block's type and the script block's character
+  encoding. They are determined when the script is run,
+  based on the attributes on the element at that time.

+
+  
When a script element that is neither marked as
+  having "already started" nor marked as being
+  "parser-inserted" experiences one of the events listed
+  in the following list, the user agent must synchronously run the script
+  element:

+
+  
Running a script: When a
+  script element is to be run, the user agent must act as
+  follows:

+
+  
  1. 
+
+    
    If either:
    
+
+    
    • the script element has a type attribute and its value is
+     the empty string, or
      • 
+
+     
    • the script element has no type attribute but it has a language attribute and
+     that attribute's value is the empty string, or
      • 
+
+     
    • the script element has neither a type attribute nor a language attribute, then
      • 
+
+    
    ...let the script block's type for this
+    script element be "text/javascript".
    
+
+    
    Otherwise, if the script element has a type attribute, let the
+    script block's type for this script element be
+    the value of that attribute with any leading or trailing sequences
+    of space characters
+    removed.
    
+
+    
    Otherwise, the element has a non-empty language attribute; let
+    the script block's type for this script
+    element be the concatenation of the string "text/" followed by the value of the language attribute.
     
+
+    
    The language attribute is never
+    conforming, and is always ignored if there is a type attribute present.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the script element has a charset attribute, then let
+    the script block's character encoding for this
+    script element be the encoding given by the charset attribute.
    
+
+    
    Otherwise, let the script block's character encoding
+    for this script element be the same as the encoding of the document
+    itself.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If the script element has an event attribute and a for attribute, then run these
+    substeps:
    
+
+    
    1. Let for be the value of the for attribute.
      2. 
+
+     
    2. Let event be the value of the event attribute.
      3. 
+
+     
    3. Strip leading and trailing whitespace from
+     event and for.
      4. 
+
+     
    4. If for is not an ASCII
+     case-insensitive match for the string "window", then the user agent must abort these
+     steps at this point. The script is not executed.
      5. 
+
+     
    5. If event is not an ASCII
+     case-insensitive match for either the string "onload" or the string "onload()", then the user agent must abort these
+     steps at this point. The script is not executed.
      6. 
+
+    
    4. 
+
+   
  4. 
+
+    
    If scripting is
+    disabled for the script element, or if the
+    user agent does not support the scripting language
+    given by the script block's type for this
+    script element, then the user agent must abort these
+    steps at this point. The script is not executed.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If the element has no src
+    attribute, and its child nodes consist only of comment nodes and
+    empty text nodes, then the user
+    agent must abort these steps at this point. The script is not
+    executed.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    The user agent must set the element's "already
+    started" flag.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    If the element has a src
+    attribute whose value is not the empty string, then the value of
+    that attribute must be resolved
+    relative to the element, and if that is successful, the specified
+    resource must then be fetched, from the
+    origin of the element's Document.
    
+    
+
+    
    If the src attribute's
+    value is the empty string or if it could not be resolved, then the
+    user agent must queue a task to fire a simple
+    event named error at the
+    element, and abort these steps.
    
+
+    
    For historical reasons, if the URL is a javascript:
+    URL, then the user agent must not, despite the requirements
+    in the definition of the fetching
+    algorithm, actually execute the script in the URL; instead the
+    user agent must act as if it had received an empty HTTP 400
+    response.
    
+
+    
    Once the resource's Content Type
+    metadata is available, if it ever is, apply the
+    algorithm for extracting an encoding from a
+    Content-Type to it. If this returns an encoding, and the
+    user agent supports that encoding, then let the script
+    block's character encoding be that encoding.
    
+
+    
    For performance reasons, user agents may start fetching the
+    script as soon as the attribute is set, instead, in the hope that
+    the element will be inserted into the document. Either way, once
+    the element is inserted into the document, the load must have
+    started. If the UA performs such prefetching, but the element is
+    never inserted in the document, or the src attribute is dynamically
+    changed, then the
+    user agent will not execute the script, and the fetching process
+    will have been effectively wasted.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    Then, the first of the following options that describes the
+    situation must be followed:
    
+
+    
    If the element has a src attribute, and the element has
+     a defer attribute, and the
+     element has been flagged as "parser-inserted", and
+     the element does not have an async attribute
    
+
+     
    
+
+      
    The element must be added to the end of the list of
+      scripts that will execute when the document has finished
+      parsing.
    
+
+      
    The task that the
+      networking task source places on the task
+      queue once the fetching
+      algorithm has completed must set the element's
+      "ready to be parser-executed" flag. The parser will
+      handle executing the script.
    
+
+     
    
+
+
+     
    If the element has a
+     src attribute, and the
+     element has been flagged as "parser-inserted", and
+     the element does not have an async attribute
    
+
+     
    
+
+      
    The element is the pending parsing-blocking
+      script. (There can only be one such script at a
+      time.)
    
+
+      
    The task that the
+      networking task source places on the task
+      queue once the fetching
+      algorithm has completed must set the element's
+      "ready to be parser-executed" flag. The parser will
+      handle executing the script.
    
+
+     
    
+
+
+     
    If the element does not
+     have a src attribute, but
+     there is a style sheet blocking scripts, and the
+     element has been flagged as "parser-inserted"
    
+
+     
    
+
+      
    The element is the pending parsing-blocking
+      script. (There can only be one such script at a
+      time.)
    
+
+      
    Set the element's "ready to be parser-executed"
+      flag. The parser will handle executing the script.
    
+
+     
    
+
+
+     
    If the element has a src attribute
    
+
+     
    
+
+      
    The element must be added to the set of scripts that
+      will execute as soon as possible.
    
+
+      
    The task that the
+      networking task source places on the task
+      queue once the fetching
+      algorithm has completed must execute the script block and then remove
+      the element from the set of scripts that will execute as
+      soon as possible.
    
+
+     
    
+
+
+     
    Otherwise
    
+
+     
    The user agent must immediately execute the script block, even if other
+     scripts are already executing.
    
+
+    
    9. 
+
+  
Fetching an external script must delay the load
+  event of the element's document until the task that is queued by the networking task source once
+  the resource has been fetched (defined
+  above) has been run.

+
+  
The pending parsing-blocking script is used by the
+  parser.

+
+  
Executing a script
+  block: When the steps above require that the script block be
+  executed, the user agent must act as follows:

+
+  
If the load resulted in an error (for example a DNS error, or
+   an HTTP 404 error)

+
+   
Executing the script block must just consist of firing a simple event named
+   error at the element.

+
+   
If the load was successful

+
+   
+   

+
+    
  1. 
+
+      
    Initialize the script block's source as
+      follows:
    
+
+      
    If the script is from an external file and the script block's type is a text-based language
    
+
+       
    
+
+        
    The contents of that file, interpreted as string of
+        Unicode characters, are the script source.
    
+
+        
    For each of the rows in the following table, starting with
+        the first one and going down, if the file has as many or more
+        bytes available than the number of bytes in the first column,
+        and the first bytes of the file match the bytes given in the
+        first column, then set the script block's character
+        encoding to the encoding given in the cell in the second
+        column of that row, irrespective of any previous value:
    
+
+        
+        
    Bytes in Hexadecimal
+           Encoding
+         
    FE FF
+           UTF-16BE
+          
    FF FE
+           UTF-16LE
+          
    EF BB BF
+           UTF-8
+
+        
    This step looks for Unicode Byte Order Marks
+        (BOMs).
    
+
+        
    The file must then be converted to Unicode using the
+        character encoding given by the script block's character
+        encoding.
    
+
+       
    
+
+       
    If the script is from an external file and the script block's type is an XML-based language
    
+
+       
    
+
+        
    The external file is the script source. When it is later
+        executed, it must be interpreted in a manner consistent with
+        the specification defining the language given by the
+        script block's type.
    
+
+       
    
+
+       
    If the script is inline and the script block's type is a text-based language
    
+
+       
    
+
+        
    The value of the text
+        IDL attribute at the time the element's "already
+        started" flag was set is the script source.
    
+
+       
    
+
+       
    If the script is inline and the script block's type is an XML-based language
    
+
+       
    
+
+        
    The child nodes of the script element at the
+        time the element's "already started" flag was set
+        are the script source.
    
+
+       
    
+
+      
    2. 
+
+     
  2. 
+
+      
    Create a
+      script from the script element node, using
+      the script block's source and the script
+      block's type.
    
+
+      
    This is where the script is compiled and
+      actually executed.
    
+
+     
    3. 
+
+     
  3. 
+
+      
    If the script is from an external file, fire a simple
+      event named load at the
+      script element.
    
+
+      
    Otherwise, the script is internal; queue a task
+      to fire a simple event named load at the script
+      element.
    
+
+     
    4. 
+
+    

+
+  
The IDL attributes src, type, charset, async, and defer, each must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  
script . text [ = value ]

+
+   

+
+    
Returns the contents of the element, ignoring child nodes that
+    aren't text nodes.

+
+    
Can be set, to replace the element's children with the given
+    value.

+
+   

+
+  

+
+  
The IDL attribute text must return a
+  concatenation of the contents of all the text nodes that are direct children of the
+  script element (ignoring any other nodes such as
+  comments or elements), in tree order. On setting, it must act the
+  same way as the textContent IDL attribute.

+
+  

+
+  
When inserted using the document.write() method,
+  script elements execute (typically synchronously), but
+  when inserted using innerHTML and outerHTML attributes, they do not
+  execute at all.

+
+  

+
+   
In this example, two script elements are used. One
+   embeds an external script, and the other includes some data.

+
+   
<script src="game-engine.js"></script>
+<script type="text/x-game-map">
+........U.........e
+o............A....e
+.....A.....AAA....e
+.A..AAA...AAAAA...e
+</script>

+
+   
The data in this case might be used by the script to generate
+   the map of a video game. The data doesn't have to be used that way,
+   though; maybe the map data is actually embedded in other parts of
+   the page's markup, and the data block here is just used by the
+   site's search engine to help users who are looking for particular
+   features in their game maps.

+
+  

+
+  

+
+   
The following sample shows how a script element can be used to
+   define a function that is then used by other parts of the
+   document. It also shows how a script element can be
+   used to invoke script while the document is being parsed, in this
+   case to initialize the form's output.

+
+   
<script>
+ function calculate(form) {
+   var price = 52000;
+   if (form.elements.brakes.checked)
+     price += 1000;
+   if (form.elements.radio.checked)
+     price += 2500;
+   if (form.elements.turbo.checked)
+     price += 5000;
+   if (form.elements.sticker.checked)
+     price += 250;
+   form.elements.result.value = price;
+ }
+</script>
+<form name="pricecalc" onsubmit="return false">
+ <fieldset>
+  <legend>Work out the price of your car</legend>
+  <p>Base cost: £52000.</p>
+  <p>Select additional options:</p>
+  <ul>
+   <li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li>
+   <li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li>
+   <li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li>
+   <li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li>
+  </ul>
+  <p>Total: £<output name=result onformchange="calculate(form)"></output></p>
+ </fieldset>
+ <script>
+  document.forms.pricecalc.dispatchFormChange();
+ </script>
+</form>

+
+  

+
+
+
+  
4.3.1.1 Scripting languages

+
+  

+
+  
A user agent is said to support the scripting language
+  if the script block's type is an ASCII
+  case-insensitive match for the MIME type string
+  of a scripting language that the user agent implements.

+
+  

+
+  
The following lists some MIME type strings and the
+  languages to which they refer:

+
+  
"application/ecmascript"

+   
"application/javascript"

+   
"application/x-ecmascript"

+   
"application/x-javascript"

+   
"text/ecmascript"

+   
"text/javascript"

+   
"text/javascript1.0"

+   
"text/javascript1.1"

+   
"text/javascript1.2"

+   
"text/javascript1.3"

+   
"text/javascript1.4"

+   
"text/javascript1.5"

+   
"text/jscript"

+   
"text/livescript"

+   
"text/x-ecmascript"

+   
"text/x-javascript"

+   
JavaScript. [ECMA262]

+
+   
"text/javascript;e4x=1"

+   
JavaScript with ECMAScript for XML. [ECMA357]

+
+  

+
+  
User agents may support other MIME
+  types and other languages.

+
+  
+  
When examining types to determine if they support the language,
+  user agents must not ignore unknown MIME parameters — types
+  with unknown parameters must be assumed to be unsupported. The charset parameter must be treated as an unknown
+  parameter for the purpose of comparing MIME
+  types here.

+
+  

+
+
+  
4.3.1.2 Restrictions for contents of script elements

+
+  
The textContent of a script element must match the
+  script production in the following ABNF, the
+  character set for which is Unicode. [ABNF]

+
+  
script        = data1 *( escape [ script-start data3 ] "-->" data1 ) [ escape ]
+escape        = "<!--" data2 *( script-start data3 script-end data2 )
+
+data1         = <any string that doesn't contain a substring that matches not-data1>
+not-data1     = "<!--"             
+
+data2         = <any string that doesn't contain a substring that matches not-data2>
+not-data2     = script-start / "-->"  
+
+data3         = <any string that doesn't contain a substring that matches not-data3>
+not-data3     = script-end / "-->"
+
+script-start  = lt       s c r i p t tag-end
+script-end    = lt slash s c r i p t tag-end
+
+lt            =  %x003C ; U+003C LESS-THAN SIGN character (<)
+slash         =  %x002F ; U+002F SOLIDUS character (/)
+
+s             =  %x0053 ; U+0053 LATIN CAPITAL LETTER S
+s             =/ %x0073 ; U+0073 LATIN SMALL LETTER S
+c             =  %x0043 ; U+0043 LATIN CAPITAL LETTER C
+c             =/ %x0063 ; U+0063 LATIN SMALL LETTER C
+r             =  %x0052 ; U+0052 LATIN CAPITAL LETTER R
+r             =/ %x0072 ; U+0072 LATIN SMALL LETTER R
+i             =  %x0049 ; U+0049 LATIN CAPITAL LETTER I
+i             =/ %x0069 ; U+0069 LATIN SMALL LETTER I
+p             =  %x0050 ; U+0050 LATIN CAPITAL LETTER P
+p             =/ %x0070 ; U+0070 LATIN SMALL LETTER P
+t             =  %x0054 ; U+0054 LATIN CAPITAL LETTER T
+t             =/ %x0074 ; U+0074 LATIN SMALL LETTER T
+
+tag-end       =  %x0009 ; U+0009 CHARACTER TABULATION
+tag-end       =/ %x000A ; U+000A LINE FEED (LF)
+tag-end       =/ %x000C ; U+000C FORM FEED (FF)
+tag-end       =/ %x0020 ; U+0020 SPACE
+tag-end       =/ %x002F ; U+002F SOLIDUS (/)
+tag-end       =/ %x003E ; U+003E GREATER-THAN SIGN (>)

+
+  
When a script element contains script
+  documentation, there are further restrictions on the contents
+  of the element, as described in the section below.

+
+
+  
4.3.1.3 Inline documentation for external scripts

+
+  
If a script element's src attribute is specified, then the
+  contents of the script element, if any, must be such
+  that the value of the text IDL
+  attribute, which is derived from the element's contents, matches the
+  documentation production in the following
+  ABNF, the character set for which is Unicode. [ABNF]

+
+  
documentation = *( *( space / tab / comment ) [ line-comment ] newline )
+comment       = slash star *( not-star / star not-slash ) 1*star slash
+line-comment  = slash slash *not-newline
+
+; characters
+tab           = %x0009 ; U+0009 TAB
+newline       = %x000A ; U+000A LINE FEED (LF)
+space         = %x0020 ; U+0020 SPACE
+star          = %x002A ; U+002A ASTERISK (*)
+slash         = %x002F ; U+002F SOLIDUS (/)
+not-newline   = %x0000-0009 / %x000B-10FFFF
+                ; a Unicode character other than U+000A LINE FEED (LF)
+not-star      = %x0000-0029 / %x002B-10FFFF
+                ; a Unicode character other than U+002A ASTERISK (*)
+not-slash     = %x0000-002E / %x0030-10FFFF
+                ; a Unicode character other than U+002F SOLIDUS (/)

+
+  
This corresponds to putting the contents of the
+  element in JavaScript comments.

+
+  
This requirement is in addition to the earlier
+  restrictions on the syntax of contents of script
+  elements.

+
+  

+
+   
This allows authors to include documentation, such as license
+   information or API information, inside their documents while still
+   referring to external script files. The syntax is constrained so
+   that authors don't accidentally include what looks like valid
+   script while also providing a src attribute.

+
+   
<script src="cool-effects.js">
+ // create new instances using:
+ //    var e = new Effect();
+ // start the effect using .play, stop using .stop:
+ //    e.play();
+ //    e.stop();
+</script>

+
+  

+
+
+
+  
4.3.2 The noscript element

+
+  
Categories

+   
Metadata content.

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
In a head element of an HTML document, if there are no ancestor noscript elements.

+   
Where phrasing content is expected in HTML documents, if there are no ancestor noscript elements.

+   
Content model:

+   
When scripting is disabled, in a head element: in any order, zero or more link elements, zero or more style elements, and zero or more meta elements.

+   
When scripting is disabled, not in a head element: transparent, but there must be no noscript element descendants.

+   
Otherwise: text that conforms to the requirements given in the prose.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The noscript element represents nothing
+  if scripting is enabled, and
+  represents its children if scripting is disabled. It is used
+  to present different markup to user agents that support scripting
+  and those that don't support scripting, by affecting how the
+  document is parsed.

+
+  
When used in HTML documents, the allowed content
+  model is as follows:

+
+  
In a head element, if scripting is disabled for the
+   noscript element

+
+   
The noscript element must contain only
+   link, style, and meta
+   elements.

+
+   
In a head element, if scripting is enabled for the
+   noscript element

+
+   
The noscript element must contain only text,
+   except that invoking the HTML fragment parsing
+   algorithm  with
+   the noscript element as the context element and the text contents as the input must result in a list of nodes that consists
+   only of link, style, and
+   meta elements that would be conforming if they were
+   children of the noscript element, and no parse errors.

+
+   
Outside of head elements, if scripting is disabled for the
+   noscript element

+
+   
The noscript element's content model is
+   transparent, with the additional restriction that a
+   noscript element must not have a noscript
+   element as an ancestor (that is, noscript can't be
+   nested).

+
+   
Outside of head elements, if scripting is enabled for the
+   noscript element

+
+   

+
+    
The noscript element must contain only text,
+    except that the text must be such that running the following
+    algorithm results in a conforming document with no
+    noscript elements and no script
+    elements, and such that no step in the algorithm causes an
+    HTML parser to flag a parse error:

+
+    
  1. Remove every script element from the
+     document.
    2. 
+
+     
  2. Make a list of every noscript element in the
+     document. For every noscript element in that list,
+     perform the following steps:
+
+      
    1. Let the parent element be the parent
+       element of the noscript element.
      2. 
+
+       
    2. Take all the children of the parent element
+       that come before the noscript element, and call these
+       elements the before children.
      3. 
+
+       
    3. Take all the children of the parent element
+       that come after the noscript element, and
+       call these elements the after children.
      4. 
+
+       
    4. Let s be the concatenation of all the
+       text node children of the noscript
+       element.
      5. 
+
+       
    5. Set the innerHTML
+       attribute of the parent element to the value
+       of s. (This, as a side-effect, causes the
+       noscript element to be removed from the
+       document.)
      6. 
+
+       
    6. Insert the before children at the start of
+       the parent element, preserving their original
+       relative order.
      7. 
+
+       
    7. Insert the after children at the end of the
+       parent element, preserving their original
+       relative order.
      8. 
+
+      
    3. 
+
+    

+
+  
All these contortions are required because, for
+  historical reasons, the noscript element is handled
+  differently by the HTML parser based on whether scripting was enabled or not when the
+  parser was invoked.

+
+  
The noscript element must not be used in XML
+  documents.

+
+  
The noscript element is only
+  effective in the HTML syntax, it has no effect in
+  the XHTML syntax.

+
+  

+
+  
The noscript element has no other requirements. In
+  particular, children of the noscript element are not
+  exempt from form submission, scripting, and so forth,
+  even when scripting is enabled
+  for the element.

+
+  

+
+  

+
+   
In the following example, a noscript element is
+   used to provide fallback for a script.

+
+   
<form action="calcSquare.php">
+ <p>
+  <label for=x>Number</label>:
+  <input id="x" name="x" type="number">
+ </p>
+ <script>
+  var x = document.getElementById('x');
+  var output = document.createElement('p');
+  output.textContent = 'Type a number; it will be squared right then!';
+  x.form.appendChild(output);
+  x.form.onsubmit = function () { return false; }
+  x.oninput = function () {
+    var v = x.valueAsNumber;
+    output.textContent = v + ' squared is ' + v * v;
+  };
+ </script>
+ <noscript>
+  <input type=submit value="Calculate Square">
+ </noscript>
+</form>

+
+   
When script is disabled, a button appears to do the calculation
+   on the server side. When script is enabled, the value is computed
+   on-the-fly instead.

+
+   
The noscript element is a blunt
+   instrument. Sometimes, scripts might be enabled, but for some
+   reason the page's script might fail. For this reason, it's
+   generally better to avoid using noscript, and to
+   instead design the script to change the page from being a
+   scriptless page to a scripted page on the fly, as in the next
+   example:

+
+   
<form action="calcSquare.php">
+ <p>
+  <label for=x>Number</label>:
+  <input id="x" name="x" type="number">
+ </p>
+ <input id="submit" type=submit value="Calculate Square">
+ <script>
+  var x = document.getElementById('x');
+  var output = document.createElement('p');
+  output.textContent = 'Type a number; it will be squared right then!';
+  x.form.appendChild(output);
+  x.form.onsubmit = function () { return false; }
+  x.oninput = function () {
+    var v = x.valueAsNumber;
+    output.textContent = v + ' squared is ' + v * v;
+  };
+  var submit = document.getElementById('submit');
+  submit.parentNode.removeChild(submit);
+ </script>
+</form>

+
+   
The above technique is also useful in XHTML, since
+   noscript is not supported in the XHTML
+   syntax.

+
+  

+
+
+
+  
4.4 Sections

+
+  
4.4.1 The body element

+
+  
Categories

+   
Sectioning root.

+   
Contexts in which this element may be used:

+   
As the second element in an html element.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
onafterprint

+   
onbeforeprint

+   
onbeforeunload

+   
onblur

+   
onerror

+   
onfocus

+   
onhashchange

+   
onload

+   
onmessage

+   
onoffline

+   
ononline

+   
onpagehide

+   
onpageshow

+   
onpopstate

+   
onredo

+   
onresize

+   
onstorage

+   
onundo

+   
onunload

+   
DOM interface:

+   

+
interface HTMLBodyElement : HTMLElement {
+           attribute Function onafterprint;
+           attribute Function onbeforeprint;
+           attribute Function onbeforeunload;
+           attribute Function onblur;
+           attribute Function onerror;
+           attribute Function onfocus;
+           attribute Function onhashchange;
+           attribute Function onload;
+           attribute Function onmessage;
+           attribute Function onoffline;
+           attribute Function ononline;
+           attribute Function onpopstate;
+           attribute Function onpagehide;
+           attribute Function onpageshow;
+           attribute Function onredo;
+           attribute Function onresize;
+           attribute Function onstorage;
+           attribute Function onundo;
+           attribute Function onunload;
+};

+

+  
The body element represents the main
+  content of the document.

+
+  
In conforming documents, there is only one body
+  element. The document.body
+  IDL attribute provides scripts with easy access to a document's
+  body element.

+
+  

+
+  
Some DOM operations (for example, parts of the
+  drag and drop model) are defined in terms of "the
+  body element". This refers to a particular element in the
+  DOM, as per the definition of the term, and not any arbitrary
+  body element.

+
+  

+
+  
The body element exposes as event handler
+  content attributes a number of the event
+  handlers of the Window object. It also mirrors
+  their event handler IDL attributes.

+
+  
The onblur, onerror, onfocus, and onload event
+  handlers of the Window object, exposed on the
+  body element, shadow the generic event
+  handlers with the same names normally supported by HTML
+  elements.

+
+  
Thus, for example, a bubbling error event fired on a child of the
+  body element of a Document would first trigger
+  the onerror event handler
+  content attributes of that element, then that of the root
+  html element, and only then would it trigger
+  the onerror event handler content
+  attribute on the body element. This is because
+  the event would bubble from the target, to the body, to
+  the html, to the Document, to the
+  Window, and the event
+  handler on the body is watching the
+  Window not the body. A regular event
+  listener attached to the body using addEventListener(), however, would fire when the
+  event bubbled through the body and not when it reaches
+  the Window object.

+
+  

+
+   
This page updates an indicator to show whether or not the user
+   is online:

+
+   
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Online or offline?</title>
+  <script>
+   function update(online) {
+     document.getElementById('status').textContent =
+       online ? 'Online' : 'Offline';
+   }
+  </script>
+ </head>
+ <body ononline="update(true)"
+       onoffline="update(false)"
+       onload="update(navigator.onLine)">
+  <p>You are: <span id="status">(Unknown)</span></p>
+ </body>
+</html>

+
+  

+
+
+
+  
4.4.2 The section element

+
+  
Categories

+   
Flow content.

+   
Sectioning content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The section element represents a
+  generic section of a document or application. A section, in this
+  context, is a thematic grouping of content, typically with a
+  heading.

+
+  
Examples of sections would be chapters, the
+  various tabbed pages in a tabbed dialog box, or the numbered
+  sections of a thesis. A Web site's home page could be split into
+  sections for an introduction, news items, contact information.

+
+  
Authors are encouraged to use the
+  article element instead of the section
+  element when it would make sense to syndicate the contents of the
+  element.

+
+  
The section
+  element is not a generic container element. When an element is
+  needed for styling purposes or as a convenience for scripting,
+  authors are encouraged to use the div element
+  instead. A general rule is that the section element is
+  appropriate only if the element's contents would be listed
+  explicitly in the document's outline.

+
+  

+
+   
In the following example, we see an article (part of a larger
+   Web page) about apples, containing two short sections.

+
+   
<article>
+ <hgroup>
+  <h1>Apples</h1>
+  <h2>Tasty, delicious fruit!</h2>
+ </hgroup>
+ <p>The apple is the pomaceous fruit of the apple tree.</p>
+ <section>
+  <h1>Red Delicious</h1>
+  <p>These bright red apples are the most common found in many
+  supermarkets.</p>
+ </section>
+ <section>
+  <h1>Granny Smith</h1>
+  <p>These juicy, green apples make a great filling for
+  apple pies.</p>
+ </section>
+</article>

+
+   
Notice how the use of section means that the author
+   can use h1 elements throughout, without having to
+   worry about whether a particular section is at the top level, the
+   second level, the third level, and so on.

+
+  

+
+  

+
+   
Here is a graduation programme with two sections, one for the
+   list of people graduating, and one for the description of the
+   ceremony.

+
+   
<!DOCTYPE Html>
+<Html
+ ><Head
+   ><Title
+     >Graduation Ceremony Summer 2022</Title
+   ></Head
+ ><Body
+   ><H1
+     >Graduation</H1
+   ><Section
+     ><H1
+       >Ceremony</H1
+     ><P
+       >Opening Procession</P
+     ><P
+       >Speech by Validactorian</P
+     ><P
+       >Speech by Class President</P
+     ><P
+       >Presentation of Diplomas</P
+     ><P
+       >Closing Speech by Headmaster</P
+   ></Section
+   ><Section
+     ><H1
+       >Graduates</H1
+     ><Ul
+       ><Li
+         >Molly Carpenter</Li
+       ><Li
+         >Anastasia Luccio</Li
+       ><Li
+         >Ebenezar McCoy</Li
+       ><Li
+         >Karrin Murphy</Li
+       ><Li
+         >Thomas Raith</Li
+       ><Li
+         >Susan Rodriguez</Li
+     ></Ul
+   ></Section
+ ></Body
+></Html>

+
+  

+
+
+
+  
4.4.3 The nav element

+
+  
Categories

+   
Flow content.

+   
Sectioning content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The nav element represents a section of
+  a page that links to other pages or to parts within the page: a
+  section with navigation links.

+
+  
Not all groups of links on a page need to be in a
+  nav element — only sections that consist of major
+  navigation blocks are appropriate for the nav
+  element. In particular, it is common for footers to have a short
+  list of links to various pages of a site, such as the terms of
+  service, the home page, and a copyright page. The
+  footer element alone is sufficient for such cases,
+  without a nav element.

+
+  
User agents (such as screen readers) that are
+  targeted at users who can benefit from navigation information being
+  omitted in the initial rendering, or who can benefit from navigation
+  information being immediately available, can use this element as a
+  way to determine what content on the page to initially skip and/or
+  provide on request.

+
+  

+
+   
In the following example, the page has several places where
+   links are present, but only one of those places is considered a
+   navigation section.

+
+   
<body>
+ <header>
+  <h1>Wake up sheeple!</h1>
+  <p><a href="news.html">News</a> -
+     <a href="blog.html">Blog</a> -
+     <a href="forums.html">Forums</a></p>
+  <p>Last Modified: <time>2009-04-01</time></p>
+  <nav>
+   <h1>Navigation</h1>
+   <ul>
+    <li><a href="articles.html">Index of all articles</a></li>
+    <li><a href="today.html">Things sheeple need to wake up for today</a></li>
+    <li><a href="successes.html">Sheeple we have managed to wake</a></li>
+   </ul>
+  </nav>
+ </header>
+ <div>
+  <article>
+   <header>
+    <h1>My Day at the Beach</h1>
+   </header>
+   <div>
+    <p>Today I went to the beach and had a lot of fun.</p>
+    ...more content...
+   </div>
+   <footer>
+    <p>Posted <time pubdate datetime="2009-10-10T14:36-08:00">Thursday</time>.</p>
+   </footer>
+  </article>
+  ...more blog posts...
+ </div>
+ <footer>
+  <p>Copyright © 2006 The Example Company</p>
+  <p><a href="about.html">About</a> -
+     <a href="policy.html">Privacy Policy</a> -
+     <a href="contact.html">Contact Us</a></p>
+ </footer>
+</body>

+
+   
Notice the div elements being used to wrap all the
+   contents of the page other than the header and footer, and all the
+   contents of the blog entry other than its header and footer.

+
+  

+
+  

+
+   
In the following example, there are two nav
+   elements, one for primary navigation around the site, and one for
+   secondary navigation around the page itself.

+
+   
<body>
+ <h1>The Wiki Center Of Exampland</h1>
+ <nav>
+  <ul>
+   <li><a href="/">Home</a></li>
+   <li><a href="/events">Current Events</a></li>
+   ...more...
+  </ul>
+ </nav>
+ <article>
+  <header>
+   <h1>Demos in Exampland</h1>
+   <p>Written by A. N. Other.</p>
+  </header>
+  <nav>
+   <ul>
+    <li><a href="#public">Public demonstrations</a></li>
+    <li><a href="#destroy">Demolitions</a></li>
+    ...more...
+   </ul>
+  </nav>
+  <div>
+   <section id="public">
+    <h1>Public demonstrations</h1>
+    <p>...more...</p>
+   </section>
+   <section id="destroy">
+    <h1>Demolitions</h1>
+    <p>...more...</p>
+   </section>
+   ...more...
+  </div>
+  <footer>
+   <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p>
+  </footer>
+ </article>
+ <footer>
+  <p><small>© copyright 1998 Exampland Emperor</small></p>
+ </footer>
+</body>

+
+  

+
+
+  
4.4.4 The article element

+
+  
Categories

+   
Flow content.

+   
Sectioning content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The article element represents a
+  self-contained composition in a document, page, application, or site
+  and that is intended to be independently distributable or reusable,
+  e.g. in syndication. This could be a forum post, a magazine or
+  newspaper article, a blog entry, a user-submitted comment, an
+  interactive widget or gadget, or any other independent item of
+  content.

+
+  
When article elements are nested, the inner
+  article elements represent articles that are in
+  principle related to the contents of the outer article. For
+  instance, a blog entry on a site that accepts user-submitted
+  comments could represent the comments as article
+  elements nested within the article element for the blog
+  entry.

+
+  
Author information associated with an article
+  element (q.v. the address element) does not apply to
+  nested article elements.

+
+  
When used specifically with content to be
+  redistributed in syndication, the article element is
+  similar in purpose to the entry element in
+  Atom. [ATOM]
+
+  
The time element's pubdate attribute can be used to
+  provide the publication date for an article
+  element.

+
+  

+
+   
This example shows a blog post using the article
+   element:

+
+   
<article>
+ <header>
+  <h1>The Very First Rule of Life</h1>
+  <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
+ </header>
+ <p>If there's a microphone anywhere near you, assume it's hot and
+ sending whatever you're saying to the world. Seriously.</p>
+ <p>...</p>
+ <footer>
+  <a href="?comments=1">Show comments...</a>
+ </footer>
+</article>

+
+   
Here is that same blog post, but showing some of the comments:

+
+   
<article>
+ <header>
+  <h1>The Very First Rule of Life</h1>
+  <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
+ </header>
+ <p>If there's a microphone anywhere near you, assume it's hot and
+ sending whatever you're saying to the world. Seriously.</p>
+ <p>...</p>
+ <section>
+  <h1>Comments</h1>
+  <article>
+   <footer>
+    <p>Posted by: George Washington</p>
+    <p><time pubdate datetime="2009-10-10T19:10-08:00"></time></p>
+   </footer>
+   <p>Yeah! Especially when talking about your lobbyist friends!</p>
+  </article>
+  <article>
+   <footer>
+    <p>Posted by: George Hammond</p>
+    <p><time pubdate datetime="2009-10-10T19:15-08:00"></time></p>
+   </footer>
+   <p>Hey, you have the same first name as me.</p>
+  </article>
+ </section>
+</article>

+
+   
Notice the use of footer to give the information
+   each comment (such as who wrote it and when): the
+   footer element can appear at the start of its
+   section when appropriate, such as in this case. (Using
+   header in this case wouldn't be wrong either; it's
+   mostly a matter of authoring preference.)

+
+  

+
+
+
+
+  
4.4.5 The aside element

+
+  
Categories

+   
Flow content.

+   
Sectioning content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The aside element represents a section
+  of a page that consists of content that is tangentially related to
+  the content around the aside element, and which could
+  be considered separate from that content. Such sections are often
+  represented as sidebars in printed typography.

+
+  
The element can be used for typographical effects like pull
+  quotes or sidebars, for advertising, for groups of nav
+  elements, and for other content that is considered separate from the
+  main content of the page.

+
+  
It's not appropriate to use the aside
+  element just for parentheticals, since those are part of the main
+  flow of the document.

+
+  

+
+   
The following example shows how an aside is used to mark up
+   background material on Switzerland in a much longer news story on
+   Europe.

+
+   
<aside>
+ <h1>Switzerland</h1>
+ <p>Switzerland, a land-locked country in the middle of geographic
+ Europe, has not joined the geopolitical European Union, though it is
+ a signatory to a number of European treaties.</p>
+</aside>

+
+  

+
+  

+
+   
The following example shows how an aside is used to mark up
+   a pull quote in a longer article.

+
+   
...
+
+<p>He later joined a large company, continuing on the same work.
+<q>I love my job. People ask me what I do for fun when I'm not at
+work. But I'm paid to do my hobby, so I never know what to
+answer. Some people wonder what they would do if they didn't have to
+work... but I know what I would do, because I was unemployed for a
+year, and I filled that time doing exactly what I do now.</q></p>
+
+<aside>
+ <q> People ask me what I do for fun when I'm not at work. But I'm
+ paid to do my hobby, so I never know what to answer. </q>
+</aside>
+
+<p>Of course his work — or should that be hobby? —
+isn't his only passion. He also enjoys other pleasures.</p>
+
+...

+
+  

+
+  

+
+   
The following extract shows how aside can be used
+   for blogrolls and other side content on a blog:

+
+   
<body>
+ <header>
+  <h1>My wonderful blog</h1>
+  <p>My tagline</p>
+ </header>
+ <aside>
+  <!-- this aside contains two sections that are tangentially related
+  to the page, namely, links to other blogs, and links to blog posts
+  from this blog -->
+  <nav>
+   <h1>My blogroll</h1>
+   <ul>
+    <li><a href="http://blog.example.com/">Example Blog</a>
+   </ul>
+  </nav>
+  <nav>
+   <h1>Archives</h1>
+   <ol reversed>
+    <li><a href="/last-post">My last post</a>
+    <li><a href="/first-post">My first post</a>
+   </ol>
+  </nav>
+ </aside>
+ <aside>
+  <!-- this aside is tangentially related to the page also, it
+  contains twitter messages from the blog author -->
+  <h1>Twitter Feed</h1>
+  <blockquote cite="http://twitter.example.net/t31351234">
+   I'm on vacation, writing my blog.
+  </blockquote>
+  <blockquote cite="http://twitter.example.net/t31219752">
+   I'm going to go on vacation soon.
+  </blockquote>
+ </aside>
+ <article>
+  <!-- this is a blog post -->
+  <h1>My last post</h1>
+  <p>This is my last post.</p>
+  <footer>
+   <p><a href="/last-post" rel=bookmark>Permalink</a>
+  </footer>
+ </article>
+ <article>
+  <!-- this is also a blog post -->
+  <h1>My first post</h1>
+  <p>This is my first post.</p>
+  <aside>
+   <!-- this aside is about the blog post, since it's inside the
+   <article> element; it would be wrong, for instance, to put the
+   blogroll here, since the blogroll isn't really related to this post
+   specifically, only to the page as a whole -->
+   <h1>Posting</h1>
+   <p>While I'm thinking about it, I wanted to say something about
+   posting. Posting is fun!</p>
+  </aside>
+  <footer>
+   <p><a href="/first-post" rel=bookmark>Permalink</a>
+  </footer>
+ </article>
+ <footer>
+  <nav>
+   <a href="/archives">Archives</a> —
+   <a href="/about">About me</a> —
+   <a href="/copyright">Copyright</a>
+  </nav>
+ </footer>
+</body>

+
+  

+
+
+
+  
4.4.6 The h1, h2,
+  h3, h4,
+  h5, and h6
+  elements

+
+  
Categories

+   
Flow content.

+   
Heading content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
As a child of an hgroup element.

+   
Where flow content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLHeadingElement : HTMLElement {};

+   

+  
These elements represent headings
+  for their sections.

+
+  
The semantics and meaning of these elements are defined in the
+  section on headings and sections.

+
+  
These elements have a rank given by the number in
+  their name. The h1 element is said to have the highest
+  rank, the h6 element has the lowest rank, and two
+  elements with the same name have equal rank.

+
+  

+
+   
These two snippets are equivalent:

+
+   
<body>
+<h1>Let's call it a draw(ing surface)</h1>
+<h2>Diving in</h2>
+<h2>Simple shapes</h2>
+<h2>Canvas coordinates</h2>
+<h3>Canvas coordinates diagram</h3>
+<h2>Paths</h2>
+</body>

+
+   
<body>
+ <h1>Let's call it a draw(ing surface)</h1>
+ <section>
+  <h1>Diving in</h1>
+ </section>
+ <section>
+  <h1>Simple shapes</h1>
+ </section>
+ <section>
+  <h1>Canvas coordinates</h1>
+  <section>
+   <h1>Canvas coordinates diagram</h1>
+  </section>
+ </section>
+ <section>
+  <h1>Paths</h1>
+ </section>
+</body>

+
+  

+
+
+
+
+  
4.4.7 The hgroup element

+
+  
Categories

+   
Flow content.

+   
Heading content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
One or more h1, h2, h3, h4, h5, and/or h6 elements.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The hgroup element represents the
+  heading of a section. The element is used to group a set of
+  h1–h6 elements when the heading has
+  multiple levels, such as subheadings, alternative titles, or
+  taglines.

+
+  
For the purposes of document summaries, outlines, and the like,
+  the text of hgroup elements is defined to be the text
+  of the highest ranked
+  h1–h6 element descendant of the
+  hgroup element, if there are any such elements, and the
+  first such element if there are multiple elements with that
+  rank. If there are no such elements, then the text of
+  the hgroup element is the empty string.

+
+  
Other elements of heading content in the
+  hgroup element indicate subheadings or subtitles.

+
+  
The rank of an hgroup element is the
+  rank of the highest-ranked h1–h6
+  element descendant of the hgroup element, if there are
+  any such elements, or otherwise the same as for an h1
+  element (the highest rank).

+
+  
The section on headings and sections
+  defines how hgroup elements are assigned to individual
+  sections.

+
+  

+
+   
Here are some examples of valid headings. In each case, the
+   emphasized text represents the text that would be used as the
+   heading in an application extracting heading data and ignoring
+   subheadings.

+
+   
<hgroup>
+ <h1>The reality dysfunction</h1>
+ <h2>Space is not the only void</h2>
+</hgroup>

+
+   
<hgroup>
+ <h1>Dr. Strangelove</h1>
+ <h2>Or: How I Learned to Stop Worrying and Love the Bomb</h2>
+</hgroup>

+
+  
The point of using hgroup in these examples is to
+  mask the h2 element (which acts as a secondary title)
+  from the outline algorithm.

+
+  

+
+
+  
4.4.8 The header element

+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content, but with no header or
+   footer element descendants.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The header element represents a group
+  of introductory or navigational aids.

+
+  
A header element is intended to usually
+  contain the section's heading (an
+  h1–h6 element or an
+  hgroup element), but this is not required. The
+  header element can also be used to wrap a section's
+  table of contents, a search form, or any relevant logos.

+
+  

+
+  
Here are some sample headers. This first one is for a game:

+
+   
<header>
+ <p>Welcome to...</p>
+ <h1>Voidwars!</h1>
+</header>

+
+   
The following snippet shows how the element can be used to mark
+   up a specification's header:

+
+   
<header>
+ <hgroup>
+  <h1>Scalable Vector Graphics (SVG) 1.2</h1>
+  <h2>W3C Working Draft 27 October 2004</h2>
+ </hgroup>
+ <dl>
+  <dt>This version:</dt>
+  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20041027/">http://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd>
+  <dt>Previous version:</dt>
+  <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20040510/">http://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd>
+  <dt>Latest version of SVG 1.2:</dt>
+  <dd><a href="http://www.w3.org/TR/SVG12/">http://www.w3.org/TR/SVG12/</a></dd>
+  <dt>Latest SVG Recommendation:</dt>
+  <dd><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></dd>
+  <dt>Editor:</dt>
+  <dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd>
+  <dt>Authors:</dt>
+  <dd>See <a href="#authors">Author List</a></dd>
+ </dl>
+ <p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notic ...
+</header>

+
+  

+
+  
The header element is not
+  sectioning content; it doesn't introduce a new
+  section.

+
+  

+
+  
In this example, the page has a page heading given by the
+  h1 element, and two subsections whose headings are
+  given by h2 elements. The content after the
+  header element is still part of the last subsection
+  started in the header element, because the
+  header element doesn't take part in the
+  outline algorithm.

+
+   
<body>
+ <header>
+  <h1>Little Green Guys With Guns</h1>
+  <nav>
+   <ul>
+    <li><a href="/games">Games</a>
+    <li><a href="/forum">Forum</a>
+    <li><a href="/download">Download</a>
+   </ul>
+  </nav>
+  <h2>Important News</h2> <!-- this starts a second subsection -->
+  <!-- this is part of the subsection entitled "Important News" -->
+  <p>To play today's games you will need to update your client.</p>
+  <h2>Games</h2> <!-- this starts a third subsection -->
+ </header>
+ <p>You have three active games:</p>
+ <!-- this is still part of the subsection entitled "Games" -->
+ ...

+
+  

+
+
+
+
+  
+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content, but with no header or
+   footer element descendants.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The footer element represents a footer
+  for its nearest ancestor sectioning content or
+  sectioning root element. A footer typically contains
+  information about its section such as who wrote it, links to related
+  documents, copyright data, and the like.

+
+  
Contact information for the author or editor of a
+  section belongs in an address element, possibly itself
+  inside a footer.

+
+  
Footers don't necessarily have to appear at the end of a
+  section, though they usually do.

+
+  
When the footer element contains entire sections,
+  they represent appendices, indexes,
+  long colophons, verbose license agreements, and other such
+  content.

+
+  
The footer element is not
+  sectioning content; it doesn't introduce a new
+  section.

+
+  
When the nearest ancestor sectioning content or
+  sectioning root element is the body
+  element, then it applies to the whole page.

+
+  

+
+   
Here is a page with two footers, one at the top and one at the
+   bottom, with the same content:

+
+   
<body>
+ <footer><a href="../">Back to index...</a></footer>
+ <hgroup>
+  <h1>Lorem ipsum</h1>
+  <h2>The ipsum of all lorems</h2>
+ </hgroup>
+ <p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod
+ tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
+ veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex
+ ea commodo consequat. Duis aute irure dolor in reprehenderit in
+ voluptate velit esse cillum dolore eu fugiat nulla
+ pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
+ culpa qui officia deserunt mollit anim id est laborum.</p>
+ <footer><a href="../">Back to index...</a></footer>
+</body>

+
+  

+
+  

+
+   
Here is an example which shows the footer element
+   being used both for a site-wide footer and for a section
+   footer.

+
+   
<!DOCTYPE HTML>
+<HTML><HEAD>
+<TITLE>The Ramblings of a Scientist</TITLE>
+<BODY>
+<H1>The Ramblings of a Scientist</H1>
+<ARTICLE>
+ <H1>Episode 15</H1>
+ <VIDEO SRC="/fm/015.ogv" CONTROLS PRELOAD>
+  <P><A HREF="/fm/015.ogv">Download video</A>.</P>
+ </VIDEO>
+ <FOOTER> <!-- footer for article -->
+  <P>Published <TIME PUBDATE DATETIME="2009-10-21T18:26-07:00"></TIME></P>
+ </FOOTER>
+</ARTICLE>
+<ARTICLE>
+ <H1>My Favorite Trains</H1>
+ <P>I love my trains. My favorite train of all time is a Köf.</P>
+ <P>It is fun to see them pull some coal cars because they look so
+ dwarfed in comparison.</P>
+ <FOOTER> <!-- footer for article -->
+  <P>Published <TIME PUBDATE DATETIME="2009-09-15T14:54-07:00"></TIME></P>
+ </FOOTER>
+</ARTICLE>
+<FOOTER> <!-- site wide footer -->
+ <NAV>
+  <P><A HREF="/credits.html">Credits</A> —
+     <A HREF="/tos.html">Terms of Service</A> —
+     <A HREF="/index.html">Blog Index</A></P>
+ </NAV>
+ <P>Copyright © 2009 Gordon Freeman</P>
+</FOOTER>
+</BODY>
+</HTML>

+
+  

+
+
+  
4.4.10 The address element

+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content, but with no heading
+   content descendants, no sectioning content
+   descendants, and no header, footer, or
+   address element descendants.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The address element represents the
+  contact information for its nearest article or
+  body element ancestor. If that is the body
+  element, then the contact information applies to the document
+  as a whole.

+
+  

+   
For example, a page at the W3C Web site related to HTML might
+   include the following contact information:

+   
<ADDRESS>
+ <A href="../People/Raggett/">Dave Raggett</A>,
+ <A href="../People/Arnaud/">Arnaud Le Hors</A>,
+ contact persons for the <A href="Activity">W3C HTML Activity</A>
+</ADDRESS>

+  

+
+  
The address element must not be used to represent
+  arbitrary addresses (e.g. postal addresses), unless those addresses
+  are in fact the relevant contact information. (The p
+  element is the appropriate element for marking up postal addresses
+  in general.)

+
+  
The address element must not contain information
+  other than contact information.

+
+  

+   
For example, the following is non-conforming use of the
+   address element:

+   
<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>

+  

+
+  
Typically, the address element would be included
+  along with other information in a footer element.

+
+  

+
+  
The contact information for a node node is a
+  collection of address elements defined by the first
+  applicable entry from the following list:

+
+  
If node is an article element

+   
If node is a body element

+
+   

+
+    
The contact information consists of all the
+    address elements that have node
+    as an ancestor and do not have another body or
+    article element ancestor that is a descendant of node.

+
+   

+
+   
If node has an ancestor element that is an article element

+   
If node has an ancestor element that is a body element

+
+   

+
+    
The contact information of node is the same
+    as the contact information of the nearest article or
+    body element ancestor, whichever is nearest.

+
+   

+
+   
If node's Document has a body element

+
+   

+
+    
The contact information of node is the same
+    as the contact information the body element of the
+    Document.

+
+   

+
+   
Otherwise

+
+   

+
+    
There is no contact information for node.

+
+   

+
+  
User agents may expose the contact information of a node to the
+  user, or use it for other purposes, such as indexing sections based
+  on the sections' contact information.

+
+  

+
+
+
+  
4.4.11 Headings and sections

+
+  
The h1–h6 elements and the
+  hgroup element are headings.

+
+  
The first element of heading content in an element
+  of sectioning content represents the
+  heading for that section. Subsequent headings of equal or higher
+  rank start new (implied) sections, headings of lower
+  rank start implied subsections that are part of the
+  previous one. In both cases, the element represents the
+  heading of the implied section.

+
+  
Certain elements are said to be sectioning roots, including blockquote and
+  td elements. These elements can have their own
+  outlines, but the sections and headings inside these elements do not
+  contribute to the outlines of their ancestors.

+
+  
+  
Sectioning content elements are always considered
+  subsections of their nearest ancestor sectioning root
+  or their nearest ancestor element of sectioning
+  content, whichever is nearest, regardless of what implied
+  sections other headings may have created.

+
+  

+   
For the following fragment:

+   
<body>
+ <h1>Foo</h1>
+ <h2>Bar</h2>
+ <blockquote>
+  <h3>Bla</h3>
+ </blockquote>
+ <p>Baz</p>
+ <h2>Quux</h2>
+ <section>
+  <h3>Thud</h3>
+ </section>
+ <p>Grunt</p>
+</body>

+   
...the structure would be:

+   
  1. 
+     Foo (heading of explicit body section, containing the "Grunt" paragraph)
+     
    1. 
+       Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
+      
      2. 
+      
    2. 
+       Quux (heading starting implied section with no content other than the heading itself)
+      
      3. 
+      
    3. 
+       Thud (heading of explicit section section)
+      
      4. 
+     
    2. 
+   
Notice how the section ends the earlier implicit
+   section so that a later paragraph ("Grunt") is back at the top
+   level.

+  

+
+  
Sections may contain headings of any rank, but
+  authors are strongly encouraged to either use only h1
+  elements, or to use elements of the appropriate rank
+  for the section's nesting level.

+
+  
Authors are also encouraged to explicitly wrap sections in
+  elements of sectioning content, instead of relying on
+  the implicit sections generated by having multiple headings in one
+  element of sectioning content.

+
+  

+   
For example, the following is correct:

+
+   
<body>
+ <h4>Apples</h4>
+ <p>Apples are fruit.</p>
+ <section>
+  <h2>Taste</h2>
+  <p>They taste lovely.</p>
+  <h6>Sweet</h6>
+  <p>Red apples are sweeter than green ones.</p>
+  <h1>Color</h1>
+  <p>Apples come in various colors.</p>
+ </section>
+</body>

+
+   
However, the same document would be more clearly expressed
+   as:

+
+   
<body>
+ <h1>Apples</h1>
+ <p>Apples are fruit.</p>
+ <section>
+  <h2>Taste</h2>
+  <p>They taste lovely.</p>
+  <section>
+   <h3>Sweet</h3>
+   <p>Red apples are sweeter than green ones.</p>
+  </section>
+ </section>
+ <section>
+  <h2>Color</h2>
+  <p>Apples come in various colors.</p>
+ </section>
+</body>

+
+   
Both of the documents above are semantically identical and would
+   produce the same outline in compliant user agents.

+
+  

+
+
+  
4.4.11.1 Creating an outline

+
+  

+
+  
+
+  
This section defines an algorithm for creating an outline for a
+  sectioning content element or a sectioning
+  root element. It is defined in terms of a walk over the nodes
+  of a DOM tree, in tree order, with each node being visited when it
+  is entered and when it is exited during the walk.

+
+  

+
+  
The outline for a sectioning content
+  element or a sectioning root element consists of a list
+  of one or more potentially nested sections. A section is a container that
+  corresponds to some nodes in the original DOM tree. Each section can
+  have one heading associated with it, and can contain any number of
+  further nested sections. The algorithm for the
+  outline also associates each node in the DOM tree with a particular
+  section and potentially a heading. (The sections in the
+  outline aren't section elements, though some may
+  correspond to such elements — they are merely conceptual
+  sections.)

+
+  

+
+   
The following markup fragment:

+
+   
<body>
+ <h1>A</h1>
+ <p>B</p>
+ <h2>C</h2>
+ <p>D</p>
+ <h2>E</h2>
+ <p>F</p>
+</body>

+
+   
...results in the following outline being created for the
+   body node (and thus the entire document):

+
+   
  1. 
+     
    Section created for body node.
    
+     
    Associated with heading "A".
    
+     
    Also associated with paragraph "B".
    
+     
    Nested sections:
    
+     
    1. 
+       
      Section implied for first h2 element.
      
+       
      Associated with heading "C".
      
+       
      Also associated with paragraph "D".
      
+       
      No nested sections.
      
+      
      2. 
+      
    2. 
+       
      Section implied for second h2 element.
      
+       
      Associated with heading "E".
      
+       
      Also associated with paragraph "F".
      
+       
      No nested sections.
      
+      
      3. 
+     
    2. 
+   

+
+  

+
+  
The algorithm that must be followed during a walk of a DOM
+  subtree rooted at a sectioning content element or a
+  sectioning root element to determine that element's
+  outline is as follows:

+
+  
  1. Let current outlinee be null. (It holds
+   the element whose outline is being created.)
    2. 
+
+   
  2. Let current section be null. (It holds a
+   pointer to a section, so that
+   elements in the DOM can all be associated with a section.)
    3. 
+
+   
  3. Create a stack to hold elements, which is used to handle
+   nesting. Initialize this stack to empty.
    4. 
+
+   
  4. 
+
+    
    As you walk over the DOM in tree order, trigger
+    the first relevant step below for each element as you enter and
+    exit it.
    
+
+    
    If the top of the stack is an element, and you are exiting
+     that element
    
+
+     
    
+
+      
    The element being exited is a heading
+      content element.
    
+
+      
    Pop that element from the stack.
    
+
+     
    
+
+
+     
    If the top of the stack is a heading content
+     element
    
+
+     
    Do nothing.
    
+
+
+     
    When entering a sectioning content element or a
+     sectioning root element
    
+
+     
    
+
+      
    If current outlinee is not null, and the
+      current section has no heading, create an
+      implied heading and let that be the heading for the current section.
    
+
+      
    If current outlinee is not null, push
+      current outlinee onto the stack.
    
+
+      
    Let current outlinee be the element
+      that is being entered.
    
+
+      
    Let current section be a newly created
+      section for the current outlinee element.
    
+
+      
    Let there be a new outline for the new current outlinee, initialized with just the new
+      current section as the only section in the outline.
    
+
+     
    
+
+
+     
    When exiting a sectioning content element, if
+     the stack is not empty
    
+
+     
    
+
+      
    Pop the top element from the stack, and let the current outlinee be that element.
    
+
+      
    Let current section be the last section
+      in the outline of the current
+      outlinee element.
    
+
+      
    Append the outline of the sectioning
+      content element being exited to the current
+      section. (This does not change which section is the last
+      section in the outline.)
    
+
+     
    
+
+
+     
    When exiting a sectioning root element, if the
+     stack is not empty
    
+
+     
    
+
+      
    Run these steps:
    
+
+      
    1. Pop the top element from the stack, and let the current outlinee be that element.
      2. 
+
+       
    2. Let current section be the last
+       section in the outline of the current
+       outlinee element.
      3. 
+
+       
    3. Finding the deepest child: If current section has no child sections, stop
+       these steps.
      4. 
+
+       
    4. Let current section be the last
+       child section of the
+       current current section.
      5. 
+
+       
    5. Go back to the substep labeled finding the deepest
+       child.
      6. 
+
+      
    
+
+
+     
    When exiting a sectioning content element or a
+     sectioning root element
    
+
+     
    
+
+      
    The current outlinee is
+      the element being exited.
    
+
+      
    Let current section be the first section in the
+      outline of the current outlinee
+      element.
    
+
+      
    Skip to the next step in the overall set of steps. (The walk
+      is over.)
    
+
+     
    
+
+
+     
    If the current outlinee is null
    
+
+     
    Do nothing.
    
+
+
+     
    When entering a heading content element
    
+
+     
    
+
+      
    If the current section has no heading,
+      let the element being entered be the heading for the current section.
    
+
+      
    Otherwise, if the element being entered has a
+      rank equal to or greater than the heading of the
+      last section of the outline of the current outlinee, then create a new section and append it to the
+      outline of the current outlinee
+      element, so that this new section is the new last section of
+      that outline. Let current section be that
+      new section. Let the element being entered be the new heading
+      for the current section.
    
+
+      
    Otherwise, run these substeps:
    
+
+      
    1. Let candidate section be current section.
      2. 
+
+       
    2. If the element being entered has a rank
+       lower than the rank of the heading of the candidate section, then create a new section, and append it to candidate section. (This does not change which
+       section is the last section in the outline.) Let current section be this new section. Let the
+       element being entered be the new heading for the current section. Abort these substeps.
      
+
+       
    3. Let new candidate section be the
+       section that contains candidate section in the outline of
+       current outlinee.
      4. 
+
+       
    4. Let candidate section be new candidate section.
      5. 
+
+       
    5. Return to step 2.
      6. 
+
+      
    Push the element being entered onto the stack. (This causes
+      the algorithm to skip any descendants of the element.)
    
+
+      
    Recall that h1 has the
+      highest rank, and h6 has the lowest
+      rank.
    
+
+     
    
+
+
+     
    Otherwise
    
+
+     
    Do nothing.
    
+
+    
    In addition, whenever you exit a node,
+    after doing the steps above, if current
+    section is not null, associate the node with the section current
+    section.
    
+
+   
    5. 
+
+   
  5. If the current outlinee is null,
+   then there was no sectioning content element or
+   sectioning root element in the DOM. There is no
+   outline. Abort these steps.
    6. 
+
+   
  6. Associate any nodes that were not associated with a section in the steps above with current outlinee as their section.
    7. 
+
+   
  7. Associate all nodes with the heading of the section with which they are
+   associated, if any.
    8. 
+
+   
  8. If current outlinee is the body
+   element, then the outline created for that element is the
+   outline of the entire document.
    9. 
+
+  
The tree of sections created by the algorithm above, or a proper
+  subset thereof, must be used when generating document outlines, for
+  example when generating tables of contents.

+
+  
When creating an interactive table of contents, entries should
+  jump the user to the relevant sectioning content
+  element, if the section was
+  created for a real element in the original document, or to the
+  relevant heading content element, if the section in the tree was generated for
+  a heading in the above process.

+
+  
Selecting the first section of the document therefore
+  always takes the user to the top of the document, regardless of
+  where the first heading in the body is to be found.

+
+  
The outline depth of a heading content
+  element associated with a section section
+  is the number of sections that
+  are ancestors of section in the
+  outline that section finds itself
+  in when the outlines of its
+  Document's elements are created, plus 1. The
+  outline depth of a heading content element
+  not associated with a section
+  is 1.

+
+  
User agents should provide default headings for sections that do
+  not have explicit section headings.

+
+  

+
+   
Consider the following snippet:

+
+   
<body>
+ <nav>
+  <p><a href="/">Home</a></p>
+ </nav>
+ <p>Hello world.</p>
+ <aside>
+  <p>My cat is cute.</p>
+ </aside>
+</body>

+
+   
Although it contains no headings, this snippet has three
+   sections: a document (the body) with two subsections
+   (a nav and an aside). A user agent could
+   present the outline as follows:

+
+   
  1. Untitled document
+     
    1. Navigation
      2. 
+      
    2. Sidebar
      3. 
+     
    2. 
+   
These default headings ("Untitled document", "Navigation",
+   "Sidebar") are not specified by this specification, and might vary
+   with the user's language, the page's language, the user's
+   preferences, the user agent implementor's preferences, etc.

+
+  

+
+  

+
+   
The following JavaScript function shows how the tree walk could
+   be implemented. The root argument is the root
+   of the tree to walk, and the enter and exit arguments are callbacks that are called with
+   the nodes as they are entered and exited. [ECMA262]

+
+   
function (root, enter, exit) {
+  var node = root;
+  start: while (node) {
+    enter(node);
+    if (node.firstChild) {
+      node = node.firstChild;
+      continue start;
+    }
+    while (node) {
+      exit(node);
+      if (node.nextSibling) {
+        node = node.nextSibling;
+        continue start;
+      }
+      if (node == root)
+        node = null;
+      else
+        node = node.parentNode;
+    }
+  }
+}

+
+  

+
+  

+
+
+
+  
4.5 Grouping content

+
+  
4.5.1 The p element

+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLParagraphElement : HTMLElement {};

+   

+  
The p element represents a
+  paragraph.

+
+  

+   
The following examples are conforming HTML fragments:

+   
<p>The little kitten gently seated himself on a piece of
+carpet. Later in his life, this would be referred to as the time the
+cat sat on the mat.</p>

+   
<fieldset>
+ <legend>Personal information</legend>
+ <p>
+   <label>Name: <input name="n"></label>
+   <label><input name="anon" type="checkbox"> Hide from other users</label>
+ </p>
+ <p><label>Address: <textarea name="a"></textarea></label></p>
+</fieldset>

+   
<p>There was once an example from Femley,<br>
+Whose markup was of dubious quality.<br>
+The validator complained,<br>
+So the author was pained,<br>
+To move the error from the markup to the rhyming.</p>

+  

+
+  
The p element should not be used when a more
+  specific element is more appropriate.

+
+  

+
+   
The following example is technically correct:

+
+
<section>
+ <!-- ... -->
+ <p>Last modified: 2001-04-23</p>
+ <p>Author: fred@example.com</p>
+</section>

+
+   
However, it would be better marked-up as:

+
+
<section>
+ <!-- ... -->
+ <footer>Last modified: 2001-04-23</footer>
+ <address>Author: fred@example.com</address>
+</section>

+
+   
Or:

+
+
<section>
+ <!-- ... -->
+ <footer>
+  <p>Last modified: 2001-04-23</p>
+  <address>Author: fred@example.com</address>
+ </footer>
+</section>

+
+  

+
+
+  
4.5.2 The hr element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLHRElement : HTMLElement {};

+   

+  
The hr element represents a
+  paragraph-level thematic break, e.g. a scene change in
+  a story, or a transition to another topic within a section of a
+  reference book.

+
+  

+
+   
The following fictional extract from a project manual shows two
+   sections that use the hr element to separate topics
+   within the section.

+
+   
<section>
+ <h1>Communication</h1>
+ <p>There are various methods of communication. This section
+ covers a few of the important ones used by the project.</p>
+ <hr>
+ <p>Communication stones seem to come in pairs and have mysterious
+ properties:</p>
+ <ul>
+  <li>They can transfer thoughts in two directions once activated
+  if used alone.</li>
+  <li>If used with another device, they can transfer one's
+  consciousness to another body.</li>
+  <li>If both stones are used with another device, the
+  consciousnesses switch bodies.</li>
+ </ul>
+ <hr>
+ <p>Radios use the electromagnetic spectrum in the meter range and
+ longer.</p>
+ <hr>
+ <p>Signal flares use the electromagnetic spectrum in the
+ nanometer range.</p>
+</section>
+<section>
+ <h1>Food</h1>
+ <p>All food at the project is rationed:</p>
+ <dl>
+  <dt>Potatoes</dt>
+  <dd>Two per day</dd>
+  <dt>Soup</dt>
+  <dd>One bowl per day</dd>
+ </dl>
+ <hr>
+ <p>Cooking is done by the chefs on a set rotation.</p>
+</section>

+
+   
There is no need for an hr element between the
+   sections themselves, since the section elements and
+   the h1 elements imply thematic changes themselves.

+
+  

+
+  

+
+   
The following extract from Pandora's Star by Peter
+   F. Hamilton shows two paragraphs that precede a scene change and
+   the paragraph that follows it. The scene change, represented in the
+   printed book by a gap containing a solitary centered star between
+   the second and third paragraphs, is here represented using the
+   hr element.

+
+   
+
+   
<p>Dudley was ninety-two, in his second life, and fast approaching
+time for another rejuvenation. Despite his body having the physical
+age of a standard fifty-year-old, the prospect of a long degrading
+campaign within academia was one he regarded with dread. For a
+supposedly advanced civilization, the Intersolar Commonwearth could be
+appallingly backward at times, not to mention cruel.</p>
+<p><i>Maybe it won't be that bad</i>, he told himself. The lie was
+comforting enough to get him through the rest of the night's
+shift.</p>
+<hr>
+<p>The Carlton AllLander drove Dudley home just after dawn. Like the
+astronomer, the vehicle was old and worn, but perfectly capable of
+doing its job. It had a cheap diesel engine, common enough on a
+semi-frontier world like Gralmond, although its drive array was a
+thoroughly modern photoneural processor. With its high suspension and
+deep-tread tyres it could plough along the dirt track to the
+observatory in all weather and seasons, including the metre-deep snow
+of Gralmond's winters.</p>

+
+  

+
+  
The hr element does not affect the
+  document's outline.

+
+
+  
4.5.3 The pre element

+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLPreElement : HTMLElement {};

+   

+  
The pre element represents a block of
+  preformatted text, in which structure is represented by typographic
+  conventions rather than by elements.

+
+  
In the HTML syntax, a leading
+  newline character immediately following the pre element
+  start tag is stripped.

+
+  
Some examples of cases where the pre element could
+  be used:

+
+  
  • Including an e-mail, with paragraphs indicated by blank lines,
+   lists indicated by lines prefixed with a bullet, and so on.
    • 
+
+   
  • Including fragments of computer code, with structure indicated
+   according to the conventions of that language.
    • 
+
+   
  • Displaying ASCII art.
    • 
+
+  
Authors are encouraged to consider how preformatted
+  text will be experienced when the formatting is lost, as will be the
+  case for users of speech synthesizers, braille displays, and the
+  like. For cases like ASCII art, it is likely that an alternative
+  presentation, such as a textual description, would be more
+  universally accessible to the readers of the document.

+
+  
To represent a block of computer code, the pre
+  element can be used with a code element; to represent a
+  block of computer output the pre element can be used
+  with a samp element. Similarly, the kbd
+  element can be used within a pre element to indicate
+  text that the user is to enter.

+
+  

+
+   
In the following snippet, a sample of computer code is
+   presented.

+
+   
<p>This is the <code>Panel</code> constructor:</p>
+<pre><code>function Panel(element, canClose, closeHandler) {
+  this.element = element;
+  this.canClose = canClose;
+  this.closeHandler = function () { if (closeHandler) closeHandler() };
+}</code></pre>

+
+  

+
+  

+
+   
In the following snippet, samp and kbd
+   elements are mixed in the contents of a pre element to
+   show a session of Zork I.

+
+   
<pre><samp>You are in an open field west of a big white house with a boarded
+front door.
+There is a small mailbox here.
+
+></samp> <kbd>open mailbox</kbd>
+
+<samp>Opening the mailbox reveals:
+A leaflet.
+
+></samp></pre>

+
+  

+
+  

+
+   
The following shows a contemporary poem that uses the
+   pre element to preserve its unusual formatting, which
+   forms an intrinsic part of the poem itself.

+
+   
<pre>                maxling
+
+it is with a          heart
+               heavy
+
+that i admit loss of a feline
+        so           loved
+
+a friend lost to the
+        unknown
+                                (night)
+
+~cdr 11dec07</pre>

+
+  

+
+
+
+  
4.5.4 The blockquote element

+
+  
Categories

+   
Flow content.

+   
Sectioning root.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
cite

+   
DOM interface:

+   

+
interface HTMLQuoteElement : HTMLElement {
+           attribute DOMString cite;
+};

+    
The HTMLQuoteElement interface is
+    also used by the q element.

+   

+  
The blockquote element represents a
+  section that is quoted from another source.

+
+  
Content inside a blockquote must be quoted from
+  another source, whose address, if it has one, may be cited in the
+  cite
+  attribute.

+
+  
If the cite attribute
+  is present, it must be a valid URL potentially surrounded by
+  spaces. To obtain the corresponding
+  citation link, the value of the attribute must be resolved relative to the element. User
+  agents should allow users to follow such citation links.

+
+  

+
+  
The cite IDL
+  attribute must reflect the element's cite content attribute.

+
+  

+
+  

+
+   
This next example shows the use of cite alongside
+   blockquote:

+
+   
<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p>
+<blockquote cite="http://quotes.example.org/s/sonnet130.html">
+  <p>My mistress' eyes are nothing like the sun,<br>
+  Coral is far more red, than her lips red,<br>
+  ...

+
+  

+
+  

+
+   
This example shows how a forum post could use
+   blockquote to show what post a user is replying
+   to. The article element is used for each post, to mark
+   up the threading.

+
+   
<article>
+ <h1><a href="http://bacon.example.com/?blog=109431">Bacon on a crowbar</a></h1>
+ <article>
+  <header><strong>t3yw</strong> 12 points 1 hour ago</header>
+  <p>I bet a narwhal would love that.</p>
+  <footer><a href="?pid=29578">permalink</a></footer>
+  <article>
+   <header><strong>greg</strong> 8 points 1 hour ago</header>
+   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
+   <p>Dude narwhals don't eat bacon.</p>
+   <footer><a href="?pid=29579">permalink</a></footer>
+   <article>
+    <header><strong>t3yw</strong> 15 points 1 hour ago</header>
+    <blockquote>
+     <blockquote><p>I bet a narwhal would love that.</p></blockquote>
+     <p>Dude narwhals don't eat bacon.</p>
+    </blockquote>
+    <p>Next thing you'll be saying they don't get capes and wizard
+    hats either!</p>
+    <footer><a href="?pid=29580">permalink</a></footer>
+    <article>
+     <article>
+      <header><strong>boing</strong> -5 points 1 hour ago</header>
+      <p>narwhals are worse than ceiling cat</p>
+      <footer><a href="?pid=29581">permalink</a></footer>
+     </article>
+    </article>
+   </article>
+  </article>
+  <article>
+   <header><strong>fred</strong> 1 points 23 minutes ago</header>
+   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
+   <p>I bet they'd love to peel a banana too.</p>
+   <footer><a href="?pid=29582">permalink</a></footer>
+  </article>
+ </article>
+</article>

+
+  

+
+  
Examples of how to
+  represent a conversation are shown in a later section; it is not
+  appropriate to use the cite and blockquote
+  elements for this purpose.

+
+
+
+  
4.5.5 The ol element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Zero or more li elements.

+   
Content attributes:

+   
Global attributes

+   
reversed

+   
start

+   
DOM interface:

+   

+
interface HTMLOListElement : HTMLElement {
+           attribute boolean reversed;
+           attribute long start;
+};

+   

+  
The ol element represents a list of
+  items, where the items have been intentionally ordered, such that
+  changing the order would change the meaning of the document.

+
+  
The items of the list are the li element child nodes
+  of the ol element, in tree order.

+
+  
The reversed
+  attribute is a boolean attribute. If present, it
+  indicates that the list is a descending list (..., 3, 2, 1). If the
+  attribute is omitted, the list is an ascending list (1, 2, 3,
+  ...).

+
+  
The start
+  attribute, if present, must be a valid integer giving
+  the ordinal value of the first list item.

+
+  

+
+  
If the start attribute is
+  present, user agents must parse it as an integer, in order to determine the
+  attribute's value. The default value, used if the attribute is
+  missing or if the value cannot be converted to a number according to
+  the referenced algorithm, is 1 if the element has no reversed attribute, and is the
+  number of child li elements otherwise.

+
+  
The first item in the list has the ordinal value given by the
+  ol element's start
+  attribute, unless that li element has a value attribute with a value that can
+  be successfully parsed, in which case it has the ordinal value given
+  by that value attribute.

+
+  
Each subsequent item in the list has the ordinal value given by
+  its value attribute, if it has
+  one, or, if it doesn't, the ordinal value of the previous item, plus
+  one if the reversed is absent,
+  or minus one if it is present.

+
+  
The reversed IDL
+  attribute must reflect the value of the reversed content attribute.

+
+  
The start IDL
+  attribute must reflect the value of the start content attribute.

+
+  

+
+  
+
+  

+
+   
The following markup shows a list where the order matters, and
+   where the ol element is therefore appropriate. Compare
+   this list to the equivalent list in the ul section to
+   see an example of the same items using the ul
+   element.

+
+   
<p>I have lived in the following countries (given in the order of when
+I first lived there):</p>
+<ol>
+ <li>Switzerland
+ <li>United Kingdom
+ <li>United States
+ <li>Norway
+</ol>

+
+   
Note how changing the order of the list changes the meaning of
+   the document. In the following example, changing the relative order
+   of the first two items has changed the birthplace of the
+   author:

+
+   
<p>I have lived in the following countries (given in the order of when
+I first lived there):</p>
+<ol>
+ <li>United Kingdom
+ <li>Switzerland
+ <li>United States
+ <li>Norway
+</ol>

+
+  

+
+
+  
4.5.6 The ul element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Zero or more li elements.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLUListElement : HTMLElement {};

+   

+  
The ul element represents a list of
+  items, where the order of the items is not important — that
+  is, where changing the order would not materially change the meaning
+  of the document.

+
+  
The items of the list are the li element child nodes
+  of the ul element.

+
+  

+
+   
The following markup shows a list where the order does not
+   matter, and where the ul element is therefore
+   appropriate. Compare this list to the equivalent list in the
+   ol section to see an example of the same items using
+   the ol element.

+
+   
<p>I have lived in the following countries:</p>
+<ul>
+ <li>Norway
+ <li>Switzerland
+ <li>United Kingdom
+ <li>United States
+</ul>

+
+   
Note that changing the order of the list does not change the
+   meaning of the document. The items in the snippet above are given
+   in alphabetical order, but in the snippet below they are given in
+   order of the size of their current account balance in 2007, without
+   changing the meaning of the document whatsoever:

+
+   
<p>I have lived in the following countries:</p>
+<ul>
+ <li>Switzerland
+ <li>Norway
+ <li>United Kingdom
+ <li>United States
+</ul>

+
+  

+
+
+  
4.5.7 The li element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
Inside ol elements.

+   
Inside ul elements.

+   
Inside menu elements.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
If the element is a child of an ol element: value

+   
DOM interface:

+   

+
interface HTMLLIElement : HTMLElement {
+           attribute long value;
+};

+   

+  
The li element represents a list
+  item. If its parent element is an ol, ul,
+  or menu element, then the element is an item of the
+  parent element's list, as defined for those elements. Otherwise, the
+  list item has no defined list-related relationship to any other
+  li element.

+
+  
The value
+  attribute, if present, must be a valid integer giving
+  the ordinal value of the list item.

+
+  

+
+  
If the value attribute is
+  present, user agents must parse it as an integer, in order to determine the
+  attribute's value. If the attribute's value cannot be converted to a
+  number, the attribute must be treated as if it was absent. The
+  attribute has no default value.

+
+  
The value attribute is
+  processed relative to the element's parent ol element
+  (q.v.), if there is one. If there is not, the attribute has no
+  effect.

+
+  
The value IDL
+  attribute must reflect the value of the value content attribute.

+
+  

+
+  

+   
The following example, the top ten movies are listed (in reverse
+   order). Note the way the list is given a title by using a
+   figure element and its figcaption
+   element.

+   
<figure>
+ <figcaption>The top 10 movies of all time</figcaption>
+ <ol>
+  <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li>
+  <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
+  <li value="8"><cite>A Bug's Life</cite>, 1998</li>
+  <li value="7"><cite>Toy Story</cite>, 1995</li>
+  <li value="6"><cite>Monsters, Inc</cite>, 2001</li>
+  <li value="5"><cite>Cars</cite>, 2006</li>
+  <li value="4"><cite>Toy Story 2</cite>, 1999</li>
+  <li value="3"><cite>Finding Nemo</cite>, 2003</li>
+  <li value="2"><cite>The Incredibles</cite>, 2004</li>
+  <li value="1"><cite>Ratatouille</cite>, 2007</li>
+ </ol>
+</figure>

+
+   
The markup could also be written as follows, using the reversed attribute on the
+   ol element:

+
+   
<figure>
+ <figcaption>The top 10 movies of all time</figcaption>
+ <ol reversed>
+  <li><cite>Josie and the Pussycats</cite>, 2001</li>
+  <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
+  <li><cite>A Bug's Life</cite>, 1998</li>
+  <li><cite>Toy Story</cite>, 1995</li>
+  <li><cite>Monsters, Inc</cite>, 2001</li>
+  <li><cite>Cars</cite>, 2006</li>
+  <li><cite>Toy Story 2</cite>, 1999</li>
+  <li><cite>Finding Nemo</cite>, 2003</li>
+  <li><cite>The Incredibles</cite>, 2004</li>
+  <li><cite>Ratatouille</cite>, 2007</li>
+ </ol>
+</figure>

+  

+
+  
If the li element is the child of a
+  menu element and itself has a child that defines a
+  command, then the
+  li element will match the :enabled and :disabled pseudo-classes in the
+  same way as the first such child element does.

+
+
+
+  
4.5.8 The dl element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Zero or more groups each consisting of one or more
+   dt elements followed by one or more dd
+   elements.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLDListElement : HTMLElement {};

+   

+  
The dl element represents an
+  association list consisting of zero or more name-value groups (a
+  description list). Each group must consist of one or more names
+  (dt elements) followed by one or more values
+  (dd elements). Within a single dl element,
+  there should not be more than one dt element for each
+  name.

+
+  
Name-value groups may be terms and definitions, metadata topics
+  and values, or any other groups of name-value data.

+
+  
The values within a group are alternatives; multiple paragraphs
+  forming part of the same value must all be given within the same
+  dd element.

+
+  
The order of the list of groups, and of the names and values
+  within each group, may be significant.

+
+  

+
+  
If a dl element is empty, it contains no groups.

+
+  
If a dl element contains non-whitespace text nodes, or elements other than dt and
+  dd, then those elements or text
+  nodes do not form part of any groups in that
+  dl.

+
+  
If a dl element contains only dt
+  elements, then it consists of one group with names but no
+  values.

+
+  
If a dl element contains only dd
+  elements, then it consists of one group with values but no
+  names.

+
+  
If a dl element starts with one or more
+  dd elements, then the first group has no associated
+  name.

+
+  
If a dl element ends with one or more
+  dt elements, then the last group has no associated
+  value.

+
+  
When a dl element doesn't match its
+  content model, it is often due to accidentally using dd
+  elements in the place of dt elements and vice
+  versa. Conformance checkers can spot such mistakes and might be able
+  to advise authors how to correctly use the markup.

+
+  

+
+  

+   
In the following example, one entry ("Authors") is linked to two
+   values ("John" and "Luke").

+   
<dl>
+ <dt> Authors
+ <dd> John
+ <dd> Luke
+ <dt> Editor
+ <dd> Frank
+</dl>

+  

+
+  

+   
In the following example, one definition is linked to two
+   terms.

+   
<dl>
+ <dt lang="en-US"> <dfn>color</dfn> </dt>
+ <dt lang="en-GB"> <dfn>colour</dfn> </dt>
+ <dd> A sensation which (in humans) derives from the ability of
+ the fine structure of the eye to distinguish three differently
+ filtered analyses of a view. </dd>
+</dl>

+  

+
+  

+   
The following example illustrates the use of the dl
+   element to mark up metadata of sorts. At the end of the example,
+   one group has two metadata labels ("Authors" and "Editors") and two
+   values ("Robert Rothman" and "Daniel Jackson").

+   
<dl>
+ <dt> Last modified time </dt>
+ <dd> 2004-12-23T23:33Z </dd>
+ <dt> Recommended update interval </dt>
+ <dd> 60s </dd>
+ <dt> Authors </dt>
+ <dt> Editors </dt>
+ <dd> Robert Rothman </dd>
+ <dd> Daniel Jackson </dd>
+</dl>

+  

+
+  

+
+   
The following example shows the dl element used to
+   give a set of instructions. The order of the instructions here is
+   important (in the other examples, the order of the blocks was not
+   important).

+
+   
<p>Determine the victory points as follows (use the
+first matching case):</p>
+<dl>
+ <dt> If you have exactly five gold coins </dt>
+ <dd> You get five victory points </dd>
+ <dt> If you have one or more gold coins, and you have one or more silver coins </dt>
+ <dd> You get two victory points </dd>
+ <dt> If you have one or more silver coins </dt>
+ <dd> You get one victory point </dd>
+ <dt> Otherwise </dt>
+ <dd> You get no victory points </dd>
+</dl>

+  

+
+  

+   
The following snippet shows a dl element being used
+   as a glossary. Note the use of dfn to indicate the
+   word being defined.

+   
<dl>
+ <dt><dfn>Apartment</dfn>, n.</dt>
+ <dd>An execution context grouping one or more threads with one or
+ more COM objects.</dd>
+ <dt><dfn>Flat</dfn>, n.</dt>
+ <dd>A deflated tire.</dd>
+ <dt><dfn>Home</dfn>, n.</dt>
+ <dd>The user's login directory.</dd>
+</dl>

+  

+
+  
The dl element is inappropriate for
+  marking up dialogue. Examples of how to
+  mark up dialogue are shown below.

+
+
+
+  
4.5.9 The dt element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
Before dd or dt elements inside dl elements.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The dt element represents the term, or
+  name, part of a term-description group in a description list
+  (dl element).

+
+  
The dt element itself, when used in a
+  dl element, does not indicate that its contents are a
+  term being defined, but this can be indicated using the
+  dfn element.

+
+  

+
+   
This example shows a list of frequently asked questions (a FAQ)
+   marked up using the dt element for questions and the
+   dd element for answers.

+
+   
<article>
+ <h1>FAQ</h1>
+ <dl>
+  <dt>What do we want?</dt>
+  <dd>Our data.</dd>
+  <dt>When do we want it?</dt>
+  <dd>Now.</dd>
+  <dt>Where is it?</dt>
+  <dd>We are not sure.</dd>
+ </dl>
+</article>

+
+  

+
+
+
+  
4.5.10 The dd element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
After dt or dd elements inside dl elements.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The dd element represents the
+  description, definition, or value, part of a term-description group
+  in a description list (dl element).

+
+  

+
+   
A dl can be used to define a vocabulary list, like
+   in a dictionary. In the following example, each entry, given by a
+   dt with a dfn, has several
+   dds, showing the various parts of the definition.

+
+   
+   
<dl>
+ <dt><dfn>happiness</dfn></dt>
+ <dd class="pronunciation">/'hæ p. nes/</dd>
+ <dd class="part-of-speech"><i><abbr>n.</abbr></i></dd>
+ <dd>The state of being happy.</dd>
+ <dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd>
+ <dt><dfn>rejoice</dfn></dt>
+ <dd class="pronunciation">/ri jois'/</dd>
+ <dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd>
+ <dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd>
+</dl>

+  

+
+
+  
4.5.11 The figure element

+
+  
Categories

+   
Flow content.

+   
Sectioning root.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Either: One figcaption element followed by flow content.

+   
Or: Flow content followed by one figcaption element.

+   
Or: Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The figure element represents some
+  flow content, optionally with a caption, that is
+  self-contained and is typically referenced as a single unit from the
+  main flow of the document.

+
+  
The element can thus be used to annotate illustrations, diagrams,
+  photos, code listings, etc, that are referred to from the main
+  content of the document, but that could, without affecting the flow
+  of the document, be moved away from that primary content, e.g. to
+  the side of the page, to dedicated pages, or to an appendix.

+
+  
The first figcaption
+  element child of the element, if any, represents the caption of the
+  figure element's contents. If there is no child
+  figcaption element, then there is no caption.

+
+  

+
+   
This example shows the figure element to mark up a
+   code listing.

+
+   
<p>In <a href="#l4">listing 4</a> we see the primary core interface
+API declaration.</p>
+<figure id="l4">
+ <figcaption>Listing 4. The primary core interface API declaration.</figcaption>
+ <pre><code>interface PrimaryCore {
+ boolean verifyDataLine();
+ void sendData(in sequence&lt;byte> data);
+ void initSelfDestruct();
+}</code></pre>
+</figure>
+<p>The API is designed to use UTF-8.</p>

+
+  

+
+  

+
+   
Here we see a figure element to mark up a
+   photo.

+
+   
<figure>
+ <img src="bubbles-work.jpeg"
+      alt="Bubbles, sitting in his office chair, works on his
+           latest project intently.">
+ <figcaption>Bubbles at work</figcaption>
+</figure>

+
+  

+
+  

+
+   
In this example, we see an image that is not
+   a figure, as well as an image and a video that are.

+
+   
<h2>Malinko's comics</h2>
+
+<p>This case centered on some sort of "intellectual property"
+infringement related to a comic (see Exhibit A). The suit started
+after a trailer ending with these words:
+
+<blockquote>
+ <img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!">
+</blockquote>
+
+<p>...was aired. A lawyer, armed with a Bigger Notebook, launched a
+preemptive strike using snowballs. A complete copy of the trailer is
+included with Exhibit B.
+
+<figure>
+ <img src="ex-a.png" alt="Two squiggles on a dirty piece of paper.">
+ <figcaption>Exhibit A. The alleged <cite>rough copy</cite> comic.</figcaption>
+</figure>
+
+<figure>
+ <video src="ex-b.mov"></video>
+ <figcaption>Exhibit B. The <cite>Rough Copy</cite> trailer.</figcaption>
+</figure>
+
+<p>The case was resolved out of court.

+
+  

+
+  

+
+   
Here, a part of a poem is marked up using
+   figure.

+
+   
<figure>
+ <p>'Twas brillig, and the slithy toves<br>
+ Did gyre and gimble in the wabe;<br>
+ All mimsy were the borogoves,<br>
+ And the mome raths outgrabe.</p>
+ <figcaption><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</figcaption>
+</figure>

+
+  

+
+  

+
+   
In this example, which could be part of a much larger work
+   discussing a castle, the figure has three images in it.

+
+   
<figure>
+ <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423."
+      alt="The castle has one tower, and a tall wall around it.">
+ <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858."
+      alt="The castle now has two towers and two walls.">
+ <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999."
+      alt="The castle lies in ruins, the original tower all that remains in one piece.">
+ <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption>
+</figure>

+
+  

+
+
+  
4.5.12 The figcaption element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the first or last child of a figure element.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The figcaption element represents a
+  caption or legend for the rest of the contents of the
+  figcaption element's parent figure
+  element, if any.

+
+
+
+  
4.5.13 The div element

+
+  
Categories

+   
Flow content.

+   
formatBlock candidate.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLDivElement : HTMLElement {};

+   

+  
The div element has no special meaning at all. It
+  represents its children. It can be used with the class, lang, and title attributes to mark up semantics
+  common to a group of consecutive elements.

+
+  
Authors are strongly encouraged to view the
+  div element as an element of last resort, for when no
+  other element is suitable. Use of the div element
+  instead of more appropriate elements leads to poor accessibility for
+  readers and poor maintainability for authors.

+
+  

+
+   
For example, a blog post would be marked up using
+   article, a chapter using section, a
+   page's navigation aids using nav, and a group of form
+   controls using fieldset.

+
+   
On the other hand, div elements can be useful for
+   stylistic purposes or to wrap multiple paragraphs within a section
+   that are all to be annotated in a similar way. In the following
+   example, we see div elements used as a way to set the
+   language of two paragraphs at once, instead of setting the language
+   on the two paragraph elements separately:

+
+   
<article lang="en-US">
+ <h1>My use of language and my cats</h1>
+ <p>My cat's behavior hasn't changed much since her absence, except
+ that she plays her new physique to the neighbors regularly, in an
+ attempt to get pets.</p>
+ <div lang="en-GB">
+  <p>My other cat, coloured black and white, is a sweetie. He followed
+  us to the pool today, walking down the pavement with us. Yesterday
+  he apparently visited our neighbours. I wonder if he recognises that
+  their flat is a mirror image of ours.</p>
+  <p>Hm, I just noticed that in the last paragraph I used British
+  English. But I'm supposed to write in American English. So I
+  shouldn't say "pavement" or "flat" or "colour"...</p>
+ </div>
+ <p>I should say "sidewalk" and "apartment" and "color"!</p>
+</article>

+
+  

+
+
+  
4.6 Text-level semantics

+
+  
4.6.1 The a element

+
+  
Categories

+   
Flow content.

+   
When the element only contains phrasing content: phrasing content.

+   
Interactive content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Transparent, but there must be no interactive content descendant.

+   
Content attributes:

+   
Global attributes

+   
href

+   
target

+
+   
ping

+
+   
rel

+   
media

+   
hreflang

+   
type

+   
DOM interface:

+   

+
interface HTMLAnchorElement : HTMLElement {
+  stringifier attribute DOMString href;
+           attribute DOMString target;
+
+           attribute DOMString ping;
+
+           attribute DOMString rel;
+  readonly attribute DOMTokenList relList;
+           attribute DOMString media;
+           attribute DOMString hreflang;
+           attribute DOMString type;
+
+           attribute DOMString text;
+
+  // URL decomposition IDL attributes
+           attribute DOMString protocol;
+           attribute DOMString host;
+           attribute DOMString hostname;
+           attribute DOMString port;
+           attribute DOMString pathname;
+           attribute DOMString search;
+           attribute DOMString hash;
+};

+   

+  
If the a element has an href attribute, then it
+  represents a hyperlink (a hypertext
+  anchor).

+
+  
+
+  
If the a element has no href attribute, then the element
+  represents a placeholder for where a link might
+  otherwise have been placed, if it had been relevant.

+
+  
The target,
+
+  ping,
+
+  rel, media, hreflang, and type attributes must be omitted
+  if the href attribute is
+  not present.

+
+  

+   
If a site uses a consistent navigation toolbar on every page,
+   then the link that would normally link to the page itself could be
+   marked up using an a element:

+   
<nav>
+ <ul>
+  <li> <a href="/">Home</a> </li>
+  <li> <a href="/news">News</a> </li>
+  <li> <a>Examples</a> </li>
+  <li> <a href="/legal">Legal</a> </li>
+ </ul>
+</nav>

+  

+
+  

+
+  
The href, target
+
+  and ping
+
+  attributes affect what
+  happens when users follow
+  hyperlinks created using the a element.  The
+  rel, media, hreflang, and type attributes may be used to
+  indicate to the user the likely nature of the target resource before
+  the user follows the link.

+
+  
The activation behavior of a elements
+  that represent hyperlinks is to run
+  the following steps:

+
+  
  1. If the DOMActivate
+   event in question is not trusted (i.e. a click() method call was the reason for the
+   event being dispatched), and the a element's target attribute is such that
+   applying the rules for choosing a browsing context given a
+   browsing context name, using the value of the target attribute as the
+   browsing context name, would result in there not being a chosen
+   browsing context, then raise an INVALID_ACCESS_ERR
+   exception and abort these steps.
    2. 
+
+   
  2. If the target of the click
+   event is an img element with an ismap attribute specified, then
+   server-side image map processing must be performed, as follows:
    
+
+    
    1. If the DOMActivate
+     event was dispatched as the result of a real
+     pointing-device-triggered click
+     event on the img element, then let x be the distance in CSS pixels from the left edge
+     of the image's left border, if it has one, or the left edge of
+     the image otherwise, to the location of the click, and let y be the distance in CSS pixels from the top edge
+     of the image's top border, if it has one, or the top edge of the
+     image otherwise, to the location of the click. Otherwise, let
+     x and y be zero.
      2. 
+
+     
    2. Let the hyperlink suffix be a U+003F
+     QUESTION MARK character, the value of x
+     expressed as a base-ten integer using ASCII digits, a U+002C
+     COMMA character (,), and the value of y
+     expressed as a base-ten integer using ASCII digits. ASCII digits
+     are the characters in the range U+0030 DIGIT ZERO (0) to U+0039
+     DIGIT NINE (9).
      3. 
+
+    
    3. 
+
+   
  3. Finally, the user agent must follow the hyperlink defined by the
+   a element. If the steps above defined a hyperlink
+   suffix, then take that into account when following the
+   hyperlink.
    4. 
+
+  

+
+  
a . text

+
+   

+
+    
Same as textContent.

+
+   

+
+  

+
+  
The IDL attributes href,
+
+  ping,
+
+  target, rel, media, hreflang, and type, must
+  reflect the respective content attributes of the same
+  name.

+
+  
The IDL attribute relList must
+  reflect the rel
+  content attribute.

+
+  
The text IDL
+  attribute, on getting, must return the same value as the
+  textContent IDL attribute on the element, and on
+  setting, must act as if the textContent IDL attribute
+  on the element had been set to the new value.

+
+  
The a element also supports the complement of
+  URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the
+  rules given for URL decomposition IDL attributes, with the input being the result of resolving the element's href attribute relative to the
+  element, if there is such an attribute and resolving it is
+  successful, or the empty string otherwise; and the common setter action being the
+  same as setting the element's href attribute to the new output
+  value.

+
+  

+
+  

+
+   
The a element may be wrapped around entire
+   paragraphs, lists, tables, and so forth, even entire sections, so
+   long as there is no interactive content within (e.g. buttons or
+   other links). This example shows how this can be used to make an
+   entire advertising block into a link:

+
+   
<aside class="advertising">
+ <h1>Advertising</h1>
+ <a href="http://ad.example.com/?adid=1929&amp;pubid=1422">
+  <section>
+   <h1>Mellblomatic 9000!</h1>
+   <p>Turn all your widgets into mellbloms!</p>
+   <p>Only $9.99 plus shipping and handling.</p>
+  </section>
+ </a>
+ <a href="http://ad.example.com/?adid=375&amp;pubid=1422">
+  <section>
+   <h1>The Mellblom Browser</h1>
+   <p>Web browsing at the speed of light.</p>
+   <p>No other browser goes faster!</p>
+  </section>
+ </a>
+</aside>

+
+  

+
+
+  
4.6.2 The em element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The em element represents stress
+  emphasis of its contents.

+
+  
The level of emphasis that a particular piece of content has is
+  given by its number of ancestor em elements.

+
+  
The placement of emphasis changes the meaning of the sentence.
+  The element thus forms an integral part of the content. The precise
+  way in which emphasis is used in this way depends on the
+  language.

+
+  

+
+   
These examples show how changing the emphasis changes the
+   meaning. First, a general statement of fact, with no emphasis:

+
+   
<p>Cats are cute animals.</p>

+
+   
By emphasizing the first word, the statement implies that the
+   kind of animal under discussion is in question (maybe someone is
+   asserting that dogs are cute):

+
+   
<p><em>Cats</em> are cute animals.</p>

+
+   
Moving the emphasis to the verb, one highlights that the truth
+   of the entire sentence is in question (maybe someone is saying cats
+   are not cute):

+
+   
<p>Cats <em>are</em> cute animals.</p>

+
+   
By moving it to the adjective, the exact nature of the cats
+   is reasserted (maybe someone suggested cats were mean
+   animals):

+
+   
<p>Cats are <em>cute</em> animals.</p>

+
+   
Similarly, if someone asserted that cats were vegetables,
+   someone correcting this might emphasize the last word:

+
+   
<p>Cats are cute <em>animals</em>.</p>

+
+   
By emphasizing the entire sentence, it becomes clear that the
+   speaker is fighting hard to get the point across. This kind of
+   emphasis also typically affects the punctuation, hence the
+   exclamation mark here.

+
+   
<p><em>Cats are cute animals!</em></p>

+
+   
Anger mixed with emphasizing the cuteness could lead to markup
+   such as:

+
+   
<p><em>Cats are <em>cute</em> animals!</em></p>

+
+  

+
+  

+
+   
The em element isn't a generic "italics"
+   element. Sometimes, text is intended to stand out from the rest of
+   the paragraph, as if it was in a different mood or voice. For this,
+   the i element is more appropriate.

+
+   
The em element also isn't intended to convey
+   importance; for that purpose, the strong element is
+   more appropriate.

+
+   
+
+  

+
+
+
+  
4.6.3 The strong element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The strong element represents strong
+  importance for its contents.

+
+  
The relative level of importance of a piece of content is given
+  by its number of ancestor strong elements; each
+  strong element increases the importance of its
+  contents.

+
+  
Changing the importance of a piece of text with the
+  strong element does not change the meaning of the
+  sentence.

+
+  

+   
Here is an example of a warning notice in a game, with the
+   various parts marked up according to how important they are:

+   
+   
<p><strong>Warning.</strong> This dungeon is dangerous.
+<strong>Avoid the ducks.</strong> Take any gold you find.
+<strong><strong>Do not take any of the diamonds</strong>,
+they are explosive and <strong>will destroy anything within
+ten meters.</strong></strong> You have been warned.</p>

+  

+
+
+  
4.6.4 The small element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The small element represents side
+  comments such as small print.

+
+  
Small print typically features disclaimers, caveats,
+  legal restrictions, or copyrights. Small print is also sometimes
+  used for attribution, or for satisfying licensing requirements.

+
+  
The small element does not
+  "de-emphasize" or lower the importance of text emphasized by the
+  em element or marked as important with the
+  strong element. To mark text as not emphasized or
+  important, simply do not mark it up with the em or
+  strong elements respectively.

+
+  
The small element should not be used for extended
+  spans of text, such as multiple paragraphs, lists, or sections of
+  text. It is only intended for short runs of text. The text of a page
+  listing terms of use, for instance, would not be a suitable
+  candidate for the small element: in such a case, the
+  text is not a side comment, it is the main content of the page.

+
+  

+
+   
In this example the footer contains contact information and a
+   copyright notice.

+
+   
<footer>
+ <address>
+  For more details, contact
+  <a href="mailto:js@example.com">John Smith</a>.
+ </address>
+ <p><small>© copyright 2038 Example Corp.</small></p>
+</footer>

+
+  

+
+  

+
+   
In this second example, the small element is used
+   for a side comment in an article.

+
+   
<p>Example Corp today announced record profits for the
+second quarter <small>(Full Disclosure: Foo News is a subsidiary of
+Example Corp)</small>, leading to speculation about a third quarter
+merger with Demo Group.</p>

+
+   
This is distinct from a sidebar, which might be multiple
+   paragraphs long and is removed from the main flow of text. In the
+   following example, we see a sidebar from the same article. This
+   sidebar also has small print, indicating the source of the
+   information in the sidebar.

+
+   
<aside>
+ <h1>Example Corp</h1>
+ <p>This company mostly creates small software and Web
+ sites.</p>
+ <p>The Example Corp company mission is "To provide entertainment
+ and news on a sample basis".</p>
+ <p><small>Information obtained from <a
+ href="http://example.com/about.html">example.com</a> home
+ page.</small></p>
+</aside>

+
+  

+
+  

+
+   
In this last example, the small element is marked
+   as being important small print.

+
+   
<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>

+
+  

+
+
+  
4.6.5 The cite element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The cite element represents the title
+  of a work (e.g.
+  a book,
+  a paper,
+  an essay,
+  a poem,
+  a score,
+  a song,
+  a script,
+  a film,
+  a TV show,
+  a game,
+  a sculpture,
+  a painting,
+  a theatre production,
+  a play,
+  an opera,
+  a musical,
+  an exhibition,
+  a legal case report,
+  etc). This can be a work that is being quoted or
+  referenced in detail (i.e. a citation), or it can just be a work
+  that is mentioned in passing.

+
+  
A person's name is not the title of a work — even if people
+  call that person a piece of work — and the element must
+  therefore not be used to mark up people's names. (In some cases, the
+  b element might be appropriate for names; e.g. in a
+  gossip article where the names of famous people are keywords
+  rendered with a different style to draw attention to them. In other
+  cases, if an element is really needed, the
+  span element can be used.)

+
+
+
+  

+
+   
This next example shows a typical use of the cite
+   element:

+
+   
<p>My favorite book is <cite>The Reality Dysfunction</cite> by
+Peter F. Hamilton. My favorite comic is <cite>Pearls Before
+Swine</cite> by Stephan Pastis. My favorite track is <cite>Jive
+Samba</cite> by the Cannonball Adderley Sextet.</p>

+
+  

+
+  

+
+   
This is correct usage:

+
+   
<p>According to the Wikipedia article <cite>HTML</cite>, as it
+stood in mid-February 2008, leaving attribute values unquoted is
+unsafe. This is obviously an over-simplification.</p>

+
+   
The following, however, is incorrect usage, as the
+   cite element here is containing far more than the
+   title of the work:

+
+   
<!-- do not copy this example, it is an example of bad usage! -->
+<p>According to <cite>the Wikipedia article on HTML</cite>, as it
+stood in mid-February 2008, leaving attribute values unquoted is
+unsafe. This is obviously an over-simplification.</p>

+
+  

+
+  

+
+   
The cite element is obviously a key part of any
+   citation in a bibliography, but it is only used to mark the
+   title:

+
+   
<p><cite>Universal Declaration of Human Rights</cite>, United Nations,
+December 1948. Adopted by General Assembly resolution 217 A (III).</p>

+
+  

+
+  
A citation is not a quote (for
+  which the q element is appropriate).

+
+  

+
+   
This is incorrect usage, because cite is not for
+   quotes:

+
+   
<p><cite>This is wrong!</cite>, said Ian.</p>

+
+   
This is also incorrect usage, because a person is not a
+   work:

+
+   
<p><q>This is still wrong!</q>, said <cite>Ian</cite>.</p>

+
+   
The correct usage does not use a cite element:

+
+   
<p><q>This is correct</q>, said Ian.</p>

+
+   
As mentioned above, the b element might be relevant
+   for marking names as being keywords in certain kinds of
+   documents:

+
+   
<p>And then <b>Ian</b> said <q>this might be right, in a
+gossip column, maybe!</q>.</p>

+
+  

+
+
+
+  
4.6.6 The q element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
cite

+   
DOM interface:

+   
Uses HTMLQuoteElement.

+  
The q element represents some phrasing content quoted from another
+  source.

+
+  
Quotation punctuation (such as quotation marks) that is quoting
+  the contents of the element must not appear immediately before,
+  after, or inside q elements; they will be inserted into
+  the rendering by the user agent.

+
+  
Content inside a q element must be quoted from
+  another source, whose address, if it has one, may be cited in the
+  cite attribute. The
+  source may be fictional, as when quoting characters in a novel or
+  screenplay.

+
+  
If the cite attribute is
+  present, it must be a valid URL potentially surrounded by
+  spaces. To obtain the corresponding
+  citation link, the value of the attribute must be resolved relative to the element. User
+  agents should allow users to follow such citation links.

+
+  
The q element must not be used in place of quotation
+  marks that do not represent quotes; for example, it is inappropriate
+  to use the q element for marking up sarcastic
+  statements.

+
+  
The use of q elements to mark up quotations is
+  entirely optional; using explicit quotation punctuation without
+  q elements is just as correct.

+
+  

+
+   
Here is a simple example of the use of the q
+   element:

+
+   
<p>The man said <q>Things that are impossible just take
+longer</q>. I disagreed with him.</p>

+
+  

+
+  

+
+   
Here is an example with both an explicit citation link in the
+   q element, and an explicit citation outside:

+
+   
<p>The W3C page <cite>About W3C</cite> says the W3C's
+mission is <q cite="http://www.w3.org/Consortium/">To lead the
+World Wide Web to its full potential by developing protocols and
+guidelines that ensure long-term growth for the Web</q>. I
+disagree with this mission.</p>

+
+  

+
+  

+
+   
In the following example, the quotation itself contains a
+   quotation:

+
+   
<p>In <cite>Example One</cite>, he writes <q>The man
+said <q>Things that are impossible just take longer</q>. I
+disagreed with him</q>. Well, I disagree even more!</p>

+
+  

+
+  

+
+   
In the following example, quotation marks are used instead of
+   the q element:

+
+   
<p>His best argument was ❝I disagree❞, which
+I thought was laughable.</p>

+
+  

+
+  

+
+   
In the following example, there is no quote — the
+   quotation marks are used to name a word. Use of the q
+   element in this case would be inappropriate.

+
+   
<p>The word "ineffable" could have been used to describe the disaster
+resulting from the campaign's mismanagement.</p>

+
+  

+
+
+  
4.6.7 The dfn element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but there must be no dfn element descendants.

+   
Content attributes:

+   
Global attributes

+   
Also, the title attribute has special semantics on this element.

+   
DOM interface:

+   
Uses HTMLElement.

+  
The dfn element represents the defining
+  instance of a term. The paragraph,
+  description list group, or section that is the nearest
+  ancestor of the dfn element must also contain the
+  definition(s) for the term given
+  by the dfn element.

+
+  
Defining term: If the dfn element has a
+  title attribute, then
+  the exact value of that attribute is the term being defined.
+  Otherwise, if it contains exactly one element child node and no
+  child text nodes, and that child
+  element is an abbr element with a title attribute, then the exact value
+  of that attribute is the term being defined. Otherwise, it
+  is the exact textContent of the dfn
+  element that gives the term being defined.

+
+  
+
+  
If the title attribute of the
+  dfn element is present, then it must contain only the
+  term being defined.

+
+  
The title attribute
+  of ancestor elements does not affect dfn elements.

+
+  
An a element that links to a dfn
+  element represents an instance of the term defined by the
+  dfn element.

+
+  

+
+   
In the following fragment, the term "GDO" is first defined in
+   the first paragraph, then used in the second.

+
+   
<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn>
+is a device that allows off-world teams to open the iris.</p>
+<!-- ... later in the document: -->
+<p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr>
+and so Hammond ordered the iris to be opened.</p>

+
+   
With the addition of an a element, the reference
+   can be made explicit:

+
+   
<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn>
+is a device that allows off-world teams to open the iris.</p>
+<!-- ... later in the document: -->
+<p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a>
+and so Hammond ordered the iris to be opened.</p>

+
+  

+
+
+
+  
4.6.8 The abbr element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
Also, the title attribute has special semantics on this element.

+   
DOM interface:

+   
Uses HTMLElement.

+  
The abbr element represents an
+  abbreviation or acronym, optionally with its expansion. The title attribute may be
+  used to provide an expansion of the abbreviation. The attribute, if
+  specified, must contain an expansion of the abbreviation, and
+  nothing else.

+
+  

+   
The paragraph below contains an abbreviation marked up with the
+   abbr element. This paragraph defines the term "Web Hypertext Application Technology
+   Working Group".

+   
<p>The <dfn id=whatwg><abbr
+title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
+is a loose unofficial collaboration of Web browser manufacturers and
+interested parties who wish to develop new technologies designed to
+allow authors to write and deploy Applications over the World Wide
+Web.</p>

+   
An alternative way to write this would be:

+   
<p>The <dfn id=whatwg>Web Hypertext Application Technology
+Working Group</dfn> (<abbr
+title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
+is a loose unofficial collaboration of Web browser manufacturers and
+interested parties who wish to develop new technologies designed to
+allow authors to write and deploy Applications over the World Wide
+Web.</p>

+  

+
+  

+   
This paragraph has two abbreviations. Notice how only one is
+   defined; the other, with no expansion associated with it, does not
+   use the abbr element.

+   
<p>The
+<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
+started working on HTML5 in 2004.</p>

+  

+
+  

+   
This paragraph links an abbreviation to its definition.

+   
<p>The <a href="#whatwg"><abbr
+title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
+community does not have much representation from Asia.</p>

+  

+
+  

+   
This paragraph marks up an abbreviation without giving an
+   expansion, possibly as a hook to apply styles for abbreviations
+   (e.g. smallcaps).

+   
<p>Philip` and Dashiva both denied that they were going to
+get the issue counts from past revisions of the specification to
+backfill the <abbr>WHATWG</abbr> issue graph.</p>

+  

+
+  
If an abbreviation is pluralized, the expansion's grammatical
+  number (plural vs singular) must match the grammatical number of the
+  contents of the element.

+
+  

+
+   
Here the plural is outside the element, so the expansion is in
+   the singular:

+
+   
<p>Two <abbr title="Working Group">WG</abbr>s worked on
+this specification: the <abbr>WHATWG</abbr> and the
+<abbr>HTMLWG</abbr>.</p>

+
+   
Here the plural is inside the element, so the expansion is in
+   the plural:

+
+   
<p>Two <abbr title="Working Groups">WGs</abbr> worked on
+this specification: the <abbr>WHATWG</abbr> and the
+<abbr>HTMLWG</abbr>.</p>

+
+  

+
+  
Abbreviations do not have to be marked up using this element. It
+  is expected to be useful in the following cases:

+
+  
  • Abbreviations for which the author wants to give expansions,
+   where using the abbr element with a title attribute is an alternative to
+   including the expansion inline (e.g. in parentheses).
    • 
+
+   
  • Abbreviations that are likely to be unfamiliar to the
+   document's readers, for which authors are encouraged to either mark
+   up the abbreviation using a abbr element with a title attribute or include the expansion
+   inline in the text the first time the abbreviation is used.
    • 
+
+   
  • Abbreviations whose presence needs to be semantically
+   annotated, e.g. so that they can be identified from a style sheet
+   and given specific styles, for which the abbr element
+   can be used without a title
+   attribute.
    • 
+
+  
Providing an expansion in a title attribute once will not necessarily
+  cause other abbr elements in the same document with the
+  same contents but without a title
+  attribute to behave as if they had the same expansion. Every
+  abbr element is independent.

+
+
+
+
+  
4.6.9 The time element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but there must be no time element descendants.

+   
Content attributes:

+   
Global attributes

+   
datetime

+   
pubdate

+   
DOM interface:

+   

+
interface HTMLTimeElement : HTMLElement {
+           attribute DOMString dateTime;
+           attribute boolean pubDate;
+  readonly attribute Date valueAsDate;
+};

+   

+  
The time element represents either a
+  time on a 24 hour clock, or a precise date in the proleptic
+  Gregorian calendar, optionally with a time and a time-zone
+  offset. [GREGORIAN]

+
+  
This element is intended as a way to encode modern dates and
+  times in a machine-readable way so that, for example, user agents
+  can offer to add birthday reminders or scheduled events to the
+  user's calendar.

+
+  
+
+  

+
+   
The time element is not intended for encoding times
+   for which a precise date or time cannot be established. For
+   example, it would be inappropriate for encoding times like "one
+   millisecond after the big bang", "the early part of the Jurassic
+   period", or "a winter around 250 BCE".

+
+   
For dates before the introduction of the Gregorian calendar,
+   authors are encouraged to not use the time element, or
+   else to be very careful about converting dates and times from the
+   period to the Gregorian calendar. This is complicated by the manner
+   in which the Gregorian calendar was phased in, which occurred at
+   different times in different countries, ranging from partway
+   through the 16th century all the way to early in the 20th.

+
+  

+
+  
The pubdate
+  attribute is a boolean attribute. If specified, it
+  indicates that the date and time given by the element is the
+  publication date and time of the nearest ancestor
+  article element, or, if the element has no ancestor
+  article element, of the document as a whole. If the
+  element has a pubdate
+  attribute specified, then the element needs a date. For
+  each article element, there must no more than one
+  time element with a pubdate attribute whose nearest
+  ancestor is that article element. Furthermore, for each
+  Document, there must be no more than one
+  time element with a pubdate attribute that does not
+  have an ancestor article element.

+
+  
The datetime
+  attribute, if present, gives the date or time being
+  specified. Otherwise, the date or time is given by the element's
+  contents.

+
+  
If the element needs a date, and the datetime attribute is present,
+  then the attribute's value must be a valid date string with
+  optional time.

+
+  
If the element needs a date, but the datetime attribute is not present,
+  then the element's textContent must be a valid
+  date string in content with optional time.

+
+  
If the element does not need a date, and the datetime attribute is present,
+  then the attribute's value must be a valid date or time
+  string.

+
+  
If the element does not need a date, but the datetime attribute is not present,
+  then the element's textContent must be a valid
+  date or time string in content.

+
+  
The date, if any, must be expressed using the Gregorian
+  calendar.

+
+  

+
+  
If the datetime attribute
+  is present, the user agent should convey the attribute's value to
+  the user when rendering the element.

+
+  

+
+  

+
+   
The time element can be used to encode dates, for
+   example in Microformats. The following shows a hypothetical way of
+   encoding an event using a variant on hCalendar that uses the
+   time element:

+
+   
<div class="vevent">
+ <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
+  <span class="summary">Web 2.0 Conference</span>:
+  <time class="dtstart" datetime="2007-10-05">October 5</time> -
+  <time class="dtend" datetime="2007-10-20">19</time>,
+  at the <span class="location">Argent Hotel, San Francisco, CA</span>
+ </div>

+
+   
(The end date is encoded as one day after the last date of the
+   event because in the iCalendar format, end dates are
+   exclusive, not inclusive.)

+
+  

+
+  

+
+   
The time element is not necessary for encoding
+   dates or times. In the following snippet, the time is encoded using
+   time, so that it can be restyled (e.g. using XBL2) to
+   match local conventions, while the year is not marked up at all,
+   since marking it up would not be particularly useful.

+
+   
<p>I usually have a snack at <time>16:00</time>.</p>
+<p>I've liked model trains since at least 1983.</p>

+
+   
Using a styling technology that supports restyling times, the
+   first paragraph from the above snippet could be rendered as follows:

+
+   
I usually have a snack at 4pm.

+
+   
Or it could be rendered as follows:

+
+   
I usually have a snack at 16h00.

+
+  

+
+  

+
+  
The dateTime IDL
+  attribute must reflect the datetime content attribute.

+
+  
The pubDate IDL
+  attribute must reflect the pubdate content attribute.

+
+  
User agents, to obtain the date, time, and time-zone offset represented by
+  a time element, must follow these steps:

+
+  
  1. If the datetime
+   attribute is present, then use the rules to parse a date or
+   time string with the flag in attribute from the value
+   of that attribute, and let the result be result.
    2. 
+
+   
  2. Otherwise, use the rules to parse a date or time
+   string with the flag in content from the element's
+   textContent, and let the result be result.
    3. 
+
+   
  3. If result is empty (because the parsing
+   failed), then the date is
+   unknown, the time is
+   unknown, and the time-zone
+   offset is unknown.
    4. 
+
+   
  4. Otherwise: if result contains a date, then
+   that is the date; if result contains a time, then that is the time; and if result contains a time-zone offset, then the
+   time-zone offset is the element's time-zone offset. (A time-zone
+   offset can only be present if both a date and a time are also
+   present.)
    5. 
+
+  

+
+  
time . valueAsDate

+
+   

+
+    
Returns a Date object representing the specified date and time.

+
+   

+
+  

+
+  
The valueAsDate IDL
+  attribute must return either null or a new Date object
+  initialised to the relevant value as defined by the following
+  list:

+
+  
If the date is known but
+   the time is not

+
+   
The time corresponding to midnight UTC (i.e. the first second)
+   of the given date.

+
+   
If the time is known but
+   the date is not

+
+   
The time corresponding to the given time of 1970-01-01, with the time
+   zone UTC.

+
+   
If both the date and the
+   time are known

+
+   
The time corresponding to the date and time, with the given time-zone offset.

+
+   
If neither the date nor
+   the time are known

+
+   
The null value.

+
+  
When a Date object is to be returned, a new one must
+  be constructed.
 
+
+  

+
+  

+
+   
In the following snippet:

+
+   
<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>

+
+   
...the time element's valueAsDate attribute would
+   have the value 1,158,969,600,000ms.

+
+  

+
+  
+
+  

+
+   
In the following snippet:

+
+   
<p>Many people get up at <time>08:00</time>.</p>

+
+   
...the time element's valueAsDate attribute would
+   have the value 28,800,000ms.

+
+  

+
+  

+
+   
In this example, an article's publication date is marked up
+   using time:

+
+   
<article>
+ <h1>Small tasks</h1>
+ <footer>Published <time pubdate>2009-08-30</time>.</footer>
+ <p>I put a bike bell on his bike.</p>
+</article>

+
+   
Here is another way that could be marked up. In this example,
+   legacy user agents would say "today", while newer user agents would
+   render the time in a locale-specific manner based on the value of
+   the attribute.

+
+   
<article>
+ <h1>Small tasks</h1>
+ <footer>Published <time pubdate datetime="2009-08-30">today</time>.</footer>
+ <p>I put a bike bell on his bike.</p>
+</article>

+
+   
Here is the same thing but with the time included only. Because
+   the element is empty, legacy user agents will not show anything
+   useful; user agents that implement this specification, on the other
+   hand, would show the date and time in a locale-specific manner.

+
+   
<article>
+ <h1>Small tasks</h1>
+ <footer>Published <time pubdate datetime="2009-08-30T07:13Z"></time>.</footer>
+ <p>I put a bike bell on his bike.</p>
+</article>

+
+  

+
+
+
+  
4.6.10 The code element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The code element represents a fragment
+  of computer code. This could be an XML element name, a filename, a
+  computer program, or any other string that a computer would
+  recognize.

+
+  
Although there is no formal way to indicate the language of
+  computer code being marked up, authors who wish to mark
+  code elements with the language used, e.g. so that
+  syntax highlighting scripts can use the right rules, may do so by
+  adding a class prefixed with "language-" to
+  the element.

+
+  

+
+   
The following example shows how the element can be used in a
+   paragraph to mark up element names and computer code, including
+   punctuation.

+
+   
<p>The <code>code</code> element represents a fragment of computer
+code.</p>
+
+<p>When you call the <code>activate()</code> method on the
+<code>robotSnowman</code> object, the eyes glow.</p>
+
+<p>The example below uses the <code>begin</code> keyword to indicate
+the start of a statement block. It is paired with an <code>end</code>
+keyword, which is followed by the <code>.</code> punctuation character
+(full stop) to indicate the end of the program.</p>

+
+  

+
+  

+
+   
The following example shows how a block of code could be marked
+   up using the pre and code elements.

+
+   
<pre><code class="language-pascal">var i: Integer;
+begin
+   i := 1;
+end.</code></pre>

+
+   
A class is used in that example to indicate the language
+   used.

+
+  

+
+  
See the pre element for more details.

+
+
+  
4.6.11 The var element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The var element represents a
+  variable. This could be an actual variable in a mathematical
+  expression or programming context, or it could just be a term used
+  as a placeholder in prose.

+
+  

+   
In the paragraph below, the letter "n" is being used as a
+   variable in prose:

+   
<p>If there are <var>n</var> pipes leading to the ice
+cream factory then I expect at <em>least</em> <var>n</var>
+flavors of ice cream to be available for purchase!</p>

+  

+
+  
For mathematics, in particular for anything beyond the simplest
+  of expressions, MathML is more appropriate. However, the
+  var element can still be used to refer to specific
+  variables that are then mentioned in MathML expressions.

+
+  

+
+   
In this example, an equation is shown, with a legend that
+   references the variables in the equation. The expression itself is
+   marked up with MathML, but the variables are mentioned in the
+   figure's legend using var.

+
+   
<figure>
+ <math>
+  <mi>a</mi>
+  <mo>=</mo>
+  <msqrt>
+   <msup><mi>b</mi><mn>2</mn></msup>
+   <mi>+</mi>
+   <msup><mi>c</mi><mn>2</mn></msup>
+  </msqrt>
+ </math>
+ <figcaption>
+  Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
+  a triangle with sides <var>b</var> and <var>c</var>
+ </figcaption>
+</figure>

+
+  

+
+
+  
4.6.12 The samp element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The samp element represents (sample)
+  output from a program or computing system.

+
+  
See the pre and kbd
+  elements for more details.

+
+  

+   
This example shows the samp element being used
+   inline:

+   
<p>The computer said <samp>Too much cheese in tray
+two</samp> but I didn't know what that meant.</p>

+
+   
This second example shows a block of sample output. Nested
+   samp and kbd elements allow for the
+   styling of specific elements of the sample output using a
+   style sheet.

+
+   
<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd>
+Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
+Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown
+
+<span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>

+  

+
+
+  
4.6.13 The kbd element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The kbd element represents user input
+  (typically keyboard input, although it may also be used to represent
+  other input, such as voice commands).

+
+  
When the kbd element is nested inside a
+  samp element, it represents the input as it was echoed
+  by the system.

+
+  
When the kbd element contains a
+  samp element, it represents input based on system
+  output, for example invoking a menu item.

+
+  
When the kbd element is nested inside another
+  kbd element, it represents an actual key or other
+  single unit of input as appropriate for the input mechanism.

+
+  

+   
Here the kbd element is used to indicate keys to press:

+   
<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>

+
+   
In this second example, the user is told to pick a particular
+   menu item. The outer kbd element marks up a block of
+   input, with the inner kbd elements representing each
+   individual step of the input, and the samp elements
+   inside them indicating that the steps are input based on something
+   being displayed by the system, in this case menu labels:

+
+   
<p>To make George eat an apple, select
+    <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd>
+</p>

+
+   
Such precision isn't necessary; the following is equally fine:

+
+   
<p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p>

+
+  

+
+
+  
4.6.14 The sub and sup elements

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which these elements may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Use HTMLElement.

+  
The sup element represents a
+  superscript and the sub element represents
+  a subscript.

+
+  
These elements must be used only to mark up typographical
+  conventions with specific meanings, not for typographical
+  presentation for presentation's sake. For example, it would be
+  inappropriate for the sub and sup elements
+  to be used in the name of the LaTeX document preparation system. In
+  general, authors should use these elements only if the
+  absence of those elements would change the meaning of the
+  content.

+
+  
In certain languages, superscripts are part of the typographical
+  conventions for some abbreviations.

+
+  

+   
<p>The most beautiful women are
+<span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and
+<span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>

+  

+
+  
The sub element can be used inside a
+  var element, for variables that have subscripts.

+
+  

+
+   
Here, the sub element is used to represents the
+   subscript that identifies the variable in a family of
+   variables:

+
+   
<p>The coordinate of the <var>i</var>th point is
+(<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>).
+For example, the 10th point has coordinate
+(<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>

+  

+
+  
Mathematical expressions often use subscripts and superscripts.
+  Authors are encouraged to use MathML for marking up mathematics, but
+  authors may opt to use sub and sup if
+  detailed mathematical markup is not desired. [MATHML]

+
+  

+   
<var>E</var>=<var>m</var><var>c</var><sup>2</sup>

+   
f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>

+  

+
+
+
+  
4.6.15 The i element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The i element represents a span of text
+  in an alternate voice or mood, or otherwise offset from the normal
+  prose, such as a taxonomic designation, a technical term, an
+  idiomatic phrase from another language, a thought, a ship name, or
+  some other prose whose typical typographic presentation is
+  italicized.

+
+  
Terms in languages different from the main text should be
+  annotated with lang attributes (or,
+  in XML, lang
+  attributes in the XML namespace).

+
+  

+   
The examples below show uses of the i element:

+   
<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p>
+<p>The term <i>prose content</i> is defined above.</p>
+<p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>

+   
In the following example, a dream sequence is marked up using
+   i elements.

+   
<p>Raymond tried to sleep.</p>
+<p><i>The ship sailed away on Thursday</i>, he
+dreamt. <i>The ship had many people aboard, including a beautiful
+princess called Carey. He watched her, day-in, day-out, hoping she
+would notice him, but she never did.</i></p>
+<p><i>Finally one night he picked up the courage to speak with
+her—</i></p>
+<p>Raymond woke with a start as the fire alarm rang out.</p>

+  

+
+  
Authors are encouraged to use the class attribute on the i
+  element to identify why the element is being used, so that if the
+  style of a particular use (e.g. dream sequences as opposed to
+  taxonomic terms) is to be changed at a later date, the author
+  doesn't have to go through the entire document (or series of related
+  documents) annotating each use. Similarly, authors are encouraged to
+  consider whether other elements might be more applicable than the
+  i element, for instance the em element for
+  marking up stress emphasis, or the dfn element to mark
+  up the defining instance of a term.

+
+  
Style sheets can be used to format i
+  elements, just like any other element can be restyled. Thus, it is
+  not the case that content in i elements will
+  necessarily be italicized.

+
+
+  
4.6.16 The b element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The b element represents a span of text
+  to be stylistically offset from the normal prose without conveying
+  any extra importance, such as key words in a document abstract,
+  product names in a review, or other spans of text whose typical
+  typographic presentation is boldened.

+
+  

+   
The following example shows a use of the b element
+   to highlight key words without marking them up as important:

+   
<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>

+  

+
+  

+   
In the following example, objects in a text adventure are
+   highlighted as being special by use of the b
+   element.

+   
<p>You enter a small room. Your <b>sword</b> glows
+brighter. A <b>rat</b> scurries past the corner wall.</p>

+  

+
+  

+   
Another case where the b element is appropriate is
+   in marking up the lede (or lead) sentence or paragraph. The
+   following example shows how a BBC
+   article about kittens adopting a rabbit as their own could be
+   marked up:

+   
<article>
+ <h2>Kittens 'adopted' by pet rabbit</h2>
+ <p><b class="lede">Six abandoned kittens have found an
+ unexpected new mother figure — a pet rabbit.</b></p>
+ <p>Veterinary nurse Melanie Humble took the three-week-old
+ kittens to her Aberdeen home.</p>
+[...]

+  

+
+  
As with the i element, authors are encouraged to use
+  the class attribute on the
+  b element to identify why the element is being used, so
+  that if the style of a particular use is to be changed at a later
+  date, the author doesn't have to go through annotating each use.

+
+  
The b element should be used as a last resort when
+  no other element is more appropriate. In particular, headings should
+  use the h1 to h6 elements, stress emphasis
+  should use the em element, importance should be denoted
+  with the strong element, and text marked or highlighted
+  should use the mark element.

+
+  

+   
The following would be incorrect usage:

+   
<p><b>WARNING!</b> Do not frob the barbinator!</p>

+   
In the previous example, the correct element to use would have
+   been strong, not b.

+  

+
+  
Style sheets can be used to format b
+  elements, just like any other element can be restyled. Thus, it is
+  not the case that content in b elements will
+  necessarily be boldened.

+
+
+
+  
4.6.17 The mark element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The mark element represents a run of
+  text in one document marked or highlighted for reference purposes,
+  due to its relevance in another context. When used in a quotation or
+  other block of text referred to from the prose, it indicates a
+  highlight that was not originally present but which has been added
+  to bring the reader's attention to a part of the text that might not
+  have been considered important by the original author when the block
+  was originally written, but which is now under previously unexpected
+  scrutiny. When used in the main prose of a document, it indicates a
+  part of the document that has been highlighted due to its likely
+  relevance to the user's current activity.

+
+  

+   
This example shows how the mark element can be used
+   to bring attention to a particular part of a quotation:

+   
<p lang="en-US">Consider the following quote:</p>
+<blockquote lang="en-GB">
+ <p>Look around and you will find, no-one's really
+ <mark>colour</mark> blind.</p>
+</blockquote>
+<p lang="en-US">As we can tell from the <em>spelling</em> of the word,
+the person writing this quote is clearly not American.</p>

+  

+
+  

+
+   
Another example of the mark element is highlighting
+   parts of a document that are matching some search string. If
+   someone looked at a document, and the server knew that the user was
+   searching for the word "kitten", then the server might return the
+   document with one paragraph modified as follows:

+
+   
<p>I also have some <mark>kitten</mark>s who are visiting me
+these days. They're really cute. I think they like my garden! Maybe I
+should adopt a <mark>kitten</mark>.</p>

+
+  

+
+  

+
+   
In the following snippet, a paragraph of text refers to a
+   specific part of a code fragment.

+
+   
<p>The highlighted part below is where the error lies:</p>
+<pre><code>var i: Integer;
+begin
+   i := <mark>1.1</mark>;
+end.</code></pre>

+
+   
This is separate from syntax highlighting, for which
+   span is more appropriate. Combining both, one would
+   get:

+
+   
<p>The highlighted part below is where the error lies:</p>
+<pre><code><span class=keyword>var</span> <span class=ident>i</span>: <span class=type>Integer</span>;
+<span class=keyword>begin</span>
+   <span class=ident>i</span> := <span class=literal><mark>1.1</mark></span>;
+<span class=keyword>end</span>.</code></pre>

+
+  

+
+  

+
+   
This is another example showing the use of mark to
+   highlight a part of quoted text that was originally not
+   emphasized. In this example, common typographic conventions have
+   led the author to explicitly style mark elements in
+   quotes to render in italics.

+
+   
<article>
+ <style scoped>
+  blockquote mark, q mark {
+    font: inherit; font-style: italic;
+    text-decoration: none;
+    background: transparent; color: inherit;
+  }
+  .bubble em {
+    font: inherit; font-size: larger;
+    text-decoration: underline;
+  }
+ </style>
+ <h1>She knew</h1>
+ <p>Did you notice the subtle joke in the joke on panel 4?</p>
+ <blockquote>
+  <p class="bubble">I didn't <em>want</em> to believe. <mark>Of course
+  on some level I realized it was a known-plaintext attack.</mark> But I
+  couldn't admit it until I saw for myself.</p>
+ </blockquote>
+ <p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it
+ explains everything neatly.</p>
+</article>

+
+   
Note, incidentally, the distinction between the em
+   element in this example, which is part of the original text being
+   quoted, and the mark element, which is highlighting a
+   part for comment.

+
+  

+
+  

+
+   
The following example shows the difference between denoting the
+   importance of a span of text (strong) as
+   opposed to denoting the relevance of a span of text
+   (mark). It is an extract from a textbook, where the
+   extract has had the parts relevant to the exam highlighted. The
+   safety warnings, important though they may be, are apparently not
+   relevant to the exam.

+
+   
<h3>Wormhole Physics Introduction</h3>
+
+<p><mark>A wormhole in normal conditions can be held open for a
+maximum of just under 39 minutes.</mark> Conditions that can increase
+the time include a powerful energy source coupled to one or both of
+the gates connecting the wormhole, and a large gravity well (such as a
+black hole).</p>
+
+<p><mark>Momentum is preserved across the wormhole. Electromagnetic
+radiation can travel in both directions through a wormhole,
+but matter cannot.</mark></p>
+
+<p>When a wormhole is created, a vortex normally forms.
+<strong>Warning: The vortex caused by the wormhole opening will
+annihilate anything in its path.</strong> Vortexes can be avoided when
+using sufficiently advanced dialing technology.</p>
+
+<p><mark>An obstruction in a gate will prevent it from accepting a
+wormhole connection.</mark></p>

+
+  

+
+
+  
4.6.18 The ruby element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
One or more groups of: phrasing content followed either by a single rt element, or an rp element, an rt element, and another rp element.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The ruby element allows one or more spans of
+  phrasing content to be marked with ruby annotations. Ruby
+  annotations are short runs of text presented alongside base text,
+  primarily used in East Asian typography as a guide for
+  pronunciation or to include other annotations. In Japanese, this
+  form of typography is also known as furigana.

+
+  
A ruby element represents the spans of
+  phrasing content it contains, ignoring all the child rt
+  and rp elements and their descendants. Those spans of
+  phrasing content have associated annotations created using the
+  rt element.

+
+  

+
+   
+   
+
+   
In this example, each ideograph in the Japanese text 漢字 is annotated with its
+   reading in hiragana.

+
+   
...
+<ruby>
+ 漢 <rt> かん </rt>
+ 字 <rt> じ　 </rt>
+</ruby>
+...

+
+   
This might be rendered as:

+
+   
The two main ideographs, each with its annotation in hiragana rendered in a smaller font above it.

+
+  

+
+  

+
+   
+
+   
In this example, each ideograph in the traditional Chinese text
+   漢字 is annotated
+   with its bopomofo reading.

+
+   
<ruby>
+ 漢 <rt> ㄏㄢˋ </rt>
+ 字 <rt> ㄗˋ　 </rt>
+</ruby>

+
+   
This might be rendered as:

+
+   
The two main ideographs, each with its bopomofo annotation rendered in a smaller font next to it.

+
+  

+
+  

+
+   
+
+   
In this example, each ideograph in the simplified Chinese text
+   汉字 is annotated
+   with its pinyin reading.

+
+   
...
+<ruby>
+ 汉 <rt> hàn </rt>
+ 字 <rt> zì  </rt>
+</ruby>
+...

+
+   
This might be rendered as:

+
+   
The two main ideographs, each with its pinyin annotation rendered in a smaller font above it.

+
+  

+
+  
+
+
+  
4.6.19 The rt element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a ruby element.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The rt element marks the ruby text component of a
+  ruby annotation.

+
+  
An rt element that is a child of
+  a ruby element represents an
+  annotation (given by its children) for the zero or more nodes of
+  phrasing content that immediately precedes it in the
+  ruby element, ignoring rp elements.

+
+  

+
+  
An rt element that is not a child of a
+  ruby element represents the same thing as its
+  children.

+
+  

+
+
+  
4.6.20 The rp element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a ruby element, either immediately before or immediately after an rt element.

+   
Content model:

+   
Phrasing content.

+
+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The rp element can be used to provide parentheses
+  around a ruby text component of a ruby annotation, to be shown by
+  user agents that don't support ruby annotations.

+
+  
An rp element that is a child of
+  a ruby element represents
+  nothing and its contents must be
+  ignored. An rp element whose
+  parent element is not a ruby element
+  represents its children.

+
+  

+
+   
The example above, in which each ideograph in the text 漢字 is annotated with its
+   phonetic reading, could be expanded to use rp so that in
+   legacy user agents the readings are in parentheses:

+
+   
...
+<ruby>
+ 漢 <rp>(</rp><rt>かん</rt><rp>)</rp>
+ 字 <rp>(</rp><rt>じ</rt><rp>)</rp>
+</ruby>
+...

+
+   
In conforming user agents the rendering would be as above, but
+   in user agents that do not support ruby, the rendering would
+   be:

+
+   
... 漢 (かん) 字 (じ) ...

+
+  

+
+
+  
4.6.21 The bdo element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
Also, the dir global attribute has special semantics on this element.

+   
DOM interface:

+   
Uses HTMLElement.

+  
The bdo element represents explicit
+  text directionality formatting control for its children. It allows
+  authors to override the Unicode bidirectional algorithm by
+  explicitly specifying a direction override. [BIDI]

+
+  
Authors must specify the dir
+  attribute on this element, with the value ltr to
+  specify a left-to-right override and with the value rtl
+  to specify a right-to-left override.

+
+  

+
+  
If the element has the dir
+  attribute set to the exact value ltr, then for the
+  purposes of the bidi algorithm, the user agent must act as if there
+  was a U+202D LEFT-TO-RIGHT OVERRIDE character at the start of the
+  element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the
+  element.

+
+  
If the element has the dir
+  attribute set to the exact value rtl, then for the
+  purposes of the bidi algorithm, the user agent must act as if there
+  was a U+202E RIGHT-TO-LEFT OVERRIDE character at the start of the
+  element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the
+  element.

+
+  
The requirements on handling the bdo element for the
+  bidi algorithm may be implemented indirectly through the style
+  layer. For example, an HTML+CSS user agent should implement these
+  requirements by implementing the CSS 'unicode-bidi' property. [CSS]

+
+  

+
+
+
+  
4.6.22 The span element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLSpanElement : HTMLElement {};

+   

+  
The span element doesn't mean anything on its own,
+  but can be useful when used together with other attributes,
+  e.g. class, lang, or dir. It represents its
+  children.

+
+  

+
+   
In this example, a code fragment is marked up using
+   span elements and class attributes so that its keywords and
+   identifiers can be color-coded from CSS:

+
+   
+
+   
<pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> &lt; 256; <span class="ident">j</span>++) {
+  <span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> &lt;&lt; 17);
+  <span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff;
+  <span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>)
+    <span class="keyword">break</span>;
+}</code></pre>

+
+  

+
+
+
+  
4.6.23 The br element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLBRElement : HTMLElement {};

+   

+  
The br element represents a line
+  break.

+
+  
br elements must be used only for line breaks that
+  are actually part of the content, as in poems or addresses.

+
+  

+
+  
The following example is correct usage of the br
+  element:

+
+   
<p>P. Sherman<br>
+42 Wallaby Way<br>
+Sydney</p>

+
+  

+
+  
br elements must not be used for separating thematic
+  groups in a paragraph.

+
+  

+
+   
The following examples are non-conforming, as they abuse the
+   br element:

+
+   
<p><a ...>34 comments.</a><br>
+<a ...>Add a comment.</a></p>

+
+   
<p><label>Name: <input name="name"></label><br>
+<label>Address: <input name="address"></label></p>

+
+   
Here are alternatives to the above, which are correct:

+
+   
<p><a ...>34 comments.</a></p>
+<p><a ...>Add a comment.</a></p>

+
+   
<p><label>Name: <input name="name"></label></p>
+<p><label>Address: <input name="address"></label></p>

+
+  

+
+  
If a paragraph consists of nothing but a single
+  br element, it represents a placeholder blank line
+  (e.g. as in a template). Such blank lines must not be used for
+  presentation purposes.

+
+  

+
+  
Any content inside br elements must not be
+  considered part of the surrounding text.

+
+  
A br element does not separate paragraphs for the
+  purposes of the Unicode bidirectional algorithm. [BIDI]

+
+  

+
+
+  
4.6.24 The wbr element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The wbr element represents a line break
+  opportunity.

+
+  

+
+   
In the following example, someone is quoted as saying something
+   which, for effect, is written as one long word. However, to ensure
+   that the text can be wrapped in a readable fashion, the individual
+   words in the quote are separated using a wbr
+   element.

+
+   
<p>So then he pointed at the tiger and screamed
+"there<wbr>is<wbr>no<wbr>way<wbr>you<wbr>are<wbr>ever<wbr>going<wbr>to<wbr>catch<wbr>me"!</p>

+
+  

+
+  

+
+  
Any content inside wbr elements must not be
+  considered part of the surrounding text.

+
+  

+
+
+
+  
4.6.25 Usage summary

+
+  
This section is non-normative.

+
+  
Element
+     Purpose
+     Example
+   
a
+     Hyperlinks
+     
Visit my <a href="drinks.html">drinks</a> page.

+
+    
em
+     Stress emphasis
+     
I must say I <em>adore</em> lemonade.

+
+    
strong
+     Importance
+     
This tea is <strong>very hot</strong>.

+
+    
small
+     Side comments
+     
These grapes are made into wine. <small>Alcohol is addictive.</small>

+
+    
cite
+     Titles of works
+     
The case <cite>Hugo v. Danielle</cite> is relevant here.

+
+    
q
+     Quotations
+     
The judge said <q>You can drink water from the fish tank</q> but advised against it.

+
+    
dfn
+     Defining instance
+     
The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals.

+
+    
abbr
+     Abbreviations
+     
Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>.

+
+    
time
+     Date and/or time
+     
Published <time>2009-10-21</time>.

+
+    
code
+     Computer code
+     
The <code>fruitdb</code> program can be used for tracking fruit production.

+
+    
var
+     Variables
+     
If there are <var>n</var> fruit in the bowl, at least <var>n</var>÷2 will be ripe.

+
+    
samp
+     Computer output
+     
The computer said <samp>Unknown error -3</samp>.

+
+    
kbd
+     User input
+     
Hit <kbd>F1</kbd> to continue.

+
+    
sub
+     Subscripts
+     
Water is H<sub>2</sub>O.

+
+    
sup
+     Superscripts
+     
The Hydrogen in heavy water is usually <sup>2</sup>H.

+
+    
i
+     Alternative voice
+     
Lemonade consists primarily of <i>Citrus limon</i>.

+
+    
b
+     Keywords
+     
Take a <b>lemon</b> and squeeze it with a <b>juicer</b>.

+
+    
mark
+     Highlight
+     
Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest.

+
+    
ruby, rt, rp
+     Ruby annotations
+     
<ruby> OJ <rp>(<rt>Orange Juice<rp>)</ruby>

+
+    
bdo
+     Text directionality formatting
+     
The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>"

+
+    
span
+     Other
+     
In French we call it <span lang="fr">sirop de sureau</span>.

+
+    
br
+     Line break
+     
Simply Orange Juice Company<br>Apopka, FL 32703<br>U.S.A.

+
+    
wbr
+     Line breaking opportunity
+     
www.simply<wbr>orange<wbr>juice.com

+
+  
4.7 Edits

+
+  
The ins and del elements represent
+  edits to the document.

+
+
+  
4.7.1 The ins element

+
+  
Categories

+   
Flow content.

+   
When the element only contains phrasing content: phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Transparent.

+   
Content attributes:

+   
Global attributes

+   
cite

+   
datetime

+   
DOM interface:

+   
Uses the HTMLModElement interface.

+  
The ins element represents an addition
+  to the document.

+
+  

+
+   
The following represents the addition of a single paragraph:

+
+   
<aside>
+ <ins>
+  <p> I like fruit. </p>
+ </ins>
+</aside>

+
+   
As does this, because everything in the aside
+   element here counts as phrasing content and therefore
+   there is just one paragraph:

+
+   
<aside>
+ <ins>
+  Apples are <em>tasty</em>.
+ </ins>
+ <ins>
+  So are pears.
+ </ins>
+</aside>

+
+  

+
+  
ins elements should not cross implied paragraph boundaries.

+
+  

+
+   
The following example represents the addition of two paragraphs,
+   the second of which was inserted in two parts. The first
+   ins element in this example thus crosses a paragraph
+   boundary, which is considered poor form.

+
+   
<aside>
+ <!-- don't do this -->
+ <ins datetime="2005-03-16T00:00Z">
+  <p> I like fruit. </p>
+  Apples are <em>tasty</em>.
+ </ins>
+ <ins datetime="2007-12-19T00:00Z">
+  So are pears.
+ </ins>
+</aside>

+
+   
Here is a better way of marking this up. It uses more elements,
+   but none of the elements cross implied paragraph boundaries.

+
+   
<aside>
+ <ins datetime="2005-03-16T00:00Z">
+  <p> I like fruit. </p>
+ </ins>
+ <ins datetime="2005-03-16T00:00Z">
+  Apples are <em>tasty</em>.
+ </ins>
+ <ins datetime="2007-12-19T00:00Z">
+  So are pears.
+ </ins>
+</aside>

+
+   
+
+  

+
+
+  
4.7.2 The del element

+
+  
Categories

+   
Flow content.

+   
When the element only contains phrasing content: phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Transparent.

+   
Content attributes:

+   
Global attributes

+   
cite

+   
datetime

+   
DOM interface:

+   
Uses the HTMLModElement interface.

+  
The del element represents a removal
+  from the document.

+
+  
del elements should not cross implied paragraph boundaries.

+
+  

+
+   
The following shows a "to do" list where items that have been
+   done are crossed-off with the date and time of their
+   completion.

+
+   
<h1>To Do</h1>
+<ul>
+ <li>Empty the dishwasher</li>
+ <li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin's lectures</del></li>
+ <li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li>
+ <li>Buy a printer</li>
+</ul>

+
+  

+
+
+
+  
4.7.3 Attributes common to ins and del elements

+
+  
The cite attribute
+  may be used to specify the address of a document that explains the
+  change. When that document is long, for instance the minutes of a
+  meeting, authors are encouraged to include a fragment identifier
+  pointing to the specific part of that document that discusses the
+  change.

+
+  
If the cite attribute is
+  present, it must be a valid URL potentially surrounded by
+  spaces that explains the change. To obtain
+  the corresponding citation link, the value of the attribute must be
+  resolved relative to the
+  element. User agents should allow users to follow such citation
+  links.

+
+
+  
The datetime
+  attribute may be used to specify the time and date of the change.

+
+  
If present, the datetime
+  attribute must be a valid global date and time string
+  value.

+
+  

+
+  
User agents must parse the datetime attribute according to the
+  parse a global date and time string algorithm. If that
+  doesn't return a time, then the modification has no associated
+  timestamp (the value is non-conforming; it is not a valid
+  global date and time string). Otherwise, the modification is
+  marked as having been made at the given datetime. User agents should
+  use the associated time-zone offset information to determine which
+  time zone to present the given datetime in.

+
+  

+
+  
The ins and del elements must implement the HTMLModElement
+  interface:

+
+  
interface HTMLModElement : HTMLElement {
+           attribute DOMString cite;
+           attribute DOMString dateTime;
+};

+
+  

+
+  
The cite IDL
+  attribute must reflect the element's cite content attribute. The dateTime IDL attribute
+  must reflect the element's datetime content attribute.

+
+  

+
+
+
+  
4.7.4 Edits and paragraphs

+
+  
This section is non-normative.

+
+  
Since the ins and del elements do not
+  affect paragraphing, it is possible,
+  in some cases where paragraphs are implied (without explicit p
+  elements), for an ins or del element to
+  span both an entire paragraph or other non-phrasing
+  content elements and part of another paragraph. For
+  example:

+
+  
<section>
+ <ins>
+  <p>
+   This is a paragraph that was inserted.
+  </p>
+  This is another paragraph whose first sentence was inserted
+  at the same time as the paragraph above.
+ </ins>
+ This is a second sentence, which was there all along.
+</section>

+
+  
By only wrapping some paragraphs in p elements, one
+  can even get the end of one paragraph, a whole second paragraph,
+  and the start of a third paragraph to be covered by the same
+  ins or del element (though this is very
+  confusing, and not considered good practice):

+
+  
<section>
+ This is the first paragraph. <ins>This sentence was
+ inserted.
+ <p>This second paragraph was inserted.</p>
+ This sentence was inserted too.</ins> This is the
+ third paragraph in this example.
+ <!-- (don't do this) -->
+</section>

+
+  
However, due to the way implied
+  paragraphs are defined, it is not possible to mark up the
+  end of one paragraph and the start of the very next one using the
+  same ins or del element. You instead have
+  to use one (or two) p element(s) and two
+  ins or del elements, as for example:

+
+  
<section>
+ <p>This is the first paragraph. <del>This sentence was
+ deleted.</del></p>
+ <p><del>This sentence was deleted too.</del> That
+ sentence needed a separate &lt;del&gt; element.</p>
+</section>

+
+  
Partly because of the confusion described above, authors are
+  strongly encouraged to always mark up all paragraphs with the
+  p element, instead of having ins or
+  del elements that cross implied
+  paragraphs boundaries.

+
+
+  
4.7.5 Edits and lists

+
+  
This section is non-normative.

+
+  
The content models of the ol and ul
+  elements do not allow ins and del elements
+  as children. Lists always represent all their items, including items
+  that would otherwise have been marked as deleted.

+
+  
To indicate that an item is inserted or deleted, an
+  ins or del element can be wrapped around
+  the contents of the li element. To indicate that an
+  item has been replaced by another, a single li element
+  can have one or more del elements followed by one or
+  more ins elements.

+
+  

+
+   
In the following example, a list that started empty had items
+   added and removed from it over time. The bits in the example that
+   have been emphasized show the parts that are the "current" state of
+   the list. The list item numbers don't take into account the edits,
+   though.

+
+   
<h1>Stop-ship bugs</h1>
+<ol>
+ <li><ins datetime="2008-02-12T15:20Z">Bug 225:
+ Rain detector doesn't work in snow</ins></li>
+ <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228:
+ Water buffer overflows in April</ins></del></li>
+ <li><ins datetime="2008-02-16T13:50Z">Bug 230:
+ Water heater doesn't use renewable fuels</ins></li>
+ <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232:
+ Carbon dioxide emissions detected after startup</ins></del></li>
+</ol>

+
+  

+
+  

+
+   
In the following example, a list that started with just fruit
+   was replaced by a list with just colors.

+
+   
<h1>List of <del>fruits</del><ins>colors</ins></h1>
+<ul>
+ <li><del>Lime</del><ins>Green</ins></li>
+ <li><del>Apple</del></li>
+ <li>Orange</li>
+ <li><del>Pear</del></li>
+ <li><ins>Teal</ins></li>
+ <li><del>Lemon</del><ins>Yellow</ins></li>
+ <li>Olive</li>
+ <li><ins>Purple</ins></li>
+</ul>

+
+  

+
+
+
+
+  
4.8 Embedded content

+
+
+  
4.8.1 The img element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
If the element has a usemap attribute: Interactive content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
alt

+   
src

+   
usemap

+   
ismap

+   
width

+   
height

+   
DOM interface:

+   

+
[NamedConstructor=Image(),
+ NamedConstructor=Image(in unsigned long width),
+ NamedConstructor=Image(in unsigned long width, in unsigned long height)]
+interface HTMLImageElement : HTMLElement {
+           attribute DOMString alt;
+           attribute DOMString src;
+           attribute DOMString useMap;
+           attribute boolean isMap;
+           attribute unsigned long width;
+           attribute unsigned long height;
+  readonly attribute unsigned long naturalWidth;
+  readonly attribute unsigned long naturalHeight;
+  readonly attribute boolean complete;
+};

+   

+  
An img element represents an image.

+
+  
+
+  
The image given by the src attribute is the
+  embedded content, and the value of the alt attribute is the
+  img element's fallback content.

+
+  
The src attribute must be
+  present, and must contain a valid non-empty URL potentially
+  surrounded by spaces referencing a non-interactive,
+  optionally animated, image resource that is neither paged nor
+  scripted.

+
+  
Images can thus be static bitmaps (e.g. PNGs, GIFs,
+  JPEGs), single-page vector documents (single-page PDFs, XML files
+  with an SVG root element), animated bitmaps (APNGs, animated GIFs),
+  animated vector graphics (XML files with an SVG root element that
+  use declarative SMIL animation), and so forth. However, this also
+  precludes SVG files with script, multipage PDF files, interactive
+  MNG files, HTML documents, plain text documents, and so forth.

+
+  
The requirements on the alt
+  attribute's value are described in the next
+  section.
+  

+
+  
The img must not be used as a layout tool. In
+  particular, img elements should not be used to display
+  transparent images, as they rarely convey meaning and rarely add
+  anything useful to the document.

+
+  

+
+  
Unless the user agent cannot support images, or its support for
+  images has been disabled, or the user agent only fetches elements on
+  demand, then, when an img is created with a src attribute, and whenever the src attribute is set subsequently, the
+  user agent must run the following steps:
 
+
+  
  1. If the element's src
+   attribute's value is the empty string, then queue a
+   task to fire a simple event named error at the img element,
+   and abort these steps.
    2. 
+
+   
  2. 
+
+    
    Otherwise, resolve the value
+    of that attribute, relative to the element, and if that is
+    successful must then fetch that resource.
     
+
+     
    Fetching the image must delay the load
+    event of the element's document until the task that is queued by the networking task source
+    once the resource has been fetched (defined below) has been run.
    
+
+    
    This, unfortunately, can be used to perform a
+    rudimentary port scan of the user's local network (especially in
+    conjunction with scripting, though scripting isn't actually
+    necessary to carry out such an attack). User agents may implement
+    cross-origin access control policies
+    that mitigate this attack.
    
+
+   
    3. 
+
+  
If the image is in a supported image type and its dimensions are
+  known, then the image is said to be available (this affects exactly
+  what the element represents, as defined below). This can be true
+  even before the image is completely downloaded, if the user agent
+  supports incremental rendering of images; in such cases, each task that is queued by the networking task source while
+  the image is being fetched must update
+  the presentation of the image appropriately. It can also stop being
+  true, e.g. if the user agent finds, after obtaining the image's
+  dimensions, that the image data is actually fatally corrupted.

+
+  
If the image was not fetched (e.g. because the UA's image support
+  is disabled, or because the src
+  attribute's value is the empty string, or if the conditions in the
+  previous paragraph are not met, then the image is not available.

+
+  
Whether the image is fetched successfully or not (e.g. whether
+  the response code was a 2xx code or equivalent) must be
+  ignored when determining the image's type and whether it is a valid
+  image.

+
+  
This allows servers to return images with error
+  responses, and have them displayed.

+
+  
The user agents should apply the image sniffing rules to determine the type
+  of the image, with the image's associated
+  Content-Type headers giving the official
+  type. If these rules are not applied, then the type of the
+  image must be the type given by the image's associated Content-Type headers.

+
+  
User agents must not support non-image resources with the
+  img element (e.g. XML files whose root element is an
+  HTML element). User agents must not run executable code
+  (e.g. scripts) embedded in the image resource. User agents must only
+  display the first page of a multipage resource (e.g. a PDF
+  file). User agents must not allow the resource to act in an
+  interactive fashion, but should honor any animation in the
+  resource.

+
+  
This specification does not specify which image types are to be
+  supported.

+
+  
The task that is
+  queued by the networking
+  task source once the resource has been fetched, must act as appropriate given the
+  following alternatives:

+
+  
If the download was successful and the image is available

+
+   
Queue a task to fire a simple event
+   named load at the img
+   element (this happens after complete starts returning
+   true).

+
+   
Otherwise (the fetching process failed without a response from
+   the remote server, or completed but the image is not a supported
+   image)

+
+   
Queue a task to fire a simple event
+   named error on the
+   img element.

+
+  
The task source for these tasks is the DOM manipulation
+  task source.

+
+  
What an img element represents depends on the src attribute and the alt attribute.

+
+  
If the src attribute is set
+   and the alt attribute is set to
+   the empty string

+
+   

+
+    
The image is either decorative or supplemental to the rest of
+    the content, redundant with some other information in the
+    document.

+
+    
If the image is available and the
+    user agent is configured to display that image, then the element
+    represents the image specified by the src attribute.

+
+    
Otherwise, the element represents nothing, and may
+    be omitted completely from the rendering. User agents may provide
+    the user with a notification that an image is present but has been
+    omitted from the rendering.

+
+   

+
+   
If the src attribute is set
+   and the alt attribute is set to a
+   value that isn't empty

+
+   

+
+    
The image is a key part of the content; the alt attribute gives a textual
+    equivalent or replacement for the image.

+
+    
If the image is available and the
+    user agent is configured to display that image, then the element
+    represents the image specified by the src attribute.

+
+    
Otherwise, the element represents the text given
+    by the alt attribute. User
+    agents may provide the user with a notification that an image is
+    present but has been omitted from the rendering.

+
+   

+
+   
If the src attribute is set
+   and the alt attribute is not

+
+   

+
+    
The image might be a key part of the content, and there is no
+    textual equivalent of the image available.

+
+    
In a conforming document, the absence of the alt attribute indicates that the image
+    is a key part of the content but that a textual replacement for
+    the image was not available when the image was generated.

+
+    
If the image is available, the
+    element represents the image specified by the src attribute.

+
+    
If the image is not available or
+    if the user agent is not configured to display the image, then the
+    user agent should display some sort of indicator that there is an
+    image that is not being rendered, and may, if requested by the
+    user, or if so configured, or when required to provide contextual
+    information in response to navigation, provide caption information
+    for the image, derived as follows:

+
+    
  1. If the image has a title
+     attribute whose value is not the empty string, then the value of
+     that attribute is the caption information; abort these
+     steps.
    2. 
+
+     
  2. If the image is the child of a figure element
+     that has a child figcaption element, then the
+     contents of the first such figcaption element are
+     the caption information; abort these steps.
    3. 
+
+    

+
+   
If the src attribute is not
+   set and either the alt attribute
+   is set to the empty string or the alt attribute is not set at all

+
+   

+
+    
The element represents nothing.

+
+   

+
+   
Otherwise

+
+   

+
+    
The element represents the text given by the alt attribute.

+
+   

+
+  
The alt attribute does not
+  represent advisory information. User agents must not present the
+  contents of the alt attribute in
+  the same way as content of the title
+  attribute.

+
+  
User agents may always provide the user with the option to
+  display any image, or to prevent any image from being
+  displayed. User agents may also apply heuristics to help the user
+  make use of the image when the user is unable to see it, e.g. due to
+  a visual disability or because they are using a text terminal with
+  no graphics capabilities. Such heuristics could include, for
+  instance, optical character recognition (OCR) of text found within
+  the image.

+
+  
While user agents are encouraged to repair cases
+  of missing alt attributes, authors
+  must not rely on such behavior. Requirements for
+  providing text to act as an alternative for images are described
+  in detail below.

+
+  
The contents of img elements, if any, are
+  ignored for the purposes of rendering.

+
+  

+
+  
The usemap attribute,
+  if present, can indicate that the image has an associated
+  image map.

+
+  
The ismap
+  attribute, when used on an element that is a descendant of an
+  a element with an href attribute, indicates by its
+  presence that the element provides access to a server-side image
+  map. This affects how events are handled on the corresponding
+  a element.

+
+  
The ismap attribute is a
+  boolean attribute. The attribute must not be specified
+  on an element that does not have an ancestor a element
+  with an href attribute.

+
+  
The img element supports dimension
+  attributes.

+
+  

+
+  
The IDL attributes alt, src, useMap, and isMap each must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  
image . width [ = value ]

+   
image . height [ = value ]

+
+   

+
+    
These attributes return the actual rendered dimensions of the
+    image, or zero if the dimensions are not known.

+
+    
They can be set, to change the corresponding content
+    attributes.

+
+   

+
+   
image . naturalWidth

+   
image . naturalHeight

+
+   

+
+    
These attributes return the intrinsic dimensions of the image,
+    or zero if the dimensions are not known.

+
+   

+
+   
image . complete

+
+   

+
+    
Returns true if the image has been downloaded, decoded, and
+    found to be valid; otherwise, returns false.

+
+   

+
+   
image = new Image( [ width [, height ] ] )

+
+   

+
+    
Returns a new img element, with the width and height attributes set to the values
+    passed in the relevant arguments, if applicable.

+
+   

+
+  

+
+  
The IDL attributes width and height must return the
+  rendered width and height of the image, in CSS pixels, if the image
+  is being rendered, and is being rendered to a visual
+  medium; or else the intrinsic width and height of the image, in CSS
+  pixels, if the image is available but
+  not being rendered to a visual medium; or else 0, if the image is
+  not available. [CSS]

+
+  
On setting, they must act as if they reflected the respective content attributes
+  of the same name.

+
+  
The IDL attributes naturalWidth and
+  naturalHeight
+  must return the intrinsic width and height of the image, in CSS
+  pixels, if the image is available, or
+  else 0. [CSS]

+
+  
The IDL attribute complete must return
+  true if the user agent has fetched the image specified in the src attribute, and it is in a supported
+  image type (i.e. it was decoded without fatal errors), even if the
+  final task queued by the
+  networking task source for the fetching of the image resource has not yet been
+  processed. Otherwise, the attribute must return false.

+
+  
The value of complete can thus change while a
+  script is executing.

+
+  
Three constructors are provided for creating
+  HTMLImageElement objects (in addition to the factory
+  methods from DOM Core such as createElement()): Image(), Image(width), and Image(width, height). When invoked as constructors,
+  these must return a new HTMLImageElement object (a new
+  img element). If the width argument
+  is present, the new object's width content attribute must be set to
+  width. If the height
+  argument is also present, the new object's height content attribute must be set
+  to height. The element's document must be the
+  active document of the browsing context of
+  the Window object on which the interface object of the
+  invoked constructor is found.

+
+  

+
+  

+
+   
A single image can have different appropriate alternative text
+   depending on the context.

+
+   
In each of the following cases, the same image is used, yet the
+   alt text is different each
+   time. The image is the coat of arms of the Carouge municipality in
+   the canton Geneva in Switzerland.

+
+   
Here it is used as a supplementary icon:

+   
<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>

+
+   
Here it is used as an icon representing the town:

+   
<p>Home town: <img src="carouge.svg" alt="Carouge"></p>

+
+   
Here it is used as part of a text on the town:

+
+   
<p>Carouge has a coat of arms.</p>
+<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
+<p>It is used as decoration all over the town.</p>

+
+   
Here it is used as a way to support a similar text where the
+   description is given as well as, instead of as an alternative to,
+   the image:

+
+   
<p>Carouge has a coat of arms.</p>
+<p><img src="carouge.svg" alt=""></p>
+<p>The coat of arms depicts a lion, sitting in front of a tree.
+It is used as decoration all over the town.</p>

+
+   
Here it is used as part of a story:

+
+   
<p>He picked up the folder and a piece of paper fell out.</p>
+<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
+red background, a green tree, and a yellow lion with its tongue
+hanging out and whose tail was shaped like an S."></p>
+<p>He stared at the folder. S! The answer he had been looking for all
+this time was simply the letter S! How had he not seen that before? It all
+came together now. The phone call where Hector had referred to a lion's tail,
+the time Marco had stuck his tongue out...</p>

+
+   
Here it is not known at the time of publication what the image
+   will be, only that it will be a coat of arms of some kind, and thus
+   no replacement text can be provided, and instead only a brief
+   caption for the image is provided, in the title attribute:

+
+   
<p>The last user to have uploaded a coat of arms uploaded this one:</p>
+<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>

+
+   
Ideally, the author would find a way to provide real replacement
+   text even in this case, e.g. by asking the previous user. Not
+   providing replacement text makes the document more difficult to use
+   for people who are unable to view images, e.g. blind users, or
+   users or very low-bandwidth connections or who pay by the byte, or
+   users who are forced to use a text-only Web browser.

+
+  

+
+  

+
+   
Here are some more examples showing the same picture used in
+   different contexts, with different appropriate alternate texts each
+   time.

+
+   
<article>
+ <h1>My cats</h1>
+ <h2>Fluffy</h2>
+ <p>Fluffy is my favorite.</p>
+ <img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
+ <p>She's just too cute.</p>
+ <h2>Miles</h2>
+ <p>My other cat, Miles just eats and sleeps.</p>
+</article>

+
+   
<article>
+ <h1>Photography</h1>
+ <h2>Shooting moving targets indoors</h2>
+ <p>The trick here is to know how to anticipate; to know at what speed and
+ what distance the subject will pass by.</p>
+ <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
+ photographed quite nicely using this technique.">
+ <h2>Nature by night</h2>
+ <p>To achieve this, you'll need either an extremely sensitive film, or
+ immense flash lights.</p>
+</article>

+
+   
<article>
+ <h1>About me</h1>
+ <h2>My pets</h2>
+ <p>I've got a cat named Fluffy and a dog named Miles.</p>
+ <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
+ <p>My dog Miles and I like go on long walks together.</p>
+ <h2>music</h2>
+ <p>After our walks, having emptied my mind, I like listening to Bach.</p>
+</article>

+
+   
<article>
+ <h1>Fluffy and the Yarn</h1>
+ <p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p>
+ <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
+ <p>He would play in the morning, he would play in the evening.</p>
+</article>

+
+  

+
+
+
+  
4.8.1.1 Requirements for providing text to act as an alternative for images

+
+  
Except where otherwise specified, the alt attribute must be specified and its
+  value must not be empty; the value must be an appropriate
+  replacement for the image. The specific requirements for the alt attribute depend on what the image
+  is intended to represent, as described in the following
+  sections.

+
+
+  
+
+  
When an a element that is a hyperlink,
+  or a button element, has no textual content but
+  contains one or more images, the alt attributes must contain text that
+  together convey the purpose of the link or button.

+
+  

+
+   
In this example, a user is asked to pick his preferred color
+   from a list of three. Each color is given by an image, but for
+   users who have configured their user agent not to display images,
+   the color names are used instead:

+
+   
<h1>Pick your color</h1>
+<ul>
+ <li><a href="green.html"><img src="green.jpeg" alt="Green"></a></li>
+ <li><a href="blue.html"><img src="blue.jpeg" alt="Blue"></a></li>
+ <li><a href="red.html"><img src="red.jpeg" alt="Red"></a></li>
+</ul>

+
+  

+
+  

+
+   
In this example, each button has a set of images to indicate the
+   kind of color output desired by the user. The first image is used
+   in each case to give the alternative text.

+
+   
<button name="rgb"><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></button>
+<button name="cmyk"><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

+
+   
Since each image represents one part of the text, it could also
+   be written like this:

+
+   
<button name="rgb"><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></button>
+<button name="cmyk"><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></button>

+
+   
However, with other alternative text, this might not work, and
+   putting all the alternative text into one image in each case might
+   make more sense:

+
+   
<button name="rgb"><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></button>
+<button name="cmyk"><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

+
+  

+
+
+
+  
4.8.1.1.2 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations

+
+  
Sometimes something can be more clearly stated in graphical
+  form, for example as a flowchart, a diagram, a graph, or a simple
+  map showing directions. In such cases, an image can be given using
+  the img element, but the lesser textual version must
+  still be given, so that users who are unable to view the image
+  (e.g. because they have a very slow connection, or because they
+  are using a text-only browser, or because they are listening to
+  the page being read out by a hands-free automobile voice Web
+  browser, or simply because they are blind) are still able to
+  understand the message being conveyed.

+
+  
The text must be given in the alt attribute, and must convey the
+  same message as the image specified in the src attribute.

+
+  
It is important to realize that the alternative text is a
+  replacement for the image, not a description of the
+  image.

+
+  

+
+   
In the following example we have a flowchart in image
+   form, with text in the alt
+   attribute rephrasing the flowchart in prose form:

+
+   
<p>In the common case, the data handled by the tokenization stage
+comes from the network, but it can also come from script.</p>
+<p><img src="images/parsing-model-overview.png" alt="The network
+passes data to the Tokenizer stage, which passes data to the Tree
+Construction stage. From there, data goes to both the DOM and to
+Script Execution. Script Execution is linked to the DOM, and, using
+document.write(), passes data to the Tokenizer."></p>

+
+  

+
+  

+
+   
Here's another example, showing a good solution and a bad
+   solution to the problem of including an image in a
+   description.

+
+   
First, here's the good solution. This sample shows how the
+   alternative text should just be what you would have put in the
+   prose if the image had never existed.

+
+   
<!-- This is the correct way to do things. -->
+<p>
+ You are standing in an open field west of a house.
+ <img src="house.jpeg" alt="The house is white, with a boarded front door.">
+ There is a small mailbox here.
+</p>

+
+   
Second, here's the bad solution. In this incorrect way of
+   doing things, the alternative text is simply a description of the
+   image, instead of a textual replacement for the image. It's bad
+   because when the image isn't shown, the text doesn't flow as well
+   as in the first example.

+
+   
<!-- This is the wrong way to do things. -->
+<p>
+ You are standing in an open field west of a house.
+ <img src="house.jpeg" alt="A white house, with a boarded front door.">
+ There is a small mailbox here.
+</p>

+
+   
Text such as "Photo of white house with boarded door" would be
+   equally bad alternative text (though it could be suitable for the
+   title attribute or in the
+   figcaption element of a figure with this
+   image).

+
+  

+
+
+  
4.8.1.1.3 A short phrase or label with an alternative graphical representation: icons, logos

+
+  
A document can contain information in iconic form. The icon is
+  intended to help users of visual browsers to recognize features at
+  a glance.

+
+  
In some cases, the icon is supplemental to a text label
+  conveying the same meaning. In those cases, the alt attribute must be present but must
+  be empty.

+
+  

+
+   
Here the icons are next to text that conveys the same meaning,
+   so they have an empty alt
+   attribute:

+
+   
<nav>
+ <p><a href="/help/"><img src="/icons/help.png" alt=""> Help</a></p>
+ <p><a href="/configure/"><img src="/icons/configuration.png" alt="">
+ Configuration Tools</a></p>
+</nav>

+
+  

+
+  
In other cases, the icon has no text next to it describing what
+  it means; the icon is supposed to be self-explanatory. In those
+  cases, an equivalent textual label must be given in the alt attribute.

+
+  

+
+   
Here, posts on a news site are labeled with an icon
+   indicating their topic.

+
+   
<body>
+ <article>
+  <header>
+   <h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1>
+   <p><img src="movies.png" alt="Movies"></p>
+  </header>
+  <p>Pixar has won yet another <i>Best Movie of the Year</i> award,
+  making this its 8th win in the last 12 years.</p>
+ </article>
+ <article>
+  <header>
+   <h1>Latest TWiT episode is online</h1>
+   <p><img src="podcasts.png" alt="Podcasts"></p>
+  </header>
+  <p>The latest TWiT episode has been posted, in which we hear
+  several tech news stories as well as learning much more about the
+  iPhone. This week, the panelists compare how reflective their
+  iPhones' Apple logos are.</p>
+ </article>
+</body>

+
+  

+
+  
Many pages include logos, insignia, flags, or emblems, which
+  stand for a particular entity such as a company, organization,
+  project, band, software package, country, or some such.

+
+  
If the logo is being used to represent the entity, e.g. as a page
+  heading, the alt attribute must
+  contain the name of the entity being represented by the logo. The
+  alt attribute must not
+  contain text like the word "logo", as it is not the fact that it is
+  a logo that is being conveyed, it's the entity itself.

+
+  
If the logo is being used next to the name of the entity that
+  it represents, then the logo is supplemental, and its alt attribute must instead be
+  empty.

+
+  
If the logo is merely used as decorative material (as branding,
+  or, for example, as a side image in an article that mentions the
+  entity to which the logo belongs), then the entry below on purely
+  decorative images applies. If the logo is actually being
+  discussed, then it is being used as a phrase or paragraph (the
+  description of the logo) with an alternative graphical
+  representation (the logo itself), and the first entry above
+  applies.

+
+  

+
+   
In the following snippets, all four of the above cases are
+   present. First, we see a logo used to represent a company:

+
+   
<h1><img src="XYZ.gif" alt="The XYZ company"></h1>

+
+   
Next, we see a paragraph which uses a logo right next to the
+   company name, and so doesn't have any alternative text:
+
+   
<article>
+ <h2>News</h2>
+ <p>We have recently been looking at buying the <img src="alpha.gif"
+ alt=""> ΑΒΓ company, a small Greek company
+ specializing in our type of product.</p>

+
+   
In this third snippet, we have a logo being used in an aside,
+   as part of the larger article discussing the acquisition:

+
+
 <aside><p><img src="alpha-large.gif" alt=""></p></aside>
+ <p>The ΑΒΓ company has had a good quarter, and our
+ pie chart studies of their accounts suggest a much bigger blue slice
+ than its green and orange slices, which is always a good sign.</p>
+</article>

+
+   
Finally, we have an opinion piece talking about a logo, and
+   the logo is therefore described in detail in the alternative
+   text.

+
+   
<p>Consider for a moment their logo:</p>
+
+<p><img src="/images/logo" alt="It consists of a green circle with a
+green question mark centered inside it."></p>
+
+<p>How unoriginal can you get? I mean, oooooh, a question mark, how
+<em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm
+sure everyone will rush to adopt those specifications now! They could
+at least have tried for some sort of, I don't know, sequence of
+rounded squares with varying shades of green and bold white outlines,
+at least that would look good on the cover of a blue book.</p>

+
+   
This example shows how the alternative text should be written
+   such that if the image isn't available, and the text is used instead,
+   the text flows seamlessly into the surrounding text, as if the
+   image had never been there in the first place.

+
+  

+
+
+  
4.8.1.1.4 Text that has been rendered to a graphic for typographical effect

+
+  
Sometimes, an image just consists of text, and the purpose of the
+  image is not to highlight the actual typographic effects used to
+  render the text, but just to convey the text itself.

+
+  
In such cases, the alt
+  attribute must be present but must consist of the same text as
+  written in the image itself.

+
+  

+
+   
Consider a graphic containing the text "Earth Day", but with the
+   letters all decorated with flowers and plants. If the text is
+   merely being used as a heading, to spice up the page for graphical
+   users, then the correct alternative text is just the same text
+   "Earth Day", and no mention need be made of the decorations:

+
+   
<h1><img src="earthdayheading.png" alt="Earth Day"></h1>

+
+  

+
+
+
+  
4.8.1.1.5 A graphical representation of some of the surrounding text

+
+  
In many cases, the image is actually just supplementary, and
+  its presence merely reinforces the surrounding text. In these
+  cases, the alt attribute must be
+  present but its value must be the empty string.

+
+  
In general, an image falls into this category if removing the
+  image doesn't make the page any less useful, but including the
+  image makes it a lot easier for users of visual browsers to
+  understand the concept.

+
+  

+
+   
A flowchart that repeats the previous paragraph in graphical form:

+
+   
<p>The network passes data to the Tokenizer stage, which
+passes data to the Tree Construction stage. From there, data goes
+to both the DOM and to Script Execution. Script Execution is
+linked to the DOM, and, using document.write(), passes data to
+the Tokenizer.</p>
+<p><img src="images/parsing-model-overview.png" alt=""></p>

+
+   
In these cases, it would be wrong to include alternative text
+   that consists of just a caption. If a caption is to be included,
+   then either the title attribute can
+   be used, or the figure and figcaption
+   elements can be used. In the latter case, the image would in fact
+   be a phrase or paragraph with an alternative graphical
+   representation, and would thus require alternative text.

+
+   
<!-- Using the title="" attribute -->
+<p>The network passes data to the Tokenizer stage, which
+passes data to the Tree Construction stage. From there, data goes
+to both the DOM and to Script Execution. Script Execution is
+linked to the DOM, and, using document.write(), passes data to
+the Tokenizer.</p>
+<p><img src="images/parsing-model-overview.png" alt=""
+        title="Flowchart representation of the parsing model."></p>

+
+   
<!-- Using <figure> and <figcaption> -->
+<p>The network passes data to the Tokenizer stage, which
+passes data to the Tree Construction stage. From there, data goes
+to both the DOM and to Script Execution. Script Execution is
+linked to the DOM, and, using document.write(), passes data to
+the Tokenizer.</p>
+<figure>
+ <img src="images/parsing-model-overview.png" alt="The Network leads
+ to the Tokenizer, which leads to the Tree Construction. The Tree
+ Construction leads to two items. The first is Script Execution, which
+ leads via document.write() back to the Tokenizer. The second item
+ from which Tree Construction leads is the DOM. The DOM is related to
+ the Script Execution.">
+ <figcaption>Flowchart representation of the parsing model.</figcaption>
+</figure>

+
+   
<!-- This is WRONG. Do not do this. Instead, do what the above examples do. -->
+<p>The network passes data to the Tokenizer stage, which
+passes data to the Tree Construction stage. From there, data goes
+to both the DOM and to Script Execution. Script Execution is
+linked to the DOM, and, using document.write(), passes data to
+the Tokenizer.</p>
+<p><img src="images/parsing-model-overview.png"
+        alt="Flowchart representation of the parsing model."></p>
+<!-- Never put the image's caption in the alt="" attribute! -->

+
+  

+
+  

+
+   
A graph that repeats the previous paragraph in graphical form:

+
+   
<p>According to a study covering several billion pages,
+about 62% of documents on the Web in 2007 triggered the Quirks
+rendering mode of Web browsers, about 30% triggered the Almost
+Standards mode, and about 9% triggered the Standards mode.</p>
+<p><img src="rendering-mode-pie-chart.png" alt=""></p>

+
+  

+
+
+
+  
4.8.1.1.6 A purely decorative image that doesn't add any information

+
+  
In general, if an image is decorative but isn't especially
+  page-specific, for example an image that forms part of a site-wide
+  design scheme, the image should be specified in the site's CSS,
+  not in the markup of the document.

+
+  
However, a decorative image that isn't discussed by the
+  surrounding text but still has some relevance can be included in a page
+  using the img element. Such images are decorative, but
+  still form part of the content. In these cases, the alt attribute must be present but its
+  value must be the empty string.

+
+  

+
+   
Examples where the image is purely decorative despite being
+   relevant would include things like a photo of the Black Rock City
+   landscape in a blog post about an event at Burning Man, or an
+   image of a painting inspired by a poem, on a page reciting that
+   poem. The following snippet shows an example of the latter
+   case (only the first verse is included in this snippet):

+
+   
<h1>The Lady of Shalott</h1>
+<p><img src="shalott.jpeg" alt=""></p>
+<p>On either side the river lie<br>
+Long fields of barley and of rye,<br>
+That clothe the wold and meet the sky;<br>
+And through the field the road run by<br>
+To many-tower'd Camelot;<br>
+And up and down the people go,<br>
+Gazing where the lilies blow<br>
+Round an island there below,<br>
+The island of Shalott.</p>

+
+  

+
+
+
+  
+
+  
When a picture has been sliced into smaller image files that are
+  then displayed together to form the complete picture again, one of
+  the images must have its alt
+  attribute set as per the relevant rules that would be appropriate
+  for the picture as a whole, and then all the remaining images must
+  have their alt attribute set to
+  the empty string.

+
+  

+
+   
In the following example, a picture representing a company logo
+   for XYZ Corp has been split into two pieces,
+   the first containing the letters "XYZ" and the second with the word
+   "Corp". The alternative text ("XYZ Corp") is all in the first
+   image.

+
+   
<h1><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></h1>

+
+  

+
+  

+
+   
In the following example, a rating is shown as three filled
+   stars and two empty stars. While the alternative text could have
+   been "★★★☆☆", the author has
+   instead decided to more helpfully give the rating in the form "3
+   out of 5". That is the alternative text of the first image, and the
+   rest have blank alternative text.

+
+   
<p>Rating: <meter max=5 value=3><img src="1" alt="3 out of 5"
+  ><img src="1" alt=""><img src="1" alt=""><img src="0" alt=""
+  ><img src="0" alt=""></meter></p>

+
+  

+
+
+
+  
+
+  
Generally, image maps should be
+  used instead of slicing an image for links.

+
+  
However, if an image is indeed sliced and any of the components
+  of the sliced picture are the sole contents of links, then one image
+  per link must have alternative text in its alt attribute representing the purpose
+  of the link.

+
+  

+
+   
In the following example, a picture representing the flying
+   spaghetti monster emblem, with each of the left noodly appendages
+   and the right noodly appendages in different images, so that the
+   user can pick the left side or the right side in an adventure.

+
+   
<h1>The Church</h1>
+<p>You come across a flying spaghetti monster. Which side of His
+Noodliness do you wish to reach out for?</p>
+<p><a href="?go=left" ><img src="fsm-left.png"  alt="Left side. "></a
+  ><img src="fsm-middle.png" alt=""
+  ><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p>

+
+  

+
+
+
+  
4.8.1.1.9 A key part of the content

+
+  
In some cases, the image is a critical part of the
+  content. This could be the case, for instance, on a page that is
+  part of a photo gallery. The image is the whole point of
+  the page containing it.

+
+  
How to provide alternative text for an image that is a key part
+  of the content depends on the image's provenance.

+
+  
The general case

+
+   

+
+    
When it is possible for detailed alternative text to be
+    provided, for example if the image is part of a series of
+    screenshots in a magazine review, or part of a comic strip, or is
+    a photograph in a blog entry about that photograph, text that can
+    serve as a substitute for the image must be given as the contents
+    of the alt attribute.

+
+    

+
+     
A screenshot in a gallery of screenshots for a new OS, with
+     some alternative text:

+
+     
<figure>
+ <img src="KDE%20Light%20desktop.png"
+      alt="The desktop is blue, with icons along the left hand side in
+           two columns, reading System, Home, K-Mail, etc. A window is
+           open showing that menus wrap to a second line if they
+           cannot fit in the window. The window has a list of icons
+           along the top, with an address bar below it, a list of
+           icons for tabs along the left edge, a status bar on the
+           bottom, and two panes in the middle. The desktop has a bar
+           at the bottom of the screen with a few buttons, a pager, a
+           list of open applications, and a clock.">
+ <figcaption>Screenshot of a KDE desktop.</figcaption>
+</figure>

+
+    

+
+    

+
+     
A graph in a financial report:

+
+     
<img src="sales.gif"
+     title="Sales graph"
+     alt="From 1998 to 2005, sales increased by the following percentages
+     with each year: 624%, 75%, 138%, 40%, 35%, 9%, 21%">

+
+     
Note that "sales graph" would be inadequate alternative text
+     for a sales graph. Text that would be a good caption is
+     not generally suitable as replacement text.

+
+    

+
+   

+
+
+   
Images that defy a complete description

+
+   

+
+    
In certain cases, the nature of the image might be such that
+    providing thorough alternative text is impractical. For example,
+    the image could be indistinct, or could be a complex fractal, or
+    could be a detailed topographical map.

+
+    
In these cases, the alt
+    attribute must contain some suitable alternative text, but it may
+    be somewhat brief.

+
+    

+
+     
Sometimes there simply is no text that can do justice to an
+     image. For example, there is little that can be said to usefully
+     describe a Rorschach inkblot test. However, a description, even
+     if brief, is still better than nothing:

+
+     
<figure>
+ <img src="/commons/a/a7/Rorschach1.jpg" alt="A shape with left-right
+ symmetry with indistinct edges, with a small gap in the center, two
+ larger gaps offset slightly from the center, with two similar gaps
+ under them. The outline is wider in the top half than the bottom
+ half, with the sides extending upwards higher than the center, and
+ the center extending below the sides.">
+ <figcaption>A black outline of the first of the ten cards
+ in the Rorschach inkblot test.</figcaption>
+</figure>

+
+     
Note that the following would be a very bad use of alternative
+     text:

+
+     
<!-- This example is wrong. Do not copy it. -->
+<figure>
+ <img src="/commons/a/a7/Rorschach1.jpg" alt="A black outline
+ of the first of the ten cards in the Rorschach inkblot test.">
+ <figcaption>A black outline of the first of the ten cards
+ in the Rorschach inkblot test.</figcaption>
+</figure>

+
+     
Including the caption in the alternative text like this isn't
+     useful because it effectively duplicates the caption for users
+     who don't have images, taunting them twice yet not helping them
+     any more than if they had only read or heard the caption
+     once.

+
+    

+
+    

+
+     
Another example of an image that defies full description is a
+     fractal, which, by definition, is infinite in detail.

+
+     
The following example shows one possible way of providing
+     alternative text for the full view of an image of the Mandelbrot
+     set.

+
+     
<img src="ms1.jpeg" alt="The Mandelbrot set appears as a cardioid with
+its cusp on the real axis in the positive direction, with a smaller
+bulb aligned along the same center line, touching it in the negative
+direction, and with these two shapes being surrounded by smaller bulbs
+of various sizes.">

+
+    

+
+   

+
+
+   
Images whose contents are not known

+
+   

+
+    
In some unfortunate cases, there might be no alternative text
+    available at all, either because the image is obtained in some
+    automated fashion without any associated alternative text (e.g. a
+    Webcam), or because the page is being generated by a script using
+    user-provided images where the user did not provide suitable or
+    usable alternative text (e.g. photograph sharing sites), or
+    because the author does not himself know what the images represent
+    (e.g. a blind photographer sharing an image on his blog).

+
+    
In such cases, the alt
+    attribute's value may be omitted, but one of the following
+    conditions must be met as well:

+
+    
Such cases are to be kept to an absolute
+    minimum. If there is even the slightest possibility of the author
+    having the ability to provide real alternative text, then it would
+    not be acceptable to omit the alt
+    attribute.

+
+    

+
+     
A photo on a photo-sharing site, if the site received the
+     image with no metadata other than the caption, could be marked up
+     as follows:

+
+     
<figure>
+ <img src="1100670787_6a7c664aef.jpg">
+ <figcaption>Bubbles traveled everywhere with us.</figcaption>
+</figure>

+
+     
It would be better, however, if a detailed description of the
+     important parts of the image obtained from the user and included
+     on the page.

+
+    

+
+    

+
+     
A blind user's blog in which a photo taken by the user is
+     shown. Initially, the user might not have any idea what the photo
+     he took shows:

+
+     
<article>
+ <h1>I took a photo</h1>
+ <p>I went out today and took a photo!</p>
+ <figure>
+  <img src="photo2.jpeg">
+  <figcaption>A photograph taken blindly from my front porch.</figcaption>
+ </figure>
+</article>

+
+     
Eventually though, the user might obtain a description of the
+     image from his friends and could then include alternative text:

+
+     
<article>
+ <h1>I took a photo</h1>
+ <p>I went out today and took a photo!</p>
+ <figure>
+  <img src="photo2.jpeg" alt="The photograph shows my hummingbird
+  feeder hanging from the edge of my roof. It is half full, but there
+  are no birds around. In the background, out-of-focus trees fill the
+  shot. The feeder is made of wood with a metal grate, and it contains
+  peanuts. The edge of the roof is wooden too, and is painted white
+  with light blue streaks.">
+  <figcaption>A photograph taken blindly from my front porch.</figcaption>
+ </figure>
+</article>

+
+    

+
+    

+
+     
Sometimes the entire point of the image is that a textual
+     description is not available, and the user is to provide the
+     description. For instance, the point of a CAPTCHA image is to see
+     if the user can literally read the graphic. Here is one way to
+     mark up a CAPTCHA (note the title
+     attribute):

+
+     
<p><label>What does this image say?
+<img src="captcha.cgi?id=8934" title="CAPTCHA">
+<input type=text name=captcha></label>
+(If you cannot see the image, you can use an <a
+href="?audio">audio</a> test instead.)</p>

+
+     
Another example would be software that displays images and
+     asks for alternative text precisely for the purpose of then
+     writing a page with correct alternative text. Such a page could
+     have a table of images, like this:

+
+     
<table>
+ <thead>
+  <tr> <th> Image <th> Description
+ <tbody>
+  <tr>
+   <td> <img src="2421.png" title="Image 640 by 100, filename 'banner.gif'">
+   <td> <input name="alt2421">
+  <tr>
+   <td> <img src="2422.png" title="Image 200 by 480, filename 'ad3.gif'">
+   <td> <input name="alt2422">
+</table>

+
+     
Notice that even in this example, as much useful information
+     as possible is still included in the title attribute.

+
+    

+
+    
Since some users cannot use images at all
+    (e.g. because they have a very slow connection, or because they
+    are using a text-only browser, or because they are listening to
+    the page being read out by a hands-free automobile voice Web
+    browser, or simply because they are blind), the alt attribute is only allowed to be
+    omitted rather than being provided with replacement text when no
+    alternative text is available and none can be made available, as
+    in the above examples. Lack of effort from the part of the author
+    is not an acceptable reason for omitting the alt attribute.

+
+   

+
+  
4.8.1.1.10 An image not intended for the user

+
+  
Generally authors should avoid using img elements
+  for purposes other than showing images.

+
+  
If an img element is being used for purposes other
+  than showing an image, e.g. as part of a service to count page
+  views, then the alt attribute must
+  be the empty string.

+
+  
In such cases, the width and
+  height attributes should both
+  be set to zero.

+
+
+
+  
4.8.1.1.11 An image in an e-mail or private document intended for a specific person who is known to be able to view images

+
+  
This section does not apply to documents that are publicly
+  accessible, or whose target audience is not necessarily personally
+  known to the author, such as documents on a Web site, e-mails sent
+  to public mailing lists, or software documentation.

+
+  
When an image is included in a private communication (such as an
+  HTML e-mail) aimed at a specific person who is known to be able to
+  view images, the alt attribute may
+  be omitted. However, even in such cases it is strongly recommended
+  that alternative text be included (as appropriate according to the
+  kind of image involved, as described in the above entries), so that
+  the e-mail is still usable should the user use a mail client that
+  does not support images, or should the document be forwarded on to
+  other users whose abilities might not include easily seeing
+  images.

+
+
+
+  
4.8.1.1.12 General guidelines

+
+  
The most general rule to consider when writing alternative text
+  is the following: the intent is that replacing every image
+  with the text of its alt attribute
+  not change the meaning of the page.

+
+  
So, in general, alternative text can be written by considering
+  what one would have written had one not been able to include the
+  image.

+
+  
A corollary to this is that the alt attribute's value should never
+  contain text that could be considered the image's caption,
+  title, or legend. It is supposed to contain
+  replacement text that could be used by users instead of the
+  image; it is not meant to supplement the image. The title attribute can be used for
+  supplemental information.

+
+  
One way to think of alternative text is to think
+  about how you would read the page containing the image to someone
+  over the phone, without mentioning that there is an image
+  present. Whatever you say instead of the image is typically a good
+  start for writing the alternative text.

+
+
+  

+
+  
4.8.1.1.13 Guidance for markup generators

+
+  
Markup generators (such as WYSIWYG authoring tools) should,
+  wherever possible, obtain alternative text from their
+  users. However, it is recognized that in many cases, this will not
+  be possible.

+
+  
For images that are the sole contents of links, markup generators
+  should examine the link target to determine the title of the target,
+  or the URL of the target, and use information obtained in this
+  manner as the alternative text.

+
+  
As a last resort, implementors should either set the alt attribute to the empty string, under
+  the assumption that the image is a purely decorative image that
+  doesn't add any information but is still specific to the surrounding
+  content, or omit the alt attribute
+  altogether, under the assumption that the image is a key part of the
+  content.

+
+  
Markup generators should generally avoid using the image's own
+  file name as the alternative text. Similarly, markup generators
+  should avoid generating alternative text from any content that will
+  be equally available to presentation user agents (e.g. Web
+  browsers).

+
+  
This is because once a page is generated, it will
+  typically not be updated, whereas the browsers that later read the
+  page can be updated by the user, therefore the browser is likely to
+  have more up-to-date and finely-tuned heuristics than the markup
+  generator did when generating the page.

+
+  

+
+  

+
+  
4.8.1.1.14 Guidance for conformance checkers

+
+  
A conformance checker must report the lack of an alt attribute as an error unless one of
+  the conditions listed below applies:

+
+  
  • The title attribute is present
+   and has a non-empty value (as described
+   above).
    • 
+
+   
  • The img element is in a figure
+   element that contains a figcaption element that
+   contains content other than inter-element whitespace
+   (as described above).
    • 
+
+   
+
+   
  • The conformance checker has been configured to assume that the
+   document is an e-mail or document intended for a specific person
+   who is known to be able to view images.
    • 
+
+   
  • The document has a meta element with a name attribute whose value is an
+   ASCII case-insensitive match for the string "generator". (This case does not
+   represent a case where the document is conforming, only that the
+   generator could not determine appropriate alternative text —
+   validators are required to not show an error in this case to
+   discourage markup generators from including bogus alternative text
+   purely in an attempt to silence validators.)
    • 
+
+  

+
+
+
+  
4.8.2 The iframe element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
Interactive content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
Text that conforms to the requirements given in the prose.

+   
Content attributes:

+   
Global attributes

+   
src

+   
srcdoc

+   
name

+   
sandbox

+   
seamless

+   
width

+   
height

+   
DOM interface:

+   

+
interface HTMLIFrameElement : HTMLElement {
+           attribute DOMString src;
+           attribute DOMString srcdoc;
+           attribute DOMString name;
+  [PutForwards=value] readonly attribute DOMSettableTokenList sandbox;
+           attribute boolean seamless;
+           attribute DOMString width;
+           attribute DOMString height;
+  readonly attribute Document contentDocument;
+  readonly attribute WindowProxy contentWindow;
+};

+   

+  
The iframe element represents a
+  nested browsing context.

+
+  
The src attribute
+  gives the address of a page that the nested browsing
+  context is to contain. The attribute, if present, must be a
+  valid non-empty URL potentially surrounded by
+  spaces.

+
+  
The srcdoc
+  attribute gives the content of the page that the nested
+  browsing context is to contain.  The value of the attribute
+  in is an iframe srcdoc document.

+
+  
For iframe elements in HTML documents,
+  the attribute, if present, must have a value using the HTML
+  syntax that consists of the following syntactic components,
+  in the given order:

+
+  
  1. Any number of comments and
+   space characters.
    2. 
+
+   
  2. Optionally, a DOCTYPE.
+
+   
  3. Any number of comments and
+   space characters.
    4. 
+
+   
  4. The root element, in the form of an html element.
    5. 
+
+   
  5. Any number of comments and
+   space characters.
    6. 
+
+  
For iframe elements in XML documents,
+  the attribute, if present, must have a value that matches the
+  production labeled document in the XML
+  specification. [XML]

+
+  
If the src attribute and the
+  srcdoc attribute are both
+  specified together, the srcdoc
+  attribute takes priority. This allows authors to provide a fallback
+  URL for legacy user agents that do not support the
+  srcdoc attribute.

+
+  

+
+  
When an iframe element is first inserted into a document, the
+  user agent must create a nested browsing context, and
+  then process the iframe attributes for the
+  first time.

+
+  
Whenever an iframe element with a nested
+  browsing context has its srcdoc attribute set or changed,
+  the user agent must process the iframe
+  attributes.

+
+  
Similarly, whenever an iframe element with a
+  nested browsing context but with no srcdoc attribute specified has its
+  src attribute set or changed,
+  the user agent must process the iframe
+  attributes.
 
+
+  
When the user agent is to process the iframe
+  attributes, it must run the first appropriate steps from the
+  following list:

+
+  
If the srcdoc attribute
+   is specified

+
+   
Navigate the element's browsing
+   context to a resource whose Content-Type is
+   text/html, whose URL is
+   about:srcdoc, and whose data consists of the value of
+   the attribute.

+
+   
If the src
+   attribute is specified but the srcdoc attribute is not

+
+   

+
+    
  1. If the value of the src attribute is the empty string,
+     jump to the empty step below.
    2. 
+
+     
  2. Resolve the value of
+     the src attribute, relative
+     to the iframe element.
    3. 
+
+     
  3. If that is not successful, then jump to the empty step below.
    4. 
+
+     
  4. If the resulting absolute URL is an
+     ASCII case-insensitive match for the string
+     "about:blank", and the user agent is processing this
+     iframe's attributes for the first time, then jump to
+     the empty step below. (In cases other than the
+     first time, about:blank is loaded
+     normally.)
    5. 
+
+     
  5. Navigate the element's browsing
+     context to the resulting absolute
+     URL.
    6. 
+
+    
Empty: When the steps above require the user agent to
+    jump to the empty step, if the user agent is
+    processing this iframe's attributes for the first
+    time, then the user agent must queue a task to
+    fire a simple event named load at the iframe
+    element. (After jumping to this step, the above steps are not
+    resumed.)

+
+   

+
+   
Otherwise

+
+   

+
+    
Queue a task to fire a simple event
+    named load at the
+    iframe element.

+
+   

+
+  
Any navigation required of the user
+  agent in the process the iframe attributes
+  algorithm must be completed with the iframe element's
+  document's browsing context as the source
+  browsing context.

+
+  
Furthermore, if the process the iframe
+  attributes algorithm was invoked for the first time for this
+  element (i.e. as a result of the element being inserted into a document), then
+  any navigation required of the user
+  agent in that algorithm must be completed with replacement
+  enabled.

+
+  

+
+  
If, when the element is created, the srcdoc attribute is not set, and
+  the src attribute is either
+  also not set or set but its value cannot be resolved, the browsing context will remain at the
+  initial about:blank page.

+
+  
If the user navigates
+  away from this page, the iframe's corresponding
+  WindowProxy object will proxy new Window
+  objects for new Document objects, but the src attribute will not change.

+
+  

+
+   
Here a blog uses the srcdoc attribute in conjunction
+   with the sandbox and seamless attributes described
+   below to provide users of user agents that support this feature
+   with an extra layer of protection from script injection in the blog
+   post comments:

+
+   
<article>
+ <h1>I got my own magazine!</h1>
+ <p>After much effort, I've finally found a publisher, and so now I
+ have my own magazine! Isn't that awesome?! The first issue will come
+ out in September, and we have articles about getting food, and about
+ getting in boxes, it's going to be great!</p>
+ <footer>
+  <p>Written by <a href="/users/cap">cap</a>.
+  <time pubdate>2009-08-21T23:32Z</time></p>
+ </footer>
+ <article>
+  <footer> At <time pubdate>2009-08-21T23:35Z</time>, <a href="/users/ch">ch</a> writes: </footer>
+  <iframe seamless sandbox="allow-same-origin" srcdoc="<p>did you get a cover picture yet?"></iframe>
+ </article>
+ <article>
+  <footer> At <time pubdate>2009-08-21T23:44Z</time>, <a href="/users/cap">cap</a> writes: </footer>
+  <iframe seamless sandbox="allow-same-origin" srcdoc="<p>Yeah, you can see it <a href=&quot;/gallery?mode=cover&amp;amp;page=1&quot;>in my gallery</a>."></iframe>
+ </article>
+ <article>
+  <footer> At <time pubdate>2009-08-21T23:58Z</time>, <a href="/users/ch">ch</a> writes: </footer>
+  <iframe seamless sandbox="allow-same-origin" srcdoc="<p>hey that's earl's table.
+<p>you should get earl&amp;amp;me on the next cover."></iframe>
+ </article>

+
+   
Notice the way that quotes have to be escaped (otherwise the
+   sandbox attribute would
+   end prematurely), and the way raw ampersands (e.g. in URLs or in
+   prose) mentioned in the sandboxed content have to be
+   doubly escaped — once so that the ampersand is
+   preserved when originally parsing the sandbox attribute, and once more
+   to prevent the ampersand from being misinterpreted when parsing the
+   sandboxed content.

+
+  

+
+  
In the HTML syntax, authors need only
+  remember to use U+0022 QUOTATION MARK characters (") to wrap the
+  attribute contents and then to escape all U+0022 QUOTATION MARK (")
+  and U+0026 AMPERSAND (&) characters, and to specify the sandbox attribute, to ensure safe
+  embedding of content.

+
+  
Due to restrictions of the XML syntax,
+  in XML a number of other characters need to be escaped also to
+  ensure correctness.

+
+  
The name
+  attribute, if present, must be a valid browsing context
+  name. The given value is used to name the nested
+  browsing context. When the browsing
+  context is created, if the attribute is present, the browsing
+  context name must be set to the value of this attribute;
+  otherwise, the browsing context name must be set to the
+  empty string.

+
+  

+
+  
Whenever the name attribute
+  is set, the nested browsing context's name must be changed to the new
+  value. If the attribute is removed, the browsing context
+  name must be set to the empty string.

+
+  
When content loads in an iframe, after any load events are fired within the content
+  itself, the user agent must queue a task to fire
+  a simple event named load at
+  the iframe element. When content whose URL
+  has the same origin as the iframe
+  element's Document fails to load (e.g. due to a DNS
+  error, network error, or if the server returned a 4xx or 5xx status
+  code or
+  equivalent), then the user agent must queue a
+  task to fire a simple event named error at the element instead. (This event
+  does not fire for parse errors,
+  script errors, or any errors for cross-origin resources.)

+
+  
The task source for these tasks is the DOM manipulation
+  task source.

+
+  
A load event is also
+  fired at the iframe element when it is created if no
+  other data is loaded in it.

+
+  
When there is an active parser in the
+  iframe, and when anything in the iframe is
+  delaying the load event of
+  the iframe's browsing context's
+  active document, the iframe must
+  delay the load event of its document.

+
+  
If, during the handling of the load event, the browsing
+  context in the iframe is again navigated, that will further delay the
+  load event.

+
+  

+
+  
The sandbox
+  attribute, when specified, enables a set of extra restrictions on
+  any content hosted by the iframe. Its value must be an
+  unordered set of unique space-separated tokens. The
+  allowed values are allow-same-origin,
+  allow-top-navigation,
+  allow-forms,
+  and allow-scripts. When
+  the attribute is set, the content is treated as being from a unique
+  origin, forms and scripts are disabled, links are
+  prevented from targeting other browsing contexts, and plugins are disabled. The
+  allow-same-origin
+  keyword allows the content to be treated as being from the same
+  origin instead of forcing it into a unique origin, the allow-top-navigation
+  keyword allows the content to navigate its
+  top-level browsing context, and the allow-forms and allow-scripts
+  keywords re-enable forms and scripts respectively (though scripts
+  are still prevented from creating popups).

+
+  
Setting both the allow-scripts and
+  allow-same-origin
+  keywords together when the embedded page has the same
+  origin as the page containing the iframe allows
+  the embedded page to simply remove the sandbox attribute.

+
+  
Sandboxing hostile content is of minimal help if
+  an attacker can convince the user to just visit the hostile content
+  directly, rather than in the iframe. To limit the
+  damage that can be caused by hostile HTML content, it should be
+  served using the text/html-sandboxed MIME type.

+
+  

+
+  
+
+  
While the sandbox
+  attribute is specified, the iframe element's
+  nested browsing context must have the flags given in
+  the following list set.  In addition, any browsing contexts nested within an
+  iframe, either directly or indirectly, must have all
+  the flags set on them as were set on the iframe's
+  Document's browsing context when the
+  iframe's Document was created.

+
+  
The sandboxed navigation browsing context flag

+
+   

+
+    
This flag prevents content from
+    navigating browsing contexts other than the sandboxed browsing
+    context itself (or browsing contexts further nested inside
+    it), and the top-level browsing context (which is
+    protected by the sandboxed top-level navigation browsing
+    context flag defined next).

+
+    
This flag also prevents content
+    from creating new auxiliary browsing contexts, e.g. using the
+    target attribute or the
+    window.open() method.

+
+   

+
+
+   
The sandboxed top-level navigation browsing context
+   flag, unless the sandbox attribute's value, when
+   split on spaces, is
+   found to have the allow-top-navigation
+   keyword set

+
+   

+
+    
This flag prevents content from
+    navigating their top-level browsing context.

+
+    
When the allow-top-navigation
+    is set, content can navigate its top-level browsing
+    context, but other browsing
+    contexts are still protected by the sandboxed
+    navigation browsing context flag defined above.

+
+   

+
+
+   
The sandboxed plugins browsing context flag

+
+   

+
+    
This flag prevents content from instantiating plugins, whether using the embed element, the object element,
+    the applet
+    element, or through navigation of a nested
+    browsing context.

+
+   

+
+
+   
The sandboxed seamless iframes flag

+
+   

+
+    
This flag prevents content from using the seamless attribute on
+    descendant iframe elements.

+
+    
This prevents a page inserted using the allow-same-origin
+    keyword from using a CSS-selector-based method of probing the DOM
+    of other pages on the same site (in particular, pages that contain
+    user-sensitive information).

+
+    
+
+   

+
+
+   
The sandboxed origin browsing context flag, unless
+   the sandbox attribute's
+   value, when split on
+   spaces, is found to have the allow-same-origin
+   keyword set

+
+   

+
+    
This flag forces content into a unique
+    origin, thus preventing it from accessing other content from
+    the same origin.

+
+    
This flag also prevents script from
+    reading from or writing to the document.cookie IDL
+    attribute, and blocks access to localStorage and openDatabase().
+    
+    [WEBSTORAGE]
+    
+    [WEBSQL]
+    

+
+    

+
+     
The allow-same-origin
+     attribute is intended for two cases.

+
+     
First, it can be used to allow content from the same site to
+     be sandboxed to disable scripting, while still allowing access to
+     the DOM of the sandboxed content.

+
+     
Second, it can be used to embed content from a third-party
+     site, sandboxed to prevent that site from opening popup windows,
+     etc, without preventing the embedded page from communicating back
+     to its originating site, using the database APIs to store data,
+     etc.

+
+    

+
+   

+
+
+   
The sandboxed forms browsing context flag, unless
+   the sandbox attribute's
+   value, when split on
+   spaces, is found to have the allow-forms
+   keyword set

+
+   

+
+    
This flag blocks form
+    submission.

+
+   

+
+
+   
The sandboxed scripts browsing context flag, unless
+   the sandbox attribute's
+   value, when split on
+   spaces, is found to have the allow-scripts
+   keyword set

+
+   

+
+    
This flag blocks script
+    execution.

+
+   

+
+
+   
The sandboxed automatic features browsing context
+   flag, unless the sandbox attribute's value, when
+   split on spaces, is
+   found to have the allow-scripts
+   keyword (defined above) set

+
+   

+
+    
This flag blocks features that trigger automatically, such as
+    automatically playing a
+    video or automatically
+    focusing a form control. It is relaxed by the same flag as
+    scripts, because when scripts are enabled these features are
+    trivially possible anyway, and it would be unfortunate to force
+    authors to use script to do them when sandboxed rather than
+    allowing them to use the declarative features.

+
+   

+
+  
These flags must not be set unless the conditions listed above
+  define them as being set.

+
+  
These flags only take effect when the
+  nested browsing context of the iframe is
+  navigated. Removing then, or removing
+  the entire sandbox
+  attribute, has no effect on an already-loaded page.

+
+  

+
+  

+
+   
In this example, some completely-unknown, potentially hostile,
+   user-provided HTML content is embedded in a page. Because it is
+   sandboxed, it is treated by the user agent as being from a unique
+   origin, despite the content being served from the same site. Thus
+   it is affected by all the normal cross-site restrictions. In
+   addition, the embedded page has scripting disabled, plugins
+   disabled, forms disabled, and it cannot navigate any frames or
+   windows other than itself (or any frames or windows it itself
+   embeds).

+
+   
<p>We're not scared of you! Here is your content, unedited:</p>
+<iframe sandbox src="getusercontent.cgi?id=12193"></iframe>

+
+   
Note that cookies are still sent to the server in the getusercontent.cgi request, though they are not
+   visible in the document.cookie IDL
+   attribute.

+
+   
It is important that the server serve the
+   user-provided HTML using the text/html-sandboxed MIME
+   type so that if the attacker convinces the user to visit that page
+   directly, the page doesn't run in the context of the site's origin,
+   which would make the user vulnerable to any attack found in the
+   page.

+
+  

+
+  

+
+   
In this example, a gadget from another site is embedded. The
+   gadget has scripting and forms enabled, and the origin sandbox
+   restrictions are lifted, allowing the gadget to communicate with
+   its originating server. The sandbox is still useful, however, as it
+   disables plugins and popups, thus reducing the risk of the user
+   being exposed to malware and other annoyances.

+
+   
<iframe sandbox="allow-same-origin allow-forms allow-scripts"
+        src="http://maps.example.com/embedded.html"></iframe>

+
+  

+
+  

+
+   
Suppose a file A contained the following fragment:

+
+   
<iframe sandbox="allow-same-origin allow-forms" src=B></iframe>

+
+   
Suppose that file B contained an iframe also:

+
+   
<iframe sandbox="allow-scripts" src=C></iframe>

+
+   
Further, suppose that file C contained a link:

+
+   
<a href=D>Link</a>

+
+   
For this example, suppose all the files were served as
+   text/html.

+
+   
Page C in this scenario has all the sandboxing flags
+   set. Scripts are disabled, because the iframe in A has
+   scripts disabled, and this overrides the allow-scripts
+   keyword set on the iframe in B. Forms are also
+   disabled, because the inner iframe (in B) does not
+   have the allow-forms keyword
+   set.

+
+   
Suppose now that a script in A removes all the sandbox attributes in A and
+   B. This would change nothing immediately. If the user clicked the
+   link in C, loading page D into the iframe in B, page D
+   would now act as if the iframe in B had the allow-same-origin
+   and allow-forms keywords
+   set, because that was the state of the nested browsing
+   context in the iframe in A when page B was
+   loaded.

+
+   
Generally speaking, dynamically removing or changing the sandbox attribute is
+   ill-advised, because it can make it quite hard to reason about what
+   will be allowed and what will not.

+
+  

+
+  
Potentially hostile files can be served from the
+  same server as the file containing the iframe element
+  by labeling them as text/html-sandboxed instead of
+  text/html. This ensures that scripts in the files are
+  unable to attack the site (as if they were actually served from
+  another server), even if the user is tricked into visiting those
+  pages directly, without the protection of the sandbox attribute.

+
+  
If the allow-scripts
+  keyword is set along with allow-same-origin
+  keyword, and the file is from the same origin as the
+  iframe's Document, then a script in the
+  "sandboxed" iframe could just reach out, remove the sandbox attribute, and then
+  reload itself, effectively breaking out of the sandbox
+  altogether.

+
+
+  
The seamless
+  attribute is a boolean attribute. When specified, it
+  indicates that the iframe element's browsing
+  context is to be rendered in a manner that makes it appear to
+  be part of the containing document (seamlessly included in the
+  parent document). Specifically, when the
+  attribute is set on an iframe element whose owner
+  Document's browsing context did not have
+  the sandboxed seamless iframes flag set when that
+  Document was created, and while either the
+  browsing context's active document has the
+  same origin as the iframe element's
+  document, or the browsing context's active
+  document's address has the same origin as the
+  iframe element's document, the following requirements
+  apply:

+
+  

+
+  
  • The user agent must set the seamless browsing
+   context flag to true for that browsing
+   context. This will cause links to
+   open in the parent browsing context.
    • 
+
+   
  • In a CSS-supporting user agent: the user agent must add all
+   the style sheets that apply to the iframe element to
+   the cascade of the active document of the
+   iframe element's nested browsing context,
+   at the appropriate cascade levels, before any style sheets
+   specified by the document itself.
    • 
+
+   
  • In a CSS-supporting user agent: the user agent must, for the
+   purpose of CSS property inheritance only, treat the root element of
+   the active document of the iframe
+   element's nested browsing context as being a child of
+   the iframe element. (Thus inherited properties on the
+   root element of the document in the iframe will
+   inherit the computed values of those properties on the
+   iframe element instead of taking their initial
+   values.)
    • 
+
+   
  • In visual media, in a CSS-supporting user agent: the user agent
+   should set the intrinsic width of the iframe to the
+   width that the element would have if it was a non-replaced
+   block-level element with 'width: auto'.
    • 
+
+   
  • In visual media, in a CSS-supporting user agent: the user
+   agent should set the intrinsic height of the iframe to
+   the height of the bounding box around the content rendered in the
+   iframe at its current width (as given in the previous
+   bullet point), as it would be if the scrolling position was such
+   that the top of the viewport for the content rendered in the
+   iframe was aligned with the origin of that content's
+   canvas.
    • 
+
+   
  • 
+
+    
    In visual media, in a CSS-supporting user agent: the user agent
+    must force the height of the initial containing block of the
+    active document of the nested browsing
+    context of the iframe to zero.
    
+
+    
    This is intended to get around the otherwise
+    circular dependency of percentage dimensions that depend on the
+    height of the containing block, thus affecting the height of the
+    document's bounding box, thus affecting the height of the
+    viewport, thus affecting the size of the initial containing
+    block.
    
+
+   
    • 
+
+   
  • In speech media, the user agent should render the nested
+   browsing context without announcing that it is a separate
+   document.
    • 
+
+   
  • 
+
+    
    User agents should, in general, act as if the active
+    document of the iframe's nested browsing
+    context was part of the document that the
+    iframe is in.
    
+
+    
    For example if the user agent supports listing
+    all the links in a document, links in "seamlessly" nested
+    documents would be included in that list without being
+    significantly distinguished from links in the document itself.
    
+
+   
    • 
+
+  
If the attribute is not specified, or if the origin
+  conditions listed above are not met, then the user agent should
+  render the nested browsing context in a manner that is
+  clearly distinguishable as a separate browsing context,
+  and the seamless browsing context flag must be set to
+  false for that browsing context.

+
+  
It is important that user agents recheck the
+  above conditions whenever the active document of the
+  nested browsing context of the iframe
+  changes, such that the seamless browsing context flag
+  gets unset if the nested browsing context is navigated to another origin.

+
+  

+
+  
The attribute can be set or removed dynamically,
+  with the rendering updating in tandem.

+
+  

+
+   
In this example, the site's navigation is embedded using a
+   client-side include using an iframe. Any links in the
+   iframe will, in new user agents, be automatically
+   opened in the iframe's parent browsing context; for
+   legacy user agents, the site could also include a base
+   element with a target
+   attribute with the value _parent. Similarly,
+   in new user agents the styles of the parent page will be
+   automatically applied to the contents of the frame, but to support
+   legacy user agents authors might wish to include the styles
+   explicitly.

+
+   
<nav><iframe seamless src="nav.include.html"></iframe></nav>

+
+  

+
+
+  
The iframe element supports dimension
+  attributes for cases where the embedded content has specific
+  dimensions (e.g. ad units have well-defined dimensions).

+
+  
An iframe element never has fallback
+  content, as it will always create a nested browsing
+  context, regardless of whether the specified initial contents
+  are successfully used.

+
+  
Descendants of iframe elements represent
+  nothing. (In legacy user agents that do not support
+  iframe elements, the contents would be parsed as markup
+  that could act as fallback content.)

+
+  
When used in HTML documents, the allowed content
+  model of iframe elements is text, except that invoking
+  the HTML fragment parsing algorithm with the
+  iframe element as the context
+  element and the text contents as the input must
+  result in a list of nodes that are all phrasing
+  content, with no parse
+  errors having occurred, with no script elements
+  being anywhere in the list or as descendants of elements in the
+  list, and with all the elements in the list (including their
+  descendants) being themselves conforming.

+
+  
The iframe element must be empty in XML
+  documents.

+
+  
The HTML parser treats markup inside
+  iframe elements as text.

+
+  

+
+  
The IDL attributes src, srcdoc, name, sandbox, and seamless must
+  reflect the respective content attributes of the same
+  name.

+
+  
The contentDocument
+  IDL attribute must return the Document object of the
+  active document of the iframe element's
+  nested browsing context.

+
+  
The contentWindow
+  IDL attribute must return the WindowProxy object of the
+  iframe element's nested browsing
+  context.

+
+  

+
+  

+
+   
Here is an example of a page using an iframe to
+   include advertising from an advertising broker:

+
+   
<iframe src="http://ads.example.com/?customerid=923513721&amp;format=banner"
+        width="468" height="60"></iframe>

+
+  

+
+
+
+
+  
4.8.3 The embed element

+
+
+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
Interactive content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
src

+   
type

+   
width

+   
height

+   
Any other attribute that has no namespace (see prose).

+   
DOM interface:

+   

+
interface HTMLEmbedElement : HTMLElement {
+           attribute DOMString src;
+           attribute DOMString type;
+           attribute DOMString width;
+           attribute DOMString height;
+};

+    

+    
Depending on the type of content instantiated by the
+    embed element, the node may also support other
+    interfaces.

+    

+   

+  
The embed element represents an
+  integration point for an external (typically non-HTML) application
+  or interactive content.

+
+  
The src attribute
+  gives the address of the resource being embedded. The attribute, if
+  present, must contain a valid non-empty URL potentially
+  surrounded by spaces.

+
+  
The type
+  attribute, if present, gives the MIME type by which the
+  plugin to instantiate is selected. The value must be a valid
+  MIME type. If both the type attribute and the src attribute are present, then the
+  type attribute must specify the
+  same type as the explicit Content-Type
+  metadata of the resource given by the src attribute.

+
+  

+
+  
When the element is created with neither a src attribute nor a type attribute, and when attributes
+  are removed such that neither attribute is present on the element
+  anymore, and when the element has a media element
+  ancestor, and when the element has an ancestor object
+  element that is not showing its fallback
+  content, any plugins instantiated for the element must be
+  removed, and the embed element represents nothing.

+
+  
If either:
+
+  
...then the user agent must render the embed element
+  in a manner that conveys that the plugin was
+  disabled. The user agent may offer the user the option to override
+  the sandbox and instantiate the plugin anyway; if the
+  user invokes such an option, the user agent must act as if the
+  conditions above did not apply for the purposes of this element.

+
+  
Plugins are disabled in sandboxed browsing
+  contexts because they might not honor the restrictions imposed by
+  the sandbox (e.g. they might allow scripting even when scripting in
+  the sandbox is disabled). User agents should convey the danger of
+  overriding the sandbox to the user if an option to do so is
+  provided.

+
+  
An embed element is said to be potentially active when the
+  following conditions are all met simultaneously:

+
+  
Whenever an embed element that was not potentially active becomes potentially active, and whenever
+  a potentially active
+  embed element's src attribute is set, changed, or
+  removed, and whenever a potentially active
+  embed element's type attribute is set, changed, or
+  removed, the appropriate set of steps from the following is then
+  applied:

+
+  
If the element has a src
+   attribute set

+
+   

+
+    
The user agent must resolve
+    the value of the element's src
+    attribute, relative to the element. If that is successful, the
+    user agent should fetch the resulting absolute
+    URL, from the element's browsing context scope
+    origin if it has one. The task that is
+    queued by the networking
+    task source once the resource has been fetched must find and instantiate an
+    appropriate plugin based on the content's type, and hand that
+    plugin the content of the resource, replacing any
+    previously instantiated plugin for the element.
 
+
+    
Fetching the resource must delay the load event of
+    the element's document.

+    
+    
+    
+
+   

+
+   
If the element has no src
+   attribute set

+
+   
The user agent should find and instantiate an appropriate
+   plugin based on the value of the type attribute.

+
+  
Whenever an embed element that was potentially active stops being
+  potentially active, any
+  plugin that had been instantiated for that element must
+  be unloaded.

+
+  
The embed element is unaffected by the
+  CSS 'display' property. The selected plugin is instantiated even if
+  the element is hidden with a 'display:none' CSS style.

+
+  
The type of the content
+  being embedded is defined as follows:

+
+  
  1. If the element has a type attribute, and that attribute's
+   value is a type that a plugin supports, then the value
+   of the type attribute is the
+   content's type.
    2. 
+
+   
  2. 
+
+    
+
+    
    Otherwise, if the <path>
+    component of the URL of the specified resource (after
+    any redirects) matches a pattern that a plugin
+    supports, then the content's
+    type is the type that that plugin can handle.
    
+
+    
    For example, a plugin might say that it can
+    handle resources with <path>
+    components that end with the four character string ".swf".
    
+
+    
+    
+
+   
    3. 
+
+   
  3. Otherwise, if the specified resource has explicit Content-Type metadata, then
+   that is the content's
+   type.
    4. 
+
+   
  4. Otherwise, the content has no type and there can be no
+   appropriate plugin for it.
    5. 
+
+   
+
+  
The embed element has no fallback
+  content. If the user agent can't find a suitable plugin, then
+  the user agent must use a default plugin. (This default could be as
+  simple as saying "Unsupported Format".)

+
+  
Whether the resource is fetched successfully or not (e.g. whether
+  the response code was a 2xx code or equivalent) must be
+  ignored when determining the resource's type and when handing the
+  resource to the plugin.

+
+  
This allows servers to return data for plugins even
+  with error responses (e.g. HTTP 500 Internal Server Error codes can
+  still contain plugin data).

+
+  

+
+  
Any namespace-less attribute other than name, align, hspace, and vspace  may be specified on the embed element,
+  so long as its name is XML-compatible and contains no
+  characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to
+  LATIN CAPITAL LETTER Z). These attributes are then passed as
+  parameters to the plugin.

+
+  
All attributes in HTML documents get
+  lowercased automatically, so the restriction on uppercase letters
+  doesn't affect such documents.

+
+  
The four exceptions are to exclude legacy attributes
+  that have side-effects beyond just sending parameters to the
+  plugin.

+
+  

+
+  
The user agent should pass the names and values of all the
+  attributes of the embed element that have no namespace
+  to the plugin used, when it is instantiated.

+
+  
If the plugin instantiated for the
+  embed element supports a scriptable interface, the
+  HTMLEmbedElement object representing the element should
+  expose that interface while the element is instantiated.

+
+  

+
+  
The embed element supports dimension
+  attributes.

+
+  

+
+  
The IDL attributes src and type each must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  

+
+   
Here's a way to embed a resource that requires a proprietary
+   plug-in, like Flash:

+
+   
<embed src="catgame.swf">

+
+   
If the user does not have the plug-in (for example if the
+   plug-in vendor doesn't support the user's platform), then the user
+   will be unable to use the resource.

+
+   
To pass the plugin a parameter "quality" with the value "high",
+   an attribute can be specified:

+
+   
<embed src="catgame.swf" quality="high">

+
+   
This would be equivalent to the following, when using an
+   object element instead:

+
+   
<object data="catgame.swf">
+ <param name="quality" value="high">
+</object>

+
+  

+
+
+
+
+  
4.8.4 The object element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
If the element has a usemap attribute: Interactive content.
 
+   
Listed,  submittable, form-associated element.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
Zero or more param elements, then, transparent.

+   
Content attributes:

+   
Global attributes

+   
data

+   
type

+   
name

+   
usemap

+   
form

+   
width

+   
height

+   
DOM interface:

+   

+
interface HTMLObjectElement : HTMLElement {
+           attribute DOMString data;
+           attribute DOMString type;
+           attribute DOMString name;
+           attribute DOMString useMap;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString width;
+           attribute DOMString height;
+  readonly attribute Document contentDocument;
+  readonly attribute WindowProxy contentWindow;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+};

+    

+    
Depending on the type of content instantiated by the
+    object element, the node also supports other
+    interfaces.

+    

+   

+  
The object element can represent an external
+  resource, which, depending on the type of the resource, will either
+  be treated as an image, as a nested browsing context,
+  or as an external resource to be processed by a
+  plugin.

+
+  
The data
+  attribute, if present, specifies the address of the resource. If
+  present, the attribute must be a valid non-empty
+  URL potentially surrounded by spaces.

+
+  
The type
+  attribute, if present, specifies the type of the resource. If
+  present, the attribute must be a valid MIME type.

+
+  
At least one of either the data attribute or the type attribute must be present.

+
+  
The name
+  attribute, if present, must be a valid browsing context
+  name. The given value is used to name the nested
+  browsing context, if applicable.

+
+  

+
+  
When the element is created, when it is popped off the
+  stack of open elements of an HTML parser
+  or XML parser, and subsequently whenever the element is
+  inserted into a
+  document or removed from a document; and whenever the element's
+  Document changes whether it is fully
+  active; and whenever an ancestor object element
+  changes to or from showing its fallback content; and
+  whenever the element's classid attribute is set,
+  changed, or removed; and, when its classid attribute is not present,
+  whenever its data attribute is
+  set, changed, or removed; and, when neither its classid attribute nor its data attribute are present, whenever
+  its type attribute is set,
+  changed, or removed: the user agent must queue a task
+  to run the following steps to (re)determine what the
+  object element represents. The task source
+  for this task is the DOM
+  manipulation task source.
 
+
+  
  1. 
+
+    
    If the user has indicated a preference that this
+    object element's fallback content be
+    shown instead of the element's usual behavior, then jump to the
+    last step in the overall set of steps (fallback).
    
+
+    
    For example, a user could ask for the element's
+    fallback content to be shown because that content
+    uses a format that the user finds more accessible.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the element has an ancestor media element, or
+    has an ancestor object element that is not
+    showing its fallback content, or if the element is
+    not in a Document
+    with a browsing context, or if the element's
+    Document is not fully active, or if the
+    element is still in the stack of open elements of an
+    HTML parser or XML parser, then jump to
+    the last step in the overall set of steps (fallback).
    
+
+   
    3. 
+
+   
  3. 
+
+    
+
+    
    If the classid
+    attribute is present, and has a value that isn't the empty string,
+    then: if the user agent can find a plugin suitable
+    according to the value of the classid attribute, and plugins aren't being sandboxed,
+    then that plugin should be
+    used, and the value of the data attribute, if any, should be
+    passed to the plugin. If no suitable
+    plugin can be found, or if the plugin
+    reports an error, jump to the last step in the overall set of
+    steps (fallback).
    
+
+    
+
+   
    4. 
+
+   
+
+   
  4. If the data attribute
+   is present and its value is not the empty string, then:
    
+
+    
    1. If the type
+     attribute is present and its value is not a type that the user
+     agent supports, and is not a type that the user agent can find a
+     plugin for, then the user agent may jump to the last
+     step in the overall set of steps (fallback) without fetching the
+     content to examine its real type.
      2. 
+
+     
    2. Resolve the
+     URL specified by the data attribute, relative to the
+     element.
      3. 
+
+     
    3. If that failed, fire a simple event named
+     error at the element, then jump
+     to the last step in the overall set of steps (fallback).
      4. 
+
+     
    4. 
+
+      
      Fetch the resulting absolute URL,
+      from the element's browsing context scope origin if
+      it has one.
      
+
+       
      Fetching the resource
+      must delay the load event of the element's document
+      until the task that is queued by the networking task
+      source once the resource has been fetched (defined next) has been run.
      
+
+     
      5. 
+
+     
    5. If the resource is not yet available (e.g. because the
+     resource was not available in the cache, so that loading the
+     resource required making a request over the network), then jump
+     to the last step in the overall set of steps (fallback). The
+     task that is queued by the networking task source
+     once the resource is available must restart this algorithm from
+     this step. Resources can load incrementally; user agents may opt
+     to consider a resource "available" whenever enough data has been
+     obtained to begin processing the resource.
      6. 
+
+     
    6. If the load failed (e.g. there was an HTTP 404 error,
+     there was a DNS error), fire a simple event named
+     error at the element, then jump
+     to the last step in the overall set of steps (fallback).
      7. 
+
+     
    7. 
+
+      
      Determine the resource type, as follows:
      
+
+
+
+      
      1. 
+
+        
        Let the resource type be unknown.
        
+
+       
        2. 
+
+       
      2. 
+
+        
+
+        
        If the user agent is configured to strictly obey
+        Content-Type headers for this resource, and the resource has
+        associated Content-Type
+        metadata, then let the resource
+        type be the type specified in the resource's Content-Type
+        metadata, and jump to the step below labeled
+        handler.
        
+
+       
        3. 
+
+       
      3. 
+
+        
        If there is a type
+        attribute present on the object element, and that
+        attribute's value is not a type that the user agent supports,
+        but it is a type that a plugin supports,
+        then let the resource type be the type
+        specified in that type
+        attribute, and jump to the step below labeled
+        handler.
        
+
+       
        4. 
+
+       
      4. 
+
+        
        Run the approprate set of steps from the following
+        list:
        
+
+        
        The resource has associated
+         Content-Type metadata
        
+
+         
        
+
+          
        1. 
+
+            
          Let binary be false.
          
+
+           
          2. 
+
+           
        2. 
+
+            
          If the type specified in the
+            resource's Content-Type metadata is
+            "text/plain", and the result of applying the
+            rules
+            for distingushing if a resource is text or binary
+            to the resource is that the resource is not
+            text/plain, then set binary to true.
          
+
+           
          3. 
+
+           
        3. 
+
+            
          If the type specified in the
+            resource's Content-Type metadata is
+            "application/octet-stream", then set binary to true.
          
+
+           
          4. 
+
+           
        4. 
+
+            
          If binary is false, then let the
+            resource type be the type specified in
+            the resource's Content-Type
+            metadata, and jump to the step below labeled
+            handler.
          
+
+           
          5. 
+
+           
        5. 
+
+            
          If there is a type attribute present on
+            the object element, and its value is not
+            application/octet-stream, then run the
+            following steps:
          
+
+            
          1. 
+
+              
            If the attribute's value is a type that a plugin supports, or
+              the attribute's value is a type that starts with "image/" that is not also an XML MIME type,
+              then let the resource type be the type specified in that type attribute.
            
+
+             
            2. 
+
+             
          2. 
+
+              
            Jump to the step below labeled handler.
            
+
+             
            3. 
+
+            
          6. 
+
+          
        
+
+         
        The resource does not have associated Content-Type
+         metadata
        
+
+         
        
+
+          
        1. 
+
+            
          If there is a type attribute present on
+            the object element, then let the tentative type be the type specified in that
+            type attribute.
          
+
+            
          Otherwise, let tentative type be the
+            sniffed type of the
+            resource.
          
+
+           
          2. 
+
+           
        2. 
+
+            
          If tentative type is not
+            application/octet-stream, then let resource type be tentative
+            type and jump to the step below labeled
+            handler.
          
+
+           
          3. 
+
+          
        
+
+        
        5. 
+
+       
      5. 
+
+        
+
+        
        If the <path> component
+        of the URL of the specified resource (after any
+        redirects) matches a pattern that a plugin
+        supports, then let resource type be the
+        type that that plugin can handle.
        
+
+        
        For example, a plugin might say that it can
+        handle resources with <path> components that end with
+        the four character string ".swf".
        
+
+        
+        
+
+       
        6. 
+
+      
      It is possible for this step to finish with resource type still being unknown, or for one of
+      the substeps above to jump straight to the next step. In both
+      cases, the next step will trigger fallback.
      
+
+     
      8. 
+
+     
    8. Handler: Handle the content as given by the first
+     of the following cases that matches:
      
+
+      
      If the resource type is not a type that
+       the user agent supports, but it is a type that a
+       plugin supports
      
+
+       
      
+
+        
      If plugins are being
+        sandboxed, jump to the last step in the overall set of
+        steps (fallback).
      
+
+        
      Otherwise, the user agent should use the plugin that supports resource type and pass the content of the
+        resource to that plugin. If the
+        plugin reports an error, then jump to the last
+        step in the overall set of steps (fallback).
      
+
+       
      
+
+
+       
      If the resource type is an XML MIME
+       type, or
+       
+       if the resource type does not start with
+       "image/"
      
+
+       
      
+
+        
      The object element must be associated with a
+        newly created nested browsing context, if it does
+        not already have one.
      
+
+        
      If the URL of the given resource is not
+        about:blank, the element's nested browsing
+        context must then be navigated to that resource, with
+        replacement enabled, and with the
+        object element's document's browsing
+        context as the source browsing
+        context. (The data attribute of the
+        object element doesn't get updated if the
+        browsing context gets further navigated to other
+        locations.)
      
+
+        
      If the URL of the given resource is
+        about:blank, then, instead, the user agent must
+        queue a task to fire a simple event
+        named load at the
+        object element.
      
+
+        
      The object element represents the
+        nested browsing context.
      
+
+        
      If the name attribute
+        is present, the browsing context name must be set
+        to the value of this attribute; otherwise, the browsing
+        context name must be set to the empty string.
      
+
+        
      It's possible that the navigation of the browsing
+        context will actually obtain the resource from a
+        different application cache. Even if the resource
+        is then found to have a different type, it is still used as
+        part of a nested browsing context; this algorithm
+        doesn't restart with the new resource.
      
+
+        
+
+       
      
+
+
+       
      If the resource type starts with
+       "image/", and support for images has not been
+       disabled
      
+
+       
      
+
+        
      Apply the image
+        sniffing rules to determine the type of the image.
      
+
+        
      The object element represents the
+        specified image. The image is not a nested browsing
+        context.
      
+
+        
      If the image cannot be rendered, e.g. because it is
+        malformed or in an unsupported format, jump to the last step
+        in the overall set of steps (fallback).
      
+
+       
      
+
+
+       
      Otherwise
      
+
+       
      
+
+        
      The given resource type is not
+        supported. Jump to the last step in the overall set of steps
+        (fallback).
      
+
+        
      If the previous step ended with the resource type being unknown, this is the case
+        that is triggered.
      
+
+       
      
+
+      
      9. 
+
+     
    9. The element's contents are not part of what the
+     object element represents.
      
+
+     
    10. 
+
+      
      Once the resource is completely loaded, queue a
+      task to fire a simple event named load at the element.
      
+
+      
      The task source for this task is the DOM manipulation task
+      source.
      
+
+     
      11. 
+
+    
    5. 
+
+   
  5. If the data attribute
+   is absent but the type
+   attribute is present, plugins aren't
+   being sandboxed, and the user agent can find a
+   plugin suitable according to the value of the type attribute, then that
+   plugin should be used. If
+   no suitable plugin can be found, or if the
+   plugin reports an error, jump to the next step
+   (fallback).
    6. 
+
+   
  6. (Fallback.) The object element
+   represents the element's children, ignoring any
+   leading param element children. This is the element's
+   fallback content. If the element has an instantiated
+   plugin, then unload it.
    7. 
+
+  
When the algorithm above instantiates a
+  plugin, the user agent should pass to the
+  plugin used the names and values of all the attributes
+  on the element, in the order they were added to the element, with
+  the attributes added by the parser being ordered in source order,
+  followed by a parameter named "PARAM" whose value is null,
+  followed by all the names and values of parameters given by
+  param elements that are children of the
+  object element, in tree order. If the
+  plugin supports a scriptable interface, the
+  HTMLObjectElement object representing the element
+  should expose that interface. The object element
+  represents the plugin. The
+  plugin is not a nested browsing
+  context.

+
+  
If either:

+
+  
...then the steps above must always act as if they had failed to
+  find a plugin, even if one would otherwise have been
+  used.

+
+  
The above algorithm is independent of CSS properties
+  (including 'display', 'overflow', and 'visibility'). For example, it
+  runs even if the element is hidden with a 'display:none' CSS style,
+  and does not run again if the element's visibility
+  changes.

+
+  
Due to the algorithm above, the contents of object
+  elements act as fallback content, used only when
+  referenced resources can't be shown (e.g. because it returned a 404
+  error). This allows multiple object elements to be
+  nested inside each other, targeting multiple user agents with
+  different capabilities, with the user agent picking the first one it
+  supports.

+
+  
Whenever the name attribute
+  is set, if the object element has a nested
+  browsing context, its name must be changed to the new value. If the attribute
+  is removed, if the object element has a browsing
+  context, the browsing context name must be set
+  to the empty string.

+
+  

+
+  
The usemap attribute,
+  if present while the object element represents an
+  image, can indicate that the object has an associated image
+  map. The attribute must be ignored if the
+  object element doesn't represent an image.

+
+  
The form attribute is used to
+  explicitly associate the object element with its
+  form owner.

+
+  

+
+  
Constraint validation: object
+  elements are always barred from constraint
+  validation.

+
+  

+
+  
The object element supports dimension
+  attributes.

+
+  

+
+  
The IDL attributes data, type, name, and useMap each must
+  reflect the respective content attributes of the same
+  name.

+
+  
The contentDocument
+  IDL attribute must return the Document object of the
+  active document of the object element's
+  nested browsing context, if it has one; otherwise, it
+  must return null.

+
+  
The contentWindow
+  IDL attribute must return the WindowProxy object of the
+  object element's nested browsing context,
+  if it has one; otherwise, it must return null.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  form IDL attribute is part of the
+  element's forms API.

+
+  

+
+  

+
+   
In the following example, a Java applet is embedded in a page
+   using the object element. (Generally speaking, it is
+   better to avoid using applets like these and instead use native
+   JavaScript and HTML to provide the functionality, since that way
+   the application will work on all Web browsers without requiring a
+   third-party plugin. Many devices, especially embedded devices, do
+   not support third-party technologies like Java.)

+
+   
<figure>
+ <object type="application/x-java-applet">
+  <param name="code" value="MyJavaClass">
+  <p>You do not have Java available, or it is disabled.</p>
+ </object>
+ <figcaption>My Java Clock</figcaption>
+</figure>

+
+  

+
+  

+
+   
In this example, an HTML page is embedded in another using the
+   object element.

+
+   
<figure>
+ <object data="clock.html"></object>
+ <figcaption>My HTML Clock</figcaption>
+</figure>

+
+  

+
+  

+
+   
The following example shows how a plugin can be used in HTML (in
+   this case the Flash plugin, to show a video file). Fallback is
+   provided for users who do not have Flash enabled, in this case
+   using the video element to show the video for those
+   using user agents that support video, and finally
+   providing a link to the video for those who have neither Flash nor
+   a video-capable browser.

+
+   
<p>Look at my video:
+ <object type="application/x-shockwave-flash">
+  <param name=movie value="http://video.example.com/library/watch.swf">
+  <param name=allowfullscreen value=true>
+  <param name=flashvars value="http://video.example.com/vids/315981">
+  <video controls src="http://video.example.com/vids/315981">
+   <a href="http://video.example.com/vids/315981">View video</a>.
+  </video>
+ </object>
+</p>

+
+  

+
+
+
+  
4.8.5 The param element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of an object element, before any flow content.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
name

+   
value

+   
DOM interface:

+   

+
interface HTMLParamElement : HTMLElement {
+           attribute DOMString name;
+           attribute DOMString value;
+};

+   

+  
The param element defines parameters for plugins
+  invoked by object elements. It does not represent anything on its own.

+
+  
The name
+  attribute gives the name of the parameter.

+
+  
The value
+  attribute gives the value of the parameter.

+
+  
Both attributes must be present. They may have any value.

+
+  

+
+  
If both attributes are present, and if the parent element of the
+  param is an object element, then the
+  element defines a parameter with the given
+  name/value pair.

+
+  
The IDL attributes name and value must both
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  

+
+   
The following example shows how the param element
+   can be used to pass a parameter to a plugin, in this case the O3D
+   plugin.

+
+   
<!DOCTYPE HTML>
+<html lang="en">
+ <head>
+  <title>O3D test page</title>
+ </head>
+ <body>
+  <p>
+   <object type="application/vnd.o3d.auto">
+    <param name="o3d_features" value="FloatingPointTextures">
+    This page requires the use of a proprietary technology. Since you
+    have not installed the software product required to view this
+    page, you should try visiting another site that instead uses open
+    vendor-neutral technologies.
+   </object>
+   <script src="o3dtest.js"></script>
+  </p>
+ </body>
+</html>

+
+  

+
+
+  
4.8.6 The video element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
If the element has a controls attribute: Interactive content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
If the element has a src attribute:
+
+ zero or more track elements, then
+
+ transparent, but with no media element descendants.

+   
If the element does not have a src attribute: one or more source elements, then
+
+ zero or more track elements, then
+
+ transparent, but with no media element descendants.

+   
Content attributes:

+   
Global attributes

+   
src

+   
poster

+   
preload

+   
autoplay

+   
loop

+   
controls

+   
width

+   
height

+   
DOM interface:

+   

+    
interface HTMLVideoElement : HTMLMediaElement {
+           attribute DOMString width;
+           attribute DOMString height;
+  readonly attribute unsigned long videoWidth;
+  readonly attribute unsigned long videoHeight;
+           attribute DOMString poster;
+};

+   

+  
A video element is used for playing videos or
+  movies.

+
+  
Content may be provided inside the video
+  element. User agents should not show this content
+  to the user; it is intended for older Web browsers which do
+  not support video, so that legacy video plugins can be
+  tried, or to show text to the users of these older browsers informing
+  them of how to access the video contents.

+
+  
In particular, this content is not intended to
+  address accessibility concerns. To make video content accessible to
+  the blind, deaf, and those with other physical or cognitive
+  disabilities, authors are expected to provide alternative media
+  streams and/or to embed accessibility aids (such as caption or
+  subtitle tracks, audio description tracks, or sign-language
+  overlays) into their media streams.

+
+  
The video element is a media element
+  whose media data is ostensibly video data, possibly
+  with associated audio data.

+
+  
The src, preload, autoplay, loop, and controls attributes are the attributes common to all media
+  elements.

+
+  
The poster
+  attribute gives the address of an image file that the user agent can
+  show while no video data is available. The attribute, if present,
+  must contain a valid non-empty URL potentially surrounded by
+  spaces. If the specified resource is to be
+  used, then, when the element is created or when the poster attribute is set, if its
+  value is not the empty string, its value must be resolved relative to the element, and
+  if that is successful, the resulting absolute URL must
+  be fetched, from the element's
+  Document's origin; this must delay
+  the load event of the element's document. The poster
+  frame is then the image obtained from that resource, if
+  any.
 
+
+  
The image given by the poster attribute, the poster
+  frame, is intended to be a representative frame of the video
+  (typically one of the first non-blank frames) that gives the user an
+  idea of what the video is like.

+
+  

+
+  
The poster IDL
+  attribute must reflect the poster content attribute.

+
+  
When no video data is available (the element's readyState attribute is either
+  HAVE_NOTHING, or HAVE_METADATA but no video
+  data has yet been obtained at all), the video element
+  represents either the poster frame, or
+  nothing.

+
+  
When a video element is paused and the current playback position is the first
+  frame of video, the element represents either the frame
+  of video corresponding to the current playback position or the poster
+  frame, at the discretion of the user agent.

+
+  
Notwithstanding the above, the poster frame should
+  be preferred over nothing, but the poster frame should
+  not be shown again after a frame of video has been shown.

+
+  
When a video element is paused at any other position, the
+  element represents the frame of video corresponding to
+  the current playback
+  position, or, if that is not yet available (e.g. because the
+  video is seeking or buffering), the last frame of the video to have
+  been rendered.

+
+  
When a video element is potentially
+  playing, it represents the frame of video at the
+  continuously increasing "current" position. When the current playback
+  position changes such that the last frame rendered is no
+  longer the frame corresponding to the current playback
+  position in the video, the new frame must be
+  rendered. Similarly, any audio associated with the video must, if
+  played, be played synchronized with the current playback
+  position, at the specified volume with the specified mute state.

+
+  
When a video element is neither potentially
+  playing nor paused
+  (e.g. when seeking or stalled), the element represents
+  the last frame of the video to have been rendered.

+
+  
Which frame in a video stream corresponds to a
+  particular playback position is defined by the video stream's
+  format.

+
+  
In addition to the above, the user agent may provide messages to
+  the user (such as "buffering", "no video loaded", "error", or more
+  detailed information) by overlaying text or icons on the video or
+  other areas of the element's playback area, or in another
+  appropriate manner.

+
+  
User agents that cannot render the video may instead make the
+  element represent a link to an
+  external video playback utility or to the video data itself.

+
+  

+
+  
video . videoWidth

+   
video . videoHeight

+
+   

+
+    
These attributes return the intrinsic dimensions of the video,
+    or zero if the dimensions are not known.

+
+   

+
+  

+
+  
The intrinsic
+  width and intrinsic height of the
+  media resource are the dimensions of the resource in
+  CSS pixels after taking into account the resource's dimensions,
+  aspect ratio, clean aperture, resolution, and so forth, as defined
+  for the format used by the resource. If an anamorphic format does
+  not define how to apply the aspect ratio to the video data's
+  dimensions to obtain the "correct" dimensions, then the user agent
+  must apply the ratio by increasing one dimension and leaving the
+  other unchanged.

+
+  
The videoWidth IDL
+  attribute must return the intrinsic width of the
+  video in CSS pixels. The videoHeight IDL
+  attribute must return the intrinsic height of
+  the video in CSS pixels. If the element's readyState attribute is HAVE_NOTHING, then the
+  attributes must return 0.

+
+  

+
+  
The video element supports dimension
+  attributes.

+
+  

+
+  
Video content should be rendered inside the element's playback
+  area such that the video content is shown centered in the playback
+  area at the largest possible size that fits completely within it,
+  with the video content's aspect ratio being preserved. Thus, if the
+  aspect ratio of the playback area does not match the aspect ratio of
+  the video, the video will be shown letterboxed or pillarboxed. Areas
+  of the element's playback area that do not contain the video
+  represent nothing.

+
+  
The intrinsic width of a video element's playback
+  area is the intrinsic
+  width of the video resource, if that is available; otherwise
+  it is the intrinsic width of the poster frame, if that
+  is available; otherwise it is 300 CSS pixels.

+
+  
The intrinsic height of a video element's playback
+  area is the intrinsic
+  height of the video resource, if that is available; otherwise
+  it is the intrinsic height of the poster frame, if that
+  is available; otherwise it is 150 CSS pixels.

+
+  
User agents should provide controls to enable or disable the
+  display of closed captions, audio description tracks, and other
+  additional data associated with the video stream, though such
+  features should, again, not interfere with the page's normal
+  rendering.

+
+  
User agents may allow users to view the video content in manners
+  more suitable to the user (e.g. full-screen or in an independent
+  resizable window). As for the other user interface features,
+  controls to enable this should not interfere with the page's normal
+  rendering unless the user agent is exposing a user interface. In such an
+  independent context, however, user agents may make full user
+  interfaces visible, with, e.g., play, pause, seeking, and volume
+  controls, even if the controls attribute is absent.

+
+  
User agents may allow video playback to affect system features
+  that could interfere with the user's experience; for example, user
+  agents could disable screensavers while video playback is in
+  progress.

+
+  
User agents should not provide a public API to
+  cause videos to be shown full-screen. A script, combined with a
+  carefully crafted video file, could trick the user into thinking a
+  system-modal dialog had been shown, and prompt the user for a
+  password. There is also the danger of "mere" annoyance, with pages
+  launching full-screen videos when links are clicked or pages
+  navigated. Instead, user-agent-specific interface features may be
+  provided to easily allow the user to obtain a full-screen playback
+  mode.

+
+  

+
+  

+
+   
This example shows how to detect when a video has failed to play
+   correctly:

+
+   
<script>
+ function failed(e) {
+   // video playback failed - show a message saying why
+   switch (e.target.error.code) {
+     case e.target.error.MEDIA_ERR_ABORTED:
+       alert('You aborted the video playback.');
+       break;
+     case e.target.error.MEDIA_ERR_NETWORK:
+       alert('A network error caused the video download to fail part-way.');
+       break;
+     case e.target.error.MEDIA_ERR_DECODE:
+       alert('The video playback was aborted due to a corruption problem or because the video used features your browser did not support.');
+       break;
+     case e.target.error.MEDIA_ERR_SRC_NOT_SUPPORTED:
+       alert('The video could not be loaded, either because the server or network failed or because the format is not supported.');
+       break;
+     default:
+       alert('An unknown error occurred.');
+       break;
+   }
+ }
+</script>
+<p><video src="tgif.vid" autoplay controls onerror="failed(event)"></video></p>
+<p><a href="tgif.vid">Download the video file</a>.</p>

+
+  

+
+
+
+
+  
+
+
+
+
+
+  
4.8.7 The audio element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
If the element has a controls attribute: Interactive content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
If the element has a src attribute: 
+
+zero or more track elements, then 
+
+transparent, but with no media element descendants.

+   
If the element does not have a src attribute: one or more source elements, then
+
+ zero or more track elements, then
+
+ transparent, but with no media element descendants.

+   
Content attributes:

+   
Global attributes

+   
src

+   
preload

+   
autoplay

+   
loop

+   
controls

+   
DOM interface:

+   

+    
[NamedConstructor=Audio(),
+ NamedConstructor=Audio(in DOMString src)]
+interface HTMLAudioElement : HTMLMediaElement {};

+   

+  
An audio element represents a sound or
+  audio stream.

+
+  
+
+  
Content may be provided inside the audio
+  element. User agents should not show this content
+  to the user; it is intended for older Web browsers which do
+  not support audio, so that legacy audio plugins can be
+  tried, or to show text to the users of these older browsers informing
+  them of how to access the audio contents.

+
+  
In particular, this content is not intended to
+  address accessibility concerns. To make audio content accessible to
+  the deaf or to those with other physical or cognitive disabilities,
+  authors are expected to provide alternative media streams and/or to
+  embed accessibility aids (such as transcriptions) into their media
+  streams.

+
+  
The audio element is a media element
+  whose media data is ostensibly audio data.

+
+  
The src, preload, autoplay, loop, and controls attributes are the attributes common to all media
+  elements.

+
+  

+
+  
When an audio element is potentially
+  playing, it must have its audio data played synchronized with
+  the current playback position, at the specified volume with the specified mute state.

+
+  
When an audio element is not potentially
+  playing, audio must not play for the element.

+
+  

+
+  
audio = new Audio( [ url ] )

+
+   

+
+    
Returns a new audio element, with the src attribute set to the value
+    passed in the argument, if applicable.

+
+   

+
+  

+
+  
Two constructors are provided for creating
+  HTMLAudioElement objects (in addition to the factory
+  methods from DOM Core such as createElement()): Audio() and Audio(src). When invoked as constructors,
+  these must return a new HTMLAudioElement object (a new
+  audio element). The element must have its preload attribute set to the
+  literal value "auto". If the src argument is present, the object created must have
+  its src content attribute set to
+  the provided value, and the user agent must invoke the object's
+  resource selection
+  algorithm before returning. The element's document must be
+  the active document of the browsing
+  context of the Window object on which the
+  interface object of the invoked constructor is found.

+
+  

+
+
+
+  
+
+
+
+  
4.8.8 The source element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a media element, before any flow content
+
+ or track elements.

+
+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
src

+   
type

+   
media

+   
DOM interface:

+   

+
interface HTMLSourceElement : HTMLElement {
+           attribute DOMString src;
+           attribute DOMString type;
+           attribute DOMString media;
+};

+   

+  
The source element allows authors to specify
+  multiple alternative media
+  resources for media
+  elements. It does not represent anything on its own.

+
+  
The src attribute
+  gives the address of the media resource. The value must
+  be a valid non-empty URL potentially surrounded by
+  spaces. This attribute must be present.

+
+  
The type
+  attribute gives the type of the media resource, to help
+  the user agent determine if it can play this media
+  resource before fetching it. If specified, its value must be
+  a valid MIME type. The codecs
+  parameter may be specified and might be necessary to specify exactly
+  how the resource is encoded. [RFC4281]

+
+  

+
+   
The following list shows some examples of how to use the codecs= MIME parameter in the type attribute.

+
+   
H.264 Simple baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>

+
+    
H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>

+
+    
H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>

+
+    
H.264 'High' profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>

+
+
+    
MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>

+
+    
MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container

+    
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>

+
+    
MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container

+    
<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>

+
+
+    
Theora video and Vorbis audio in Ogg container

+    
<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>

+
+    
Theora video and Speex audio in Ogg container

+    
<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>

+
+    
Vorbis audio alone in Ogg container

+    
<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>

+
+    
Speex audio alone in Ogg container

+    
<source src='audio.spx' type='audio/ogg; codecs=speex'>

+
+    
FLAC audio alone in Ogg container

+    
<source src='audio.oga' type='audio/ogg; codecs=flac'>

+
+    
Dirac video and Vorbis audio in Ogg container

+    
<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>

+
+    
Theora video and Vorbis audio in Matroska container

+    
<source src='video.mkv' type='video/x-matroska; codecs="theora, vorbis"'>

+
+
+
+
+
+
+
+
+
+
+
+
+   

+
+  
The media
+  attribute gives the intended media type of the media
+  resource, to help the user agent determine if this
+  media resource is useful to the user before fetching
+  it. Its value must be a valid media query.

+
+  
The default, if the media attribute is omitted, is
+  "all", meaning that by default the media
+  resource is suitable for all media.

+
+  

+
+  
If a source element is inserted as a child of a
+  media element that has no src attribute and whose networkState has the value
+  NETWORK_EMPTY, the user
+  agent must invoke the media element's resource selection
+  algorithm.

+
+  
The IDL attributes src, type, and media must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  

+
+   
If the author isn't sure if the user agents will all be able to
+   render the media resources provided, the author can listen to the
+   error event on the last
+   source element and trigger fallback behavior:

+
+   
<script>
+ function fallback(video) {
+   // replace <video> with its contents
+   while (video.hasChildNodes()) {
+     if (video.firstChild instanceof HTMLSourceElement)
+       video.removeChild(video.firstChild);
+     else
+       video.parentNode.insertBefore(video.firstChild, video);
+   }
+   video.parentNode.removeChild(video);
+ }
+</script>
+<video controls autoplay>
+ <source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
+ <source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'
+         onerror="fallback(parentNode)">
+ ...
+</video>

+
+  

+
+
+
+
+
+  
4.8.9 The track element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a media element, before any flow content.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
kind

+   
label

+   
src

+   
srclang

+   
DOM interface:

+   

+
interface HTMLTrackElement : HTMLElement {
+           attribute DOMString kind;
+           attribute DOMString label;
+           attribute DOMString src;
+           attribute DOMString srclang;
+
+  readonly attribute TimedTrack track;
+};

+   

+  
The track element allows authors to specify explicit
+  external timed tracks for media elements. It does not represent anything on its own.

+
+  
The kind
+  attribute is an enumerated attribute. The following
+  table lists the keywords defined for this attribute. The keyword
+  given in the first cell of each row maps to the state given in the
+  second cell.

+
+  
Keywords
+     State
+     Brief description
+   
subtitles
+     Subtitles
+     Translation of the dialogue, suitable for when the sound is available but not understood (e.g. because the user does not understand the language of the media resource's soundtrack).
+    
captions
+     Captions
+     Transcription of the dialogue, suitable for when the soundtrack is unavailable (e.g. because it is muted or because the user is deaf). 
+    
descriptions
+     Descriptions
+     Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is unavailable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind).
+    
chapters
+     Chapters
+     Chapter titles, intended to be used for navigating the media resource.
+    
metadata
+     Metadata
+     Tracks intended for use from script.
+  
The attribute may be omitted. The missing value default is
+  the captions state.

+
+  
The src attribute
+  gives the address of the time track data. The value must be a
+  valid non-empty URL potentially surrounded by
+  spaces. This attribute must be present.

+
+  

+
+  
If the element has a src
+  attribute whose value is not the empty string and whose value, when
+  the attribute was set, could be successfully resolved relative to the element, then the element's
+  track URL is the resulting absolute
+  URL. Otherwise, the element's track URL is the
+  empty string.

+
+  

+
+  
The srclang
+  attribute gives the language of the time track data. The value must
+  be a valid BCP 47 language tag. This attribute must be present if
+  the element's kind attribute is
+  in the subtitles
+  state. [BCP47]

+
+  

+
+  
If the element has a srclang attribute whose value is
+  not the empty string, then the element's track language
+  is the value of the attribute. Otherwise, the element has no
+  track language.

+
+  

+
+  
The label
+  attribute gives a user-readable title for the track.

+
+  
The value of the label
+  attribute, if the attribute is present, must not be the empty
+  string. Furthermore, there must not be two track
+  element children of the same media element whose kind attributes are in the same
+  state, whose srclang
+  attributes are both missing or have values that represent the same
+  language, and whose label
+  attributes are again both missing or both have the same value.

+
+  

+
+  
If the element has a label
+  attribute whose value is not the empty string, then the element's
+  track label is the value of the attribute. Otherwise, the
+  element's track label is a user-agent defined string
+  (e.g. the string "untitled" in the user's locale, or a value
+  automatically generated from the other attributes).

+
+  

+
+  
track . track

+
+   

+
+    
Returns the TimedTrack object corresponding to the timed track of the track element.

+
+   

+
+  

+
+  
The track IDL
+  attribute must, on getting, return the track element's
+  timed track's corresponding TimedTrack
+  object.

+
+  
The IDL attributes kind, label, src, and srclang must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+
+
+
+  
4.8.10 Media elements

+
+  
Media elements implement the
+  following interface:

+
+  
interface HTMLMediaElement : HTMLElement {
+
+  // error state
+  readonly attribute MediaError error;
+
+  // network state
+           attribute DOMString src;
+  readonly attribute DOMString currentSrc;
+  const unsigned short NETWORK_EMPTY = 0;
+  const unsigned short NETWORK_IDLE = 1;
+  const unsigned short NETWORK_LOADING = 2;
+  const unsigned short NETWORK_NO_SOURCE = 3;
+  readonly attribute unsigned short networkState;
+           attribute DOMString preload;
+  readonly attribute TimeRanges buffered;
+  void load();
+  DOMString canPlayType(in DOMString type);
+
+  // ready state
+  const unsigned short HAVE_NOTHING = 0;
+  const unsigned short HAVE_METADATA = 1;
+  const unsigned short HAVE_CURRENT_DATA = 2;
+  const unsigned short HAVE_FUTURE_DATA = 3;
+  const unsigned short HAVE_ENOUGH_DATA = 4;
+  readonly attribute unsigned short readyState;
+  readonly attribute boolean seeking;
+
+  // playback state
+           attribute float currentTime;
+  readonly attribute float startTime;
+  readonly attribute float duration;
+  readonly attribute boolean paused;
+           attribute float defaultPlaybackRate;
+           attribute float playbackRate;
+  readonly attribute TimeRanges played;
+  readonly attribute TimeRanges seekable;
+  readonly attribute boolean ended;
+           attribute boolean autoplay;
+           attribute boolean loop;
+  void play();
+  void pause();
+
+  // controls
+           attribute boolean controls;
+           attribute float volume;
+           attribute boolean muted;
+
+  // timed tracks
+  readonly attribute TimedTrack[] tracks;
+  MutableTimedTrack addTrack(in DOMString label, in DOMString kind, in DOMString language);
+
+};

+
+  
The media element attributes, src, preload, autoplay, loop, and controls, apply to all media elements. They are defined in
+  this section.

+
+  
+
+  
+
+  
Media elements are used to
+  present audio data, or video and audio data, to the user. This is
+  referred to as media data in this section, since this
+  section applies equally to media
+  elements for audio or for video. The term media
+  resource is used to refer to the complete set of media data,
+  e.g. the complete video file, or complete audio file.

+
+  

+
+  
Except where otherwise specified, the task source
+  for all the tasks queued in this
+  section and its subsections is the media element event task
+  source.

+
+  

+
+
+
+  
4.8.10.1 Error codes

+
+  
media . error

+
+   

+
+    
Returns a MediaError object representing the
+    current error state of the element.

+
+    
Returns null if there is no error.

+
+   

+
+  

+
+  
All media elements have an
+  associated error status, which records the last error the element
+  encountered since its resource selection
+  algorithm was last invoked. The error attribute, on
+  getting, must return the MediaError object created for
+  this last error, or null if there has not been an error.

+
+  

+
+  
interface MediaError {
+  const unsigned short MEDIA_ERR_ABORTED = 1;
+  const unsigned short MEDIA_ERR_NETWORK = 2;
+  const unsigned short MEDIA_ERR_DECODE = 3;
+  const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
+  readonly attribute unsigned short code;
+};

+
+  
media . error . code

+
+   

+
+    
Returns the current error's error code, from the list below.

+
+   

+
+  

+
+  
The code
+  attribute of a MediaError object must return the code
+  for the error, which must be one of the following:

+
+  

+
+  
MEDIA_ERR_ABORTED (numeric value 1)

+
+   
The fetching process for the media resource was
+   aborted by the user agent at the user's request.

+
+   
MEDIA_ERR_NETWORK (numeric value 2)

+
+   
A network error of some description caused the user agent to
+   stop fetching the media resource, after the resource
+   was established to be usable.

+
+   
MEDIA_ERR_DECODE (numeric value 3)

+
+   
An error of some description occurred while decoding the
+   media resource, after the resource was established to
+   be usable.

+
+   
MEDIA_ERR_SRC_NOT_SUPPORTED (numeric value 4)

+
+   
The media resource indicated by the src attribute was not suitable.

+
+  
4.8.10.2 Location of the media resource

+
+  
The src content
+  attribute on media elements gives
+  the address of the media resource (video, audio) to show. The
+  attribute, if present, must contain a valid non-empty
+  URL potentially surrounded by spaces.

+
+  

+
+  
If a src attribute of a
+  media element is set or changed, the user agent must
+  invoke the media element's media element load
+  algorithm. (Removing the src attribute does not do this, even
+  if there are source elements present.)

+
+  
The src IDL
+  attribute on media elements must
+  reflect the content attribute of the same name.

+
+  

+
+  
media . currentSrc

+
+   

+
+    
Returns the address of the current media resource.

+
+    
Returns the empty string when there is no media resource.

+
+   

+
+  

+
+  
The currentSrc IDL
+  attribute is initially the empty string. Its value is changed by the
+  resource selection
+  algorithm defined below.

+
+  

+
+  
There are two ways to specify a media
+  resource, the src
+  attribute, or source elements. The attribute overrides
+  the elements.

+
+
+
+  
4.8.10.3 MIME types

+
+  
A media resource can be described in terms of its
+  type, specifically a MIME type, optionally
+  with a codecs parameter. [RFC4281]

+
+  
Types are usually somewhat incomplete descriptions; for example
+  "video/mpeg" doesn't say anything except what
+  the container type is, and even a type like "video/mp4; codecs="avc1.42E01E,
+  mp4a.40.2"" doesn't include information like the actual
+  bitrate (only the maximum bitrate). Thus, given a type, a user agent
+  can often only know whether it might be able to play
+  media of that type (with varying levels of confidence), or whether
+  it definitely cannot play media of that type.

+
+  
A type that the user agent knows it cannot render is
+  one that describes a resource that the user agent definitely does
+  not support, for example because it doesn't recognize the container
+  type, or it doesn't support the listed codecs.

+
+  
The MIME type "application/octet-stream" with no parameters is
+  never a type that the user agent knows it cannot
+  render. User agents must treat that type as equivalent to the
+  lack of any explicit Content-Type
+  metadata when it is used to label a potential media
+  resource.

+
+  
In the absence of a 
+  specification to the contrary, the MIME type "application/octet-stream" when used with
+  parameters, e.g. "application/octet-stream;codecs=theora", is
+  a type that the user agent knows it cannot render.

+
+  
media . canPlayType(type)

+
+   

+
+    
Returns the empty string (a negative response), "maybe", or
+    "probably" based on how confident the user agent is that it can
+    play media resources of the given type.

+
+   

+
+  

+
+  
The canPlayType(type) method must return the empty
+  string if type is a type that the user
+  agent knows it cannot render; it must return "probably" if the user agent is confident that the
+  type represents a media resource that it can render if
+  used in with this audio or video element;
+  and it must return "maybe"
+  otherwise. Implementors are encouraged to return "maybe" unless the type can be confidently
+  established as being supported or not. Generally, a user agent
+  should never return "probably" if the type
+  doesn't have a codecs parameter.

+
+  

+
+  

+
+   
This script tests to see if the user agent supports a
+   (fictional) new format to dynamically decide whether to use a
+   video element or a plugin:

+
+   
<section id="video">
+ <p><a href="playing-cats.nfv">Download video</a></p>
+</section>
+<script>
+ var videoSection = document.getElementById('video');
+ var videoElement = document.createElement('video');
+ var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"');
+ if (support != "probably" && "New Fictional Video Plug-in" in navigator.plugins) {
+   // not confident of browser support
+   // but we have a plugin
+   // so use plugin instead
+   videoElement = document.createElement("embed");
+ } else if (support == "") {
+   // no support from browser and no plugin
+   // do nothing
+   videoElement = null;
+ }
+ if (videoElement) {
+   while (videoSection.hasChildNodes())
+     videoSection.removeChild(videoSection.firstChild);
+   videoElement.setAttribute("src", "playing-cats.nfv");
+   videoSection.appendChild(videoElement);
+ }
+</script>

+
+  

+
+  
The type
+  attribute of the source element allows the user agent
+  to avoid downloading resources that use formats it cannot
+  render.

+
+
+  
4.8.10.4 Network states

+
+  
media . networkState

+
+   

+
+    
Returns the current state of network activity for the element,
+    from the codes in the list below.

+
+   

+
+  

+
+  
As media elements interact
+  with the network, their current network activity is represented by
+  the networkState
+  attribute. On getting, it must return the current network state of
+  the element, which must be one of the following values:

+
+  

+
+  
NETWORK_EMPTY (numeric value 0)

+
+   
The element has not yet been initialized. All attributes are in
+   their initial states.

+
+   
NETWORK_IDLE (numeric value 1)

+
+   
The element's resource selection
+   algorithm is active and has selected a resource, but it is not actually
+   using the network at this time.

+
+   
NETWORK_LOADING (numeric value 2)

+
+   
The user agent is actively trying to download data.

+
+   
NETWORK_NO_SOURCE (numeric value 3)

+
+   
The element's resource selection
+   algorithm is active, but it has failed to find a
+   resource to use.

+
+  

+
+  
The resource selection
+  algorithm defined below describes exactly when the networkState attribute changes
+  value and what events fire to indicate changes in this state.

+
+  

+
+
+
+
+  
4.8.10.5 Loading the media resource

+
+  
media . load()

+
+   

+
+    
Causes the element to reset and start selecting and loading a
+    new media resource from scratch.

+
+   

+
+  

+
+  
All media elements have an
+  autoplaying flag, which must begin in the true state, and
+  a delaying-the-load-event flag, which must begin in the
+  false state. While the delaying-the-load-event flag is
+  true, the element must delay the load event of its
+  document.

+
+  
When the load()
+  method on a media element is invoked, the user agent
+  must run the media element load algorithm.

+
+  
The media element load algorithm consists of the
+  following steps.

+
+  
  1. Abort any already-running instance of the resource selection
+   algorithm for this element.
    2. 
+
+   
  2. 
+
+    
    If there are any tasks from
+    the media element's media element event task
+    source in one of the task
+    queues, then remove those tasks.
    
+
+    
    Basically, pending events and callbacks for the
+    media element are discarded when the media element starts loading
+    a new resource.
    
+
+   
    3. 
+
+   
  3. If the media element's networkState is set to NETWORK_LOADING or NETWORK_IDLE, queue a
+   task to fire a simple event named abort at the media
+   element.
    4. 
+
+   
  4. 
+
+    
    If the media element's networkState is not set to
+    NETWORK_EMPTY, then
+    run these substeps:
    
+
+    
    1. If a fetching process is in progress for the media
+     element, the user agent should stop it.
      2. 
+
+     
    2. Set the networkState attribute to
+     NETWORK_EMPTY.
      3. 
+
+
+     
    3. Forget the media element's media-resource-specific
+     timed tracks.
      4. 
+
+
+     
    4. If readyState is
+     not set to HAVE_NOTHING, then set it
+     to that state.
      5. 
+
+     
    5. If the paused
+     attribute is false, then set to true.
      6. 
+
+     
    6. If seeking is true,
+     set it to false.
      7. 
+
+     
    7. Set the current playback position to
+     0.
      8. 
+
+     
    8. Queue a task to fire a simple
+     event named emptied at the media
+     element.
      9. 
+
+    
    5. 
+
+   
  5. Set the playbackRate attribute to the
+   value of the defaultPlaybackRate
+   attribute.
    6. 
+
+   
  6. Set the error attribute
+   to null and the autoplaying flag to true.
    7. 
+
+   
  7. Invoke the media element's resource selection
+   algorithm.
    8. 
+
+   
  8. 
+
+    
    Playback of any previously playing media
+    resource for this element stops.
    
+
+   
    9. 
+
+  
The resource selection
+  algorithm for a media element is as follows. This
+  algorithm is always invoked synchronously, but one of the first
+  steps in the algorithm is to return and continue running the
+  remaining steps asynchronously, meaning that it runs in the
+  background with scripts and other tasks running in parallel. In addition,
+  this algorithm interacts closely with the event loop
+  mechanism; in particular, it has synchronous sections (which are triggered as part of
+  the event loop algorithm). Steps in such sections are
+  marked with ⌛.

+
+  
  1. Set the networkState to NETWORK_NO_SOURCE.
    2. 
+
+   
  2. Asynchronously await a stable state, allowing
+   the task that invoked this
+   algorithm to continue. The synchronous section
+   consists of all the remaining steps of this algorithm until the
+   algorithm says the synchronous section has
+   ended. (Steps in synchronous
+   sections are marked with ⌛.)
    3. 
+
+   
  3. 
+
+    
    ⌛ If the media element has a src attribute, then let mode be attribute.
    
+
+    
    ⌛ Otherwise, if the media element does not
+    have a src attribute but has a
+    source element child, then let mode be children and let candidate be the first such source
+    element child in tree order.
    
+
+    
    ⌛ Otherwise the media element has neither a
+    src attribute nor a
+    source element child: set the networkState to NETWORK_EMPTY, and abort
+    these steps; the synchronous section ends.
    
+
+   
    4. 
+
+   
  4. ⌛ Set the media element's
+   delaying-the-load-event flag to true (this delays the load event), and set
+   its networkState to
+   NETWORK_LOADING.
    5. 
+
+   
  5. ⌛ Queue a task to fire a simple
+   event named loadstart at the media
+   element.
    6. 
+
+   
  6. 
+
+    
    If mode is attribute, then
+    run these substeps:
    
+
+    
    1. ⌛ Process candidate: If the src attribute's value is the empty
+     string, then end the synchronous section, and jump
+     down to the failed step below.
      2. 
+
+     
    2. ⌛ Let absolute URL be the
+     absolute URL that would have resulted from resolving the URL
+     specified by the src
+     attribute's value relative to the media element when
+     the src attribute was last
+     changed.
       
+
+     
    3. ⌛ If absolute URL was obtained
+     successfully, set the currentSrc attribute to absolute URL.
      4. 
+
+     
    4. End the synchronous section, continuing the
+     remaining steps asynchronously.
      5. 
+
+     
    5. If absolute URL was obtained
+     successfully, run the resource fetch
+     algorithm with absolute URL. If that
+     algorithm returns without aborting this one, then the
+     load failed.
      6. 
+
+     
    6. 
+
+      
      Failed: Reaching this step indicates that the media
+      resource failed to load or that the given URL could
+      not be resolved. In one
+      atomic operation, run the following steps:
      
+
+      
      1. Set the error
+       attribute to a new MediaError object whose code attribute is set to
+       MEDIA_ERR_SRC_NOT_SUPPORTED.
        2. 
+
+
+       
      2. Forget the media element's media-resource-specific
+       timed tracks.
        3. 
+
+
+       
      3. Set the element's networkState attribute to
+       the NETWORK_NO_SOURCE
+       value.
        4. 
+
+      
      7. 
+
+     
    7. Queue a task to fire a simple
+     event named error
+     at the media element.
      8. 
+
+     
    8. Set the element's delaying-the-load-event flag
+     to false. This stops delaying
+     the load event.
      9. 
+
+     
    9. Abort these steps. Until the load() method is invoked or the
+     src attribute is changed, the
+     element won't attempt to load another resource.
      10. 
+     
+
+    
    Otherwise, the source elements will be used; run
+    these substeps:
    
+
+    
    1. 
+
+      
      ⌛ Let pointer be a position
+      defined by two adjacent nodes in the media
+      element's child list, treating the start of the list
+      (before the first child in the list, if any) and end of the list
+      (after the last child in the list, if any) as nodes in their own
+      right. One node is the node before pointer,
+      and the other node is the node after pointer. Initially, let pointer be the position between the candidate node and the next node, if there are
+      any, or the end of the list, if it is the last node.
      
+
+      
      As nodes are inserted and removed into the media
+      element, pointer must be updated as
+      follows:
      
+
+      
      If a new node is inserted between the two nodes that
+       define pointer
      
+
+       
      Let pointer be the point between the
+       node before pointer and the new node. In
+       other words, insertions at pointer go after
+       pointer.
      
+
+       
      If the node before pointer is removed
      
+
+       
      Let pointer be the point between the
+       node after pointer and the node before the
+       node after pointer. In other words, pointer doesn't move relative to the remaining
+       nodes.
      
+
+       
      If the node after pointer is removed
      
+
+       
      Let pointer be the point between the
+       node before pointer and the node after the
+       node before pointer. Just as with the
+       previous case, pointer doesn't move
+       relative to the remaining nodes.
      
+
+      
      Other changes don't affect pointer.
      
+
+     
      2. 
+
+     
    2. ⌛ Process candidate: If candidate does not have a src attribute, or if its src attribute's value is the empty
+     string, then end the synchronous section, and jump
+     down to the failed step below.
      3. 
+
+     
    3. ⌛ Let absolute URL be the
+     absolute URL that would have resulted from resolving the URL
+     specified by candidate's src attribute's value relative to
+     the candidate when the src attribute was last
+     changed.
       
+
+     
    4. ⌛ If absolute URL was not
+     obtained successfully, then end the synchronous
+     section, and jump down to the failed step
+     below.
      5. 
+
+     
    5. ⌛ If candidate has a type attribute whose value, when
+     parsed as a MIME type (including any codecs
+     described by the codecs parameter),
+     represents a type that the user agent knows it cannot
+     render, then end the synchronous section, and
+     jump down to the failed step below.
      6. 
+
+     
    6. ⌛ If candidate has a media attribute whose value does
+     not match the
+     environment, then end the synchronous
+     section, and jump down to the failed step
+     below.
      7. 
+
+     
    7. ⌛ Set the currentSrc attribute to absolute URL.
      8. 
+
+     
    8. End the synchronous section, continuing the
+     remaining steps asynchronously.
      9. 
+
+     
    9. Run the resource
+     fetch algorithm with absolute URL. If
+     that algorithm returns without aborting this one, then
+     the load failed.
      10. 
+
+     
    10. Failed: Queue a task to
+     fire a simple event named error at the candidate element, in the context of the fetching process that was used to try to
+     obtain candidate's corresponding media
+     resource in the resource fetch
+     algorithm.
      11. 
+
+     
    11. Asynchronously await a stable state. The
+     synchronous section consists of all the remaining
+     steps of this algorithm until the algorithm says the
+     synchronous section has ended. (Steps in synchronous sections are
+     marked with ⌛.)
      12. 
+
+
+     
    12. ⌛ Forget the media element's
+     media-resource-specific timed tracks.
      13. 
+
+
+     
    13. ⌛ Find next candidate: Let candidate be null.
      14. 
+
+     
    14. ⌛ Search loop: If the node after
+     pointer is the end of the list, then jump to
+     the waiting step below.
      15. 
+
+     
    15. ⌛ If the node after pointer is
+     a source element, let candidate
+     be that element.
      16. 
+
+     
    16. ⌛ Advance pointer so that the
+     node before pointer is now the node that was
+     after pointer, and the node after pointer is the node after the node that used to be
+     after pointer, if any.
      17. 
+
+     
    17. ⌛ If candidate is null, jump
+     back to the search loop step. Otherwise, jump
+     back to the process candidate step.
      18. 
+
+     
    18. ⌛ Waiting: Set the element's networkState attribute to
+     the NETWORK_NO_SOURCE
+     value.
      19. 
+
+     
    19. ⌛ Set the element's delaying-the-load-event
+     flag to false. This stops delaying the load event.
      20. 
+
+     
    20. End the synchronous section, continuing the
+     remaining steps asynchronously.
      21. 
+
+     
    21. Wait until the node after pointer is a
+     node other than the end of the list. (This step might wait
+     forever.)
      22. 
+
+     
    22. Asynchronously await a stable state. The
+     synchronous section consists of all the remaining
+     steps of this algorithm until the algorithm says the
+     synchronous section has ended. (Steps in synchronous sections are
+     marked with ⌛.)
      23. 
+
+     
    23. ⌛ Set the element's delaying-the-load-event
+     flag back to true (this delays the load event again, in case it hasn't been
+     fired yet).
      
+
+     
    24. ⌛ Set the networkState back to NETWORK_LOADING.
      25. 
+
+     
    25. ⌛ Jump back to the find next
+     candidate step above.
      26. 
+
+    
    7. 
+
+  
The resource fetch
+  algorithm for a media element and a given
+  absolute URL is as follows:

+
+  
  1. Let the current media resource be the
+   resource given by the absolute URL passed to this
+   algorithm. This is now the element's media
+   resource.
    2. 
+
+   
  2. 
+
+    
    Begin to fetch the current media
+    resource, from the media element's
+    Document's origin.
     
+
+    
    Every 350ms (±200ms) or for every byte received, whichever
+    is least frequent, queue a task to
+    fire a simple event named progress at the element.
    
+
+    
    If at any point the user agent has received no data for more
+    than about three seconds, then queue a task to
+    fire a simple event named stalled at the element.
    
+
+    
    User agents may allow users to selectively block or slow
+    media data downloads. When a media
+    element's download has been blocked altogether, the user
+    agent must act as if it was stalled (as opposed to acting as if
+    the connection was closed). The rate of the download may also be
+    throttled automatically by the user agent, e.g. to balance the
+    download with other connections sharing the same bandwidth.
    
+
+    
    User agents may decide to not download more content at any
+    time, e.g. after buffering five minutes of a one hour media
+    resource, while waiting for the user to decide whether to play the
+    resource or not, or while waiting for user input in an interactive
+    resource. When a media element's download has been
+    suspended, the user agent must set the networkState to NETWORK_IDLE and queue
+    a task to fire a simple event named suspend at the element. If and
+    when downloading of the resource resumes, the user agent must set
+    the networkState to
+    NETWORK_LOADING.
    
+
+    
    The preload attribute provides a
+    hint regarding how much buffering the author thinks is advisable,
+    even in the absence of the autoplay attribute.
    
+
+    
    When a user agent decides to completely stall a download,
+    e.g. if it is waiting until the user starts playback before
+    downloading any further content, the element's
+    delaying-the-load-event flag must be set to
+    false. This stops delaying the
+    load event.
    
+
+    
    The user agent may use whatever means necessary to fetch the
+    resource (within the constraints put forward by this and other
+    specifications); for example, reconnecting to the server in the
+    face of network errors, using HTTP range retrieval requests, or
+    switching to a streaming protocol. The user agent must consider a
+    resource erroneous only if it has given up trying to fetch it.
    
+
+    
    The networking task source tasks to process the data as it is
+    being fetched must, when appropriate, include the relevant
+    substeps from the following list:
    
+
+    
    If the media data cannot be fetched at all, due
+     to network errors, causing the user agent to give up trying to
+     fetch the resource
    
+
+     
    If the media resource is found to have Content-Type metadata that, when
+     parsed as a MIME type (including any codecs
+     described by the codecs parameter),
+     represents a type that the user agent knows it cannot
+     render (even if the actual media data is in a
+     supported format)
    
+
+     
    If the media data can be fetched but is found by
+     inspection to be in an unsupported format, or can otherwise not
+     be rendered at all
    
+
+     
    
+
+      
    DNS errors, HTTP 4xx and 5xx errors (and equivalents in
+      other protocols), and other fatal network errors that occur
+      before the user agent has established whether the current media resource is usable, as well as
+      the file using an unsupported container format, or using
+      unsupported codecs for all the data, must cause the user agent
+      to execute the following steps:
    
+
+      
    1. The user agent should cancel the fetching
+       process.
      2. 
+
+       
    2. Abort this subalgorithm, returning to the resource selection
+       algorithm.
      
+
+      
    
+
+
+     
+     
+
+
+     
    Once enough of the media
+     data has been fetched to determine the duration of the
+     media resource, its dimensions, and other
+     metadata,
+
+     and once the timed tracks are ready
+
+     
    
+
+     
    
+
+      
    This indicates that the resource is usable. The user agent
+      must follow these substeps:
    
+
+      
    1. Set the current playback position to the
+       earliest possible position.
      2. 
+
+       
    2. Set the readyState attribute to
+       HAVE_METADATA.
      3. 
+
+       
    3. For video elements, set the videoWidth and videoHeight
+       attributes.
      4. 
+
+       
    4. 
+
+        
      Set the duration
+        attribute to the duration of the resource.
      
+
+        
      The user agent will queue a task to
+        fire a simple event named durationchange at the
+        element at this point.
      
+
+       
      5. 
+
+       
    5. 
+
+        
      Queue a task to fire a simple
+        event named loadedmetadata at the
+        element.
      
+
+        
      Before this task is run, as part of the event
+        loop mechanism, the rendering will have been updated to resize
+        the video element if appropriate.
      
+
+       
      6. 
+
+       
    6. 
+
+        
      If either the media resource or the address
+        of the current media resource indicate a
+        particular start time, then seek to that time. Ignore any
+        resulting exceptions (if the position is out of range, it is
+        effectively ignored).
      
+
+        
      For example, a fragment identifier could be
+        used to indicate a start position.
      
+
+       
      7. 
+
+       
    7. 
+
+        
      Once the readyState attribute
+        reaches HAVE_CURRENT_DATA,
+        after the loadeddata event has been
+        fired, set the element's delaying-the-load-event
+        flag to false. This stops delaying the load event.
      
+
+        
      A user agent that is attempting to reduce
+        network usage while still fetching the metadata for each
+        media resource would also stop buffering at this
+        point, causing the networkState attribute
+        to switch to the NETWORK_IDLE value.
      
+
+       
      8. 
+
+      
    The user agent is required to
+      determine the duration of the media resource and
+      go through this step before playing.
     
+
+     
    
+
+
+     
    Once the entire media resource has been fetched (but potentially before any of it
+     has been decoded)
    
+
+     
    
+
+      
    Queue a task to fire a simple event
+      named progress at the
+      media element.
    
+
+     
    
+
+
+     
    If the connection is interrupted, causing the user agent to
+     give up trying to fetch the resource
    
+
+     
    
+
+      
    Fatal network errors that occur after the user agent has
+      established whether the current media
+      resource is usable must cause the user agent to execute
+      the following steps:
    
+
+      
    1. The user agent should cancel the fetching
+       process.
      2. 
+
+       
    2. Set the error
+       attribute to a new MediaError object whose code attribute is set to
+       MEDIA_ERR_NETWORK.
      3. 
+
+       
    3. Queue a task to fire a simple
+       event named error
+       at the media element.
      4. 
+
+       
    4. Set the element's networkState attribute to
+       the NETWORK_EMPTY
+       value and queue a task to fire a simple
+       event named emptied at the
+       element.
      5.  
+
+       
    5. Set the element's delaying-the-load-event
+       flag to false. This stops delaying the load event.
      6. 
+
+       
    6. Abort the overall resource selection
+       algorithm.
      7. 
+
+      
    
+
+
+     
    If the media data is
+     corrupted
    
+
+     
    
+
+      
    Fatal errors in decoding the media data that
+      occur after the user agent has established whether the current media resource is usable must cause the
+      user agent to execute the following steps:
    
+
+      
    1. The user agent should cancel the fetching
+       process.
      2. 
+
+       
    2. Set the error
+       attribute to a new MediaError object whose code attribute is set to
+       MEDIA_ERR_DECODE.
      3. 
+
+       
    3. Queue a task to fire a simple
+       event named error
+       at the media element.
      4. 
+
+       
    4. Set the element's networkState attribute to
+       the NETWORK_EMPTY
+       value and queue a task to fire a simple
+       event named emptied at the
+       element.
      5.  
+
+       
    5. Set the element's delaying-the-load-event
+       flag to false. This stops delaying the load event.
      6. 
+
+       
    6. Abort the overall resource selection
+       algorithm.
      7. 
+
+      
    
+
+
+     
    If the media data fetching process is aborted by
+     the user
    
+
+     
    
+
+      
    The fetching process is aborted by the user, e.g. because the
+      user navigated the browsing context to another page, the user
+      agent must execute the following steps. These steps are not
+      followed if the load()
+      method itself is invoked while these steps are running, as the
+      steps above handle that particular kind of abort.
    
+
+      
    1. The user agent should cancel the fetching
+       process.
      2. 
+
+       
    2. Set the error
+       attribute to a new MediaError object whose code attribute is set to
+       MEDIA_ERR_ABORTED.
      3. 
+
+       
    3. Queue a task to fire a simple
+       event named abort
+       at the media element.
      4. 
+
+       
    4. If the media element's readyState attribute has a
+       value equal to HAVE_NOTHING, set the
+       element's networkState attribute to
+       the NETWORK_EMPTY
+       value and queue a task to fire a simple
+       event named emptied
+       at the element. Otherwise, set the element's networkState attribute to
+       the NETWORK_IDLE
+       value.
      5. 
+
+       
    5. Set the element's delaying-the-load-event
+       flag to false. This stops delaying the load event.
      6. 
+
+       
    6. Abort the overall resource selection
+       algorithm.
      7. 
+
+      
    
+
+
+     
    If the media data can
+     be fetched but has non-fatal errors or uses, in part, codecs that
+     are unsupported, preventing the user agent from rendering the
+     content completely correctly but not preventing playback
+     altogether
    
+
+     
    
+
+      
    The server returning data that is partially usable but cannot
+      be optimally rendered must cause the user agent to render just
+      the bits it can handle, and ignore the rest.
    
+
+      
+
+     
    
+
+
+
+     
    If the media resource is found to declare a media-resource-specific timed track that the user agent supports
    
+
+     
    
+
+      
    Run the steps to expose a media-resource-specific timed
+      track with the relevant data.
    
+
+     
    
+
+
+    
    When the networking task source has queued the last task as part of fetching the media resource
+    (i.e. once the download has completed), if the fetching process
+    completes without errors, including decoding the media data, and
+    if all of the data is available to the user agent without network
+    access, then, the user agent must move on to the next step. This
+    might never happen, e.g. when streaming an infinite resource such
+    as Web radio, or if the resource is longer than the user agent's
+    ability to cache data.
    
+
+    
    While the user agent might still need network access to obtain
+    parts of the media resource, the user agent must
+    remain on this step.
    
+
+    
    For example, if the user agent has discarded
+    the first half of a video, the user agent will remain at this step
+    even once the playback has
+    ended, because there is always the chance the user will
+    seek back to the start. In fact, in this situation, once playback has ended, the user agent
+    will end up dispatching a stalled event, as described
+    earlier.
    
+
+   
    3. 
+
+   
  3. If the user agent ever reaches this step (which can only
+   happen if the entire resource gets loaded and kept available):
+   abort the overall resource selection
+   algorithm.
    4. 
+
+  

+
+  
The preload
+  attribute is an enumerated attribute. The following table
+  lists the keywords and states for the attribute — the keywords
+  in the left column map to the states in the cell in the second
+  column on the same row as the keyword.

+
+  
 Keyword
+      State
+      Brief description
+   
none
+     None
+     Hints to the user agent that either the author does not expect the user to need the media resource, or that the server wants to minimise unnecessary traffic.
+    
metadata
+     Metadata
+     Hints to the user agent that the author does not expect the user to need the media resource, but that fetching the resource metadata (dimensions, first frame, track list, duration, etc) is reasonable.
+    
auto
+     Automatic
+     Hints to the user agent that the user agent can put the user's needs first without risk to the server, up to and including optimistically downloading the entire resource.
+  
The empty string is also a valid keyword, and maps to the Automatic state. The
+  attribute's missing value default is user-agent defined,
+  though the Metadata state is
+  suggested as a compromise between reducing server load and providing
+  an optimal user experience.

+
+  

+
+  
The preload attribute is
+  intended to provide a hint to the user agent about what the author
+  thinks will lead to the best user experience. The attribute may be
+  ignored altogether, for example based on explicit user preferences
+  or based on the available connectivity.

+
+  
The preload IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  

+
+  
The autoplay attribute can overrride
+  the preload attribute (since
+  if the media plays, it naturally has to buffer first, regardless of
+  the hint given by the preload attribute). Including
+  both is not an error, however.

+
+  
media . buffered

+
+   

+
+    
Returns a TimeRanges object that represents the
+    ranges of the media resource that the user agent has
+    buffered.

+
+   

+
+  

+
+  
The buffered
+  attribute must return a new static normalized
+  TimeRanges object that represents the ranges of
+  the media resource, if any, that the user agent has
+  buffered, at the time the attribute is evaluated. Users agents must
+  accurately determine the ranges available, even for media streams
+  where this can only be determined by tedious inspection.

+
+  
Typically this will be a single range anchored at
+  the zero point, but if, e.g. the user agent uses HTTP range requests
+  in response to seeking, then there could be multiple ranges.

+
+  
User agents may discard previously buffered data.

+
+  
Thus, a time position included within a range of the
+  objects return by the buffered attribute at one time can
+  end up being not included in the range(s) of objects returned by the
+  same attribute at later times.

+
+  

+
+
+
+  
4.8.10.6 Offsets into the media resource

+
+  
media . duration

+
+   

+
+    
Returns the length of the media resource, in
+    seconds.

+
+    
Returns NaN if the duration isn't available.

+
+    
Returns Infinity for unbounded streams.

+
+   

+
+   
media . currentTime [ = value ]

+
+   

+
+    
Returns the current playback position, in seconds.

+
+    
Can be set, to seek to the given time.

+
+    
Will throw an INVALID_STATE_ERR exception if there
+    is no selected media resource. Will throw an
+    INDEX_SIZE_ERR exception if the given time is not
+    within the ranges to which the user agent can seek.

+
+   

+
+   
media . startTime

+
+   

+
+    
Returns the earliest possible position, in
+    seconds. This is the time for the start of the current clip. It
+    might not be zero if the clip's timeline is not zero-based, or if
+    the resource is a streaming resource (in which case it gives the
+    earliest time that the user agent is able to seek back to).

+
+   

+
+  

+
+  
The duration
+  attribute must return the length of the media resource,
+  in seconds. If no media data is available, then the
+  attributes must return the Not-a-Number (NaN) value. If the
+  media resource is known to be unbounded (e.g. a
+  streaming radio), then the attribute must return the positive
+  Infinity value.

+
+  
The user agent must determine the duration of the media
+  resource before playing any part of the media
+  data and before setting readyState to a value equal to
+  or greater than HAVE_METADATA, even if doing
+  so requires seeking to multiple parts of the resource.

+
+  
When the length of the media
+  resource changes (e.g. from being unknown to known, or from a
+  previously established length to a new length) the user agent must
+  queue a task to fire a simple event named
+  durationchange at the
+  media element.

+
+  
If an "infinite" stream ends for some reason,
+  then the duration would change from positive Infinity to the time of
+  the last frame or sample in the stream, and the durationchange event would be
+  fired. Similarly, if the user agent initially estimated the
+  media resource's duration instead of determining it
+  precisely, and later revises the estimate based on new information,
+  then the duration would change and the durationchange event would be
+  fired.

+
+  
Media elements have a
+  current playback position, which must initially be
+  zero. The current position is a time.

+
+  
The currentTime
+  attribute must, on getting, return the current playback
+  position, expressed in seconds. On setting, the user agent
+  must seek to the new value
+  (which might raise an exception).

+
+  
If the media resource is a streaming resource, then
+  the user agent might be unable to obtain certain parts of the
+  resource after it has expired from its buffer. Similarly, some media resources might have a timeline
+  that doesn't start at zero. The earliest possible
+  position is the earliest position in the stream or resource
+  that the user agent can ever obtain again.

+
+  
The startTime
+  attribute must, on getting, return the earliest possible
+  position, expressed in seconds.

+
+  
When the earliest possible position changes, then:
+  if the current playback position is before the
+  earliest possible position, the user agent must seek to the earliest possible
+  position; otherwise, if the user agent has not fired a timeupdate event at the
+  element in the past 15 to 250ms and is not still running event
+  handlers for such an event, then the user agent must queue a
+  task to fire a simple event named timeupdate at the element.

+
+  
Because of the above requirement and the requirement
+  in the resource fetch
+  algorithm that kicks in when the metadata of the clip becomes
+  known, the current playback position can never be
+  less than the earliest possible position.

+
+  
User agents must act as if the timeline of the media
+  resource increases linearly starting from the earliest
+  possible position, even if the underlying media
+  data has out-of-order or even overlapping time codes.

+
+  
For example, if two clips have been concatenated
+  into one video file, but the video format exposes the original times
+  for the two clips, the video data might expose a timeline that goes,
+  say, 00:15..00:29 and then 00:05..00:38. However, the user agent
+  would not expose those times; it would instead expose the times as
+  00:15..00:29 and 00:29..01:02, as a single video.

+
+  

+
+  
The loop
+  attribute is a boolean attribute that, if specified,
+  indicates that the media element is to seek back to the
+  start of the media resource upon reaching the end.

+
+  

+
+  
The loop IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  

+
+
+
+  
4.8.10.7 The ready states

+
+  
media . readyState

+
+   

+
+    
Returns a value that expresses the current state of the element
+    with respect to rendering the current playback
+    position, from the codes in the list below.

+
+   

+
+  

+
+  
Media elements have a
+  ready state, which describes to what degree they are ready
+  to be rendered at the current playback position. The
+  possible values are as follows; the ready state of a media element
+  at any particular time is the greatest value describing the state of
+  the element:

+
+  

+
+  
HAVE_NOTHING (numeric value 0)

+
+   
No information regarding the media resource is
+   available. No data for the current playback position
+   is available. Media elements
+   whose networkState
+   attribute are set to NETWORK_EMPTY are always in
+   the HAVE_NOTHING
+   state.

+
+   
HAVE_METADATA (numeric value 1)

+
+   
Enough of the resource has been obtained that the duration of
+   the resource is available. In the case of a video
+   element, the dimensions of the video are also available. The API
+   will no longer raise an exception when seeking. No media
+   data is available for the immediate current playback
+   position.
+
+   The timed tracks
+   are ready.
+
+   

+
+   
HAVE_CURRENT_DATA (numeric value 2)

+
+   
Data for the immediate current playback position
+   is available, but either not enough data is available that the user
+   agent could successfully advance the current playback
+   position in the direction of playback at all
+   without immediately reverting to the HAVE_METADATA state, or
+   there is no more data to obtain in the direction of
+   playback. For example, in video this corresponds to the user
+   agent having data from the current frame, but not the next frame;
+   and to when playback has
+   ended.

+
+   
HAVE_FUTURE_DATA (numeric value 3)

+
+   
Data for the immediate current playback position
+   is available, as well as enough data for the user agent to advance
+   the current playback position in the direction
+   of playback at least a little without immediately reverting
+   to the HAVE_METADATA
+   state. For example, in video this corresponds to the user agent
+   having data for at least the current frame and the next frame. The
+   user agent cannot be in this state if playback has ended, as the current playback
+   position can never advance in this case.

+
+   
HAVE_ENOUGH_DATA (numeric value 4)

+
+   
All the conditions described for the HAVE_FUTURE_DATA state
+   are met, and, in addition, the user agent estimates that data is
+   being fetched at a rate where the current playback
+   position, if it were to advance at the rate given by the
+   defaultPlaybackRate
+   attribute, would not overtake the available data before playback
+   reaches the end of the media resource.

+
+  

+
+  
When the ready state of a media element whose networkState is not NETWORK_EMPTY changes, the
+  user agent must follow the steps given below:

+
+  
If the previous ready state was HAVE_NOTHING, and the new
+   ready state is HAVE_METADATA

+
+   

+
+    
A loadedmetadata DOM event will be fired as part of the load() algorithm.

+
+   

+
+   
+
+   
If the previous ready state
+   was HAVE_METADATA and
+   the new ready state is HAVE_CURRENT_DATA or
+   greater

+
+   

+
+    
If this is the first time this occurs for
+    this media element since the load() algorithm was last invoked,
+    the user agent must queue a task to fire a
+    simple event named loadeddata at the element.

+
+    
If the new ready state is HAVE_FUTURE_DATA or
+    HAVE_ENOUGH_DATA,
+    then the relevant steps below must then be run also.

+
+   

+
+   
+   
If the previous ready state was HAVE_FUTURE_DATA or more,
+   and the new ready state is HAVE_CURRENT_DATA or
+   less

+
+   

+
+    
A waiting DOM
+    event can be fired,
+    depending on the current state of playback.

+
+   

+
+   
+   
If the previous ready state was HAVE_CURRENT_DATA or
+   less, and the new ready state is HAVE_FUTURE_DATA

+
+   

+
+    
The user agent must queue a task to fire a
+    simple event named canplay.

+
+    
If the element is potentially playing, the user
+    agent must queue a task to fire a simple
+    event named playing.

+
+   

+
+   
+   
If the new ready state is HAVE_ENOUGH_DATA

+
+   

+
+    
If the previous ready state was HAVE_CURRENT_DATA or
+    less, the user agent must queue a task to fire
+    a simple event named canplay, and, if the element is also
+    potentially playing, queue a task to
+    fire a simple event named playing.

+
+    
If the autoplaying flag is true, and the paused attribute is true, and the
+    media element has an autoplay attribute specified,
+    and the media element is in a Document
+    whose browsing context did not have the
+    sandboxed automatic features browsing context flag
+    set when the Document was created, then the user
+    agent may also set the paused attribute to false,
+    queue a task to fire a simple event
+    named play, and queue
+    a task to fire a simple event named playing.

+
+    
User agents are not required to autoplay, and it
+    is suggested that user agents honor user preferences on the
+    matter. Authors are urged to use the autoplay attribute rather than
+    using script to force the video to play, so as to allow the user
+    to override the behavior if so desired.

+
+    
In any case, the user agent must finally queue a
+    task to fire a simple event named canplaythrough.

+
+   

+
+  

+
+  
It is possible for the ready state of a media
+  element to jump between these states discontinuously. For example,
+  the state of a media element can jump straight from HAVE_METADATA to HAVE_ENOUGH_DATA without
+  passing through the HAVE_CURRENT_DATA and
+  HAVE_FUTURE_DATA
+  states.

+
+  

+
+  
The readyState IDL
+  attribute must, on getting, return the value described above that
+  describes the current ready state of the media
+  element.

+
+  

+
+  
The autoplay
+  attribute is a boolean attribute. When present, the
+  user agent (as described in the algorithm
+  described herein) will automatically begin playback of the
+  media resource as soon as it can do so without
+  stopping.

+
+  
Authors are urged to use the autoplay attribute rather than
+  using script to trigger automatic playback, as this allows the user
+  to override the automatic playback when it is not desired, e.g. when
+  using a screen reader. Authors are also encouraged to consider not
+  using the automatic playback behavior at all, and instead to let the
+  user agent wait for the user to start playback explicitly.

+
+  

+
+  
The autoplay
+  IDL attribute must reflect the content attribute of the
+  same name.

+
+  

+
+
+
+  
4.8.10.8 Playing the media resource

+
+  
media . paused

+
+   

+
+    
Returns true if playback is paused; false otherwise.

+
+   

+
+   
media . ended

+
+   

+
+    
Returns true if playback has reached the end of the media resource.

+
+   

+
+   
media . defaultPlaybackRate [ = value ]

+
+   

+
+    
Returns the default rate of playback, for when the user is not
+    fast-forwarding or reversing through the media
+    resource.

+
+    
Can be set, to change the default rate of playback.

+
+    
The default rate has no direct effect on playback, but if the
+    user switches to a fast-forward mode, when they return to the
+    normal playback mode, it is expected that the rate of playback
+    will be returned to the default rate of playback.

+
+   

+
+   
media . playbackRate [ = value ]

+
+   

+
+    
Returns the current rate playback, where 1.0 is normal speed.

+
+    
Can be set, to change the rate of playback.

+
+   

+
+   
media . played

+
+   

+
+    
Returns a TimeRanges object that represents the
+    ranges of the media resource that the user agent has
+    played.

+
+   

+
+   
media . play()

+
+   

+
+    
Sets the paused attribute
+    to false, loading the media resource and beginning
+    playback if necessary. If the playback had ended, will restart it
+    from the start.

+
+   

+
+   
media . pause()

+
+   

+
+    
Sets the paused attribute
+    to true, loading the media resource if necessary.

+
+   

+
+  

+
+  
The paused
+  attribute represents whether the media element is
+  paused or not. The attribute must initially be true.

+
+  
A media element is said to be potentially
+  playing when its paused
+  attribute is false, the readyState attribute is either
+  HAVE_FUTURE_DATA or
+  HAVE_ENOUGH_DATA,
+  the element has not ended playback, playback has not
+  stopped due to errors, and the element has not paused
+  for user interaction.

+
+  
A media element is said to have ended
+  playback when the element's readyState attribute is HAVE_METADATA or greater, and
+  either the current playback position is the end of the
+  media resource and the direction of
+  playback is forwards and the media element does
+  not have a loop attribute
+  specified, or the current playback position is the
+  earliest possible position and the direction of
+  playback is backwards.

+
+  
The ended
+  attribute must return true if the media element has
+  ended playback and the direction of
+  playback is forwards, and false otherwise.

+
+  
A media element is said to have stopped due to
+  errors when the element's readyState attribute is HAVE_METADATA or greater, and
+  the user agent encounters a
+  non-fatal error during the processing of the media
+  data, and due to that error, is not able to play the content
+  at the current playback position.

+
+  
A media element is said to have paused for user
+  interaction when its paused attribute is false, the readyState attribute is either
+  HAVE_FUTURE_DATA or
+  HAVE_ENOUGH_DATA and
+  the user agent has reached a point in the media
+  resource where the user has to make a selection for the
+  resource to continue.

+
+  
It is possible for a media element to have both
+  ended playback and paused for user
+  interaction at the same time.

+
+  
When a media element that is potentially
+  playing stops playing because it has paused for user
+  interaction, the user agent must queue a task to
+  fire a simple event named timeupdate at the element.

+
+  
When a media element
+  that is potentially playing stops playing because its
+  readyState attribute
+  changes to a value lower than HAVE_FUTURE_DATA, without
+  the element having ended playback, or playback having
+  stopped due to errors, or playback having paused
+  for user interaction, or the seeking algorithm being invoked, the
+  user agent must queue a task to fire a simple
+  event named timeupdate
+  at the element, and queue a task to fire a simple
+  event named waiting at
+  the element.

+
+  
When the current playback position reaches the end
+  of the media resource when the direction of
+  playback is forwards, then the user agent must follow these
+  steps:

+
+  
  1. If the media element has a loop attribute specified, then seek to the earliest possible
+   position of the media resource and abort these
+   steps.
    2.  
+
+   
  2. Stop playback.
    The ended attribute becomes
+   true.
    3. 
+
+   
  3. The user agent must queue a task to fire
+   a simple event named timeupdate at the element.
    4. 
+
+   
  4. The user agent must queue a task to fire
+   a simple event named ended
+   at the element.
    5. 
+
+  
When the current playback position reaches the
+  earliest possible position of the media
+  resource when the direction of playback is
+  backwards, then the user agent must follow these steps:

+
+  
  1. Stop playback.
    2. 
+
+   
  2. The user agent must queue a task to fire
+   a simple event named timeupdate at the element.
    3. 
+
+  
The defaultPlaybackRate
+  attribute gives the desired speed at which the media
+  resource is to play, as a multiple of its intrinsic
+  speed. The attribute is mutable: on getting it must return the last
+  value it was set to, or 1.0 if it hasn't yet been set; on setting
+  the attribute must be set to the new value.

+
+  
The playbackRate
+  attribute gives the speed at which the media resource
+  plays, as a multiple of its intrinsic speed. If it is not equal to
+  the defaultPlaybackRate,
+  then the implication is that the user is using a feature such as
+  fast forward or slow motion playback. The attribute is mutable: on
+  getting it must return the last value it was set to, or 1.0 if it
+  hasn't yet been set; on setting the attribute must be set to the new
+  value, and the playback must change speed (if the element is
+  potentially playing).

+
+  
If the playbackRate
+  is positive or zero, then the direction of playback is
+  forwards. Otherwise, it is backwards.

+
+  
The "play" function in a user agent's interface must set the
+  playbackRate attribute
+  to the value of the defaultPlaybackRate
+  attribute before invoking the play() method's steps. Features such
+  as fast-forward or rewind must be implemented by only changing the
+  playbackRate
+  attribute.

+
+  
When the defaultPlaybackRate or
+  playbackRate attributes
+  change value (either by being set by script or by being changed
+  directly by the user agent, e.g. in response to user control) the
+  user agent must queue a task to fire a simple
+  event named ratechange
+  at the media element.

+
+  
The played
+  attribute must return a new static normalized
+  TimeRanges object that represents the ranges of
+  the media resource, if any, that the user agent has so
+  far rendered, at the time the attribute is evaluated.

+
+  
When the play()
+  method on a media element is invoked, the user agent
+  must run the following steps.

+
+  
  1. If the media element's networkState attribute has
+   the value NETWORK_EMPTY, invoke the
+   media element's resource selection
+   algorithm.
    2. 
+
+   
  2. 
+
+    
    If the playback has ended
+    and the direction of playback is forwards, seek to the earliest possible
+    position of the media resource.
    
+
+    
    This will cause the user
+    agent to queue a task to fire a simple
+    event named timeupdate at the media
+    element.
     
+
+   
    3. 
+
+   
  3. 
+
+    
    If the media element's paused attribute is true, run
+    the following substeps:
    
+
+    
    1. Change the value of paused to false.
      2. 
+
+     
    2. Queue a task to fire a simple event
+     named play at the element.
      3. 
+
+     
    3. 
+
+      
      If the media element's readyState attribute has the
+      value HAVE_NOTHING,
+      HAVE_METADATA, or
+      HAVE_CURRENT_DATA,
+      queue a task to fire a simple event
+      named waiting at the
+      element.
      
+
+      
      Otherwise, the media element's readyState attribute has the
+      value HAVE_FUTURE_DATA or
+      HAVE_ENOUGH_DATA;
+      queue a task to fire a simple event
+      named playing at the
+      element.
      
+
+     
      4. 
+
+    
    4. 
+
+   
  4. Set the media element's autoplaying
+   flag to false.
    5. 
+
+  
When the pause()
+  method is invoked, the user agent must run the following steps:

+
+  
  1. If the media element's networkState attribute has
+   the value NETWORK_EMPTY, invoke the
+   media element's resource selection
+   algorithm.
    2. 
+
+   
  2. Set the media element's autoplaying
+   flag to false.
    3. 
+
+   
  3. If the media element's paused attribute is false, run the
+   following steps:
    
+
+    
    1. Change the value of paused to true.
      2. 
+
+     
    2. Queue a task to fire a simple
+     event named timeupdate at the
+     element.
      3. 
+
+     
    3. Queue a task to fire a simple
+     event named pause
+     at the element.
      4. 
+
+    
    4. 
+
+  
When a media element is
+  potentially playing and its Document is a
+  fully active Document, its current
+  playback position must increase monotonically at playbackRate units of media
+  time per unit time of wall clock time.

+
+  
This specification doesn't define how the user agent
+  achieves the appropriate playback rate — depending on the
+  protocol and media available, it is plausible that the user agent
+  could negotiate with the server to have the server provide the media
+  data at the appropriate rate, so that (except for the period between
+  when the rate is changed and when the server updates the stream's
+  playback rate) the client doesn't actually have to drop or
+  interpolate any frames.

+
+  
When the playbackRate
+  is negative (playback is backwards), any corresponding audio must be
+  muted. When the playbackRate is so low or so
+  high that the user agent cannot play audio usefully, the
+  corresponding audio must also be muted. If the playbackRate is not 1.0, the
+  user agent may apply pitch adjustments to the audio as necessary to
+  render it faithfully.

+
+  
The playbackRate can
+  be 0.0, in which case the current playback position
+  doesn't move, despite playback not being paused (paused doesn't become true, and the
+  pause event doesn't fire).

+
+  
Media elements that are
+  potentially playing while not in a
+  Document must not play any video, but should
+  play any audio component. Media elements must not stop playing just
+  because all references to them have been removed; only once a media
+  element to which no references exist has reached a point where no
+  further audio remains to be played for that element (e.g. because
+  the element is paused, or because the end of the clip has been
+  reached, or because its playbackRate is 0.0) may the
+  element be garbage collected.

+
+  
When the current playback position of a media
+  element changes (e.g. due to playback or seeking), the user
+  agent must run the following steps. If the current playback
+  position changes while the steps are running, then the user
+  agent must wait for the steps to complete, and then must immediately
+  rerun the steps. (These steps are thus run as often as possible or
+  needed — if one iteration takes a long time, this can cause
+  certain ranges to be skipped over as the user agent rushes ahead to
+  "catch up".)

+
+  
  1. If the time was reached through the usual monotonic increase
+   of the current playback position during normal playback, and if the
+   user agent has not fired a timeupdate event at the
+   element in the past 15 to 250ms and is not still running event
+   handlers for such an event, then the user agent must queue a
+   task to fire a simple event named timeupdate at the
+   element. (In the other cases, such as explicit seeks, relevant
+   events get fired as part of the overall process of changing the
+   current playback position.)
    
+
+   
    The event thus is not to be fired faster than about
+   66Hz or slower than 4Hz (assuming the event handlers don't take
+   longer than 250ms to run). User agents are encouraged to vary the
+   frequency of the event based on the system load and the average
+   cost of processing the event each time, so that the UI updates are
+   not any more frequent than the user agent can comfortably handle
+   while decoding the video.
    2. 
+
+
+  
When a media element is removed from a
+  Document, if the media element's
+  networkState attribute
+  has a value other than NETWORK_EMPTY then the user
+  agent must act as if the pause() method had been invoked.

+
+  
If the media element's
+  Document stops being a fully active
+  document, then the playback will stop
+  until the document is active again.

+
+  

+
+
+
+  
4.8.10.9 Seeking

+
+  
media . seeking

+
+   

+
+    
Returns true if the user agent is currently seeking.

+
+   

+
+   
media . seekable

+
+   

+
+    
Returns a TimeRanges object that represents the
+    ranges of the media resource to which it is possible
+    for the user agent to seek.

+
+   

+
+  

+
+  
The seeking
+  attribute must initially have the value false.

+
+  
When the user agent is required to seek to a particular new
+  playback position in the media resource, it means
+  that the user agent must run the following steps. This algorithm
+  interacts closely with the event loop mechanism; in
+  particular, it has a synchronous
+  section (which is triggered as part of the event
+  loop algorithm). Steps in that section are marked with
+  ⌛.

+
+  
  1. If the media element's readyState is HAVE_NOTHING, then raise an
+   INVALID_STATE_ERR exception (if the seek was in
+   response to a DOM method call or setting of an IDL attribute), and
+   abort these steps.
    2. 
+
+   
  2. If the element's seeking IDL attribute is true,
+   then another instance of this algorithm is already running. Abort
+   that other instance of the algorithm without waiting for the step
+   that it is running to complete.
    3. 
+
+   
  3. Set the seeking IDL
+   attribute to true.
    4. 
+
+   
  4. Queue a task to fire a
+   simple event named timeupdate at the
+   element.
    5. 
+
+   
  5. If the seek was in response to a DOM method call or setting
+   of an IDL attribute, then continue the script. The remainder of
+   these steps must be run asynchronously. With the exception of the
+   steps marked with ⌛, they could be aborted at any time by
+   another instance of this algorithm being invoked.
    6. 
+
+   
  6. If the new playback position is later
+   than the end of the media resource, then let it be the
+   end of the media resource instead.
    7. 
+
+   
  7. If the new playback position is less
+   than the earliest possible position, let it be that
+   position instead.
    8. 
+
+   
  8. If the (possibly now changed) new playback
+   position is not in one of the ranges given in the seekable attribute, then let it
+   be the position in one of the ranges given in the seekable attribute that is the
+   nearest to the new playback position. If two
+   positions both satisfy that constraint (i.e. the new
+   playback position is exactly in the middle between two ranges
+   in the seekable attribute)
+   then use the position that is closest to the current playback
+   position. If there are no ranges given in the seekable attribute then set the
+   seeking IDL attribute to
+   false and abort these steps.
    9. 
+
+   
  9. Set the current playback position to the given
+   new playback position.
    10. 
+
+   
  10. If the media element was potentially
+   playing immediately before it started seeking, but seeking
+   caused its readyState
+   attribute to change to a value lower than HAVE_FUTURE_DATA, then
+   queue a task to fire a simple event named
+   waiting at the
+   element.
    11. 
+
+   
  11. If, when it reaches this step, the user agent has still not
+   established whether or not the media data for the new playback position is available, and, if it is,
+   decoded enough data to play back that position, then queue a
+   task to fire a simple event named seeking at the element.
    12. 
+
+   
  12. Wait until it has established whether or not the media
+   data for the new playback position is
+   available, and, if it is, until it has decoded enough data to play
+   back that position.
    13. 
+
+   
  13. Await a stable state. The synchronous
+   section consists of all the remaining steps of this
+   algorithm. (Steps in the synchronous section are
+   marked with ⌛.)
    14. 
+
+   
  14. ⌛ Set the seeking IDL attribute to
+   false.
    15. 
+
+   
  15. ⌛ Queue a task to fire a simple
+   event named seeked
+   at the element.
    16. 
+
+  
The seekable
+  attribute must return a new static normalized
+  TimeRanges object that represents the ranges of
+  the media resource, if any, that the user agent is able
+  to seek to, at the time the attribute is evaluated.

+
+  
If the user agent can seek to anywhere in the
+  media resource, e.g. because it a simple movie file and
+  the user agent and the server support HTTP Range requests, then the
+  attribute would return an object with one range, whose start is the
+  time of the first frame (typically zero), and whose end is the same
+  as the time of the first frame plus the duration attribute's value (which
+  would equal the time of the last frame).

+
+  
The range might be continuously changing, e.g. if
+  the user agent is buffering a sliding window on an infinite
+  stream. This is the behavior seen with DVRs viewing live TV, for
+  instance.

+
+  
Media resources might be
+  internally scripted or interactive. Thus, a media
+  element could play in a non-linear fashion. If this happens,
+  the user agent must act as if the algorithm for seeking was used whenever the
+  current playback position changes in a discontinuous
+  fashion (so that the relevant events fire).

+
+  

+
+
+
+  
4.8.10.10 Timed tracks

+
+  
4.8.10.10.1 Timed track model

+
+  
A media element can have a group of associated timed tracks, known as the media
+  element's list of timed tracks. The timed tracks are sorted as follows:

+
+  
  1. The timed tracks corresponding
+   to track element children of the media
+   element, in tree order.
    2. 
+
+   
  2. Any timed tracks added using
+   the addTrack() method, in
+   the order they were added, oldest first.
    3. 
+
+   
  3. Any media-resource-specific timed tracks (timed tracks corresponding to data in
+   the media resource), in the order defined by the
+   media resource's format specification.
    4. 
+
+  
A timed track consists of:

+
+  
The kind of timed track
+
+   

+
+    
This decides how the track is handled by the user agent. The
+    kind is represented by a string. The possible strings are:

+
+    
  • subtitles
+     
  • captions
+     
  • descriptions
+     
  • chapters
+     
  • metadata
+    
The kind of track can
+    change dynamically, in the case of a timed track
+    corresponding to a track element.

+
+   

+
+   
A label
+
+   

+
+    
This is a human-readable string intended to identify the track
+    for the user. In certain cases, the label might be generated
+    automatically.

+
+    
The label of a track can
+    change dynamically, in the case of a timed track
+    corresponding to a track element or in the case of an
+    automatically-generated label whose value depends on variable
+    factors such as the user's preferred user interface language.

+
+   

+
+   
A language
+
+   

+
+    
This is a string (a BCP 47 language tag) representing the
+    language of the timed track's cues. [BCP47]

+
+    
The language of a timed
+    track can change dynamically, in the case of a timed
+    track corresponding to a track element.

+
+   

+
+   
A readiness state
+
+   

+
+    
One of the following:

+
+    
Not loaded
+
+     

+
+      
Indicates that the timed track is known to exist (e.g. it has
+      been declared with a track element), but its cues
+      have not been obtained.

+
+     

+
+     
Loading
+
+     

+
+      
Indicates that the timed track is loading and there have been
+      no fatal errors encountered so far. Further cues might still be
+      added to the track.

+
+     

+
+     
Loaded
+
+     

+
+      
Indicates that the timed track has been loaded with no fatal
+      errors. No new cues will be added to the track except if the
+      timed track corresponds to a
+      MutableTimedTrack object.

+
+     

+
+     
Failed to load
+
+     

+
+      
Indicates that the timed track was enabled, but when the user
+      agent attempted to obtain it, this failed in some way
+      (e.g. URL could not be resolved, network error, unknown timed track
+      format). Some or all of the cues are likely missing and will not
+      be obtained.

+
+     

+
+    
The readiness
+    state of a timed track changes dynamically as
+    the track is obtained.

+
+   

+
+   
A mode
+
+   

+
+    
One of the following:

+
+    
Disabled
+
+     

+
+      
Indicates that the timed track is not active. Other than for
+      the purposes of exposing the track in the DOM, the user agent is
+      ignoring the timed track. No cues are active, no events are
+      fired, and the user agent will not attempt to obtain the track's
+      cues.

+
+     

+
+     
Hidden
+
+     

+
+      
Indicates that the timed track is active, but that the user
+      agent is not actively displaying the cues. If no attempt has yet
+      been made to obtain the track's cues, the user will perform such
+      an attempt momentarily. The user agent is maintaining a list of
+      which cues are active, and events are being fired
+      accordingly.

+
+     

+
+     
Showing
+
+     

+
+      
Indicates that the timed track is active. If no attempt has
+      yet been made to obtain the track's cues, the user will perform
+      such an attempt momentarily. The user agent is maintaining a
+      list of which cues are active, and events are being fired
+      accordingly. In addition, for timed tracks whose kind is subtitles or captions, the cues
+      are being displayed over the video as appropriate; for timed
+      tracks whose kind is descriptions,
+      the user agent is making the cues available to the user in a
+      non-visual fashion; and for timed tracks whose kind is chapters, the user
+      agent is making available to the user a mechanism by which the
+      user can navigate to any point in the media
+      resource by selecting a cue.

+
+     

+
+    

+
+   
A list of zero or more cues
+
+   

+
+    
A list of timed track cues.

+
+    
The list of cues of a
+    timed track can change dynamically, either because the
+    timed track has not yet been loaded or is still loading, or in the case of a timed
+    track corresponding to a MutableTimedTrack
+    object, where individual cues can be added or removed
+    dynamically using the API.

+
+   

+
+  
Each timed track has a corresponding
+  TimedTrack object.

+
+  
A timed track cue is the unit of time-sensitive data
+  in a timed track, corresponding for instance for
+  subtitles and captions to the text that appears at a particular time
+  and disappears at another time.

+
+  
Each timed track cue consists of:

+
+  
An identifier
+   

+    
An arbitrary string.

+   

+
+   
A start time
+   

+    
A time, in seconds and fractions of a second, at which the cue
+    becomes relevant.

+   

+
+   
An end time
+   

+    
A time, in seconds and fractions of a second, at which the cue
+    stops being relevant.

+   

+
+   
A pause-on-exit flag
+   

+    
A boolean indicating whether playback of the media
+    resource is to pause when the cue stops being relevant.

+   

+
+   
A writing direction
+   

+    
A writing direction, either horizontal (a line extends
+    horizontally and is positioned vertically, with consecutive lines
+    displayed below each other), vertical growing right (a
+    line extends vertically and is positioned horizontally, with
+    consecutive lines displayed to the right of each other), or vertical growing left (a
+    line extends vertically and is positioned horizontally, with
+    consecutive lines displayed to the left of each other).

+   

+
+   
A snap-to-lines flag
+   

+    
A boolean indicating whether the line's position is a line position
+    (positioned to a multiple of the line dimensions of the first line
+    of the cue), or whether it is a percentage of the dimension of the
+    video.

+   

+
+   
A line position
+   

+    
A number giving the position of the lines of the cue, to be
+    interpreted as defined by the writing direction and snap-to-lines flag of the cue.

+   

+
+   
A text position
+   

+    
A number giving the position of the text of the cue within each
+    line, to be interpreted as a percentage of the video, as defined
+    by the writing
+    direction.

+   

+
+   
A size
+   

+    
A number giving the size of the box within which the text of
+    each line of the cue is to be aligned, to be interpreted as a
+    percentage of the video, as defined by the writing direction.

+   

+
+   
An alignment
+   

+    
An alignment for the text of each line of the cue, either start alignment (the
+    text is aligned towards its start side), middle alignment (the text is aligned
+    centered between its start and end sides), end alignment (the text is aligned
+    towards its end side). Which sides are the start and end sides
+    depends on the Unicode bidirectional algorithm and the writing
+    direction. [BIDI]

+   

+
+   
A voice identifier
+   

+    
A string identifying the voice with which the cue is associated.

+   

+
+   
The text of the cue
+   

+    
The raw text of the cue, and rules for its interpretation,
+    allowing the text to be converted to an equivalent fragment of
+    HTML.

+   

+
+  
A timed track cue is immutable.

+
+  
Each timed track cue has a corresponding
+  TimedTrackCue object, and can be associated with a
+  particular timed track. Once a timed track
+  cue is associated with a particular timed track,
+  the association is permanent.

+
+  
The timed tracks of a
+  media element are ready if all the timed
+  tracks whose mode was
+  not in the disabled state
+  when the element's resource selection
+  algorithm last started now have a timed track readiness
+  state of loaded or
+  failed to load.

+
+
+  
4.8.10.10.2 Sourcing in-band timed tracks

+
+  
A media-resource-specific timed track is a timed
+  track that corresponds to data found in the media
+  resource.

+
+
+  

+
+  
Rules for processing and rendering such data are defined by the
+  relevant specifications, e.g. the specification of the video format
+  if the media resource is a video.

+
+  
When a media resource contains data that the user
+  agent recognises and supports as being equivalent to a timed
+  track, the user agent runs the
+  steps to expose a media-resource-specific timed track
+  with the relevant data, as follows:

+
+  
  1. Associate the relevant data with a new timed
+   track and its corresponding new TimedTrack
+   object. The timed track is a
+   media-resource-specific timed track.
    2. 
+
+   
  2. Set the new timed track's kind, label,
+   and language based on the
+   semantics of the relevant data, as defined by the relevant
+   specification.
    3. 
+
+   
  3. Populate the new timed track's list of cues with the cues
+   parsed so far, folllowing the guidelines for exposing
+   cues, and begin updating it dynamically as
+   necessary.
    4. 
+
+   
  4. 
+
+    
    Set the new timed track's readiness state to the value that most
+    correctly describes the current state, and begin updating it
+    dynamically as necessary.
    
+
+    
    For example, if the relevant data in the
+    media resource has been fully parsed and completely
+    describes the cues, then the timed track would be
+    loaded. On the other hand,
+    if the data for the cues is interleaved with the media
+    data, and the media resource as a whole is
+    still being downloaded, then the loading state might be more accurate.
    
+
+   
    5. 
+
+   
  5. Set the new timed track's mode to the mode consistent with the user's
+   preferences and the requirements of the relevant specification for
+   the data.
    6. 
+
+   
  6. Add the new timed track to the media
+   element's list of timed tracks.
    7. 
+
+  
When a media element is to forget the media
+  element's media-resource-specific timed tracks, the user
+  agent must remove from the media element's list
+  of timed tracks all the media-resource-specific timed tracks.

+
+  

+
+
+
+  

+
+  
4.8.10.10.3 Sourcing out-of-band timed tracks

+
+  
When a track element is created, it must be
+  associated with a new timed track and its corresponding
+  new TimedTrack object.

+
+  
The timed track kind is determined from the state of
+  the element's kind attribute
+  according to the following table; for a state given in a cell of the
+  first column, the kind is the
+  string given in the second column:

+
+  
State
+     String
+   
Subtitles
+     subtitles
+    
Captions
+     captions
+    
Descriptions
+     descriptions
+    
Chapters
+     chapters
+    
Metadata
+     metadata
+  
The timed track label is the element's track
+  label.

+
+  
The timed track language is the element's
+  track language, if any, or the empty string
+  otherwise.

+
+  
As the kind, label, and srclang attributes are added,
+  removed, or changed, the timed track must update
+  accordingly, as per the definitions above.

+
+  
Changes to the track URL are handled in
+  the algorithm below.

+
+  
...cues...

+
+  
When a track element's parent element changes and
+  the new parent is a media element, then add the
+  track element's corresponding timed track
+  to the media element's list of timed
+  tracks.

+
+  
When a track element's parent element changes and
+  the old parent was a media element, then remove the
+  track element's corresponding timed track
+  from the media element's list of timed
+  tracks.

+
+  
When a timed track corresponding to a
+  track element is added to a media
+  element's list of timed tracks, update the mode appropriately.

+
+  
When a timed track corresponding to a
+  track element is created with timed track
+  mode set to hidden or
+  showing, and when a
+  timed track corresponding to a track
+  element is created with timed track mode set to disabled and subsequently
+  changes its timed track mode to hidden or showing for the first time, the user agent must
+  immediately and synchronously run the 
+  following steps:

+
+  
  1. Set the timed track readiness state to loading.
    2. 
+
+   
  2. Let URL be the track URL of
+   the track element.
    3. 
+
+   
  3. Asynchronously run the remaining steps, while continuing
+   with whatever task was responsible for creating the timed
+   track or changing the timed track
+   mode.
    4. 
+
+   
  4. 
+
+    
    Download: Fetch URL, if
+    it isn't the empty string.
    
+
+    
    The tasks queued by the fetching
+    algorithm on the networking task source to
+    process the data as it is being fetched must ...this is where cross-origin checks go.
    
+
+    
    If the fetching algorithm fails for
+    any reason (network error, the server returns an error code, the
+    cross-origin checks mentioned above fail, etc), or if URL is the empty string, then queue a
+    task to first change the timed track readiness state
+    to failed to load
+    and then fire a simple event named error at the track
+    element; and then, once that task is queued, move on to the step below labeled
+    monitoring.
    
+
+    
    If the fetching algorithm does not
+    fail, then, when it completes, queue a task to first
+    change the timed track readiness state to loaded and then fire a
+    simple event named load at
+    the track element; and then, once that task is queued, move on to the step below labeled
+    monitoring.
    
+
+    
    If, while the fetching algorithm is
+    active, either:
    
+
+    
    ...then the user agent must run the following steps:
    
+
+    
    1. Abort the fetching
+     algorithm.
      2. 
+
+     
    2. Queue a task to fire a simple
+     event named abort at
+     the track element.
      3. 
+
+     
    3. Let URL be the new track
+     URL.
      4. 
+
+     
    4. Jump back to the top of the step labeled
+     download.
      5. 
+
+    
    5. 
+
+   
  5. Monitoring: Wait until the track URL is
+   no longer equal to URL, at the same time as the
+   timed track mode is set to hidden or showing.
    6. 
+
+   
  6. Jump to the step labeled download.
    7. 
+
+  

+
+
+  

+
+  
4.8.10.10.4 Guidelines for exposing cues in various formats as
+  timed track cues

+
+  
...also, how to handle discarding cues that are
+  before startTime, for cues that are in-band

+
+  

+
+
+  
4.8.10.10.5 Timed track API

+
+
+
+  
interface TimedTrack {
+  readonly attribute DOMString kind;
+  readonly attribute DOMString label;
+  readonly attribute DOMString language;
+
+  const unsigned short NONE = 0;
+  const unsigned short LOADING = 1;
+  const unsigned short LOADED = 2;
+  const unsigned short ERROR = 3;
+  readonly attribute unsigned short readyState;
+  readonly attribute Function onload;
+  readonly attribute Function onerror;
+
+  const unsigned short OFF = 0;
+  const unsigned short HIDDEN = 1;
+  const unsigned short SHOWING = 2;
+           attribute unsigned short mode;
+
+  readonly attribute TimedTrackCueList cues;
+  readonly attribute TimedTrackCueList activeCues;
+  readonly attribute Function onentercue;
+  readonly attribute Function onexitcue;
+};
+
+interface MutableTimedTrack : TimedTrack {
+ void addCue(in TimedTrackCue cue);
+ void removeCue(in TimedTrackCue cue);
+};
+
+interface TimedTrackCueList {
+  readonly attribute unsigned long length;
+  getter TimedTrackCue (in unsigned long index);
+  TimedTrackCue getCueById(in DOMString id);
+};
+
+[Constructor(in DOMString id, in float startTime, in float endTime, in DOMString settings, in DOMString text, in optional boolean pauseOnExit)]
+interface TimedTrackCue {
+  readonly attribute TimedTrack track;
+  readonly attribute DOMString id;
+
+  readonly attribute float startTime;
+  readonly attribute float endTime;
+  readonly attribute boolean pauseOnExit;
+
+  readonly attribute DOMString direction;
+  readonly attribute boolean snapToLines;
+  readonly attribute long linePosition;
+  readonly attribute long textPosition;
+  readonly attribute long size;
+  readonly attribute DOMString alignment;
+
+  readonly attribute DOMString voice;
+  DOMString getCueAsSource();
+  DocumentFragment getCueAsHTML();
+};

+
+  
domintro
+
+  

+
+  
...
+
+  
+
+  

+
+
+  
4.8.10.10.6 Event definitions

+
+  
...
+
+
+
+
+  
4.8.10.11 WebSRT

+
+  
The WebSRT format (Web Subtitle Resource Tracks) is a format
+  intended for marking up external timed track resources.

+
+
+  
4.8.10.11.1 Syntax

+
+  
A WebSRT file must consist of a WebSRT file
+  body encoded as UTF-8.

+
+  
A WebSRT file body consists of zero or more WebSRT cues separated from each other by
+  two or more WebSRT line
+  terminators.

+
+  
A WebSRT cue consists of the following components, in
+  the given order:

+
+  
  1. Optionally, a WebSRT cue identifier.
    2. 
+   
  2. WebSRT cue timings.
    3. 
+   
  3. Optionally, WebSRT cue settings.
    4. 
+   
  4. A WebSRT line terminator.
    5. 
+   
  5. Optionally, a WebSRT voice declaration.
    6. 
+   
  6. One or more WebSRT cue text lines, each separated from the next by a WebSRT line terminator.
    7. 
+   
  7. Zero or more WebSRT line terminators.
    8. 
+  
A WebSRT line terminator consists of one of the
+  following:

+
+  
  • A U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.
    • 
+   
  • A single U+000A LINE FEED (LF) character.
    • 
+   
  • A single U+000D CARRIAGE RETURN (CR) character.
    • 
+  
A WebSRT cue identifier is any sequence of one or more
+  characters not containing the substring "-->"
+  (U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN
+  SIGN).

+
+  
The WebSRT cue timings part of a WebSRT
+  cue consists of the following components, in the given
+  order:

+
+  
  1. A WebSRT timestamp representing the start time
+   offset of the cue.
    2. 
+
+   
  2. Optionally, a U+0020 SPACE character.
    3. 
+
+   
  3. The string "-->" (U+002D HYPHEN-MINUS,
+   U+002D HYPHEN-MINUS, U+003E GREATER-THAN SIGN).
    4. 
+
+   
  4. Optionally, a U+0020 SPACE character.
    5. 
+
+   
  5. A WebSRT timestamp representing the end time
+   offset of the cue.
    6. 
+
+  
The WebSRT cue settings part of a WebSRT
+  cue consists of the following components, in the given
+  order:

+
+  
  1. ...
+
+  
WebSRT voice declaration; WebSRT cue text line; WebSRT timestamp

+
+
+  

+
+  
4.8.10.11.2 Parsing

+
+  
A WebSRT parser, given an input byte stream and a
+  timed track list of cues output,
+  must convert the bytes into a string of Unicode characters by
+  interpreting them as UTF-8, and then must parse the resulting string
+  according to the WebSRT parser algorithm below. A
+  WebSRT parser, specifically its conversion and parsing
+  steps, is typically run asynchronously, with the input byte stream
+  being updated incrementally as the resource is downloaded; this is
+  called an incremental WebSRT parser.

+
+  
When convering the bytes into Unicode characters, bytes or
+  sequences of bytes that are not valid UTF-8 sequences must be
+  interpreted as a U+FFFD REPLACEMENT CHARACTER, and all U+0000 NULL
+  characters must be replaced by U+FFFD REPLACEMENT CHARACTERs.

+
+  
The WebSRT parser algorithm is as follows:

+
+  
  1. Let input be the string being
+   parsed.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string. In an incremental WebSRT parser, when this
+   algorithm (or further algorithms that it uses) moves the position pointer, the user agent must wait until
+   appropriate further characters from the byte stream have been added
+   to input before moving the pointer, so that the
+   algorithm never reads past the end of the input
+   string. Once the byte stream has ended, and all characters have
+   been added to input, then the position pointer may, when so instructed by the
+   algorithms, be moved past the end of input.
    3. 
+
+   
  3. Cue loop: Collect a sequence of
+   characters that are either U+000D CARRIAGE RETURN (CR) or
+   U+000A LINE FEED (LF) characters.
    4. 
+
+   
  4. Let id be the empty string.
    5. 
+
+   
  5. Collect a sequence of characters that are
+   not U+000D CARRIAGE RETURN (CR) or U+000A LINE FEED (LF)
+   characters. Let line be those characters, if
+   any.
    6. 
+
+   
  6. If line is the empty string, then jump
+   to the step labeled end.
    7. 
+
+   
  7. If line contains the three-character
+   substring "-->" (U+002D HYPHEN-MINUS, U+002D
+   HYPHEN-MINUS, U+003E GREATER-THAN SIGN), then jump to the step
+   labeled timing below.
    8. 
+
+   
  8. Let id be line.
    9. 
+
+   
  9. If position is past the end of input, then jump to the step labeled
+   end.
    10. 
+
+   
  10. If the character indicated by position
+   is a U+000D CARRIAGE RETURN (CR) character, advance position to the next character in input.
    11. 
+
+   
  11. If the character indicated by position
+   is a U+000A LINE FEED (LF) character, advance position to the next character in input.
    12. 
+
+   
  12. Collect a sequence of characters that are
+   not U+000D CARRIAGE RETURN (CR) or U+000A LINE FEED (LF)
+   characters. Let line be those characters, if
+   any.
    13. 
+
+   
  13. If line is the empty string, then jump
+   to the step labeled cue loop.
    14. 
+
+   
  14. Timings: ...
    15. 
+
+   
  15. End: The file has ended. Abort these steps. The
+   WebSRT parser has finished.
    16. 
+
+  

+
+
+
+
+  
4.8.10.12 User interface

+
+  
The controls
+  attribute is a boolean attribute. If present, it
+  indicates that the author has not provided a scripted controller and
+  would like the user agent to provide its own set of controls.

+
+  

+
+  
If the attribute is present, or if scripting is disabled for the
+  media element, then the user agent should expose a
+  user interface to the user. This user interface should include
+  features to begin playback, pause playback, seek to an arbitrary
+  position in the content (if the content supports arbitrary seeking),
+  change the volume, change the display of closed captions
+
+  
+
+  or embedded
+  sign-language tracks, select different audio tracks or turn on audio
+  descriptions, and show the media content in manners more suitable to
+  the user (e.g. full-screen video or in an independent resizable
+  window). Other controls may also be made available.

+
+  
Even when the attribute is absent, however, user agents may
+  provide controls to affect playback of the media resource
+  (e.g. play, pause, seeking, and volume controls), but such features
+  should not interfere with the page's normal rendering. For example,
+  such features could be exposed in the media element's
+  context menu.

+
+  
Where possible (specifically, for starting, stopping, pausing,
+  and unpausing playback, for muting or changing the volume of the
+  audio, and for seeking), user interface features exposed by the user
+  agent must be implemented in terms of the DOM API described above,
+  so that, e.g., all the same events fire.

+
+  
The controls
+  IDL attribute must reflect the content attribute of the
+  same name.

+
+  

+
+  
media . volume [ = value ]

+
+   

+
+    
Returns the current playback volume, as a number in the range
+    0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.

+
+    
Can be set, to change the volume.

+
+    
Throws an INDEX_SIZE_ERR if the new value is not
+    in the range 0.0 .. 1.0.

+
+   

+
+   
media . muted [ = value ]

+
+   

+
+    
Returns true if audio is muted, overriding the volume attribute, and false if the
+    volume attribute is being
+    honored.

+
+    
Can be set, to change whether the audio is muted or not.

+
+   

+
+  

+
+  
The volume
+  attribute must return the playback volume of any audio portions of
+  the media element, in the range 0.0 (silent) to 1.0
+  (loudest). Initially, the volume must be 1.0, but user agents may
+  remember the last set value across sessions, on a per-site basis or
+  otherwise, so the volume may start at other values. On setting, if
+  the new value is in the range 0.0 to 1.0 inclusive, the attribute
+  must be set to the new value and the playback volume must be
+  correspondingly adjusted as soon as possible after setting the
+  attribute, with 0.0 being silent, and 1.0 being the loudest setting,
+  values in between increasing in loudness. The range need not be
+  linear. The loudest setting may be lower than the system's loudest
+  possible setting; for example the user could have set a maximum
+  volume. If the new value is outside the range 0.0 to 1.0 inclusive,
+  then, on setting, an INDEX_SIZE_ERR exception must be
+  raised instead.

+
+  
The muted
+  attribute must return true if the audio channels are muted and false
+  otherwise. Initially, the audio channels should not be muted
+  (false), but user agents may remember the last set value across
+  sessions, on a per-site basis or otherwise, so the muted state may
+  start as muted (true). On setting, the attribute must be set to the
+  new value; if the new value is true, audio playback for this
+  media resource must then be muted, and if false, audio
+  playback must then be enabled.

+
+  
Whenever either the muted or
+  volume attributes are changed,
+  the user agent must queue a task to fire a simple
+  event named volumechange at the media
+  element.

+
+  

+
+
+
+
+  
4.8.10.13 Time ranges

+
+  
Objects implementing the TimeRanges interface
+  represent a list of ranges (periods) of time.

+
+  
interface TimeRanges {
+  readonly attribute unsigned long length;
+  float start(in unsigned long index);
+  float end(in unsigned long index);
+};

+
+  
media . length

+
+   

+
+    
Returns the number of ranges in the object.

+
+   

+
+   
time = media . start(index)

+
+   

+
+    
Returns the time for the start of the range with the given index.

+
+    
Throws an INDEX_SIZE_ERR if the index is out of range.

+
+   

+
+   
time = media . end(index)

+
+   

+
+    
Returns the time for the end of the range with the given index.

+
+    
Throws an INDEX_SIZE_ERR if the index is out of range.

+
+   

+
+  

+
+  
The length
+  IDL attribute must return the number of ranges represented by the object.

+
+  
The start(index) method must return the position
+  of the start of the indexth range represented by
+  the object, in seconds measured from the start of the timeline that
+  the object covers.

+
+  
The end(index) method must return the position
+  of the end of the indexth range represented by
+  the object, in seconds measured from the start of the timeline that
+  the object covers.

+
+  
These methods must raise INDEX_SIZE_ERR exceptions
+  if called with an index argument greater than or
+  equal to the number of ranges represented by the object.

+
+  
When a TimeRanges object is said to be a
+  normalized TimeRanges object, the ranges it
+  represents must obey the following criteria:

+
+  
  • The start of a range must be greater than the end of all
+   earlier ranges.
    • 
+
+   
  • The start of a range must be less than the end of that same
+   range.
    • 
+
+  
In other words, the ranges in such an object are ordered, don't
+  overlap, aren't empty, and don't touch (adjacent ranges are folded
+  into one bigger range).

+
+  
The timelines used by the objects returned by the buffered, seekable and played IDL attributes of media elements must be the same as that
+  element's media resource's timeline.

+
+  

+
+
+  
4.8.10.14 Event summary

+
+  
This section is non-normative.

+
+  
The following events fire on media
+  elements as part of the processing model described above:

+
+  
Event name
+     Interface
+     Dispatched when...
+     Preconditions
+
+   
loadstart
+     Event
+     The user agent begins looking for media data, as part of the resource selection algorithm.
+     networkState equals NETWORK_LOADING
+    
progress
+     Event
+     The user agent is fetching media data.
+     networkState equals NETWORK_LOADING
+    
suspend
+     Event
+     The user agent is intentionally not currently fetching media data, but does not have the entire media resource downloaded.
+     networkState equals NETWORK_IDLE
+    
abort
+     Event
+     The user agent stops fetching the media data before it is completely downloaded, but not due to an error.
+     error is an object with the code MEDIA_ERR_ABORTED.
+         networkState equals either NETWORK_EMPTY or NETWORK_IDLE, depending on when the download was aborted.
+    
error
+     Event
+     An error occurs while fetching the media data.
+     error is an object with the code MEDIA_ERR_NETWORK or higher.
+         networkState equals either NETWORK_EMPTY or NETWORK_IDLE, depending on when the download was aborted.
+    
emptied
+     Event
+     A media element whose networkState was previously not in the NETWORK_EMPTY state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the load() method was invoked while the resource selection algorithm was already running).
+     networkState is NETWORK_EMPTY; all the IDL attributes are in their initial states.
+    
stalled
+     Event
+     The user agent is trying to fetch media data, but data is unexpectedly not forthcoming.
+     networkState is NETWORK_LOADING.
+
+   
play
+     Event
+     Playback has begun. Fired after the play() method has returned, or when the autoplay attribute has caused playback to begin.
+     paused is newly false.
+    
pause
+     Event
+     Playback has been paused. Fired after the pause() method has returned.
+     paused is newly true.
+
+   
loadedmetadata
+     Event
+     The user agent has just determined the duration and dimensions of the media resource
+
+ and the timed tracks are ready.
+
+     readyState is newly equal to HAVE_METADATA or greater for the first time.
+    
loadeddata
+     Event
+     The user agent can render the media data at the current playback position for the first time.
+     readyState newly increased to HAVE_CURRENT_DATA or greater for the first time.
+    
waiting
+     Event
+     Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course.
+     readyState is newly equal to or less than HAVE_CURRENT_DATA, and paused is false. Either seeking is true, or the current playback position is not contained in any of the ranges in buffered. It is possible for playback to stop for two other reasons without paused being false, but those two reasons do not fire this event: maybe playback ended, or playback stopped due to errors.
+    
playing
+     Event
+     Playback has started.
+     readyState is newly equal to or greater than HAVE_FUTURE_DATA, paused is false, seeking is false, or the current playback position is contained in one of the ranges in buffered.
+    
canplay
+     Event
+     The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content.
+     readyState newly increased to HAVE_FUTURE_DATA or greater.
+    
canplaythrough
+     Event
+     The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering.
+     readyState is newly equal to HAVE_ENOUGH_DATA.
+
+   
seeking
+     Event
+     The seeking IDL attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.
+     
+    
seeked
+     Event
+     The seeking IDL attribute changed to false.
+     
+    
timeupdate
+     Event
+     The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously.
+     
+    
ended
+     Event
+     Playback has stopped because the end of the media resource was reached.
+     currentTime equals the end of the media resource; ended is true.
+
+   
ratechange
+     Event
+     Either the defaultPlaybackRate or the playbackRate attribute has just been updated.
+     
+    
durationchange
+     Event
+     The duration attribute has just been updated.
+     
+    
volumechange
+     Event
+     Either the volume attribute or the muted attribute has changed. Fired after the relevant attribute's setter has returned.
+     
+  

+
+  
4.8.10.15 Security and privacy considerations

+
+  
The main security and privacy implications of the
+  video and audio elements come from the
+  ability to embed media cross-origin. There are two directions that
+  threats can flow: from hostile content to a victim page, and from a
+  hostile page to victim content.

+
+  
If a victim page embeds hostile content, the threat is that the
+  content might contain scripted code that attempts to interact with
+  the Document that embeds the content. To avoid this,
+  user agents must ensure that there is no access from the content to
+  the embedding page. In the case of media content that uses DOM
+  concepts, the embedded content must be treated as if it was in its
+  own unrelated top-level browsing context.

+
+  
For instance, if an SVG animation was embedded in
+  a video element, the user agent would not give it
+  access to the DOM of the outer page. From the perspective of scripts
+  in the SVG resource, the SVG file would appear to be in a lone
+  top-level browsing context with no parent.

+
+  
If a hostile page embeds victim content, the threat is that the
+  embedding page could obtain information from the content that it
+  would not otherwise have access to. The API does expose some
+  information: the existence of the media, its type, its duration, its
+  size, and the performance characteristics of its host. Such
+  information is already potentially problematic, but in practice the
+  same information can more or less be obtained using the
+  img element, and so it has been deemed acceptable.

+
+  
However, significantly more sensitive information could be
+  obtained if the user agent further exposes metadata within the
+  content such as subtitles or chapter titles. This version of the API
+  does not expose such information. Future extensions to this API will
+  likely reuse a mechanism such as CORS to check that the embedded
+  content's site has opted in to exposing such information. [CORS]
 
+
+  
An attacker could trick a user running within a
+  corporate network into visiting a site that attempts to load a video
+  from a previously leaked location on the corporation's intranet. If
+  such a video included confidential plans for a new product, then
+  being able to read the subtitles would present a confidentiality
+  breach.

+
+  

+
+
+  
4.8.11 The canvas element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Embedded content.

+   
Contexts in which this element may be used:

+   
Where embedded content is expected.

+   
Content model:

+   
Transparent.

+   
Content attributes:

+   
Global attributes

+   
width

+   
height

+   
DOM interface:

+   

+    
interface HTMLCanvasElement : HTMLElement {
+           attribute unsigned long width;
+           attribute unsigned long height;
+
+  DOMString toDataURL(in optional DOMString type, in any... args);
+
+  object getContext(in DOMString contextId);
+};

+   

+  
The canvas element provides scripts with a
+  resolution-dependent bitmap canvas, which can be used for rendering
+  graphs, game graphics, or other visual images on the fly.

+
+  
Authors should not use the canvas element in a
+  document when a more suitable element is available. For example, it
+  is inappropriate to use a canvas element to render a
+  page heading: if the desired presentation of the heading is
+  graphically intense, it should be marked up using appropriate
+  elements (typically h1) and then styled using CSS and
+  supporting technologies such as XBL.

+
+  
When authors use the canvas element, they must also
+  provide content that, when presented to the user, conveys
+  essentially the same function or purpose as the bitmap canvas. This
+  content may be placed as content of the canvas
+  element. The contents of the canvas element, if any,
+  are the element's fallback content.

+
+  
In interactive visual media, if scripting is enabled for the
+  canvas element, and if support for canvas
+  elements has been enabled, the canvas element
+  represents embedded content consisting of
+  a dynamically created image.

+
+  
In non-interactive, static, visual media, if the
+  canvas element has been previously painted on (e.g. if
+  the page was viewed in an interactive visual medium and is now being
+  printed, or if some script that ran during the page layout process
+  painted on the element), then the canvas element
+  represents embedded content with the
+  current image and size. Otherwise, the element represents its
+  fallback content instead.

+
+  
In non-visual media, and in visual media if scripting is disabled for the
+  canvas element or if support for canvas
+  elements has been disabled, the canvas element
+  represents its fallback content
+  instead.

+
+  
+  
When a canvas element represents
+  embedded content, the user can still focus descendants
+  of the canvas element (in the fallback
+  content). This allows authors to make an interactive canvas
+  keyboard-focusable: authors should have a one-to-one mapping of
+  interactive regions to focusable elements in the fallback
+  content.

+
+  
The canvas element has two attributes to control the
+  size of the coordinate space: width and height. These
+  attributes, when specified, must have values that are valid non-negative
+  integers. The rules for parsing
+  non-negative integers must be used to obtain their numeric
+  values. If an attribute is missing, or if parsing its value returns
+  an error, then the default value must be used instead. The
+  width attribute defaults to
+  300, and the height
+  attribute defaults to 150.

+
+  
The intrinsic dimensions of the canvas element equal
+  the size of the coordinate space, with the numbers interpreted in
+  CSS pixels. However, the element can be sized arbitrarily by a
+  style sheet. During rendering, the image is scaled to fit this layout
+  size.

+
+  

+
+  
The size of the coordinate space does not necessarily represent
+  the size of the actual bitmap that the user agent will use
+  internally or during rendering. On high-definition displays, for
+  instance, the user agent may internally use a bitmap with two device
+  pixels per unit in the coordinate space, so that the rendering
+  remains at high quality throughout.

+
+  
When the canvas element is created, and subsequently
+  whenever the width and height attributes are set (whether
+  to a new value or to the previous value), the bitmap and any
+  associated contexts must be cleared back to their initial state and
+  reinitialized with the newly specified coordinate space
+  dimensions.

+
+  
When the canvas is initialized, its bitmap must be cleared to
+  transparent black.

+
+  
The width and
+  height IDL
+  attributes must reflect the respective content
+  attributes of the same name.

+
+  

+
+  

+   
Only one square appears to be drawn in the following example:

+   
  // canvas is a reference to a <canvas> element
+  var context = canvas.getContext('2d');
+  context.fillRect(0,0,50,50);
+  canvas.setAttribute('width', '300'); // clears the canvas
+  context.fillRect(0,100,50,50);
+  canvas.width = canvas.width; // clears the canvas
+  context.fillRect(100,0,50,50); // only this square remains

+  

+
+  
To draw on the canvas, authors must first obtain a reference to a
+  context using the getContext(contextId) method of the
+  canvas element.

+
+  
context = canvas . getContext(contextId)

+
+   

+
+    
Returns an object that exposes an API for drawing on the canvas.

+
+    
Returns null if the given context ID is not supported.

+
+   

+
+  
This specification only defines one context, with the name "2d". If getContext() is called with
+  that exact string for its contextId argument,
+  then the UA must return a reference to an object implementing
+  CanvasRenderingContext2D. Other specifications may
+  define their own contexts, which would return different
+  objects.

+
+  
+
+  

+
+  
Vendors may also define experimental contexts using the syntax
+  vendorname-context, for example, moz-3d.

+
+  
When the UA is passed an empty string or a string specifying a
+  context that it does not support, then it must return null. String
+  comparisons must be case-sensitive.

+
+  

+
+  
url = canvas . toDataURL( [ type, ... ])

+
+   

+
+    
Returns a data: URL for the image in the
+    canvas.

+
+    
The first argument, if provided, controls the type of the image
+    to be returned (e.g. PNG or JPEG). The default is image/png; that type is also used if the given
+    type isn't supported. The other arguments are specific to the
+    type, and control the way that the image is generated, as given in
+    the table below.

+
+   

+
+  

+
+  
The toDataURL() method
+  must, when called with no arguments, return a data: URL containing a representation of the image
+  as a PNG file. [PNG]

+
+  
If the canvas has no pixels (i.e. either its horizontal dimension
+  or its vertical dimension is zero) then the method must return the
+  string "data:,". (This is the shortest data: URL; it represents the empty string in a text/plain resource.)

+
+  
When the toDataURL(type) method is called with one or
+  more arguments, it must return a data:
+  URL containing a representation of the image in the format given by
+  type. The possible values are MIME types with no parameters, for example
+  image/png, image/jpeg, or even maybe
+  image/svg+xml if the implementation actually keeps
+  enough information to reliably render an SVG image from the
+  canvas.

+
+  
For image types that do not support an alpha channel, the image
+  must be composited onto a solid black background using the
+  source-over operator, and the resulting image must be the one used
+  to create the data: URL.

+
+  
Only support for image/png is required. User agents
+  may support other types. If the user agent does not support the
+  requested type, it must return the image using the PNG format.

+
+  
User agents must convert the
+  provided type to ASCII lowercase before establishing if they
+  support that type and before creating the data: URL.

+
+  

+
+  
When trying to use types other than
+  image/png, authors can check if the image was really
+  returned in the requested format by checking to see if the returned
+  string starts with one the exact strings "data:image/png," or "data:image/png;". If it does, the image is PNG, and
+  thus the requested type was not supported. (The one exception to
+  this is if the canvas has either no height or no width, in which
+  case the result might simply be "data:,".)

+
+  

+
+  
If the method is invoked with the first argument giving a type
+  corresponding to one of the types given in the first column of the
+  following table, and the user agent supports that type, then the
+  subsequent arguments, if any, must be treated as described in the
+  second cell of that row.

+
+  

+
+  
 Type  Other arguments
+   
 image/jpeg
+      The second argument, if it is a
+     number in the range 0.0 to 1.0 inclusive, must
+     be treated as the desired quality level. If it is not a number or is outside that range, the
+     user agent must use its default value, as if the argument had
+     been omitted.
+  

+
+  
For the purposes of these rules, an argument is considered to be
+  a number if it is converted to an IDL double value by the rules for
+  handling arguments of type any in the Web IDL
+  specification. [WEBIDL]

+
+  
Other arguments must be ignored and must not cause the user agent
+  to raise an exception. A future version of this specification will
+  probably define other parameters to be passed to toDataURL() to allow authors to
+  more carefully control compression settings, image metadata,
+  etc.

+
+  

+
+  
+
+  

+
+  
4.8.11.1 The 2D context

+
+  
+
+  
When the getContext()
+  method of a canvas element is invoked with 2d as the argument, a
+  CanvasRenderingContext2D object is returned.

+
+  
+
+  

+
+
+  
There is only one CanvasRenderingContext2D object
+  per canvas, so calling the getContext() method with the
+  2d argument a second time
+  must return the same object.

+
+  

+
+  
The 2D context represents a flat Cartesian surface whose origin
+  (0,0) is at the top left corner, with the coordinate space having
+  x values increasing when going right, and y values increasing when going down.

+
+  
interface CanvasRenderingContext2D {
+
+  // back-reference to the canvas
+  readonly attribute HTMLCanvasElement canvas;
+
+  // state
+  void save(); // push state on state stack
+  void restore(); // pop state stack and restore state
+
+  // transformations (default transform is the identity matrix)
+  void scale(in float x, in float y);
+  void rotate(in float angle);
+  void translate(in float x, in float y);
+  void transform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
+  void setTransform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
+
+  // compositing
+           attribute float globalAlpha; // (default 1.0)
+           attribute DOMString globalCompositeOperation; // (default source-over)
+
+  // colors and styles
+           attribute any strokeStyle; // (default black)
+           attribute any fillStyle; // (default black)
+  CanvasGradient createLinearGradient(in float x0, in float y0, in float x1, in float y1);
+  CanvasGradient createRadialGradient(in float x0, in float y0, in float r0, in float x1, in float y1, in float r1);
+  CanvasPattern createPattern(in HTMLImageElement image, in DOMString repetition);
+  CanvasPattern createPattern(in HTMLCanvasElement image, in DOMString repetition);
+  CanvasPattern createPattern(in HTMLVideoElement image, in DOMString repetition);
+
+  // line caps/joins
+           attribute float lineWidth; // (default 1)
+           attribute DOMString lineCap; // "butt", "round", "square" (default "butt")
+           attribute DOMString lineJoin; // "round", "bevel", "miter" (default "miter")
+           attribute float miterLimit; // (default 10)
+
+  // shadows
+           attribute float shadowOffsetX; // (default 0)
+           attribute float shadowOffsetY; // (default 0)
+           attribute float shadowBlur; // (default 0)
+           attribute DOMString shadowColor; // (default transparent black)
+
+  // rects
+  void clearRect(in float x, in float y, in float w, in float h);
+  void fillRect(in float x, in float y, in float w, in float h);
+  void strokeRect(in float x, in float y, in float w, in float h);
+
+  // path API
+  void beginPath();
+  void closePath();
+  void moveTo(in float x, in float y);
+  void lineTo(in float x, in float y);
+  void quadraticCurveTo(in float cpx, in float cpy, in float x, in float y);
+  void bezierCurveTo(in float cp1x, in float cp1y, in float cp2x, in float cp2y, in float x, in float y);
+  void arcTo(in float x1, in float y1, in float x2, in float y2, in float radius);
+  void rect(in float x, in float y, in float w, in float h);
+  void arc(in float x, in float y, in float radius, in float startAngle, in float endAngle, in boolean anticlockwise);
+  void fill();
+  void stroke();
+  void clip();
+  boolean isPointInPath(in float x, in float y);
+
+  // focus management
+  boolean drawFocusRing(in Element element, in float xCaret, in float yCaret, in optional boolean canDrawCustom);
+
+  // text
+           attribute DOMString font; // (default 10px sans-serif)
+           attribute DOMString textAlign; // "start", "end", "left", "right", "center" (default: "start")
+           attribute DOMString textBaseline; // "top", "hanging", "middle", "alphabetic", "ideographic", "bottom" (default: "alphabetic")
+  void fillText(in DOMString text, in float x, in float y, in optional float maxWidth);
+  void strokeText(in DOMString text, in float x, in float y, in optional float maxWidth);
+  TextMetrics measureText(in DOMString text);
+
+  // drawing images
+  void drawImage(in HTMLImageElement image, in float dx, in float dy, in optional float dw, in float dh);
+  void drawImage(in HTMLImageElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
+  void drawImage(in HTMLCanvasElement image, in float dx, in float dy, in optional float dw, in float dh);
+  void drawImage(in HTMLCanvasElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
+  void drawImage(in HTMLVideoElement image, in float dx, in float dy, in optional float dw, in float dh);
+  void drawImage(in HTMLVideoElement image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
+
+  // pixel manipulation
+  ImageData createImageData(in float sw, in float sh);
+  ImageData createImageData(in ImageData imagedata);
+  ImageData getImageData(in float sx, in float sy, in float sw, in float sh);
+  void putImageData(in ImageData imagedata, in float dx, in float dy, in optional float dirtyX, in float dirtyY, in float dirtyWidth, in float dirtyHeight);
+};
+
+interface CanvasGradient {
+  // opaque object
+  void addColorStop(in float offset, in DOMString color);
+};
+
+interface CanvasPattern {
+  // opaque object
+};
+
+interface TextMetrics {
+  readonly attribute float width;
+};
+
+interface ImageData {
+  readonly attribute unsigned long width;
+  readonly attribute unsigned long height;
+  readonly attribute CanvasPixelArray data;
+};
+
+interface CanvasPixelArray {
+  readonly attribute unsigned long length;
+  getter octet (in unsigned long index);
+  setter void (in unsigned long index, in octet value);
+};

+
+  
context . canvas

+
+   

+
+    
Returns the canvas element.

+
+   

+
+  

+
+  
The canvas
+  attribute must return the canvas element that the
+  context paints on.

+
+  
Except where otherwise specified, for the 2D context interface,
+  any method call with a numeric argument whose value is infinite or a
+  NaN value must be ignored.

+
+  
+
+  
Whenever the CSS value currentColor is used
+  as a color in this API, the "computed value of the 'color' property"
+  for the purposes of determining the computed value of the currentColor keyword is the computed value of the
+  'color' property on the element in question at the time that the
+  color is specified (e.g. when the appropriate attribute is set, or
+  when the method is called; not when the color is rendered or
+  otherwise used). If the computed value of the 'color' property is
+  undefined for a particular case (e.g. because the element is not
+  in a Document), then the "computed value
+  of the 'color' property" for the purposes of determining the
+  computed value of the currentColor keyword is
+  fully opaque black. [CSSCOLOR]

+
+  

+
+
+
+  
4.8.11.1.1 The canvas state

+
+  
Each context maintains a stack of drawing states. Drawing states consist of:

+
+  
The current path and the current bitmap are not part
+  of the drawing state. The current path is persistent, and can only
+  be reset using the beginPath() method. The
+  current bitmap is a property of the canvas, not the context.

+
+  
context . save()

+
+   

+
+    
Pushes the current state onto the stack.

+
+   

+
+   
context . restore()

+
+   

+
+    
Pops the top state on the stack, restoring the context to that state.

+
+   

+
+  

+
+  
The save()
+  method must push a copy of the current drawing state onto the
+  drawing state stack.

+
+  
The restore() method
+  must pop the top entry in the drawing state stack, and reset the
+  drawing state it describes. If there is no saved state, the method
+  must do nothing.

+
+  
+
+  

+
+
+  
4.8.11.1.2 Transformations

+
+  
The transformation matrix is applied to coordinates when creating
+  shapes and paths.
 
+
+  

+
+  
When the context is created, the transformation matrix must
+  initially be the identity transform. It may then be adjusted using
+  the transformation methods.

+
+  
The transformations must be performed in reverse order. For
+  instance, if a scale transformation that doubles the width is
+  applied, followed by a rotation transformation that rotates drawing
+  operations by a quarter turn, and a rectangle twice as wide as it is
+  tall is then drawn on the canvas, the actual result will be a
+  square.

+
+  

+
+  
context . scale(x, y)

+
+   

+
+    
Changes the transformation matrix to apply a scaling transformation with the given characteristics.

+
+   

+
+   
context . rotate(angle)

+
+   

+
+    
Changes the transformation matrix to apply a rotation transformation with the given characteristics. The angle is in radians.

+
+   

+
+   
context . translate(x, y)

+
+   

+
+    
Changes the transformation matrix to apply a translation transformation with the given characteristics.

+
+   

+
+   
context . transform(m11, m12, m21, m22, dx, dy)

+
+   

+
+    
Changes the transformation matrix to apply the matrix given by the arguments as described below.

+
+   

+
+   
context . setTransform(m11, m12, m21, m22, dx, dy)

+
+   

+
+    
Changes the transformation matrix to the matrix given by the arguments as described below.

+
+   

+
+  

+
+  
The scale(x, y) method must
+  add the scaling transformation described by the arguments to the
+  transformation matrix. The x argument represents
+  the scale factor in the horizontal direction and the y argument represents the scale factor in the
+  vertical direction. The factors are multiples.

+
+  
The rotate(angle) method must add the rotation
+  transformation described by the argument to the transformation
+  matrix. The angle argument represents a
+  clockwise rotation angle expressed in radians.

+
+  
The translate(x, y) method must
+  add the translation transformation described by the arguments to the
+  transformation matrix. The x argument represents
+  the translation distance in the horizontal direction and the y argument represents the translation distance in the
+  vertical direction. The arguments are in coordinate space units.

+
+  
The transform(m11, m12, m21, m22, dx,
+  dy) method must multiply the
+  current transformation matrix with the matrix described by:

+
+  

+
+  
+    
+    
+   
+    
+    
+   
+    
+    
+   
m11m21dx
m12m22dy
001

+
+  
The setTransform(m11, m12, m21, m22, dx,
+  dy) method must reset the current
+  transform to the identity matrix, and then invoke the transform(m11, m12, m21, m22, dx,
+  dy) method with the same arguments.

+
+  

+
+
+  
4.8.11.1.3 Compositing

+
+  
context . globalAlpha [ = value ]

+
+   

+
+    
Returns the current alpha value applied to rendering operations.

+
+    
Can be set, to change the alpha value. Values outside of the
+    range 0.0 .. 1.0 are ignored.

+
+   

+
+
+   
context . globalCompositeOperation [ = value ]

+
+   

+
+    
Returns the current composition operation, from the list below.

+
+    
Can be set, to change the composition operation. Unknown values
+    are ignored.

+
+   

+
+  

+
+  
All drawing operations are affected by the global compositing
+  attributes, globalAlpha and globalCompositeOperation.

+
+  
+
+  
The globalAlpha
+  attribute gives an alpha value that is applied to shapes and images
+  before they are composited onto the canvas. The value must be in the
+  range from 0.0 (fully transparent) to 1.0 (no additional
+  transparency). If an attempt is made to set the attribute to a value
+  outside this range, including Infinity and Not-a-Number (NaN)
+  values, the attribute must retain its previous value. When the
+  context is created, the globalAlpha attribute must
+  initially have the value 1.0.

+
+  
The globalCompositeOperation
+  attribute sets how shapes and images are drawn onto the existing
+  bitmap, once they have had globalAlpha and the
+  current transformation matrix applied. It must be set to a value
+  from the following list. In the descriptions below, the source
+  image, A, is the shape or image being rendered,
+  and the destination image, B, is the current
+  state of the bitmap.

+
+  

+
+  
source-atop

+
+   
A atop B. Display the
+   source image wherever both images are opaque. Display the
+   destination image wherever the destination image is opaque but the
+   source image is transparent. Display transparency elsewhere.

+
+   
source-in

+
+   
A in B. Display the
+   source image wherever both the source image and destination image
+   are opaque. Display transparency elsewhere.

+
+   
source-out

+
+   
A out B. Display the
+   source image wherever the source image is opaque and the
+   destination image is transparent. Display transparency
+   elsewhere.

+
+   
source-over (default)

+
+   
A over B. Display the
+   source image wherever the source image is opaque. Display the
+   destination image elsewhere.

+
+
+   
destination-atop

+
+   
B atop A. Same as source-atop but using the
+   destination image instead of the source image and vice versa.

+
+   
destination-in

+
+   
B in A. Same as source-in but using the destination
+   image instead of the source image and vice versa.

+
+   
destination-out

+
+   
B out A. Same as source-out but using the destination
+   image instead of the source image and vice versa.

+
+   
destination-over

+
+   
B over A. Same as source-over but using the
+   destination image instead of the source image and vice versa.

+
+
+
+
+   
lighter

+
+   
A plus B. Display the
+   sum of the source image and destination image, with color values
+   approaching 1 as a limit.

+
+
+   
copy

+
+   
A (B is
+   ignored). Display the source image instead of the destination
+   image.

+
+
+   
xor

+
+   
A xor B. Exclusive OR
+   of the source image and destination image.

+
+
+   
vendorName-operationName

+
+   
Vendor-specific extensions to the list of
+   composition operators should use this syntax.

+
+  

+
+  
These values are all case-sensitive — they must be used
+  exactly as shown. User agents must not recognize values that are not
+  a case-sensitive match for one of the values given
+  above.

+
+  
The operators in the above list must be treated as described by
+  the Porter-Duff operator given at the start of their description
+  (e.g. A over B). [PORTERDUFF]

+
+  
On setting, if the user agent does not recognize the specified
+  value, it must be ignored, leaving the value of globalCompositeOperation
+  unaffected.

+
+  
When the context is created, the globalCompositeOperation
+  attribute must initially have the value
+  source-over.

+
+  

+
+
+  
4.8.11.1.4 Colors and styles

+
+  
context . strokeStyle [ = value ]

+
+   

+
+    
Returns the current style used for stroking shapes.

+
+    
Can be set, to change the stroke style.

+
+    
The style can be either a string containing a CSS color, or a
+    CanvasGradient or CanvasPattern
+    object. Invalid values are ignored.

+
+   

+
+   
context . fillStyle [ = value ]

+
+   

+
+    
Returns the current style used for filling shapes.

+
+    
Can be set, to change the fill style.

+
+    
The style can be either a string containing a CSS color, or a
+    CanvasGradient or CanvasPattern
+    object. Invalid values are ignored.

+
+   

+
+  

+
+  
+
+  
The strokeStyle
+  attribute represents the color or style to use for the lines around
+  shapes, and the fillStyle
+  attribute represents the color or style to use inside the
+  shapes.

+
+  
Both attributes can be either strings,
+  CanvasGradients, or CanvasPatterns. On
+  setting, strings must be parsed as CSS <color> values and the
+  color assigned, and CanvasGradient and
+  CanvasPattern objects must be assigned themselves. [CSSCOLOR] If the value is a string but
+  is not a valid color, or is neither a string, a
+  CanvasGradient, nor a CanvasPattern, then
+  it must be ignored, and the attribute must retain its previous
+  value.

+
+  
When set to a CanvasPattern or
+  CanvasGradient object, the assignment is
+  live, meaning that changes made to the object after the
+  assignment do affect subsequent stroking or filling of shapes.

+
+  
On getting, if the value is a color, then the serialization of the color
+  must be returned. Otherwise, if it is not a color but a
+  CanvasGradient or CanvasPattern, then the
+  respective object must be returned. (Such objects are opaque and
+  therefore only useful for assigning to other attributes or for
+  comparison to other gradients or patterns.)

+
+  
The serialization of a color for a color value is a
+  string, computed as follows: if it has alpha equal to 1.0, then the
+  string is a lowercase six-digit hex value, prefixed with a "#"
+  character (U+0023 NUMBER SIGN), with the first two digits
+  representing the red component, the next two digits representing the
+  green component, and the last two digits representing the blue
+  component, the digits being in the range 0-9 a-f (U+0030 to U+0039
+  and U+0061 to U+0066). Otherwise, the color value has alpha less
+  than 1.0, and the string is the color value in the CSS rgba() functional-notation format: the literal
+  string rgba (U+0072 U+0067 U+0062 U+0061)
+  followed by a U+0028 LEFT PARENTHESIS, a base-ten integer in the
+  range 0-255 representing the red component (using digits 0-9, U+0030
+  to U+0039, in the shortest form possible), a literal U+002C COMMA
+  and U+0020 SPACE, an integer for the green component, a comma and a
+  space, an integer for the blue component, another comma and space, a
+  U+0030 DIGIT ZERO, a U+002E FULL STOP (representing the decimal
+  point), one or more digits in the range 0-9 (U+0030 to U+0039)
+  representing the fractional part of the alpha value, and finally a
+  U+0029 RIGHT PARENTHESIS.

+
+  
When the context is created, the strokeStyle and fillStyle attributes must
+  initially have the string value #000000.

+
+  

+
+  
There are two types of gradients, linear gradients and radial
+  gradients, both represented by objects implementing the opaque
+  CanvasGradient interface.

+
+  
Once a gradient has been created (see below),
+  stops are placed along it to define how the colors are distributed
+  along the gradient. The color of the gradient at
+  each stop is the color specified for that stop. Between each such
+  stop, the colors and the alpha component must be linearly
+  interpolated over the RGBA space without premultiplying the alpha
+  value to find the color to use at that offset. Before the first
+  stop, the color must be the color of the first stop. After the last
+  stop, the color must be the color of the last stop. When there are
+  no stops, the gradient is transparent black.

+
+  
gradient . addColorStop(offset, color)

+
+   

+
+    
Adds a color stop with the given color to the gradient at the
+    given offset. 0.0 is the offset at one end of the gradient, 1.0 is
+    the offset at the other end.

+
+    
Throws an INDEX_SIZE_ERR exception if the offset
+    is out of range. Throws a SYNTAX_ERR exception if the
+    color cannot be parsed.

+
+   

+
+   
gradient = context . createLinearGradient(x0, y0, x1, y1)

+
+   

+
+    
Returns a CanvasGradient object that represents a
+    linear gradient that paints along the line given by the
+    coordinates represented by the arguments.

+
+    
If any of the arguments are not finite numbers, throws a
+    NOT_SUPPORTED_ERR exception.

+
+   

+
+   
gradient = context . createRadialGradient(x0, y0, r0, x1, y1, r1)

+
+   

+
+    
Returns a CanvasGradient object that represents a
+    radial gradient that paints along the cone given by the circles
+    represented by the arguments.

+
+    
If any of the arguments are not finite numbers, throws a
+    NOT_SUPPORTED_ERR exception. If either of the radii
+    are negative, throws an INDEX_SIZE_ERR exception.

+
+   

+
+  

+
+  
The addColorStop(offset, color)
+  method on the CanvasGradient interface adds a new stop
+  to a gradient. If the offset is less than 0,
+  greater than 1, infinite, or NaN, then an
+  INDEX_SIZE_ERR exception must be raised. If the color cannot be parsed as a CSS color, then a
+  SYNTAX_ERR exception must be raised. Otherwise, the
+  gradient must have a new stop placed, at offset offset relative to the whole gradient, and with the
+  color obtained by parsing color as a CSS
+  <color> value. If multiple stops are added at the same offset
+  on a gradient, they must be placed in the order added, with the
+  first one closest to the start of the gradient, and each subsequent
+  one infinitesimally further along towards the end point (in effect
+  causing all but the first and last stop added at each point to be
+  ignored).

+
+  
The createLinearGradient(x0, y0, x1,
+  y1) method takes four arguments
+  that represent the start point (x0, y0) and end point (x1, y1) of the gradient. If any of the arguments to createLinearGradient()
+  are infinite or NaN, the method must raise a
+  NOT_SUPPORTED_ERR exception. Otherwise, the method must
+  return a linear CanvasGradient initialized with the
+  specified line.

+
+  
Linear gradients must be rendered such that all points on a line
+  perpendicular to the line that crosses the start and end points have
+  the color at the point where those two lines cross (with the colors
+  coming from the interpolation and
+  extrapolation described above). The points in the linear
+  gradient must be transformed as described by the current transformation
+  matrix when rendering.

+
+  
If x0 = x1 and y0 = y1, then
+  the linear gradient must paint nothing.

+
+  
The createRadialGradient(x0, y0, r0,
+  x1, y1, r1) method takes six arguments, the
+  first three representing the start circle with origin (x0, y0) and radius r0, and the last three representing the end circle
+  with origin (x1, y1) and
+  radius r1. The values are in coordinate space
+  units. If any of the arguments are infinite or NaN, a
+  NOT_SUPPORTED_ERR exception must be raised. If either
+  of r0 or r1 are negative, an
+  INDEX_SIZE_ERR exception must be raised. Otherwise,
+  the method must return a radial CanvasGradient
+  initialized with the two specified circles.

+
+  
Radial gradients must be rendered by following these steps:

+
+  
  1. If x0 = x1 and y0 = y1 and r0 = r1, then the radial gradient must
+   paint nothing. Abort these steps.
    2. 
+
+   
  2. 
+
+    
    Let x(ω) = (x1-x0)ω + x0
    
+
+    
    Let y(ω) = (y1-y0)ω + y0
    
+
+    
    Let r(ω) = (r1-r0)ω + r0
    
+
+    
    Let the color at ω be the color at
+    that position on the gradient (with the colors coming from the interpolation and extrapolation
+    described above).
    
+
+   
    3. 
+
+   
  3. For all values of ω where r(ω) > 0,
+   starting with the value of ω nearest to
+   positive infinity and ending with the value of ω nearest to negative infinity, draw the
+   circumference of the circle with radius r(ω) at position (x(ω), y(ω)), with the color at ω, but only painting on the parts of the
+   canvas that have not yet been painted on by earlier circles in this
+   step for this rendering of the gradient.
    4. 
+
+  
This effectively creates a cone, touched by the two
+  circles defined in the creation of the gradient, with the part of
+  the cone before the start circle (0.0) using the color of the first
+  offset, the part of the cone after the end circle (1.0) using the
+  color of the last offset, and areas outside the cone untouched by
+  the gradient (transparent black).

+
+  
The points in the radial gradient must be transformed as
+  described by the current
+  transformation matrix when rendering.

+
+  
Gradients must be painted only where the relevant stroking or
+  filling effects requires that they be drawn.

+
+
+
+  

+
+  
Patterns are represented by objects implementing the opaque
+  CanvasPattern interface.

+
+  
pattern = context . createPattern(image, repetition)

+
+   

+
+    
Returns a CanvasPattern object that uses the given image
+    and repeats in the direction(s) given by the repetition argument.

+
+    
The allowed values for repetition are repeat (both directions), repeat-x (horizontal only), repeat-y (vertical only), and no-repeat (neither). If the repetition argument is empty or null, the value
+    repeat is used.

+
+    
If the first argument isn't an img,
+    canvas, or video element, throws a
+    TYPE_MISMATCH_ERR exception. If the image has no
+    image data, throws an INVALID_STATE_ERR exception. If
+    the second argument isn't one of the allowed values, throws a
+    SYNTAX_ERR exception. If the image isn't yet fully
+    decoded, then the method returns null.

+
+   

+
+  

+
+  
To create objects of this type, the createPattern(image, repetition)
+  method is used. The first argument gives the image to use as the
+  pattern (either an HTMLImageElement,
+  HTMLCanvasElement, or HTMLVideoElement
+  object). Modifying this image after calling the createPattern() method
+  must not affect the pattern. The second argument must be a string
+  with one of the following values: repeat,
+  repeat-x, repeat-y,
+  no-repeat. If the empty string or null is
+  specified, repeat must be assumed. If an
+  unrecognized value is given, then the user agent must raise a
+  SYNTAX_ERR exception. User agents must recognize the
+  four values described above exactly (e.g. they must not do case
+  folding). The method must return a CanvasPattern object
+  suitably initialized.

+
+  
The image argument is an instance of either
+  HTMLImageElement, HTMLCanvasElement, or
+  HTMLVideoElement. If the image is
+  null, the implementation must raise a TYPE_MISMATCH_ERR
+  exception.
 
+
+  
If the image argument is an
+  HTMLImageElement object whose complete attribute is false, or
+  if the image argument is an
+  HTMLVideoElement object whose readyState attribute is either
+  HAVE_NOTHING or HAVE_METADATA, then the
+  implementation must return null.

+  
+
+  
If the image argument is an
+  HTMLCanvasElement object with either a horizontal
+  dimension or a vertical dimension equal to zero, then the
+  implementation must raise an INVALID_STATE_ERR
+  exception.

+  
+
+  
Patterns must be painted so that the top left of the first image
+  is anchored at the origin of the coordinate space, and images are
+  then repeated horizontally to the left and right (if the
+  repeat-x string was specified) or vertically up and
+  down (if the repeat-y string was specified) or in all
+  four directions all over the canvas (if the repeat
+  string was specified). The images are not scaled by this process;
+  one CSS pixel of the image must be painted on one coordinate space
+  unit. Of course, patterns must actually be painted only where the
+  stroking or filling effect requires that they be drawn, and are
+  affected by the current transformation matrix.

+
+  
When the createPattern() method
+  is passed an animated image as its image
+  argument, the user agent must use the poster frame of the animation,
+  or, if there is no poster frame, the first frame of the
+  animation.

+  
+
+  
When the image argument is an
+  HTMLVideoElement, then the frame at the current
+  playback position must be used as the source image, and the
+  source image's dimensions must be the intrinsic width and
+  intrinsic height
+  of the media resource (i.e. after any aspect-ratio
+  correction has been applied).

+  
+
+  
+
+  

+
+
+
+  
4.8.11.1.5 Line styles

+
+  
context . lineWidth [ = value ]

+
+   

+
+    
Returns the current line width.

+
+    
Can be set, to change the line width. Values that are not
+    finite values greater than zero are ignored.

+
+   

+
+   
context . lineCap [ = value ]

+
+   

+
+    
Returns the current line cap style.

+
+    
Can be set, to change the line cap style.

+
+    
The possible line cap styles are butt,
+    round, and square. Other values are
+    ignored.

+
+   

+
+   
context . lineJoin [ = value ]

+
+   

+
+    
Returns the current line join style.

+
+    
Can be set, to change the line join style.

+
+    
The possible line join styles are bevel,
+    round, and miter. Other values are
+    ignored.

+
+   

+
+   
context . miterLimit [ = value ]

+
+   

+
+    
Returns the current miter limit ratio.

+
+    
Can be set, to change the miter limit ratio. Values that are
+    not finite values greater than zero are ignored.

+
+   

+
+  

+
+  
The lineWidth
+  attribute gives the width of lines, in coordinate space units. On
+  getting, it must return the current value. On setting, zero,
+  negative, infinite, and NaN values must be ignored, leaving the
+  value unchanged; other values must change the current value to the
+  new value.

+
+  
When the context is created, the lineWidth attribute must
+  initially have the value 1.0.

+
+  
The lineCap attribute
+  defines the type of endings that UAs will place on the end of
+  lines. The three valid values are butt,
+  round, and square. The butt
+  value means that the end of each line has a flat edge perpendicular
+  to the direction of the line (and that no additional line cap is
+  added). The round value means that a semi-circle with
+  the diameter equal to the width of the line must then be added on to
+  the end of the line. The square value means that a
+  rectangle with the length of the line width and the width of half
+  the line width, placed flat against the edge perpendicular to the
+  direction of the line, must be added at the end of each line.

+
+  
On getting, it must return the current value. On setting, if the
+  new value is one of the literal strings butt,
+  round, and square, then the current value
+  must be changed to the new value; other values must ignored, leaving
+  the value unchanged.

+
+  
When the context is created, the lineCap attribute must
+  initially have the value butt.

+
+  
The lineJoin
+  attribute defines the type of corners that UAs will place where two
+  lines meet. The three valid values are bevel,
+  round, and miter.

+
+  
On getting, it must return the current value. On setting, if the
+  new value is one of the literal strings bevel,
+  round, and miter, then the current value
+  must be changed to the new value; other values must be ignored,
+  leaving the value unchanged.

+
+  
When the context is created, the lineJoin attribute must
+  initially have the value miter.

+
+  
A join exists at any point in a subpath shared by two consecutive
+  lines. When a subpath is closed, then a join also exists at its
+  first point (equivalent to its last point) connecting the first and
+  last lines in the subpath.

+
+  
In addition to the point where the join occurs, two additional
+  points are relevant to each join, one for each line: the two corners
+  found half the line width away from the join point, one
+  perpendicular to each line, each on the side furthest from the other
+  line.

+
+  
A filled triangle connecting these two opposite corners with a
+  straight line, with the third point of the triangle being the join
+  point, must be rendered at all joins. The lineJoin attribute controls
+  whether anything else is rendered. The three aforementioned values
+  have the following meanings:

+
+  
The bevel value means that this is all that is
+  rendered at joins.

+
+  
The round value means that a filled arc connecting
+  the two aforementioned corners of the join, abutting (and not
+  overlapping) the aforementioned triangle, with the diameter equal to
+  the line width and the origin at the point of the join, must be
+  rendered at joins.

+
+  
The miter value means that a second filled triangle
+  must (if it can given the miter length) be rendered at the join,
+  with one line being the line between the two aforementioned corners,
+  abutting the first triangle, and the other two being continuations of
+  the outside edges of the two joining lines, as long as required to
+  intersect without going over the miter length.

+
+  
The miter length is the distance from the point where the join
+  occurs to the intersection of the line edges on the outside of the
+  join. The miter limit ratio is the maximum allowed ratio of the
+  miter length to half the line width. If the miter length would cause
+  the miter limit ratio to be exceeded, this second triangle must not
+  be rendered.

+
+  
The miter limit ratio can be explicitly set using the miterLimit
+  attribute. On getting, it must return the current value. On setting,
+  zero, negative, infinite, and NaN values must be ignored, leaving
+  the value unchanged; other values must change the current value to
+  the new value.

+
+  
When the context is created, the miterLimit attribute must
+  initially have the value 10.0.

+
+  
+
+  

+
+
+  
4.8.11.1.6 Shadows

+
+  
All drawing operations are affected by the four global shadow
+  attributes.

+
+  
context . shadowColor [ = value ]

+
+   

+
+    
Returns the current shadow color.

+
+    
Can be set, to change the shadow color. Values that cannot be parsed as CSS colors are ignored.

+
+   

+
+   
context . shadowOffsetX [ = value ]

+   
context . shadowOffsetY [ = value ]

+
+   

+
+    
Returns the current shadow offset.

+
+    
Can be set, to change the shadow offset. Values that are not finite numbers are ignored.

+
+   

+
+   
context . shadowBlur [ = value ]

+
+   

+
+    
Returns the current level of blur applied to shadows.

+
+    
Can be set, to change the blur level. Values that are not finite numbers greater than or equal to zero are ignored.

+
+   

+
+  

+
+  
The shadowColor
+  attribute sets the color of the shadow.

+
+  
When the context is created, the shadowColor attribute
+  initially must be fully-transparent black.

+
+  
On getting, the serialization of the color must be returned.

+
+  
On setting, the new value must be parsed as a CSS <color>
+  value and the color assigned. If the value is not a valid color,
+  then it must be ignored, and the attribute must retain its previous
+  value. [CSSCOLOR]

+
+  
The shadowOffsetX
+  and shadowOffsetY
+  attributes specify the distance that the shadow will be offset in
+  the positive horizontal and positive vertical distance
+  respectively. Their values are in coordinate space units. They are
+  not affected by the current transformation matrix.

+
+  
When the context is created, the shadow offset attributes must
+  initially have the value 0.

+
+  
On getting, they must return their current value. On setting, the
+  attribute being set must be set to the new value, except if the
+  value is infinite or NaN, in which case the new value must be
+  ignored.

+
+  
The shadowBlur
+  attribute specifies the size of the blurring effect. (The units do
+  not map to coordinate space units, and are not affected by the
+  current transformation matrix.)

+
+  
When the context is created, the shadowBlur attribute must
+  initially have the value 0.

+
+  
On getting, the attribute must return its current value. On
+  setting the attribute must be set to the new value, except if the
+  value is negative, infinite or NaN, in which case the new value must
+  be ignored.

+
+  
Shadows are only drawn
+  if the opacity component of the alpha component of the color
+  of shadowColor is
+  non-zero and either the shadowBlur is non-zero, or
+  the shadowOffsetX
+  is non-zero, or the shadowOffsetY is
+  non-zero.

+
+  
When shadows are drawn, they must be rendered as follows:

+
+  
  1.  
    Let A be an infinite transparent black
+   bitmap on which the source image for which a shadow is being
+   created has been rendered.
     
    2. 
+
+   
  2.  
    Let B be an infinite transparent black
+   bitmap, with a coordinate space and an origin identical to A.
     
    3. 
+
+   
  3.  
    Copy the alpha channel of A to B, offset by shadowOffsetX in the
+   positive x direction, and shadowOffsetY in the
+   positive y direction.
     
    4. 
+
+   
  4.  
    If shadowBlur is greater than
+   0:
    
+
+    
    1.  
      If shadowBlur is less than
+     8, let σ be half the value of shadowBlur; otherwise,
+     let σ be the square root of multiplying
+     the value of shadowBlur by
+     2.
      2. 
+
+     
    2.  
      Perform a 2D Gaussian Blur on B,
+     using σ as the standard deviation.
      
+      
      3. 
+
+    
    User agents may limit values of σ to
+    an implementation-specific maximum value to avoid exceeding
+    hardware limitations during the Gaussian blur operation.
    
+
+   
    5. 
+
+   
  5.  
    Set the red, green, and blue components of every pixel in
+   B to the red, green, and blue components
+   (respectively) of the color of shadowColor.
     
    6. 
+
+   
  6.  
    Multiply the alpha component of every pixel in B by the alpha component of the color of shadowColor.
     
    7. 
+
+   
  7.  
    The shadow is in the bitmap B, and is
+   rendered as part of the drawing model described below.
     
    8. 
+
+  

+
+  
If the current composition operation is copy, shadows effectively won't render
+  (since the shape will overwrite the shadow).

+
+
+  
4.8.11.1.7 Simple shapes (rectangles)

+
+  
There are three methods that immediately draw rectangles to the
+  bitmap. They each take four arguments; the first two give the x and y coordinates of the top
+  left of the rectangle, and the second two give the width w and height h of the rectangle,
+  respectively.

+
+  

+
+  
The current
+  transformation matrix must be applied to the following four
+  coordinates, which form the path that must then be closed to get the
+  specified rectangle: (x, y), (x+w, y),
+  (x+w,
+  y+h),
+  (x, y+h).

+
+  
Shapes are painted without affecting the current path, and are
+  subject to the clipping region,
+  and, with the exception of clearRect(), also shadow effects, global alpha, and global composition
+  operators.

+
+  

+
+  
context . clearRect(x, y, w, h)

+
+   

+
+    
Clears all pixels on the canvas in the given rectangle to transparent black.

+
+   

+
+   
context . fillRect(x, y, w, h)

+
+   

+
+    
Paints the given rectangle onto the canvas, using the current fill style.

+
+   

+
+   
context . strokeRect(x, y, w, h)

+
+   

+
+    
Paints the box that outlines the given rectangle onto the canvas, using the current stroke style.

+
+   

+
+  

+
+  
The clearRect(x, y, w, h) method must clear the pixels in the
+  specified rectangle that also intersect the current clipping region
+  to a fully transparent black, erasing any previous image. If either
+  height or width are zero, this method has no effect.

+
+  
The fillRect(x, y, w, h) method must paint the specified
+  rectangular area using the fillStyle. If either height
+  or width are zero, this method has no effect.

+
+  
The strokeRect(x, y, w, h) method must stroke the specified
+  rectangle's path using the strokeStyle, lineWidth, lineJoin, and (if
+  appropriate) miterLimit attributes. If
+  both height and width are zero, this method has no effect, since
+  there is no path to stroke (it's a point). If only one of the two is
+  zero, then the method will draw a line instead (the path for the
+  outline is just a straight line along the non-zero dimension).

+
+  

+
+
+  
4.8.11.1.8 Complex shapes (paths)

+
+  
The context always has a current path. There is only one current
+  path, it is not part of the drawing state.

+
+  
A path has a list of zero or more subpaths. Each
+  subpath consists of a list of one or more points, connected by
+  straight or curved lines, and a flag indicating whether the subpath
+  is closed or not. A closed subpath is one where the last point of
+  the subpath is connected to the first point of the subpath by a
+  straight line. Subpaths with fewer than two points are ignored when
+  painting the path.

+
+  
context . beginPath()

+
+   

+
+    
Resets the current path.

+
+   

+
+   
context . moveTo(x, y)

+
+   

+
+    
Creates a new subpath with the given point.

+
+   

+
+   
context . closePath()

+
+   

+
+    
Marks the current subpath as closed, and starts a new subpath with a point the same as the start and end of the newly closed subpath.

+
+   

+
+   
context . lineTo(x, y)

+
+   

+
+    
Adds the given point to the current subpath, connected to the previous one by a straight line.

+
+   

+
+   
context . quadraticCurveTo(cpx, cpy, x, y)

+
+   

+
+    
Adds the given point to the current path, connected to the previous one by a quadratic Bézier curve with the given control point.

+
+   

+
+   
context . bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y)

+
+   

+
+    
Adds the given point to the current path, connected to the previous one by a cubic Bézier curve with the given control points.

+
+   

+
+   
context . arcTo(x1, y1, x2, y2, radius)

+
+   

+
+    
Adds a point to the current path, connected to the previous one
+    by a straight line, then adds a second point to the current path,
+    connected to the previous one by an arc whose properties are
+    described by the arguments.

+
+    
Throws an INDEX_SIZE_ERR exception if the given
+    radius is negative.

+
+   

+
+   
context . arc(x, y, radius, startAngle, endAngle, anticlockwise)

+
+   

+
+    
Adds points to the subpath such that the arc described by the
+    circumference of the circle described by the arguments, starting
+    at the given start angle and ending at the given end angle, going
+    in the given direction, is added to the path, connected to the
+    previous point by a straight line.

+
+    
Throws an INDEX_SIZE_ERR exception if the given
+    radius is negative.

+
+   

+
+   
context . rect(x, y, w, h)

+
+   

+
+    
Adds a new closed subpath to the path, representing the given rectangle.

+
+   

+
+   
context . fill()

+
+   

+
+    
Fills the subpaths with the current fill style.

+
+   

+
+   
context . stroke()

+
+   

+
+    
Strokes the subpaths with the current stroke style.

+
+   

+
+   
context . clip()

+
+   

+
+    
Further constrains the clipping region to the given path.

+
+   

+
+   
context . isPointInPath(x, y)

+
+   

+
+    
Returns true if the given point is in the current path.

+
+   

+
+  

+
+  
Initially, the context's path must have zero subpaths.

+
+  
The points and lines added to the path by these methods must be
+  transformed according to the current transformation
+  matrix as they are added.

+
+
+  
The beginPath()
+  method must empty the list of subpaths so that the context once
+  again has zero subpaths.

+
+
+  
The moveTo(x, y) method must
+  create a new subpath with the specified point as its first (and
+  only) point.

+
+  
When the user agent is to ensure there is a subpath
+  for a coordinate (x, y), the
+  user agent must check to see if the context has any subpaths, and if
+  it does not, then the user agent must create a new subpath with the
+  point (x, y) as its first
+  (and only) point, as if the moveTo() method had been
+  called.

+
+
+  
The closePath()
+  method must do nothing if the context has no subpaths. Otherwise, it
+  must mark the last subpath as closed, create a new subpath whose
+  first point is the same as the previous subpath's first point, and
+  finally add this new subpath to the path.

+
+  
If the last subpath had more than one point in its
+  list of points, then this is equivalent to adding a straight line
+  connecting the last point back to the first point, thus "closing"
+  the shape, and then repeating the last (possibly implied) moveTo() call.

+
+
+  
New points and the lines connecting them are added to subpaths
+  using the methods described below. In all cases, the methods only
+  modify the last subpath in the context's paths.

+
+
+  
The lineTo(x, y) method must
+  ensure there is a subpath for (x, y) if the context has
+  no subpaths. Otherwise, it must connect the last point in the
+  subpath to the given point (x, y) using a straight line, and must then add the given
+  point (x, y) to the
+  subpath.

+
+
+  
The quadraticCurveTo(cpx, cpy, x,
+  y) method must ensure there
+  is a subpath for (cpx,
+  cpy), and then must connect the last
+  point in the subpath to the given point (x, y) using a quadratic Bézier curve with control
+  point (cpx, cpy), and must
+  then add the given point (x, y) to the subpath. [BEZIER]

+
+
+  
The bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y) method must
+  ensure there is a subpath for (cp1x, cp1y), and then must
+  connect the last point in the subpath to the given point (x, y) using a cubic Bézier
+  curve with control points (cp1x, cp1y) and (cp2x, cp2y). Then, it must add the point (x, y) to the subpath. [BEZIER]

+
+  
The arcTo(x1, y1, x2,
+  y2, radius)
+  method must first ensure there is a subpath for (x1, y1). Then, the behavior depends on the
+  arguments and the last point in the subpath, as described below.

+
+  
Negative values for radius must cause the
+  implementation to raise an INDEX_SIZE_ERR
+  exception.

+
+  
Let the point (x0, y0) be
+  the last point in the subpath.

+
+  
If the point (x0, y0) is
+  equal to the point (x1, y1),
+  or if the point (x1, y1) is
+  equal to the point (x2, y2),
+  or if the radius radius is zero, then the method
+  must add the point (x1, y1)
+  to the subpath, and connect that point to the previous point (x0, y0) by a straight line.

+
+  
Otherwise, if the points (x0, y0), (x1, y1), and (x2, y2) all lie on a single straight line, then the
+  method must add the point (x1, y1) to the subpath, and connect that point to the
+  previous point (x0, y0) by a
+  straight line.

+
+  
Otherwise, let The Arc be the shortest arc
+  given by circumference of the circle that has radius radius, and that has one point tangent to the
+  half-infinite line that crosses the point (x0,
+  y0) and ends at the point (x1, y1), and that has a different
+  point tangent to the half-infinite line that ends at the point (x1, y1) and crosses the point
+  (x2, y2). The points at
+  which this circle touches these two lines are called the start and
+  end tangent points respectively. The method must connect the point
+  (x0, y0) to the start
+  tangent point by a straight line, adding the start tangent point to
+  the subpath, and then must connect the start tangent point to the
+  end tangent point by The Arc, adding the end
+  tangent point to the subpath.

+
+  
The arc(x, y, radius,
+  startAngle, endAngle, anticlockwise) method draws an arc. If
+  the context has any subpaths, then the method must add a straight
+  line from the last point in the subpath to the start point of the
+  arc. In any case, it must draw the arc between the start point of
+  the arc and the end point of the arc, and add the start and end
+  points of the arc to the subpath. The arc and its start and end
+  points are defined as follows:

+
+  
Consider a circle that has its origin at (x,
+  y) and that has radius radius. The points at startAngle
+  and endAngle along this circle's circumference,
+  measured in radians clockwise from the positive x-axis, are the
+  start and end points respectively.

+
+  
If the anticlockwise argument is false and
+  endAngle-startAngle is equal to or greater than
+  2π, or, if the anticlockwise
+  argument is true and startAngle-endAngle is
+  equal to or greater than 2π, then the arc is the
+  whole circumference of this circle.

+
+  
+
+  
Otherwise, the arc is the path along the circumference of this
+  circle from the start point to the end point, going anti-clockwise
+  if the anticlockwise argument is true, and
+  clockwise otherwise. Since the points are on the circle, as opposed
+  to being simply angles from zero, the arc can never cover an angle
+  greater than 2π radians. If the two points are the
+  same, or if the radius is zero, then the arc is defined as being of
+  zero length in both directions.

+
+  
Negative values for radius must cause the
+  implementation to raise an INDEX_SIZE_ERR
+  exception.

+
+  
The rect(x, y, w, h) method must create a new subpath
+  containing just the four points (x, y), (x+w,
+  y), (x+w, y+h),
+  (x, y+h), with those four points connected by straight
+  lines, and must then mark the subpath as closed. It must then create
+  a new subpath with the point (x, y) as the only point in the subpath.

+
+
+  
+
+
+  
The fill()
+  method must fill all the subpaths of the current path, using
+  fillStyle, and using
+  the non-zero winding number rule. Open subpaths must be implicitly
+  closed when being filled (without affecting the actual
+  subpaths).

+
+  
Thus, if two overlapping but otherwise independent
+  subpaths have opposite windings, they cancel out and result in no
+  fill. If they have the same winding, that area just gets painted
+  once.

+
+  
The stroke() method
+  must calculate the strokes of all the subpaths of the current path,
+  using the lineWidth,
+  lineCap, lineJoin, and (if
+  appropriate) miterLimit attributes, and
+  then fill the combined stroke area using the strokeStyle
+  attribute.

+
+  
Since the subpaths are all stroked as one,
+  overlapping parts of the paths in one stroke operation are treated
+  as if their union was what was painted.

+
+  
Paths, when filled or stroked, must be painted without affecting
+  the current path, and must be subject to shadow effects, global alpha, the clipping region, and global composition
+  operators. (Transformations affect the path when the path is
+  created, not when it is painted, though the stroke style is
+  still affected by the transformation during painting.)

+
+  
Zero-length line segments must be pruned before stroking a
+  path. Empty subpaths must be ignored.

+
+
+  
The clip()
+  method must create a new clipping region by calculating
+  the intersection of the current clipping region and the area
+  described by the current path, using the non-zero winding number
+  rule. Open subpaths must be implicitly closed when computing the
+  clipping region, without affecting the actual subpaths. The new
+  clipping region replaces the current clipping region.

+
+  
When the context is initialized, the clipping region must be set
+  to the rectangle with the top left corner at (0,0) and the width and
+  height of the coordinate space.

+
+  
+
+
+  
The isPointInPath(x, y) method must
+  return true if the point given by the x and y coordinates passed to the method, when treated as
+  coordinates in the canvas coordinate space unaffected by the current
+  transformation, is inside the current path as determined by the
+  non-zero winding number rule; and must return false
+  otherwise. Points on the path itself are considered to be inside the
+  path. If either of the arguments is infinite or NaN, then the method
+  must return false.

+
+  

+
+
+  
4.8.11.1.9 Focus management
 
+
+  
When a canvas is interactive, authors should include focusable
+  elements in the element's fallback content corresponding to each
+  focusable part of the canvas.

+
+  
To indicate which focusable part of the canvas is currently
+  focused, authors should use the drawFocusRing() method,
+  passing it the element for which a ring is being drawn. This method
+  only draws the focus ring if the element is focused, so that it can
+  simply be called whenever drawing the element, without checking
+  whether the element is focused or not first. The position of the
+  center of the control, or of the editing caret if the control has
+  one, should be given in the x and y arguments.

+
+  
shouldDraw = context . drawFocusRing(element, x, y, [ canDrawCustom ])

+
+   

+
+    
If the given element is focused, draws a focus ring around the
+    current path, following the platform conventions for focus
+    rings. The given coordinate is used if the user's attention needs
+    to be brought to a particular position (e.g. if a magnifier is
+    following the editing caret in a text field).

+
+    
If the canDrawCustom argument is true, then
+    the focus ring is only drawn if the user has configured his system
+    to draw focus rings in a particular manner. (For example, high
+    contrast focus rings.)

+
+    
Returns true if the given element is focused, the canDrawCustom argument is true, and the user has
+    not configured his system to draw focus rings in a particular
+    manner. Otherwise, returns false.

+
+    
When the method returns true, the author is expected to
+    manually draw a focus ring.

+
+   

+
+  

+
+  
The drawFocusRing(element, x, y, [canDrawCustom])
+  method, when invoked, must run the following steps:

+
+  
  1. If element is not focused or is not a
+   descendant of the element with whose context the method is
+   associated, then return false and abort these steps.
    2. 
+
+   
  2. Transform the given point (x, y) according to the current transformation
+   matrix.
    3. 
+
+   
  3. Optionally, inform the user that the focus is at the given
+   (transformed) coordinate on the canvas. (For example, this could
+   involve moving the user's magnification tool.)
    4. 
+
+   
  4. 
+
+    
    If the user has requested the use of particular focus rings
+    (e.g. high-contrast focus rings), or if the canDrawCustom argument is absent or false, then
+    draw a focus ring of the appropriate style along the path,
+    following platform conventions, return false, and abort these
+    steps.
    
+
+    
    The focus ring should not be subject to the shadow effects, the global alpha, or the global composition
+    operators, but should be subject to the clipping region.
    
+
+   
    5. 
+
+   
  5. Return true.
    6. 
+
+  

+
+  

+
+   
This canvas element has a couple of checkboxes:

+
+   
<canvas height=400 width=750>
+ <label><input type=checkbox id=showA> Show As</label>
+ <label><input type=checkbox id=showB> Show Bs</label>
+ <!-- ... -->
+</canvas>
+<script>
+ function drawCheckbox(context, element, x, y) {
+   context.save();
+   context.font = '10px sans-serif';
+   context.textAlign = 'left';
+   context.textBaseline = 'middle';
+   var metrics = context.measureText(element.labels[0].textContent);
+   context.beginPath();
+   context.strokeStyle = 'black';
+   context.rect(x-5, y-5, 10, 10);
+   context.stroke();
+   if (element.checked) {
+     context.fillStyle = 'black';
+     context.fill();
+   }
+   context.fillText(element.labels[0].textContent, x+5, y);
+   context.beginPath();
+   context.rect(x-7, y-7, 12 + metrics.width+2, 14);
+   if (context.drawFocusRing(element, x, y, true)) {
+     context.strokeStyle = 'silver';
+     context.stroke();
+   }
+   context.restore();
+ }
+ function drawBase() { /* ... */ }
+ function drawAs() { /* ... */ }
+ function drawBs() { /* ... */ }
+ function redraw() {
+   var canvas = document.getElementsByTagName('canvas')[0];
+   var context = canvas.getContext('2d');
+   context.clearRect(0, 0, canvas.width, canvas.height);
+   drawCheckbox(context, document.getElementById('showA'), 20, 40);
+   drawCheckbox(context, document.getElementById('showB'), 20, 60);
+   drawBase();
+   if (document.getElementById('showA').checked)
+     drawAs();
+   if (document.getElementById('showB').checked)
+     drawBs();
+ }
+ function processClick(event) {
+   var canvas = document.getElementsByTagName('canvas')[0];
+   var context = canvas.getContext('2d');
+   var x = event.clientX - canvas.offsetLeft;
+   var y = event.clientY - canvas.offsetTop;
+   drawCheckbox(context, document.getElementById('showA'), 20, 40);
+   if (context.isPointInPath(x, y))
+     document.getElementById('showA').checked = !(document.getElementById('showA').checked);
+   drawCheckbox(context, document.getElementById('showB'), 20, 60);
+   if (context.isPointInPath(x, y))
+     document.getElementById('showB').checked = !(document.getElementById('showB').checked);
+   redraw();
+ }
+ document.getElementsByTagName('canvas')[0].addEventListener('focus', redraw, true);
+ document.getElementsByTagName('canvas')[0].addEventListener('blur', redraw, true);
+ document.getElementsByTagName('canvas')[0].addEventListener('change', redraw, true);
+ document.getElementsByTagName('canvas')[0].addEventListener('click', processClick, false);
+ redraw();
+</script>

+
+
+  

+
+
+  
4.8.11.1.10 Text
 
+
+  
context . font [ = value ]

+
+   

+
+    
Returns the current font settings.

+
+    
Can be set, to change the font. The syntax is the same as for
+    the CSS 'font' property; values that cannot be parsed as CSS font
+    values are ignored.

+
+    
Relative keywords and lengths are computed relative to the font
+    of the canvas element.

+
+   

+
+   
context . textAlign [ = value ]

+
+   

+
+    
Returns the current text alignment settings.

+
+    
Can be set, to change the alignment. The possible values are
+    start, end, left, right, and center. Other values are ignored. The default is
+    start.

+
+   

+
+   
context . textBaseline [ = value ]

+
+   

+
+    
Returns the current baseline alignment settings.

+
+    
Can be set, to change the baseline alignment. The possible
+    values and their meanings are given below. Other values are
+    ignored. The default is alphabetic.

+
+   

+
+   
context . fillText(text, x, y [, maxWidth ] )

+   
context . strokeText(text, x, y [, maxWidth ] )

+
+   

+
+    
Fills or strokes (respectively) the given text at the given
+    position. If a maximum width is provided, the text will be scaled
+    to fit that width if necessary.

+
+   

+
+   
metrics = context . measureText(text)

+
+   

+
+    
Returns a TextMetrics object with the metrics of the given text in the current font.

+
+   

+
+   
metrics . width

+
+   

+
+    
Returns the advance width of the text that was passed to the
+    measureText()
+    method.

+
+   

+
+  

+
+  
The font IDL
+  attribute, on setting, must be parsed the same way as the 'font'
+  property of CSS (but without supporting property-independent style
+  sheet syntax like 'inherit'), and the resulting font must be
+  assigned to the context, with the 'line-height' component forced to
+  'normal', with the 'font-size' component converted to CSS pixels,
+  and with system fonts being computed to explicit values. If the new
+  value is syntactically incorrect (including using
+  property-independent style sheet syntax like 'inherit' or
+  'initial'), then it must be ignored, without assigning a new font
+  value. [CSS]

+
+  
Font names must be interpreted in the context of the
+  canvas element's stylesheets; any fonts embedded using
+  @font-face must therefore be available once
+  they are loaded. (If a font is referenced before it is fully loaded,
+  then it must be treated as if it was an unknown font, falling back
+  to another as described by the relevant CSS specifications.) [CSSFONTS]

+
+  
Only vector fonts should be used by the user agent; if a user
+  agent were to use bitmap fonts then transformations would likely
+  make the font look very ugly.

+
+  
On getting, the font
+  attribute must return the serialized form of the current font of the context
+  (with no 'line-height' component). [CSSOM]

+
+  

+
+   
For example, after the following statement:

+
+   
context.font = 'italic 400 12px/2 Unknown Font, sans-serif';

+
+   
...the expression context.font would
+   evaluate to the string "italic 12px "Unknown Font", sans-serif". The
+   "400" font-weight doesn't appear because that is the default
+   value. The line-height doesn't appear because it is forced to
+   "normal", the default value.

+
+  

+
+  
When the context is created, the font of the context must be set
+  to 10px sans-serif. When the 'font-size' component is set to lengths
+  using percentages, 'em' or 'ex' units, or the 'larger' or 'smaller'
+  keywords, these must be interpreted relative to the computed value
+  of the 'font-size' property of the corresponding canvas
+  element at the time that the attribute is set. When the
+  'font-weight' component is set to the relative values 'bolder' and
+  'lighter', these must be interpreted relative to the computed value
+  of the 'font-weight' property of the corresponding
+  canvas element at the time that the attribute is
+  set. If the computed values are undefined for a particular case
+  (e.g. because the canvas element is not in a
+  Document), then the relative keywords must be
+  interpreted relative to the normal-weight 10px sans-serif
+  default.

+
+  
The textAlign IDL
+  attribute, on getting, must return the current value. On setting, if
+  the value is one of start, end, left, right, or center, then the
+  value must be changed to the new value. Otherwise, the new value
+  must be ignored. When the context is created, the textAlign attribute must
+  initially have the value start.

+
+  
The textBaseline
+  IDL attribute, on getting, must return the current value. On
+  setting, if the value is one of top, hanging, middle, alphabetic,
+  ideographic,
+  or bottom,
+  then the value must be changed to the new value. Otherwise, the new
+  value must be ignored. When the context is created, the textBaseline attribute
+  must initially have the value alphabetic.

+
+  

+
+  
The textBaseline
+  attribute's allowed keywords correspond to alignment points in the
+  font:

+
+  
The top of the em square is
+  roughly at the top of the glyphs in a font, the hanging baseline is
+  where some glyphs like आ are anchored, the middle is half-way
+  between the top of the em square and the bottom of the em square,
+  the alphabetic baseline is where characters like Á, ÿ,
+  f, and Ω are anchored, the ideographic baseline is
+  where glyphs like 私 and 達 are anchored, and the bottom
+  of the em square is roughly at the bottom of the glyphs in a
+  font. The top and bottom of the bounding box can be far from these
+  baselines, due to glyphs extending far outside the em square.

+
+  
The keywords map to these alignment points as follows:

+
+  
top
+   
The top of the em square

+
+   
hanging
+   
The hanging baseline

+
+   
middle
+   
The middle of the em square

+
+   
alphabetic
+   
The alphabetic baseline

+
+   
ideographic
+   
The ideographic baseline

+
+   
bottom
+   
The bottom of the em square

+
+  

+
+  
The fillText() and
+  strokeText()
+  methods take three or four arguments, text, x, y, and optionally maxWidth, and render the given text at the given (x, y) coordinates ensuring that the text isn't wider
+  than maxWidth if specified, using the current
+  font, textAlign, and textBaseline
+  values. Specifically, when the methods are called, the user agent
+  must run the following steps:

+
+  
  1. Let font be the current font of the
+   context, as given by the font attribute.
    2. 
+
+   
  2. Replace all the space
+   characters in text with U+0020 SPACE
+   characters.
    3. 
+
+   
  3. Form a hypothetical infinitely wide CSS line box containing
+   a single inline box containing the text text,
+   with all the properties at their initial values except the 'font'
+   property of the inline box set to font and the
+   'direction' property of the inline box set to the
+   directionality of the canvas element. [CSS]
    4. 
+
+   
+
+   
  4. If the maxWidth argument was specified
+   and the hypothetical width of the inline box in the hypothetical
+   line box is greater than maxWidth CSS pixels,
+   then change font to have a more condensed font
+   (if one is available or if a reasonably readable one can be
+   synthesized by applying a horizontal scale factor to the font) or a
+   smaller font, and return to the previous step.
    5. 
+
+   
  5. 
+
+    
    Let the anchor point be a point on the
+    inline box, determined by the textAlign and textBaseline values, as
+    follows:
    
+
+    
    Horizontal position:
    
+
+    
     If textAlign is left
    
+     
     If textAlign is start and the directionality of the
+     canvas element is 'ltr'
    
+     
     If textAlign is end and the directionality of the
+     canvas element is 'rtl'
    
+
+     
    Let the anchor point's horizontal
+     position be the left edge of the inline box.
    
+
+
+     
     If textAlign is right
    
+     
     If textAlign is end and  the directionality of the
+     canvas element is 'ltr'
    
+     
     If textAlign is start and the directionality of the
+     canvas element is 'rtl'
    
+
+     
    Let the anchor point's horizontal
+     position be the right edge of the inline box.
    
+
+
+     
     If textAlign is center
    
+
+     
    Let the anchor point's horizontal
+     position be half way between the left and right edges of the
+     inline box.
    
+
+    
    Vertical position:
    
+
+    
     If textBaseline is top
    
+
+     
    Let the anchor point's vertical position
+     be the top of the em box of the first available font of the
+     inline box.
    
+
+
+     
     If textBaseline is hanging
    
+
+     
    Let the anchor point's vertical position
+     be the hanging baseline of the first available font of the inline
+     box.
    
+
+
+     
     If textBaseline is middle
    
+
+     
    Let the anchor point's vertical position
+     be half way between the bottom and the top of the em box of the
+     first available font of the inline box.
    
+
+
+     
     If textBaseline is alphabetic
    
+
+     
    Let the anchor point's vertical position
+     be the alphabetic baseline of the first available font of the inline
+     box.
    
+
+
+     
     If textBaseline is ideographic
    
+
+     
    Let the anchor point's vertical position
+     be the ideographic baseline of the first available font of the inline
+     box.
    
+
+
+     
     If textBaseline is bottom
    
+
+     
    Let the anchor point's vertical position
+     be the bottom of the em box of the first available font of the
+     inline box.
    
+
+    
    6. 
+
+   
  6. 
+
+    
    Paint the hypothetical inline box as the shape given by the
+    text's glyphs, as transformed by the current transformation
+    matrix, and anchored and sized so that before applying the
+    current transformation
+    matrix, the anchor point is at (x, y) and each CSS pixel is
+    mapped to one coordinate space unit.
    
+
+    
    For fillText()
+    fillStyle must be
+    applied to the glyphs and strokeStyle must be
+    ignored. For strokeText() the reverse
+    holds and strokeStyle must be
+    applied to the glyph outlines and fillStyle must be
+    ignored.
    
+
+    
    Text is painted without affecting the current path, and is
+    subject to shadow effects, global alpha, the clipping region, and global composition
+    operators.
    
+
+   
    7. 
+
+  
The measureText()
+  method takes one argument, text. When the method
+  is invoked, the user agent must replace all the space characters in text with
+  U+0020 SPACE characters, and then must form a hypothetical
+  infinitely wide CSS line box containing a single inline box
+  containing the text text, with all the
+  properties at their initial values except the 'font' property of the
+  inline element set to the current font of the context, as given by
+  the font attribute, and
+  must then return a new TextMetrics object with its
+  width attribute set to
+  the width of that inline box, in CSS pixels. [CSS]

+
+  
The TextMetrics interface is used for the objects
+  returned from measureText(). It has one
+  attribute, width, which is set
+  by the measureText()
+  method.

+
+  
Glyphs rendered using fillText() and strokeText() can spill out
+  of the box given by the font size (the em square size) and the width
+  returned by measureText() (the text
+  width). This version of the specification does not provide a way to
+  obtain the bounding box dimensions of the text. If the text is to be
+  rendered and removed, care needs to be taken to replace the entire
+  area of the canvas that the clipping region covers, not just the box
+  given by the em square height and measured text width.

+
+  
+  
+  
+  
+
+  

+
+  
A future version of the 2D context API may provide a
+  way to render fragments of documents, rendered using CSS, straight
+  to the canvas. This would be provided in preference to a dedicated
+  way of doing multiline layout.

+
+
+
+  
4.8.11.1.11 Images

+
+  
To draw images onto the canvas, the drawImage method
+  can be used.

+
+  
This method can be invoked with three different sets of arguments:

+
+  
  • drawImage(image, dx, dy)
+   
  • drawImage(image, dx, dy, dw, dh)
+   
  • drawImage(image, sx, sy, sw, sh, dx, dy, dw, dh)
+  
Each of those three can take either an
+  HTMLImageElement, an HTMLCanvasElement, or
+  an HTMLVideoElement for the image
+  argument.

+
+  
context . drawImage(image, dx, dy)

+   
context . drawImage(image, dx, dy, dw, dh)

+   
context . drawImage(image, sx, sy, sw, sh, dx, dy, dw, dh)

+
+   

+
+    
Draws the given image onto the canvas. The arguments are
+    interpreted as follows:

+
+    
The sx and sy parameters give the x and y coordinates of the source rectangle; the sw and sh arguments give the width and height of the source rectangle; the dx and dy give the x and y coordinates of the destination rectangle; and the dw and dh arguments give the width and height of the destination rectangle.

+
+    
If the first argument isn't an img,
+    canvas, or video element, throws a
+    TYPE_MISMATCH_ERR exception. If the image has no
+    image data, throws an INVALID_STATE_ERR exception. If
+    the numeric arguments don't make sense (e.g. the destination is a
+    0×0 rectangle), throws an INDEX_SIZE_ERR
+    exception. If the image isn't yet fully decoded, then nothing is
+    drawn.

+
+   

+
+  

+
+  
If not specified, the dw and dh arguments must default to the values of sw and sh, interpreted such that
+  one CSS pixel in the image is treated as one unit in the canvas
+  coordinate space. If the sx, sy, sw, and sh arguments are omitted, they must default to 0, 0,
+  the image's intrinsic width in image pixels, and the image's
+  intrinsic height in image pixels, respectively.

+
+  
The image argument is an instance of either
+  HTMLImageElement, HTMLCanvasElement, or
+  HTMLVideoElement. If the image is
+  null, the implementation must raise a TYPE_MISMATCH_ERR
+  exception.
 
+
+  
If the image argument is an
+  HTMLImageElement object whose complete attribute is false, or
+  if the image argument is an
+  HTMLVideoElement object whose readyState attribute is either
+  HAVE_NOTHING or HAVE_METADATA, then the
+  implementation must return without drawing anything.

+  
+
+  
If the image argument is an
+  HTMLCanvasElement object with either a horizontal
+  dimension or a vertical dimension equal to zero, then the
+  implementation must raise an INVALID_STATE_ERR
+  exception.

+  
+
+  
The source rectangle is the rectangle whose corners are the four
+  points (sx, sy), (sx+sw, sy), (sx+sw, sy+sh), (sx, sy+sh).

+
+  
If the source rectangle is not entirely within the source image,
+  or if one of the sw or sh
+  arguments is zero, the implementation must raise an
+  INDEX_SIZE_ERR exception.

+
+  
The destination rectangle is the rectangle whose corners are the
+  four points (dx, dy),
+  (dx+dw, dy), (dx+dw, dy+dh), (dx, dy+dh).

+
+  
When drawImage() is
+  invoked, the region of the image specified by the source rectangle
+  must be painted on the region of the canvas specified by the
+  destination rectangle, after applying the current transformation
+  matrix to the points of the destination rectangle.

+
+  
The original image data of the source image must be used, not the
+  image as it is rendered (e.g. width and height attributes on the source
+  element have no effect). The image data must be processed in the
+  original direction, even if the dimensions given are negative. 

+
+  
This specification does not define the algorithm to
+  use when scaling the image, if necessary.

+
+  
When a canvas is drawn onto itself, the drawing
+  model requires the source to be copied before the image is drawn
+  back onto the canvas, so it is possible to copy parts of a canvas
+  onto overlapping parts of itself.

+
+  
When the drawImage() method
+  is passed an animated image as its image
+  argument, the user agent must use the poster frame of the animation,
+  or, if there is no poster frame, the first frame of the
+  animation.

+  
+
+  
When the image argument is an
+  HTMLVideoElement, then the frame at the current
+  playback position must be used as the source image, and the
+  source image's dimensions must be the intrinsic width and
+  intrinsic height
+  of the media resource (i.e. after any aspect-ratio
+  correction has been applied).

+  
+
+  
Images are painted without affecting the current path, and are
+  subject to shadow effects, global alpha, the clipping region, and global composition
+  operators.

+
+  

+
+
+
+  
4.8.11.1.12 Pixel manipulation

+
+  
imagedata = context . createImageData(sw, sh)

+
+   

+
+    
Returns an ImageData object with the given
+    dimensions in CSS pixels (which might map to a different number of
+    actual device pixels exposed by the object itself). All the pixels
+    in the returned object are transparent black.

+
+   

+
+   
imagedata = context . createImageData(imagedata)

+
+   

+
+    
Returns an ImageData object with the same
+    dimensions as the argument. All the pixels in the returned object
+    are transparent black.

+
+    
Throws a NOT_SUPPORTED_ERR exception if the
+    argument is null.

+
+   

+
+   
imagedata = context . getImageData(sx, sy, sw, sh)

+
+   

+
+    
Returns an ImageData object containing the image
+    data for the given rectangle of the canvas.

+
+    
Throws a NOT_SUPPORTED_ERR exception if any of the
+    arguments are not finite. Throws an INDEX_SIZE_ERR
+    exception if the either of the width or height arguments are
+    zero.

+
+   

+
+   
imagedata . width

+   
imagedata . height

+
+   

+
+    
Returns the actual dimensions of the data in the ImageData object, in device pixels.

+
+   

+
+   
imagedata . data

+
+   

+
+    
Returns the one-dimensional array containing the data in RGBA order, as integers in the range 0 to 255.

+
+   

+
+   
context . putImageData(imagedata, dx, dy [, dirtyX, dirtyY, dirtyWidth, dirtyHeight ])

+
+   

+
+    
Paints the data from the given ImageData object
+    onto the canvas. If a dirty rectangle is provided, only the pixels
+    from that rectangle are painted.

+
+    
The globalAlpha
+    and globalCompositeOperation
+    attributes, as well as the shadow attributes, are ignored for the
+    purposes of this method call; pixels in the canvas are replaced
+    wholesale, with no composition, alpha blending, no shadows,
+    etc.

+
+    
If the first argument isn't an ImageData object,
+    throws a TYPE_MISMATCH_ERR exception. Throws a
+    NOT_SUPPORTED_ERR exception if any of the other
+    arguments are not finite.

+
+   

+
+  

+
+  
The createImageData()
+  method is used to instantiate new blank ImageData
+  objects. When the method is invoked with two arguments sw and sh, it must return an
+  ImageData object representing a rectangle with a width
+  in CSS pixels equal to the absolute magnitude of sw and a height in CSS pixels equal to the absolute
+  magnitude of sh. When invoked with a single imagedata argument, it must return an
+  ImageData object representing a rectangle with the same
+  dimensions as the ImageData object passed as the
+  argument. The ImageData object return must be filled
+  with transparent black.

+
+  
The getImageData(sx, sy, sw,
+  sh) method must return an
+  ImageData object representing the underlying pixel data
+  for the area of the canvas denoted by the rectangle whose corners are
+  the four points (sx, sy),
+  (sx+sw, sy), (sx+sw, sy+sh), (sx, sy+sh), in canvas
+  coordinate space units. Pixels outside the canvas must be returned
+  as transparent black. Pixels must be returned as non-premultiplied
+  alpha values.

+
+  
If any of the arguments to createImageData() or
+  getImageData() are
+  infinite or NaN, or if the createImageData()
+  method is invoked with only one argument but that argument is null,
+  the method must instead raise a NOT_SUPPORTED_ERR
+  exception. If either the sw or sh arguments are zero, the method must instead raise
+  an INDEX_SIZE_ERR exception.

+
+  
ImageData objects must be initialized so that their
+  width attribute
+  is set to w, the number of physical device
+  pixels per row in the image data, their height attribute is
+  set to h, the number of rows in the image data,
+  and their data
+  attribute is initialized to a CanvasPixelArray object
+  holding the image data. At least one pixel's worth of image data
+  must be returned.

+
+  
The CanvasPixelArray object provides ordered,
+  indexed access to the color components of each pixel of the image
+  data. The data must be represented in left-to-right order, row by
+  row top to bottom, starting with the top left, with each pixel's
+  red, green, blue, and alpha components being given in that order for
+  each pixel. Each component of each device pixel represented in this
+  array must be in the range 0..255, representing the 8 bit value for
+  that component. The components must be assigned consecutive indices
+  starting with 0 for the top left pixel's red component.

+
+  
The CanvasPixelArray object thus represents h×w×4 integers. The
+  length
+  attribute of a CanvasPixelArray object must return this
+  number.

+
+  
The object's indices of the supported indexed
+  properties are the numbers in the range 0 .. h×w×4-1.

+
+  
When a CanvasPixelArray object is indexed to retrieve an indexed
+  property index, the value returned must be
+  the value of the indexth component in the
+  array.

+
+  
When a CanvasPixelArray object is indexed to modify an indexed
+  property index with value value, the value of the indexth
+  component in the array must be set to value.

+
+  
The width and height (w and h) might be different from the sw
+  and sh arguments to the above methods, e.g. if
+  the canvas is backed by a high-resolution bitmap, or if the sw and sh arguments are
+  negative.

+
+  
The putImageData(imagedata, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight) method writes data from
+  ImageData structures back to the canvas.

+
+  
If any of the arguments to the method are infinite or NaN, the
+  method must raise a NOT_SUPPORTED_ERR exception.

+
+  
If the first argument to the method is null or not an
+  ImageData object then the putImageData() method
+  must raise a TYPE_MISMATCH_ERR exception.

+
+  
When the last four arguments are omitted, they must be assumed to
+  have the values 0, 0, the width member of the imagedata structure, and the height member of the imagedata structure, respectively.

+
+  
When invoked with arguments that do not, per the last few
+  paragraphs, cause an exception to be raised, the putImageData() method
+  must act as follows:

+
+  
  1. 
+
+    
    Let dxdevice be the x-coordinate
+    of the device pixel in the underlying pixel data of the canvas
+    corresponding to the dx coordinate in the
+    canvas coordinate space.
    
+
+    
    Let dydevice be the y-coordinate
+    of the device pixel in the underlying pixel data of the canvas
+    corresponding to the dy coordinate in the
+    canvas coordinate space.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If dirtyWidth is negative, let dirtyX be dirtyX+dirtyWidth, and let dirtyWidth be equal to the absolute magnitude of
+    dirtyWidth.
    
+
+    
    If dirtyHeight is negative, let dirtyY be dirtyY+dirtyHeight, and let dirtyHeight be equal to the absolute magnitude of
+    dirtyHeight.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If dirtyX is negative, let dirtyWidth be dirtyWidth+dirtyX, and
+    let dirtyX be zero.
    
+
+    
    If dirtyY is negative, let dirtyHeight be dirtyHeight+dirtyY, and
+    let dirtyY be zero.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If dirtyX+dirtyWidth is greater than the width attribute of the imagedata argument, let dirtyWidth be the value of that width attribute, minus the
+    value of dirtyX.
    
+
+    
    If dirtyY+dirtyHeight is greater than the height attribute of the imagedata argument, let dirtyHeight be the value of that height attribute, minus the
+    value of dirtyY.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If, after those changes, either dirtyWidth
+    or dirtyHeight is negative or zero, stop these
+    steps without affecting the canvas.
    
+
+   
    6. 
+
+   
  6. Otherwise, for all integer values of x
+   and y where dirtyX ≤ x < dirtyX+dirtyWidth
+   and dirtyY ≤ y < dirtyY+dirtyHeight, copy the four channels of
+   the pixel with coordinate (x, y) in the imagedata data
+   structure to the pixel with coordinate (dxdevice+x,
+   dydevice+y) in the underlying pixel data of the
+   canvas.
    7. 
+
+  
The handling of pixel rounding when the specified coordinates do
+  not exactly map to the device coordinate space is not defined by
+  this specification, except that the following must result in no
+  visible changes to the rendering:

+
+  
context.putImageData(context.getImageData(x, y, w, h), p, q);

+
+  
...for any value of x, y,
+  w, and h and where p is the smaller of x and the sum
+  of x and w, and q is the smaller of y and the sum
+  of y and h; and except that
+  the following two calls:

+
+  
context.createImageData(w, h);
+context.getImageData(0, 0, w, h);

+
+  
...must return ImageData objects with the same
+  dimensions, for any value of w and h. In other words, while user agents may round the
+  arguments of these methods so that they map to device pixel
+  boundaries, any rounding performed must be performed consistently
+  for all of the createImageData(), getImageData() and putImageData()
+  operations.

+
+  
Due to the lossy nature of converting to and from
+  premultiplied alpha color values, pixels that have just been set
+  using putImageData() might be
+  returned to an equivalent getImageData() as
+  different values.

+
+  
The current path, transformation matrix,
+  shadow attributes, global alpha, the clipping region, and global composition
+  operator must not affect the getImageData() and putImageData()
+  methods.

+
+  

+
+  

+
+   
The data returned by getImageData() is at the
+   resolution of the canvas backing store, which is likely to not be
+   one device pixel to each CSS pixel if the display used is a high
+   resolution display.

+
+   
In the following example, the script generates an
+   ImageData object so that it can draw onto it.

+
+   
// canvas is a reference to a <canvas> element
+var context = canvas.getContext('2d');
+
+// create a blank slate
+var data = context.createImageData(canvas.width, canvas.height);
+
+// create some plasma
+FillPlasma(data, 'green'); // green plasma
+
+// add a cloud to the plasma
+AddCloud(data, data.width/2, data.height/2); // put a cloud in the middle
+
+// paint the plasma+cloud on the canvas
+context.putImageData(data, 0, 0);
+
+// support methods
+function FillPlasma(data, color) { ... }
+function AddCloud(data, x, y) { ... }

+
+  

+
+  

+
+   
Here is an example of using getImageData() and putImageData() to
+   implement an edge detection filter.

+
+   
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Edge detection demo</title>
+  <script>
+   var image = new Image();
+   function init() {
+     image.onload = demo;
+     image.src = "image.jpeg";
+   }
+   function demo() {
+     var canvas = document.getElementsByTagName('canvas')[0];
+     var context = canvas.getContext('2d');
+
+     // draw the image onto the canvas
+     context.drawImage(image, 0, 0);
+
+     // get the image data to manipulate
+     var input = context.getImageData(0, 0, canvas.width, canvas.height);
+
+     // get an empty slate to put the data into
+     var output = context.createImageData(canvas.width, canvas.height);
+
+     // alias some variables for convenience
+     // notice that we are using input.width and input.height here
+     // as they might not be the same as canvas.width and canvas.height
+     // (in particular, they might be different on high-res displays)
+     var w = input.width, h = input.height;
+     var inputData = input.data;
+     var outputData = output.data;
+
+     // edge detection
+     for (var y = 1; y < h-1; y += 1) {
+       for (var x = 1; x < w-1; x += 1) {
+         for (var c = 0; c < 3; c += 1) {
+           var i = (y*w + x)*4 + c;
+           outputData[i] = 127 + -inputData[i - w*4 - 4] -   inputData[i - w*4] - inputData[i - w*4 + 4] +
+                                 -inputData[i - 4]       + 8*inputData[i]       - inputData[i + 4] +
+                                 -inputData[i + w*4 - 4] -   inputData[i + w*4] - inputData[i + w*4 + 4];
+         }
+         outputData[(y*w + x)*4 + 3] = 255; // alpha
+       }
+     }
+
+     // put the image data back after manipulation
+     context.putImageData(output, 0, 0);
+   }
+  </script>
+ </head>
+ <body onload="init()">
+  <canvas></canvas>
+ </body>
+</html>

+
+  

+
+
+  

+
+  
4.8.11.1.13 Drawing model

+
+  
When a shape or image is painted, user agents must follow these
+  steps, in the order given (or act as if they do):

+
+  
  1. Render the shape or image onto an infinite transparent black
+   bitmap, creating image A, as described in the
+   previous sections. For shapes, the current fill, stroke, and line
+   styles must be honored, and the stroke must itself also be
+   subjected to the current transformation matrix.
    2. 
+
+   
  2. When shadows are drawn, render the shadow from
+   image A, using the current shadow styles,
+   creating image B.
    3. 
+
+   
  3. When shadows are drawn, multiply the alpha
+   component of every pixel in B by globalAlpha.
    4. 
+
+   
  4. When shadows are drawn, composite B within the clipping region over the current canvas
+   bitmap using the current composition operator.
    5. 
+
+   
  5. Multiply the alpha component of every pixel in A by globalAlpha.
    6. 
+
+   
  6. Composite A within the clipping region
+   over the current canvas bitmap using the current composition
+   operator.
    7. 
+
+  

+
+
+  
4.8.11.1.14 Examples

+
+  
This section is non-normative.

+
+  
Here is an example of a script that uses canvas to draw pretty
+  glowing lines.

+
+  
<canvas width="800" height="450"></canvas>
+<script>
+
+ var context = document.getElementsByTagName('canvas')[0].getContext('2d');
+
+ var lastX = context.canvas.width * Math.random();
+ var lastY = context.canvas.height * Math.random();
+ var hue = 0;
+ function line() {
+   context.save();
+   context.translate(context.canvas.width/2, context.canvas.height/2);
+   context.scale(0.9, 0.9);
+   context.translate(-context.canvas.width/2, -context.canvas.height/2);
+   context.beginPath();
+   context.lineWidth = 5 + Math.random() * 10;
+   context.moveTo(lastX, lastY);
+   lastX = context.canvas.width * Math.random();
+   lastY = context.canvas.height * Math.random();
+   context.bezierCurveTo(context.canvas.width * Math.random(),
+                         context.canvas.height * Math.random(),
+                         context.canvas.width * Math.random(),
+                         context.canvas.height * Math.random(),
+                         lastX, lastY);
+
+   hue = hue + 10 * Math.random();
+   context.strokeStyle = 'hsl(' + hue + ', 50%, 50%)';
+   context.shadowColor = 'white';
+   context.shadowBlur = 10;
+   context.stroke();
+   context.restore();
+ }
+ setInterval(line, 50);
+
+ function blank() {
+   context.fillStyle = 'rgba(0,0,0,0.1)';
+   context.fillRect(0, 0, context.canvas.width, context.canvas.height);
+ }
+ setInterval(blank, 40);
+
+</script>

+
+  
+
+  

+
+  
+
+  

+
+  
4.8.11.2 Color spaces and color correction

+
+  
The canvas APIs must perform color correction at
+  only two points: when rendering images with their own gamma
+  correction and color space information onto the canvas, to convert
+  the image to the color space used by the canvas (e.g. using the 2D
+  Context's drawImage()
+  method with an HTMLImageElement object), and when
+  rendering the actual canvas bitmap to the output device.

+
+  
Thus, in the 2D context, colors used to draw shapes
+  onto the canvas will exactly match colors obtained through the getImageData()
+  method.

+
+  
The toDataURL() method
+  must not include color space information in the resource
+  returned. Where the output format allows it, the color of pixels in
+  resources created by toDataURL() must match those
+  returned by the getImageData()
+  method.

+
+  
In user agents that support CSS, the color space used by a
+  canvas element must match the color space used for
+  processing any colors for that element in CSS.

+
+  
The gamma correction and color space information of images must
+  be handled in such a way that an image rendered directly using an
+  img element would use the same colors as one painted on
+  a canvas element that is then itself
+  rendered. Furthermore, the rendering of images that have no color
+  correction information (such as those returned by the toDataURL() method) must be
+  rendered with no color correction.

+
+  
Thus, in the 2D context, calling the drawImage() method to render
+  the output of the toDataURL() method to the
+  canvas, given the appropriate dimensions, has no visible effect.

+
+  

+
+
+  

+
+  
4.8.11.3 Security with canvas elements

+
+  
Information leakage can occur if scripts from
+  one origin can access information (e.g. read pixels)
+  from images from another origin (one that isn't the same).

+
+  
To mitigate this, canvas elements are defined to
+  have a flag indicating whether they are origin-clean. All
+  canvas elements must start with their
+  origin-clean set to true. The flag must be set to false if
+  any of the following actions occur:

+
+  
Whenever the toDataURL() method of a
+  canvas element whose origin-clean flag is set to
+  false is called, the method must raise a SECURITY_ERR
+  exception.

+
+  
Whenever the getImageData() method of
+  the 2D context of a canvas element whose
+  origin-clean flag is set to false is called with otherwise
+  correct arguments, the method must raise a SECURITY_ERR
+  exception.

+
+  
Even resetting the canvas state by changing its
+  width or height attributes doesn't reset
+  the origin-clean flag.

+
+  

+
+
+
+  
4.8.12 The map element

+
+  
Categories

+   
Flow content.

+   
When the element only contains phrasing content: phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Transparent.

+   
Content attributes:

+   
Global attributes

+   
name

+   
DOM interface:

+   

+
interface HTMLMapElement : HTMLElement {
+           attribute DOMString name;
+  readonly attribute HTMLCollection areas;
+  readonly attribute HTMLCollection images;
+};

+   

+  
The map element, in conjunction with any
+  area element descendants, defines an image
+  map. The element represents its children.

+
+  
The name attribute
+  gives the map a name so that it can be referenced. The attribute
+  must be present and must have a non-empty value with no space characters. The value of the
+  name attribute must not be a
+  compatibility-caseless
+  match for the value of the name
+  attribute of another map element in the same
+  document. If the id attribute is also
+  specified, both attributes must have the same value.

+
+  
map . areas

+
+   

+
+    
Returns an HTMLCollection of the area elements in the map.

+
+   

+
+   
map . images

+
+   

+
+    
Returns an HTMLCollection of the img and object elements that use the map.

+
+   

+
+  

+
+  
The areas attribute
+  must return an HTMLCollection rooted at the
+  map element, whose filter matches only
+  area elements.

+
+  
The images
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  img and object elements that are
+  associated with this map element according to the
+  image map processing model.

+
+  
The IDL attribute name must
+  reflect the content attribute of the same name.

+
+  

+
+
+
+  
4.8.13 The area element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected, but only if there is a map element ancestor.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
alt

+   
coords

+   
shape

+   
href

+   
target

+
+   
ping

+
+   
rel

+   
media

+   
hreflang

+   
type

+   
DOM interface:

+   

+
interface HTMLAreaElement : HTMLElement {
+           attribute DOMString alt;
+           attribute DOMString coords;
+           attribute DOMString shape;
+  stringifier attribute DOMString href;
+           attribute DOMString target;
+
+           attribute DOMString ping;
+
+           attribute DOMString rel;
+  readonly attribute DOMTokenList relList;
+           attribute DOMString media;
+           attribute DOMString hreflang;
+           attribute DOMString type;
+
+  // URL decomposition IDL attributes
+           attribute DOMString protocol;
+           attribute DOMString host;
+           attribute DOMString hostname;
+           attribute DOMString port;
+           attribute DOMString pathname;
+           attribute DOMString search;
+           attribute DOMString hash;
+};

+   

+  
The area element represents either a
+  hyperlink with some text and a corresponding area on an image
+  map, or a dead area on an image map.

+
+  
If the area element has an href attribute, then the
+  area element represents a hyperlink. In
+  this case, the alt
+  attribute must be present. It specifies the text of the
+  hyperlink. Its value must be text that, when presented with the
+  texts specified for the other hyperlinks of the image
+  map, and with the alternative text of the image, but without
+  the image itself, provides the user with the same kind of choice as
+  the hyperlink would when used without its text but with its shape
+  applied to the image. The alt
+  attribute may be left blank if there is another area
+  element in the same image map that points to the same
+  resource and has a non-blank alt
+  attribute.

+
+  
If the area element has no href attribute, then the area
+  represented by the element cannot be selected, and the alt attribute must be omitted.

+
+  
In both cases, the shape and
+  coords attributes specify the
+  area.

+
+  
The shape
+  attribute is an enumerated attribute. The following
+  table lists the keywords defined for this attribute. The states
+  given in the first cell of the rows with keywords give the states to
+  which those keywords map. Some of the keywords
+  are non-conforming, as noted in the last column.

+
+  
State
+     Keywords
+     Notes
+   
Circle state
+     circle
+     
+    
circ
+     Non-conforming
+    
Default state
+     default
+     
+    
Polygon state
+     poly
+     
+    
polygon
+     Non-conforming
+    
Rectangle state
+     rect
+     
+    
rectangle
+     Non-conforming
+  
The attribute may be omitted. The missing value default is
+  the rectangle state.

+
+  
The coords
+  attribute must, if specified, contain a valid list of
+  integers. This attribute gives the coordinates for the shape
+  described by the shape
+  attribute. The processing for this attribute is
+  described as part of the image map processing
+  model.

+
+  
+
+  
In the circle state,
+  area elements must have a coords attribute present, with three
+  integers, the last of which must be non-negative. The first integer
+  must be the distance in CSS pixels from the left edge of the image
+  to the center of the circle, the second integer must be the distance
+  in CSS pixels from the top edge of the image to the center of the
+  circle, and the third integer must be the radius of the circle,
+  again in CSS pixels.

+
+  
In the default state
+  state, area elements must not have a coords attribute. (The area is the
+  whole image.)

+
+  
In the polygon state,
+  area elements must have a coords attribute with at least six
+  integers, and the number of integers must be even. Each pair of
+  integers must represent a coordinate given as the distances from the
+  left and the top of the image in CSS pixels respectively, and all
+  the coordinates together must represent the points of the polygon,
+  in order.

+
+  
In the rectangle state,
+  area elements must have a coords attribute with exactly four
+  integers, the first of which must be less than the third, and the
+  second of which must be less than the fourth. The four points must
+  represent, respectively, the distance from the left edge of the
+  image to the left side of the rectangle, the distance from the
+  top edge to the top side, the distance from the left edge to the
+  right side, and the distance from the top edge to the bottom side,
+  all in CSS pixels.

+
+  

+
+  
When user agents allow users to follow hyperlinks created using the
+  area element, as described in the next section, the
+  href,
+  target
+
+  and ping
+
+  attributes decide how the
+  link is followed. The rel,
+  media, hreflang, and type attributes may be used to
+  indicate to the user the likely nature of the target resource before
+  the user follows the link.

+
+  

+
+  
The target,
+
+  ping,
+
+  rel, media, hreflang, and type attributes must be omitted
+  if the href attribute is
+  not present.

+
+  

+
+  
The activation behavior of area
+  elements is to run the following steps:

+
+  
  1. If the DOMActivate
+   event in question is not trusted (i.e. a click() method call was the reason for the
+   event being dispatched), and the area element's target attribute is such that
+   applying the rules for choosing a browsing context given a
+   browsing context name, using the value of the target attribute as the
+   browsing context name, would result in there not being a chosen
+   browsing context, then raise an INVALID_ACCESS_ERR
+   exception and abort these steps.
    2. 
+
+   
  2. Otherwise, the user agent must follow the hyperlink defined by the
+   area element, if any.
    3. 
+
+  
The IDL attributes alt, coords, href, target,
+
+  ping,
+
+  rel, media, hreflang, and type, each must
+  reflect the respective content attributes of the same
+  name.

+
+  
The IDL attribute shape must
+  reflect the shape
+  content attribute, limited to only known values.

+
+  
The IDL attribute relList must
+  reflect the rel
+  content attribute.

+
+  
The area element also supports the complement of
+  URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the
+  rules given for URL decomposition IDL attributes, with the input being the result of resolving the element's href attribute relative to the
+  element, if there is such an attribute and resolving it is
+  successful, or the empty string otherwise; and the common setter action being the
+  same as setting the element's href attribute to the new output
+  value.

+
+  

+
+
+  
4.8.14 Image maps

+
+  
+
+  

+
+  
4.8.14.1 Authoring

+
+  

+
+  
An image map allows geometric areas on an image to be
+  associated with hyperlinks.

+
+  
An image, in the form of an img element or an
+  object element representing an image, may be associated
+  with an image map (in the form of a map element) by
+  specifying a usemap attribute on
+  the img or object element. The usemap attribute, if specified,
+  must be a valid hash-name reference to a
+  map element.

+
+  

+
+   
Consider an image that looks as follows:

+
+   
A line with four shapes in it, equally spaced: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star.

+
+   
If we wanted just the colored areas to be clickable, we could
+   do it as follows:

+
+   
<p>
+ Please select a shape:
+ <img src="shapes.png" usemap="#shapes"
+      alt="Four shapes are available: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star.">
+ <map name="shapes">
+  <area shape=rect coords="50,50,100,100"> <!-- the hole in the red box -->
+  <area shape=rect coords="25,25,125,125" href="red.html" alt="Red box.">
+  <area shape=circle coords="200,75,50" href="green.html" alt="Green circle.">
+  <area shape=poly coords="325,25,262,125,388,125" href="blue.html" alt="Blue triangle.">
+  <area shape=poly coords="450,25,435,60,400,75,435,90,450,125,465,90,500,75,465,60"
+        href="yellow.html" alt="Yellow star.">
+ </map>
+</p>

+
+  

+
+  

+
+  
4.8.14.2 Processing model

+
+  
If an img element or an object element
+  representing an image has a usemap attribute specified,
+  user agents must process it as follows:

+
+  
  1. First, rules for parsing a hash-name reference
+   to a map element must be followed. This will return
+   either an element (the map) or null.
    2. 
+
+   
  2. If that returned null, then abort these steps. The image is
+   not associated with an image map after all.
    3. 
+
+   
  3. Otherwise, the user agent must collect all the
+   area elements that are descendants of the map. Let those be the areas.
    4. 
+
+  
Having obtained the list of area elements that form
+  the image map (the areas), interactive user
+  agents must process the list in one of two ways.

+
+  
If the user agent intends to show the text that the
+  img element represents, then it must use the following
+  steps.

+
+  
In user agents that do not support images, or that
+  have images disabled, object elements cannot represent
+  images, and thus this section never applies (the fallback
+  content is shown instead). The following steps therefore only
+  apply to img elements.

+
+  
  1. Remove all the area elements in areas that have no href attribute.
    2. 
+
+   
  2. Remove all the area elements in areas that have no alt attribute, or whose alt attribute's value is the empty
+   string, if there is another area element in
+   areas with the same value in the href attribute and with a
+   non-empty alt attribute.
    3. 
+
+   
  3. Each remaining area element in areas represents a hyperlink. Those
+   hyperlinks should all be made available to the user in a manner
+   associated with the text of the img.
    
+
+   
    In this context, user agents may represent area and
+   img elements with no specified alt attributes, or whose alt
+   attributes are the empty string or some other non-visible text, in
+   a user-agent-defined fashion intended to indicate the lack of
+   suitable author-provided text.
    4. 
+
+  
If the user agent intends to show the image and allow interaction
+  with the image to select hyperlinks, then the image must be
+  associated with a set of layered shapes, taken from the
+  area elements in areas, in reverse
+  tree order (so the last specified area element in the
+  map is the bottom-most shape, and the first
+  element in the map, in tree order, is the
+  top-most shape).

+
+  
Each area element in areas must
+  be processed as follows to obtain a shape to layer onto the
+  image:

+
+  
  1. Find the state that the element's shape attribute represents.
    2. 
+
+   
  2. Use the rules for parsing a list of integers to
+   parse the element's coords
+   attribute, if it is present, and let the result be the coords list. If the attribute is absent, let the
+   coords list be the empty list.
    3. 
+
+   
  3. If the number of items in the coords
+   list is less than the minimum number given for the
+   area element's current state, as per the following
+   table, then the shape is empty; abort these steps.
    
+    
    State
+       Minimum number of items
+     
    Circle state
+       3
+      
    Default state
+       0
+      
    Polygon state
+       6
+      
    Rectangle state
+       4
+    
    4. 
+
+   
  4. Check for excess items in the coords
+   list as per the entry in the following list corresponding to the
+   shape attribute's state:
    
+    
    Circle state
    
+     
    Drop any items in the list beyond the third.
    
+     
    Default state
    
+     
    Drop all items in the list.
    
+     
    Polygon state
    
+     
    Drop the last item if there's an odd number of items.
    
+     
    Rectangle state
    
+     
    Drop any items in the list beyond the fourth.
    
+    
    5. 
+
+   
  5. If the shape attribute
+   represents the rectangle
+   state, and the first number in the list is numerically less
+   than the third number in the list, then swap those two numbers
+   around.
    6. 
+
+   
  6. If the shape attribute
+   represents the rectangle
+   state, and the second number in the list is numerically less
+   than the fourth number in the list, then swap those two numbers
+   around.
    7. 
+
+   
  7. If the shape attribute
+   represents the circle
+   state, and the third number in the list is less than or
+   equal to zero, then the shape is empty; abort these steps.
    8. 
+
+   
  8. Now, the shape represented by the element is the one
+   described for the entry in the list below corresponding to the
+   state of the shape
+   attribute:
    
+
+    
    Circle state
    
+     
    
+      
    Let x be the first number in coords, y be the second
+      number, and r be the third number.
    
+      
    The shape is a circle whose center is x
+      CSS pixels from the left edge of the image and x CSS pixels from the top edge of the image, and
+      whose radius is r pixels.
    
+     
    
+
+     
    Default state
    
+     
    
+      
    The shape is a rectangle that exactly covers the entire
+      image.
    
+     
    
+
+     
    Polygon state
    
+     
    
+
+      
    Let xi be the (2i)th entry in coords,
+      and yi be the (2i+1)th entry in coords
+      (the first entry in coords being the one
+      with index 0).
    
+
+      
    Let the coordinates be (xi, yi),
+      interpreted in CSS pixels measured from the top left of the
+      image, for all integer values of i from 0 to
+      (N/2)-1, where N is the number of items in coords.
    
+
+      
    The shape is a polygon whose vertices are given by the coordinates, and whose interior is
+      established using the even-odd rule. [GRAPHICS]
    
+
+      
+
+     
    
+
+     
    Rectangle state
    
+
+     
    
+
+      
    Let x1 be the first
+      number in coords, y1 be the second number, x2 be the third number, and y2 be the fourth number.
    
+
+      
    The shape is a rectangle whose top-left corner is given by
+      the coordinate (x1, y1) and whose bottom right
+      corner is given by the coordinate (x2, y2), those coordinates being interpreted as
+      CSS pixels from the top left corner of the image.
    
+
+     
    
+
+    
    For historical reasons, the coordinates must be interpreted
+    relative to the displayed image, even if it stretched
+    using CSS or the image element's width and
+    height attributes.
    
+
+   
    9. 
+
+  
Mouse clicks on an image associated with a set of layered shapes
+  per the above algorithm must be dispatched to the top-most shape
+  covering the point that the pointing device indicated (if any), and
+  then, must be dispatched again (with a new Event
+  object) to the image element itself. User agents may also allow
+  individual area elements representing hyperlinks to be selected and activated
+  (e.g. using a keyboard); events from this are not also propagated to
+  the image.

+
+  
Because a map element (and its
+  area elements) can be associated with multiple
+  img and object elements, it is possible
+  for an area element to correspond to multiple focusable
+  areas of the document.

+
+  
Image maps are live; if the DOM is mutated, then the
+  user agent must act as if it had rerun the algorithms for image
+  maps.

+
+  

+
+
+
+  
4.8.15 MathML

+
+  
The math element from the MathML
+  namespace falls into the embedded content,
+  phrasing content, and flow content
+  categories for the purposes of the content models in this
+  specification.

+
+  

+
+  
+
+  
User agents must handle text other than inter-element
+  whitespace found in MathML elements whose content models do
+  not allow straight text by pretending for the purposes of MathML
+  content models, layout, and rendering that that text is actually
+  wrapped in an mtext element in the
+  MathML namespace. (Such text is not, however,
+  conforming.)

+
+  
User agents must act as if any MathML element whose contents does
+  not match the element's content model was replaced, for the purposes
+  of MathML layout and rendering, by an merror
+  element in the MathML namespace containing some
+  appropriate error message.

+
+  
To enable authors to use MathML tools that only accept MathML in
+  its XML form, interactive HTML user agents are encouraged to provide
+  a way to export any MathML fragment as an XML namespace-well-formed
+  XML fragment.

+
+  

+
+  
The semantics of MathML elements are defined by the MathML
+  specification and other relevant specifications. [MATHML]

+
+  

+
+   
Here is an example of the use of MathML in an HTML document:

+
+   
<!DOCTYPE html>
+<html>
+ <head>
+  <title>The quadratic formula</title>
+ </head>
+ <body>
+  <h1>The quadratic formula</h1>
+  <p>
+   <math>
+    <mi>x</mi>
+    <mo>=</mo>
+    <mfrac>
+     <mrow>
+      <mo form="prefix">−</mo> <mi>b</mi>
+      <mo>±</mo>
+      <msqrt>
+       <msup> <mi>b</mi> <mn>2</mn> </msup>
+       <mo>−</mo>
+       <mn>4</mn> <mo>⁢</mo> <mi>a</mi> <mo>⁢</mo> <mi>c</mi>
+      </msqrt>
+     </mrow>
+     <mrow>
+      <mn>2</mn> <mo>⁢</mo> <mi>a</mi>
+     </mrow>
+    </mfrac>
+   </math>
+  </p>
+ </body>
+</html>

+
+  

+
+
+
+  
4.8.16 SVG

+
+  
The svg element from the SVG
+  namespace falls into the embedded content,
+  phrasing content, and flow content
+  categories for the purposes of the content models in this
+  specification.

+
+  

+
+  
To enable authors to use SVG tools that only accept SVG in its
+  XML form, interactive HTML user agents are encouraged to provide a
+  way to export any SVG fragment as an XML namespace-well-formed XML
+  fragment.

+
+  

+
+  
When the SVG foreignObject element contains elements
+  from the HTML namespace, such elements must all be
+  flow content. [SVG]

+
+  
The content model for title elements in the
+  SVG namespace inside HTML documents is
+  phrasing content. (This further constrains the
+  requirements given in the SVG specification.)

+
+  
The semantics of SVG elements are defined by the SVG
+  specification and other relevant specifications. [SVG]

+
+  
+  
The SVG specification includes requirements regarding the
+  handling of elements in the DOM that are not in the SVG namespace,
+  that are in SVG fragments, and that are not included in a
+  foreignObject element. This specification does
+  not define any processing for elements in SVG fragments that are not
+  in the HTML namespace; they are considered neither conforming nor
+  non-conforming from the perspective of this specification.

+
+
+
+  
4.8.17 Dimension attributes

+
+  
Author requirements:
+  The width and height attributes on
+  img, iframe, embed,
+  object, video, and, when their type attribute is in the Image Button state,
+  input elements may be specified to give the dimensions
+  of the visual content of the element (the width and height
+  respectively, relative to the nominal direction of the output
+  medium), in CSS pixels. The attributes, if specified, must have
+  values that are valid
+  non-negative integers.

+
+  
The specified dimensions given may differ from the dimensions
+  specified in the resource itself, since the resource may have a
+  resolution that differs from the CSS pixel resolution. (On screens,
+  CSS pixels have a resolution of 96ppi, but in general the CSS pixel
+  resolution depends on the reading distance.) If both attributes are
+  specified, then one of the following statements must be true:

+
+  
  • specified width - 0.5 ≤
+             specified height * target ratio ≤
+             specified width + 0.5
    • 
+
+   
  • specified height - 0.5 ≤
+             specified width / target ratio ≤
+             specified height + 0.5
    • 
+
+   
  • specified height = specified width = 0
    • 
+
+  
The target ratio is the ratio of the
+  intrinsic width to the intrinsic height in the resource. The specified width and specified
+  height are the values of the width and height attributes respectively.

+
+  
The two attributes must be omitted if the resource in question
+  does not have both an intrinsic width and an intrinsic height.

+
+  
If the two attributes are both zero, it indicates that the
+  element is not intended for the user (e.g. it might be a part of a
+  service to count page views).

+
+  
The dimension attributes are not intended to be used
+  to stretch the image.

+
+  

+
+  
User agent requirements: User agents are
+  expected to use these attributes as hints
+  for the rendering.

+
+  
The width and height IDL attributes on
+  the iframe, embed, object,
+  and video elements must reflect the
+  respective content attributes of the same name.

+
+  

+
+
+
+  
4.9 Tabular data

+
+
+  
4.9.1 The table element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
In this order: optionally a caption element,
+   followed by either zero or more colgroup elements,
+   followed optionally by a thead element, followed
+   optionally by a tfoot element, followed by either zero
+   or more tbody elements or one or more tr
+   elements, followed optionally by a tfoot element (but
+   there can only be one tfoot element child in
+   total).

+   
Content attributes:

+   
Global attributes

+   
summary (but see prose)

+   
DOM interface:

+   

+
interface HTMLTableElement : HTMLElement {
+           attribute HTMLTableCaptionElement caption;
+  HTMLElement createCaption();
+  void deleteCaption();
+           attribute HTMLTableSectionElement tHead;
+  HTMLElement createTHead();
+  void deleteTHead();
+           attribute HTMLTableSectionElement tFoot;
+  HTMLElement createTFoot();
+  void deleteTFoot();
+  readonly attribute HTMLCollection tBodies;
+  HTMLElement createTBody();
+  readonly attribute HTMLCollection rows;
+  HTMLElement insertRow(in optional long index);
+  void deleteRow(in long index);
+           attribute DOMString summary;
+};

+   

+  
The table element represents data with
+  more than one dimension, in the form of a table.

+
+  

+
+  
The table element takes part in the table
+  model.

+
+  

+
+  
Tables must not be used as layout aids. Historically, some Web
+  authors have misused tables in HTML as a way to control their page
+  layout. This usage is non-conforming, because tools attempting to
+  extract tabular data from such documents would obtain very confusing
+  results. In particular, users of accessibility tools like screen
+  readers are likely to find it very difficult to navigate pages with
+  tables used for layout.

+
+  
There are a variety of alternatives to using HTML
+  tables for layout, primarily using CSS positioning and the CSS table
+  model.

+
+  

+
+  
User agents that do table analysis on arbitrary content are
+  encouraged to find heuristics to determine which tables actually
+  contain data and which are merely being used for layout. This
+  specification does not define a precise heuristic.

+
+  

+
+  
Tables have rows and columns given by their descendants. A table
+  must not have an empty row or column, as
+  described in the description of the table
+  model. 

+
+  
For tables that consist of more than just
+  a grid of cells with headers in the first row and headers in the
+  first column, and for any table in general where the reader might
+  have difficulty understanding the content, authors should include
+  explanatory information introducing the table. This information is
+  useful for all users, but is especially useful for users who cannot
+  see the table, e.g. users of screen readers.

+
+  
Such explanatory information should introduce the purpose of the
+  table, outline its basic cell structure, highlight any trends or
+  patterns, and generally teach the user how to use the table.

+
+  

+
+   
For instance, the following table:

+
+   
+    
Characteristics with positive and negative sides
 Negative
+       Characteristic
+       Positive
+    
 Sad
+       Mood
+       Happy
+     
 Failing
+       Grade
+       Passing
+   
...might benefit from a description explaining the way the table
+   is laid out, something like "Characteristics are given in the
+   second column, with the negative side in the left column and the
+   positive side in the right column".

+
+  

+
+  
There are a variety of ways to include this information, such as:

+
+  
In prose, surrounding the table

+
+   

+    
<p>In the following table, characteristics are given in the second
+column, with the negative side in the left column and the positive
+side in the right column.</p>
+<table>
+ <caption>Characteristics with positive and negative sides</caption>
+ <thead>
+  <tr>
+   <th id="n"> Negative
+   <th> Characteristic
+   <th> Positive
+ <tbody>
+  <tr>
+   <td headers="n r1"> Sad
+   <th id="r1"> Mood
+   <td> Happy
+  <tr>
+   <td headers="n r2"> Failing
+   <th id="r2"> Grade
+   <td> Passing
+</table>

+   

+
+   
In the table's caption

+
+   

+    
<table>
+ <caption>
+  <strong>Characteristics with positive and negative sides.</strong>
+  <p>Characteristics are given in the second column, with the
+  negative side in the left column and the positive side in the right
+  column.</p>
+ </caption>
+ <thead>
+  <tr>
+   <th id="n"> Negative
+   <th> Characteristic
+   <th> Positive
+ <tbody>
+  <tr>
+   <td headers="n r1"> Sad
+   <th id="r1"> Mood
+   <td> Happy
+  <tr>
+   <td headers="n r2"> Failing
+   <th id="r2"> Grade
+   <td> Passing
+</table>

+   

+
+   
In the table's caption, in a details element

+
+   

+    
<table>
+ <caption>
+  <strong>Characteristics with positive and negative sides.</strong>
+  <details>
+   <summary>Help</summary>
+   <p>Characteristics are given in the second column, with the
+   negative side in the left column and the positive side in the right
+   column.</p>
+  </details>
+ </caption>
+ <thead>
+  <tr>
+   <th id="n"> Negative
+   <th> Characteristic
+   <th> Positive
+ <tbody>
+  <tr>
+   <td headers="n r1"> Sad
+   <th id="r1"> Mood
+   <td> Happy
+  <tr>
+   <td headers="n r2"> Failing
+   <th id="r2"> Grade
+   <td> Passing
+</table>

+   

+
+   
Next to the table, in the same figure

+
+   

+    
<figure>
+ <figcaption>Characteristics with positive and negative sides</figcaption>
+ <p>Characteristics are given in the second column, with the
+ negative side in the left column and the positive side in the right
+ column.</p>
+ <table>
+  <thead>
+   <tr>
+    <th id="n"> Negative
+    <th> Characteristic
+    <th> Positive
+  <tbody>
+   <tr>
+    <td headers="n r1"> Sad
+    <th id="r1"> Mood
+    <td> Happy
+   <tr>
+    <td headers="n r2"> Failing
+    <th id="r2"> Grade
+    <td> Passing
+ </table>
+</figure>

+   

+
+   
Next to the table, in a figure's figcaption

+
+   

+    
<figure>
+ <figcaption>
+  <strong>Characteristics with positive and negative sides</strong>
+  <p>Characteristics are given in the second column, with the
+  negative side in the left column and the positive side in the right
+  column.</p>
+ </figcaption>
+ <table>
+  <thead>
+   <tr>
+    <th id="n"> Negative
+    <th> Characteristic
+    <th> Positive
+  <tbody>
+   <tr>
+    <td headers="n r1"> Sad
+    <th id="r1"> Mood
+    <td> Happy
+   <tr>
+    <td headers="n r2"> Failing
+    <th id="r2"> Grade
+    <td> Passing
+ </table>
+</figure>

+   

+
+  
Authors may also use other techniques, or combinations of the
+  above techniques, as appropriate.

+
+  
The best option, of course, rather than writing a description
+  explaining the way the table is laid out, is to adjust the table
+  such that no explanation is needed.

+
+  

+
+   
In the case of the table used in the examples above, a simple
+   rearrangement of the table so that the headers are on the top and
+   left sides removes the need for an explanation as well as removing
+   the need for the use of headers attributes:

+
+   
<table>
+ <caption>Characteristics with positive and negative sides</caption>
+ <thead>
+  <tr>
+   <th> Characteristic
+   <th> Negative
+   <th> Positive
+ <tbody>
+  <tr>
+   <th> Mood
+   <td> Sad
+   <td> Happy
+  <tr>
+   <th> Grade
+   <td> Failing
+   <td> Passing
+</table>

+
+  

+
+  
The summary
+  attribute on table elements was suggested in earlier
+  versions of the language as a technique for providing explanatory
+  text for complex tables for users of screen readers. One of the techniques described  above should be used
+  instead.  

+
+  
In particular, authors are encouraged to consider
+  whether their explanatory text for tables is likely to be useful to
+  the visually impaired: if their text would not be useful, then it is
+  best to not include a summary attribute. Similarly, if
+  their explanatory text could help someone who is not visually
+  impaired, e.g. someone who is seeing the table for the first time,
+  then the text would be more useful before the table or in the
+  caption. For example, describing the conclusions of the
+  data in a table is useful to everyone; explaining how to read the
+  table, if not obvious from the headers alone, is useful to everyone;
+  describing the structure of the table, if it is easy to grasp
+  visually, may not be useful to everyone, but it might also not be
+  useful to users who can quickly navigate the table with an
+  accessibility tool.

+
+  
+
+  

+
+  
If a table element has a summary attribute, the user agent
+  may report the contents of that attribute to the user.

+
+  

+
+  
table . caption [ = value ]

+   

+    
Returns the table's caption element.

+    
Can be set, to replace the caption element. If the
+    new value is not a caption element, throws a
+    HIERARCHY_REQUEST_ERR exception.

+   

+
+   
caption = table . createCaption()

+   

+    
Ensures the table has a caption element, and returns it.

+   

+
+   
table . deleteCaption()

+   

+    
Ensures the table does not have a caption element.

+   

+
+   
table . tHead [ = value ]

+   

+    
Returns the table's thead element.

+    
Can be set, to replace the thead element. If the
+    new value is not a thead element, throws a
+    HIERARCHY_REQUEST_ERR exception.

+   

+
+   
thead = table . createTHead()

+   

+    
Ensures the table has a thead element, and returns it.

+   

+
+   
table . deleteTHead()

+   

+    
Ensures the table does not have a thead element.

+   

+
+   
table . tFoot [ = value ]

+   

+    
Returns the table's tfoot element.

+    
Can be set, to replace the tfoot element. If the
+    new value is not a tfoot element, throws a
+    HIERARCHY_REQUEST_ERR exception.

+   

+
+   
tfoot = table . createTFoot()

+   

+    
Ensures the table has a tfoot element, and returns it.

+   

+
+   
table . deleteTFoot()

+   

+    
Ensures the table does not have a tfoot element.

+   

+
+   
table . tBodies

+   

+    
Returns an HTMLCollection of the tbody elements of the table.

+   

+
+   
tbody = table . createTBody()

+   

+    
Creates a tbody element, inserts it into the table, and returns it.

+   

+
+   
table . rows

+   

+    
Returns an HTMLCollection of the tr elements of the table.

+   

+
+   
tr = table . insertRow(index)

+   

+    
Creates a tr element, along with a tbody if required, inserts them into the table at the position given by the argument, and returns the tr.

+    
The position is relative to the rows in the table. The index −1 is equivalent to inserting at the end of the table.

+    
If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR exception.

+   

+
+   
table . deleteRow(index)

+   

+    
Removes the tr element with the given position in the table.

+    
The position is relative to the rows in the table. The index −1 is equivalent to deleting the last row of the table.

+    
If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR exception.

+   

+
+  

+
+  
The caption IDL
+  attribute must return, on getting, the first caption
+  element child of the table element, if any, or null
+  otherwise. On setting, if the new value is a caption
+  element, the first caption element child of the
+  table element, if any, must be removed, and the new
+  value must be inserted as the first node of the table
+  element. If the new value is not a caption element,
+  then a HIERARCHY_REQUEST_ERR DOM exception must be
+  raised instead.

+
+  
The createCaption()
+  method must return the first caption element child of
+  the table element, if any; otherwise a new
+  caption element must be created, inserted as the first
+  node of the table element, and then returned.

+
+  
The deleteCaption()
+  method must remove the first caption element child of
+  the table element, if any.

+
+  
The tHead IDL
+  attribute must return, on getting, the first thead
+  element child of the table element, if any, or null
+  otherwise. On setting, if the new value is a thead
+  element, the first thead element child of the
+  table element, if any, must be removed, and the new
+  value must be inserted immediately before the first element in the
+  table element that is neither a caption
+  element nor a colgroup element, if any, or at the end
+  of the table if there are no such elements. If the new value is not
+  a thead element, then a
+  HIERARCHY_REQUEST_ERR DOM exception must be raised
+  instead.

+
+  
The createTHead()
+  method must return the first thead element child of the
+  table element, if any; otherwise a new
+  thead element must be created and inserted immediately
+  before the first element in the table element that is
+  neither a caption element nor a colgroup
+  element, if any, or at the end of the table if there are no such
+  elements, and then that new element must be returned.

+
+  
The deleteTHead()
+  method must remove the first thead element child of the
+  table element, if any.

+
+  
The tFoot IDL
+  attribute must return, on getting, the first tfoot
+  element child of the table element, if any, or null
+  otherwise. On setting, if the new value is a tfoot
+  element, the first tfoot element child of the
+  table element, if any, must be removed, and the new
+  value must be inserted immediately before the first element in the
+  table element that is neither a caption
+  element, a colgroup element, nor a thead
+  element, if any, or at the end of the table if there are no such
+  elements. If the new value is not a tfoot element, then
+  a HIERARCHY_REQUEST_ERR DOM exception must be raised
+  instead.

+
+  
The createTFoot()
+  method must return the first tfoot element child of the
+  table element, if any; otherwise a new
+  tfoot element must be created and inserted immediately
+  before the first element in the table element that is
+  neither a caption element, a colgroup
+  element, nor a thead element, if any, or at the end of
+  the table if there are no such elements, and then that new element
+  must be returned.

+
+  
The deleteTFoot()
+  method must remove the first tfoot element child of the
+  table element, if any.

+
+  
The tBodies
+  attribute must return an HTMLCollection rooted at the
+  table node, whose filter matches only
+  tbody elements that are children of the
+  table element.

+
+  
The createTBody()
+  method must create a new tbody element, insert it
+  immediately after the last tbody element in the
+  table element, if any, or at the end of the
+  table element if the table element has no
+  tbody element children, and then must return the new
+  tbody element.

+
+  
The rows attribute
+  must return an HTMLCollection rooted at the
+  table node, whose filter matches only tr
+  elements that are either children of the table element,
+  or children of thead, tbody, or
+  tfoot elements that are themselves children of the
+  table element. The elements in the collection must be
+  ordered such that those elements whose parent is a
+  thead are included first, in tree order, followed by
+  those elements whose parent is either a table or
+  tbody element, again in tree order, followed finally by
+  those elements whose parent is a tfoot element, still
+  in tree order.

+
+  
The behavior of the insertRow(index) method depends on the state of
+  the table. When it is called, the method must act as required by the
+  first item in the following list of conditions that describes the
+  state of the table and the index argument:

+
+  
If index is less than −1 or greater than
+   the number of elements in rows
+   collection:

+
+   
The method must raise an INDEX_SIZE_ERR
+   exception.

+
+   
If the rows collection has
+   zero elements in it, and the table has no
+   tbody elements in it:

+
+   
The method must create a tbody element, then
+   create a tr element, then append the tr
+   element to the tbody element, then append the
+   tbody element to the table element, and
+   finally return the tr element.

+
+   
If the rows collection has
+   zero elements in it:

+
+   
The method must create a tr element, append it to
+   the last tbody element in the table, and return the
+   tr element.

+
+   
If index is missing, equal to −1, or
+   equal to the number of items in rows collection:

+
+   
The method must create a tr element, and append it
+   to the parent of the last tr element in the rows collection. Then, the newly
+   created tr element must be returned.

+
+   
Otherwise:

+
+   
The method must create a tr element, insert it
+   immediately before the indexth tr
+   element in the rows collection,
+   in the same parent, and finally must return the newly created
+   tr element.

+
+  
When the deleteRow(index) method is called, the user agent
+  must run the following steps:

+
+  
  1. If index is equal to −1, then
+   index must be set to the number if items in the
+   rows collection, minus
+   one.
    2. 
+
+   
  2. Now, if index is less than zero, or
+   greater than or equal to the number of elements in the rows collection, the method must
+   instead raise an INDEX_SIZE_ERR exception, and these
+   steps must be aborted.
    3. 
+
+   
  3. Otherwise, the method must remove the indexth element in the rows collection from its parent.
    
+
+  
The summary IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  

+
+
+  
4.9.2 The caption element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the first element child of a table element.

+   
Content model:

+   
Flow content, but with no descendant table elements.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+
interface HTMLTableCaptionElement : HTMLElement {};

+   

+  
The caption element represents the title of the
+  table that is its parent, if it has a parent and that
+  is a table element.

+
+  

+
+  
The caption element takes part in the table
+  model.

+
+  

+
+  
When a table element is the only content in a
+  figure element other than the figcaption,
+  the caption element should be omitted in favor of the
+  figcaption.

+
+  
A caption can introduce context for a table, making it
+  significantly easier to understand.

+
+  

+
+   
Consider, for instance, the following table:

+
+   
    1  2  3  4  5  6
+    
 1  2  3  4  5  6  7
+    
 2  3  4  5  6  7  8
+    
 3  4  5  6  7  8  9
+    
 4  5  6  7  8  9  10
+    
 5  6  7  8  9  10  11
+    
 6  7  8  9  10  11  12
+   
In the abstract, this table is not clear. However, with a
+   caption giving the table's number (for reference in the main prose)
+   and explaining its use, it makes more sense:

+
+   
<caption>
+<p>Table 1.
+<p>This table shows the total score obtained from rolling two
+six-sided dice. The first row represents the value of the first die,
+the first column the value of the second die. The total is given in
+the cell that corresponds to the values of the two dice.
+</caption>

+
+ 
+   
This provides the user with more context:

+
+   
+    

+     
Table 1.
+     
This table shows the total score obtained from rolling two
+     six-sided dice. The first row represents the value of the first
+     die, the first column the value of the second die. The total is
+     given in the cell that corresponds to the values of the two dice.
+    
    1  2  3  4  5  6
+    
 1  2  3  4  5  6  7
+    
 2  3  4  5  6  7  8
+    
 3  4  5  6  7  8  9
+    
 4  5  6  7  8  9  10
+    
 5  6  7  8  9  10  11
+    
 6  7  8  9  10  11  12
+   

+
+
+
+
+  
4.9.3 The colgroup element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a table element, after any
+   caption elements and before any thead,
+   tbody, tfoot, and tr
+   elements.

+   
Content model:

+   
If the span attribute is present: Empty.

+   
If the span attribute is absent: Zero or more col elements.

+   
Content attributes:

+   
Global attributes

+   
span

+   
DOM interface:

+   

+
interface HTMLTableColElement : HTMLElement {
+           attribute unsigned long span;
+};

+   

+  
The colgroup element represents a group of one or more columns in the table that
+  is its parent, if it has a parent and that is a table
+  element.

+
+  
If the colgroup element contains no col
+  elements, then the element may have a span content attribute
+  specified, whose value must be a valid non-negative
+  integer greater than zero.

+
+  

+
+  
The colgroup element and its span attribute take part in the
+  table model.

+
+  
The span IDL
+  attribute must reflect the content attribute of the
+  same name. The value must be limited to only non-negative
+  numbers greater than zero.

+
+  

+
+
+  
4.9.4 The col element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a colgroup element that doesn't have
+   a span attribute.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
span

+   
+   
DOM interface:

+   

+    
HTMLTableColElement, same as for
+    colgroup elements. This interface defines one member,
+    span.

+   

+  
If a col element has a parent and that is a
+  colgroup element that itself has a parent that is a
+  table element, then the col element
+  represents one or more columns in the column group represented by that
+  colgroup.

+
+  
The element may have a span content attribute
+  specified, whose value must be a valid non-negative
+  integer greater than zero.

+
+  

+
+  
The col element and its span attribute take part in the
+  table model.

+
+  
The span IDL
+  attribute must reflect the content attribute of the
+  same name. The value must be limited to only non-negative
+  numbers greater than zero.

+
+  

+
+
+  
4.9.5 The tbody element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a table element, after any
+   caption, colgroup, and
+   thead elements, but only if there are no
+   tr elements that are children of the
+   table element.

+   
Content model:

+   
Zero or more tr elements

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLTableSectionElement : HTMLElement {
+  readonly attribute HTMLCollection rows;
+  HTMLElement insertRow(in optional long index);
+  void deleteRow(in long index);
+};

+    
The HTMLTableSectionElement interface is also
+    used for thead and tfoot elements.

+   

+  
The tbody element represents a block of rows that consist of a body of data for
+  the parent table element, if the tbody
+  element has a parent and it is a table.

+
+  

+
+  
The tbody element takes part in the table
+  model.

+
+  

+
+  
tbody . rows

+   

+    
Returns an HTMLCollection of the tr elements of the table section.

+   

+
+   
tr = tbody . insertRow( [ index ] )

+   

+    
Creates a tr element, inserts it into the table section at the position given by the argument, and returns the tr.

+    
The position is relative to the rows in the table section. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table section.

+    
If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR exception.

+   

+
+   
tbody . deleteRow(index)

+   

+    
Removes the tr element with the given position in the table section.

+    
The position is relative to the rows in the table section. The index −1 is equivalent to deleting the last row of the table section.

+    
If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR exception.

+   

+
+  

+
+  
The rows attribute
+  must return an HTMLCollection rooted at the element,
+  whose filter matches only tr elements that are children
+  of the element.

+
+  
The insertRow(index) method must, when invoked on an
+  element table section, act as follows:

+
+  
If index is less than −1 or greater than the
+  number of elements in the rows
+  collection, the method must raise an INDEX_SIZE_ERR
+  exception.

+
+  
If index is missing, equal to −1, or
+  equal to the number of items in the rows collection, the method must
+  create a tr element, append it to the element table section, and return the newly created
+  tr element.

+
+  
Otherwise, the method must create a tr element,
+  insert it as a child of the table section
+  element, immediately before the indexth
+  tr element in the rows collection, and finally must
+  return the newly created tr element.

+
+  
The deleteRow(index) method must remove the indexth element in the rows collection from its parent. If
+  index is less than zero or greater than or equal
+  to the number of elements in the rows collection, the method must
+  instead raise an INDEX_SIZE_ERR exception.

+
+  

+
+
+  
4.9.6 The thead element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a table element, after any
+   caption, and colgroup
+   elements and before any tbody, tfoot, and
+   tr elements, but only if there are no other
+   thead elements that are children of the
+   table element.

+   
Content model:

+   
Zero or more tr elements

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
HTMLTableSectionElement, as defined for
+   tbody elements.

+  
The thead element represents the block of rows that consist of the column labels
+  (headers) for the parent table element, if the
+  thead element has a parent and it is a
+  table.

+
+  

+
+  
The thead element takes part in the table
+  model.

+
+  

+
+
+  
4.9.7 The tfoot element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a table element, after any
+   caption, colgroup, and thead
+   elements and before any tbody and tr
+   elements, but only if there are no other tfoot
+   elements that are children of the table element.

+   
As a child of a table element, after any
+   caption, colgroup, thead,
+   tbody, and tr elements, but only if there
+   are no other tfoot elements that are children of the
+   table element.

+   
Content model:

+   
Zero or more tr elements

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
HTMLTableSectionElement, as defined for
+   tbody elements.

+  
The tfoot element represents the block of rows that consist of the column summaries
+  (footers) for the parent table element, if the
+  tfoot element has a parent and it is a
+  table.

+
+  

+
+  
The tfoot element takes part in the table
+  model.

+
+  

+
+
+  
4.9.8 The tr element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a thead element.

+   
As a child of a tbody element.

+   
As a child of a tfoot element.

+   
As a child of a table element, after any
+   caption, colgroup, and thead
+   elements, but only if there are no tbody elements that
+   are children of the table element.

+   
Content model:

+   
When the parent node is a thead element: Zero or more th elements

+   
Otherwise: Zero or more td or th elements

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLTableRowElement : HTMLElement {
+  readonly attribute long rowIndex;
+  readonly attribute long sectionRowIndex;
+  readonly attribute HTMLCollection cells;
+  HTMLElement insertCell(in optional long index);
+  void deleteCell(in long index);
+};

+   

+  
The tr element represents a row of cells in a table.

+
+  

+
+  
The tr element takes part in the table
+  model.

+
+  

+
+  
tr . rowIndex

+
+   

+
+    
Returns the position of the row in the table's rows list.

+
+    
Returns −1 if the element isn't in a table.

+
+   

+
+   
tr . sectionRowIndex

+
+   

+
+    
Returns the position of the row in the table section's rows list.

+
+    
Returns −1 if the element isn't in a table section.

+
+   

+
+   
tr . cells

+   

+
+    
Returns an HTMLCollection of the td and th elements of the row.

+
+   

+
+   
cell = tr . insertCell( [ index ] )

+
+   

+
+    
Creates a td element, inserts it into the table
+    row at the position given by the argument, and returns the
+    td.

+
+    
The position is relative to the cells in the row. The
+    index −1, which is the default if the argument is omitted,
+    is equivalent to inserting at the end of the row.

+
+    
If the given position is less than −1 or greater than
+    the number of cells, throws an INDEX_SIZE_ERR
+    exception.

+
+   

+
+   
tr . deleteCell(index)

+   

+
+    
Removes the td or th element with the
+    given position in the row.

+
+    
The position is relative to the cells in the row. The index
+    −1 is equivalent to deleting the last cell of the row.

+
+    
If the given position is less than −1 or greater than
+    the index of the last cell, or if there are no cells, throws an
+    INDEX_SIZE_ERR exception.

+
+   

+
+  

+
+  
The rowIndex
+  attribute must, if the element has a parent table
+  element, or a parent tbody, thead, or
+  tfoot element and a grandparent
+  table element, return the index of the tr
+  element in that table element's rows collection. If there is no such
+  table element, then the attribute must return
+  −1.

+
+  
The sectionRowIndex
+  attribute must, if the element has a parent table,
+  tbody, thead, or tfoot
+  element, return the index of the tr element in the
+  parent element's rows collection (for tables,
+  that's the HTMLTableElement.rows
+  collection; for table sections, that's the HTMLTableRowElement.rows
+  collection). If there is no such parent element, then the attribute
+  must return −1.

+
+  
The cells attribute
+  must return an HTMLCollection rooted at the
+  tr element, whose filter matches only td
+  and th elements that are children of the
+  tr element.

+
+  
The insertCell(index) method must act as follows:

+
+  
If index is less than −1 or greater than the
+  number of elements in the cells
+  collection, the method must raise an INDEX_SIZE_ERR
+  exception.

+
+  
If index is missing, equal to −1, or
+  equal to the number of items in cells collection, the method must create
+  a td element, append it to the tr element,
+  and return the newly created td element.

+
+  
Otherwise, the method must create a td element,
+  insert it as a child of the tr element, immediately
+  before the indexth td or
+  th element in the cells collection, and finally must
+  return the newly created td element.

+
+  
The deleteCell(index) method must remove the indexth element in the cells collection from its parent. If
+  index is less than zero or greater than or equal
+  to the number of elements in the cells collection, the method must
+  instead raise an INDEX_SIZE_ERR exception.

+
+  

+
+
+  
4.9.9 The td element

+
+  
Categories

+   
Sectioning root.

+   
Contexts in which this element may be used:

+   
As a child of a tr element.

+   
Content model:

+   
Flow content.

+   
Content attributes:

+   
Global attributes

+   
colspan

+   
rowspan

+   
headers

+   
+   
DOM interface:

+   

+    
interface HTMLTableDataCellElement : HTMLTableCellElement {};

+   

+  
The td element represents a data cell in a table.

+
+  

+
+  
The td element and its colspan, rowspan, and headers attributes take part in the
+  table model.

+
+  

+
+
+  
4.9.10 The th element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a tr element.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
colspan

+   
rowspan

+   
headers

+   
scope

+   
DOM interface:

+   

+    
interface HTMLTableHeaderCellElement : HTMLTableCellElement {
+           attribute DOMString scope;
+};

+   

+  
The th element represents a header cell in a table.

+
+  
The th element may have a scope content attribute
+  specified. The scope attribute is
+  an enumerated attribute with five states, four of which
+  have explicit keywords:

+
+  
The row
+   keyword, which maps to the row state

+
+   
The row state means the header cell applies to some of
+   the subsequent cells in the same row(s).

+
+   
The col
+   keyword, which maps to the column state

+
+   
The column state means the header cell applies to some
+   of the subsequent cells in the same column(s).

+
+   
The rowgroup keyword,
+   which maps to the row group state

+
+   
The row group state means the header cell applies to all
+   the remaining cells in the row group. A th element's
+   scope attribute must not be in
+   the row group state if
+   the element is not anchored in a row group.

+
+   
The colgroup keyword,
+   which maps to the column group state

+
+   
The column group state means the header cell applies to
+   all the remaining cells in the column group. A th
+   element's scope attribute must
+   not be in the column
+   group state if the element is not anchored in a column group.

+
+   
The auto state

+
+   
The auto state makes the header cell apply to a set of
+   cells selected based on context.

+
+  
The scope attribute's
+  missing value default is the auto state.

+
+  

+
+  
The th element and its colspan, rowspan, headers, and scope attributes take part in the
+  table model.

+
+  
The scope IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  

+
+  

+
+   
The following example shows how the scope attribute's rowgroup value affects which
+   data cells a header cell applies to.

+
+   
Here is a markup fragment showing a table:

+
+   
<table>
+ <thead>
+  <tr> <th> ID <th> Measurement <th> Average <th> Maximum
+ <tbody>
+  <tr> <td> <th scope=rowgroup> Cats <td> <td>
+  <tr> <td> 93 <th> Legs <td> 3.5 <td> 4
+  <tr> <td> 10 <th> Tails <td> 1 <td> 1
+ <tbody>
+  <tr> <td> <th scope=rowgroup> English speakers <td> <td>
+  <tr> <td> 32 <th> Legs <td> 2.67 <td> 4
+  <tr> <td> 35 <th> Tails <td> 0.33 <td> 1
+</table>

+
+   
This would result in the following table:

+
+   
 ID  Measurement  Average  Maximum
+    
  Cats  
+     
 93  Legs  3.5  4
+     
 10  Tails  1  1
+    
  English speakers  
+     
 32  Legs  2.67  4
+     
 35  Tails  0.33  1
+   
The headers in the first row all apply directly down to the rows
+   in their column.

+
+   
The headers with the explicit scope attributes apply to all the
+   cells in their row group other than the cells in the first column.

+
+   
The remaining headers apply just to the cells to the right of
+   them.

+
+   
+   

+
+
+
+  
4.9.11 Attributes common to td and th elements

+
+  
The td and th elements may have a colspan content
+  attribute specified, whose value must be a valid non-negative
+  integer greater than zero.

+
+  
The td and th elements may also have a
+  rowspan content
+  attribute specified, whose value must be a valid non-negative
+  integer.

+
+  
These attributes give the number of columns and rows respectively
+  that the cell is to span. These attributes must not be used to
+  overlap cells, as described in the description of
+  the table model.
 
+
+  
The td and th element may have a headers content
+  attribute specified. The headers attribute, if specified,
+  must contain a string consisting of an unordered set of unique
+  space-separated tokens, each of which must have the value of
+  an ID of a th element taking part in the same table as the td or
+  th element (as defined by the
+  table model).

+
+  
A th element with ID id is said
+  to be directly targeted by all td and
+  th elements in the same table that have headers attributes whose values
+  include as one of their tokens the ID id. A
+  th element A is said to be
+  targeted by a th or td element
+  B if either A is directly
+  targeted by B or if there exists an element
+  C that is itself targeted by the element
+  B and A is directly
+  targeted by C.

+
+  
A th element must not be targeted by
+  itself.

+
+  

+
+  
The colspan, rowspan, and headers attributes take part in the
+  table model.

+
+  

+
+  
The td and th elements implement
+  interfaces that inherit from the HTMLTableCellElement
+  interface:

+
+  
interface HTMLTableCellElement : HTMLElement {
+           attribute unsigned long colSpan;
+           attribute unsigned long rowSpan;
+  [PutForwards=value] readonly attribute DOMSettableTokenList headers;
+  readonly attribute long cellIndex;
+};

+
+  
cell . cellIndex

+
+   

+
+    
Returns the position of the cell in the row's cells list. This does not necessarily
+    correspond to the x-position of the cell in
+    the table, since earlier cells might cover multiple rows or
+    columns.

+
+    
Returns 0 if the element isn't in a row.

+
+   

+
+  

+
+  
The colSpan IDL
+  attribute must reflect the content attribute of the
+  same name. The value must be limited to only non-negative
+  numbers greater than zero.

+
+  
The rowSpan IDL
+  attribute must reflect the content attribute of the
+  same name. Its default value, which must be used if parsing the
+  attribute as a non-negative integer returns an error, is 1.

+
+  
The headers IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  
The cellIndex
+  IDL attribute must, if the element has a parent tr
+  element, return the index of the cell's element in the parent
+  element's cells collection. If
+  there is no such parent element, then the attribute must return
+  0.

+
+  

+
+
+  

+
+  
4.9.12 Processing model

+
+  
The various table elements and their content attributes together
+  define the table model.

+
+  
A table consists of cells
+  aligned on a two-dimensional grid of slots with coordinates (x, y). The grid is finite, and is
+  either empty or has one or more slots. If the grid has one or more
+  slots, then the x coordinates are always in the
+  range 0 ≤ x < xwidth, and the y
+  coordinates are always in the range 0 ≤ y < yheight. If one or both of xwidth and yheight are zero, then the table is empty (has
+  no slots). Tables correspond to table elements.

+
+  
A cell is a set of slots anchored
+  at a slot (cellx, celly), and with a particular
+  width and height such that
+  the cell covers all the slots with coordinates (x, y) where cellx ≤ x < cellx+width and
+  celly ≤ y < celly+height. Cells can
+  either be data cells or header cells. Data cells
+  correspond to td elements, and header cells correspond
+  to th elements. Cells of both types can have zero or
+  more associated header cells.

+
+  
It is possible, in certain error cases, for two cells to occupy
+  the same slot.

+
+  
A row is a complete set of slots
+  from x=0 to x=xwidth-1, for a particular value of y. Rows correspond to tr elements.

+
+  
A column is a complete set of
+  slots from y=0 to y=yheight-1, for a particular value of x. Columns can correspond to col
+  elements. In the absence of col elements, columns are
+  implied.

+
+  
A row group is a set of
+  rows anchored at a slot (0, groupy) with a particular height such that the row group covers all the slots
+  with coordinates (x, y)
+  where 0 ≤ x < xwidth and groupy ≤ y < groupy+height. Row groups
+  correspond to tbody, thead, and
+  tfoot elements. Not every row is necessarily in a row
+  group.

+
+  
A column group is a set
+  of columns anchored at a slot
+  (groupx, 0) with a
+  particular width such that the column group
+  covers all the slots with coordinates (x, y) where groupx ≤ x < groupx+width and
+  0 ≤ y < yheight. Column groups
+  correspond to colgroup elements. Not every column is
+  necessarily in a column group.

+
+  
Row groups cannot overlap
+  each other. Similarly, column
+  groups cannot overlap each other.

+
+  
A cell cannot cover slots that
+  are from two or more row
+  groups. It is, however, possible for a cell to be in multiple
+  column groups. All the
+  slots that form part of one cell are part of zero or one row groups and zero or more column groups.

+
+  
In addition to cells, columns, rows, row
+  groups, and column
+  groups, tables can have a
+  caption element associated with them. This gives the
+  table a heading, or legend.

+
+  
A table model error is an error with the data
+  represented by table elements and their
+  descendants. Documents must not have table model errors.

+
+
+  
4.9.12.1 Forming a table

+
+  
To determine which elements correspond to which slots in a table associated with a
+  table element, to determine the dimensions of the table
+  (xwidth and yheight), and to determine if
+  there are any table model
+  errors, user agents must use the following algorithm:

+
+  
  1. 
+    
    Let xwidth be zero.
    
+   
    2. 
+
+   
  2. 
+    
    Let yheight be zero.
    
+   
    3. 
+
+   
  3. 
+
+    
    Let pending tfoot elements be
+    a list of tfoot elements, initially empty.
    
+
+   
    4. 
+
+   
  4. 
+    
    Let the table be the table represented by the
+    table element. The xwidth and yheight variables give the
+    table's dimensions. The table is
+    initially empty.
    
+   
    5. 
+
+   
  5. 
+
+    
+
+    
    If the table element has no children elements,
+    then return the table (which will be empty),
+    and abort these steps.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Associate the first caption element child of the
+    table element with the table. If
+    there are no such children, then it has no associated
+    caption element.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Let the current element be the first
+    element child of the table element.
    
+
+    
    If a step in this algorithm ever requires the current element to be advanced to the next child of the
+    table when there is no such next child, then
+    the user agent must jump to the step labeled end, near the
+    end of this algorithm.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    While the current element is not one of the
+    following elements, advance the current element to the next child of the
+    table:
    
+
+    
    9. 
+
+   
  9. 
+
+    
    If the current element is a
+    colgroup, follow these substeps:
    
+
+    
    1. 
+
+      
      Column groups: Process the current
+      element according to the appropriate case below:
      
+
+      
      If the current element has any
+       col element children
      
+
+       
      
+
+        
      Follow these steps:
      
+
+        
      1. 
+
+          
        Let xstart have
+          the value of xwidth.
        
+
+         
        2. 
+
+         
      2. 
+
+          
        Let the current column be the first
+          col element child of the colgroup
+          element.
        
+
+         
        3. 
+
+         
      3. 
+
+          
        Columns: If the current column
+          col element has a span attribute, then parse its
+          value using the rules for parsing non-negative
+          integers.
        
+
+          
        If the result of parsing the value is not an error or
+          zero, then let span be that value.
        
+
+          
        Otherwise, if the col element has no span attribute, or if trying to
+          parse the attribute's value resulted in an error or zero,
+          then let span be 1.
        
+
+         
        4. 
+
+         
      4. 
+
+          
        Increase xwidth by
+          span.
        
+
+         
        5. 
+
+         
      5. 
+
+          
        Let the last span columns in the
+          table correspond to the current
+          column col element.
        
+
+         
        6. 
+
+         
      6. 
+
+          
        If current column is not the last
+          col element child of the colgroup
+          element, then let the current column be
+          the next col element child of the
+          colgroup element, and return to the step
+          labeled columns.
        
+
+         
        7. 
+
+         
      7. 
+
+          
        Let all the last columns in the
+          table from x=xstart to x=xwidth-1 form a
+          new column group,
+          anchored at the slot (xstart, 0), with width xwidth-xstart,
+          corresponding to the colgroup element.
        
+
+         
        8. 
+
+        
      
+
+
+       
      If the current element has no
+       col element children
      
+
+       
      
+
+        
      1. 
+
+          
        If the colgroup element has a span attribute, then parse
+          its value using the rules for parsing non-negative
+          integers.
        
+
+          
        If the result of parsing the value is not an error or
+          zero, then let span be that value.
        
+
+          
        Otherwise, if the colgroup element has no
+          span attribute, or
+          if trying to parse the attribute's value resulted in an
+          error or zero, then let span be 1.
        
+
+         
        2. 
+
+         
      2. 
+
+          
        Increase xwidth by
+          span.
        
+
+         
        3. 
+
+         
      3. 
+
+          
        Let the last span columns in the
+          table form a new column group, anchored
+          at the slot (xwidth-span,
+          0), with width span, corresponding to
+          the colgroup element.
        
+
+         
        4. 
+
+        
      
+
+      
      2. 
+
+     
    2. 
+
+      
      Advance the current element to the next child of the
+      table.
      
+
+     
      3. 
+
+     
    3. 
+
+      
      While the current element is not one of
+      the following elements, advance the current element to the next child of the
+      table:
      
+
+      
      4. 
+
+     
    4. 
+
+      
      If the current element is a
+      colgroup element, jump to the step labeled
+      column groups above.
      
+
+     
      5. 
+
+    
    10. 
+
+   
  10. 
+
+    
    Let ycurrent be
+    zero.
    
+
+   
    11. 
+
+   
  11. 
+
+    
    Let the list of downward-growing cells be
+    an empty list.
    
+
+   
    12. 
+
+   
  12. 
+
+    
    Rows: While the current element is
+    not one of the following elements, advance the current element to the next child of the
+    table:
    
+
+    
    13. 
+
+   
  13. 
+
+    
    If the current element is a
+    tr, then run the algorithm for processing
+    rows, advance
+    the current element to the next child of the
+    table, and return to the step labeled
+    rows.
    
+
+   
    14. 
+
+   
  14. 
+
+    
    Run the algorithm for ending a row group.
    
+
+   
    15. 
+
+   
  15. 
+
+    
    If the current element is a
+    tfoot, then add that element to the list of pending tfoot elements, advance the current element to the next child of the
+    table, and return to the step labeled
+    rows.
    
+
+   
    16. 
+
+   
  16. 
+
+    
    The current element is either a
+    thead or a tbody.
    
+
+    
    Run the algorithm for processing row groups.
    
+
+   
    17. 
+
+   
  17. 
+
+    
    Advance the current element to the next child of the
+    table.
    
+
+   
    18. 
+
+   
  18. 
+
+    
    Return to the step labeled rows.
    
+
+   
    19. 
+
+   
  19. 
+
+    
    End: For each tfoot element in the list of
+    pending tfoot elements, in tree
+    order, run the algorithm for processing row
+    groups.
    
+
+   
    20. 
+
+   
  20. 
+
+    
    If there exists a row or column in the
+    table containing only slots that do not have a cell anchored to them, then this is a
+    table model error.
    
+
+   
    21. 
+
+   
  21. 
+
+    
    Return the table.
    
+
+   
    22. 
+
+  
The algorithm for processing row groups, which is
+  invoked by the set of steps above for processing
+  thead, tbody, and tfoot
+  elements, is:

+
+  
  1. 
+
+    
    Let ystart have the
+    value of yheight.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    For each tr element that is a child of the element
+    being processed, in tree order, run the algorithm for
+    processing rows.
    
+
+   
    3. 
+
+   
  3. 
+
+    
+    
    If yheight > ystart, then let all the last rows in the table
+    from y=ystart
+    to y=yheight-1 form a new row group, anchored at the slot
+    with coordinate (0, ystart), with height yheight-ystart, corresponding to the element
+    being processed.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Run the algorithm for ending a row group.
    
+
+   
    5. 
+
+  
The algorithm for ending a row group, which is invoked
+  by the set of steps above when starting and ending a block of rows,
+  is:

+
+  
  1. 
+
+    
    While ycurrent is less
+    than yheight, follow these
+    steps:
    
+
+    
    1. 
+
+      
      Run the algorithm for growing downward-growing
+      cells.
      
+
+     
      2. 
+
+     
    2. 
+
+      
      Increase ycurrent by
+      1.
      
+
+     
      3. 
+
+    
    2. 
+
+   
  2. 
+
+    
    Empty the list of downward-growing
+    cells.
    
+
+   
    3. 
+
+  
The algorithm for processing rows, which is invoked by
+  the set of steps above for processing tr elements,
+  is:

+
+  
  1. 
+
+    
    If yheight is equal to
+    ycurrent, then increase
+    yheight by 1. (ycurrent is never
+    greater than yheight.)
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Let xcurrent be 0.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Run the algorithm for growing downward-growing
+    cells.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If the tr element being processed has no
+    td or th element children, then increase
+    ycurrent by 1, abort this
+    set of steps, and return to the algorithm above.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Let current cell be the first
+    td or th element in the tr
+    element being processed.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Cells: While xcurrent is less than xwidth and the slot with coordinate (xcurrent, ycurrent) already has a cell assigned to it,
+    increase xcurrent by
+    1.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    If xcurrent is equal to
+    xwidth, increase xwidth by 1. (xcurrent is never
+    greater than xwidth.)
    
+
+   
    8. 
+
+   
  8. 
+
+    
    If the current cell has a colspan attribute, then parse that
+    attribute's value, and let colspan be
+    the result.
    
+
+    
    If parsing that value failed, or returned zero, or if the
+    attribute is absent, then let colspan be 1,
+    instead.
    
+
+   
    9. 
+
+   
  9. 
+
+    
    If the current cell has a rowspan attribute, then parse that attribute's
+    value, and let rowspan be the
+    result.
    
+
+    
    If parsing that value failed or if the attribute is absent,
+    then let rowspan be 1, instead.
    
+
+   
    10. 
+
+   
  10. 
+
+    
    If rowspan is zero, then let cell grows downward be true, and set rowspan to 1. Otherwise, let cell
+    grows downward be false.
    
+
+   
    11. 
+
+   
  11. 
+
+    
    If xwidth < xcurrent+colspan,
+    then let xwidth be
+    xcurrent+colspan.
    
+
+   
    12. 
+
+   
  12. 
+
+    
    If yheight < ycurrent+rowspan,
+    then let yheight be
+    ycurrent+rowspan.
    
+
+   
    13. 
+
+   
  13. 
+
+    
    Let the slots with coordinates (x, y) such that xcurrent ≤ x < xcurrent+colspan
+    and ycurrent ≤ y < ycurrent+rowspan be
+    covered by a new cell c, anchored at (xcurrent, ycurrent), which has width colspan and height rowspan,
+    corresponding to the current cell element.
    
+
+    
    If the current cell element is a
+    th element, let this new cell c
+    be a header cell; otherwise, let it be a data cell.
    
+
+    
    To establish which header cells apply to the current cell element, use the algorithm for
+    assigning header cells described in the next section.
    
+
+    
    If any of the slots involved already had a cell covering them, then this is a
+    table model error. Those slots now have two cells
+    overlapping.
    
+
+   
    14. 
+
+   
  14. 
+
+    
    If cell grows downward is true, then add
+    the tuple {c, xcurrent, colspan} to the
+    list of downward-growing cells.
    
+
+   
    15. 
+
+   
  15. 
+
+    
    Increase xcurrent by
+    colspan.
    
+
+   
    16. 
+
+   
  16. 
+
+    
    If current cell is the last td
+    or th element in the tr element being
+    processed, then increase ycurrent by 1, abort this set of steps, and
+    return to the algorithm above.
    
+
+   
    17. 
+
+   
  17. 
+
+    
    Let current cell be the next
+    td or th element in the tr
+    element being processed.
    
+
+   
    18. 
+
+   
  18. 
+
+    
    Return to the step labelled cells.
    
+
+   
    19. 
+
+  
When the algorithms above require the user agent to run the
+  algorithm for growing downward-growing cells, the user
+  agent must, for each {cell, cellx, width}
+  tuple in the list of downward-growing cells, if
+  any, extend the cell cell so that it also covers the slots with
+  coordinates (x, ycurrent), where cellx ≤ x < cellx+width.

+
+
+
+
+  
4.9.12.2 Forming relationships between data cells and header cells

+
+  
Each cell can be assigned zero or more header cells. The
+  algorithm for assigning header cells to a cell principal cell is as follows.

+
+  
  1. 
+
+    
    Let header list be an empty list of
+    cells.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Let (principalx, principaly) be the coordinate
+    of the slot to which the principal cell is
+    anchored.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If the principal cell has a headers attribute specified
    
+
+     
    
+
+      
+
+      
    1. 
+
+        
      Take the value of the principal cell's
+        headers attribute and
+        split it on
+        spaces, letting id list be the list
+        of tokens obtained.
      
+
+       
      2. 
+
+       
    2. 
+
+        
+        
+        
      For each token in the id list, if the
+        first element in the Document with an ID equal to
+        the token is a cell in the same table, and that cell is not the
+        principal cell, then add that cell to header list.
      
+
+       
      3. 
+
+      
    
+
+
+     
    If principal cell does not have a headers attribute specified
    
+
+     
    
+
+      
    1. 
+
+        
      Let principalwidth
+        be the width of the principal cell.
      
+
+       
      2. 
+
+       
    2. 
+
+        
      Let principalheight
+        be the height of the principal cell.
      
+
+       
      3. 
+
+
+       
+
+       
    3. 
+
+        
      For each value of y from principaly to principaly+principalheight-1,
+        run the internal algorithm for scanning and assigning
+        header cells, with the principal
+        cell, the header list, the initial
+        coordinate (principalx,y), and the
+        increments Δx=−1
+        and Δy=0.
      
+
+       
      4. 
+
+
+       
+
+       
    4. 
+
+        
      For each value of x from principalx to principalx+principalwidth-1,
+        run the internal algorithm for scanning and assigning
+        header cells, with the principal
+        cell, the header list, the initial
+        coordinate (x,principaly), and the increments Δx=0 and Δy=−1.
      
+
+       
      5. 
+
+
+       
+
+       
    5. 
+
+        
      If the principal cell is anchored in a
+        row group, then add all
+        header cells that are row group
+        headers and are anchored in the same row group with an
+        x-coordinate less than or equal to
+        principalx+principalwidth-1 and
+        a y-coordinate less than or equal to
+        principaly+principalheight-1 to
+        header list.
      
+
+        
+
+       
      6. 
+
+
+       
+
+       
    6. 
+
+        
      If the principal cell is anchored in a
+        column group, then
+        add all header cells that are column group headers and are anchored in the
+        same column group with an x-coordinate
+        less than or equal to principalx+principalwidth-1 and a y-coordinate less than or equal to principaly+principalheight-1 to
+        header list.
      
+
+        
+
+       
      7. 
+
+      
    
+
+    
    4. 
+
+
+   
+
+   
  4. 
+
+    
    Remove all the empty cells from
+    the header list.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Remove any duplicates from the header
+    list.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Remove principal cell from the header list if it is there.
     
+
+   
    7. 
+
+   
  7. 
+
+    
    Assign the headers in the header list to
+    the principal cell.
    
+
+   
    8. 
+
+  
The internal algorithm for scanning and assigning header
+  cells, given a principal cell, a header list, an initial coordinate (initialx, initialy), and Δx and Δy increments, is as
+  follows:

+
+  
  1. 
+
+    
    Let x equal initialx.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Let y equal initialy.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Let opaque headers be an empty list of
+    cells.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If principal cell is a header cell
    
+
+     
    Let in header block be true, and let
+     headers from current header block be a list
+     of cells containing just the principal
+     cell.
    
+
+     
    Otherwise
    
+
+     
    Let in header block be false and let
+     headers from current header block be an
+     empty list of cells.
    
+
+    
    5. 
+
+   
  5. 
+
+    
    Loop: Increment x by Δx; increment y by Δy.
    
+
+    
    For each invocation of this algorithm, one of
+    Δx and Δy will
+    be −1, and the other will be 0.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    If either x or y is
+    less than 0, then abort this internal algorithm.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    If there is no cell covering slot (x,
+    y), or if there is more than one cell
+    covering slot (x, y),
+    return to the substep labeled loop.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    Let current cell be the cell covering
+    slot (x, y).
    
+
+   
    9. 
+
+   
  9. 
+
+    
    If current cell is a header cell
    
+
+     
    
+
+      
    1. Set in header block to
+       true.
      2. 
+
+       
    2. Add current cell to headers from current header block.
      3. 
+
+       
    3. Let blocked be false.
      4. 
+
+       
    4. 
+
+        
      If Δx is 0
      
+
+         
      
+
+          
      If there are any cells in the opaque
+          headers list anchored with the same x-coordinate as the current
+          cell, and with the same width as current
+          cell, then let blocked be
+          true.
      
+
+          
      If the current cell is not a
+          column header, then let blocked be true.
      
+
+         
      
+
+         
      If Δy is 0
      
+
+         
      
+
+          
      If there are any cells in the opaque
+          headers list anchored with the same y-coordinate as the current
+          cell, and with the same height as current cell, then let blocked be true.
      
+
+          
      If the current cell is not a
+          row header, then let blocked be true.
      
+
+         
      
+
+        
      5. 
+
+       
    5. If blocked is false, then add the
+       current cell to the headers
+       list.
      6. 
+
+      
    
+
+     
    If current cell is a data cell and in header block is true
    
+
+     
    Set in header block to false. Add
+     all the cells in headers from current header
+     block to the opaque headers list, and
+     empty the headers from current header block
+     list.
    
+
+    
    10. 
+
+   
  10. 
+
+    
    Return to the step labeled loop.
    
+
+   
    11. 
+
+  
A header cell anchored at the slot with coordinate (x, y) with width width and height height is said
+  to be a column header if any of the following conditions
+  are true:

+
+  
  • The cell's scope attribute
+   is in the column state, or
    • 
+
+   
  • The cell's scope attribute
+   is in the auto state, and
+   there are no data cells in any of the cells covering slots with
+   y-coordinates y
+   .. y+height-1.
    • 
+
+  
A header cell anchored at the slot with coordinate (x, y) with width width and height height is said
+  to be a row header if any of the following conditions
+  are true:

+
+  
  • The cell's scope attribute
+   is in the row state, or
    • 
+
+   
  • The cell's scope attribute
+   is in the auto state, the
+   cell is not a column header, and there are no data
+   cells in any of the cells covering slots with x-coordinates x .. x+width-1.
    • 
+
+  
A header cell is said to be a column group header if
+  its scope attribute is in the
+  column group state.

+
+  
A header cell is said to be a row group header if
+  its scope attribute is in the
+  row group state.

+
+  
A cell is said to be an empty cell if it contains no
+  elements and its text content, if any, consists only of
+  White_Space characters.

+
+  

+
+
+  
4.9.13 Examples

+
+  
This section is non-normative.

+
+  
The following shows how might one mark up the bottom part of
+  table 45 of the Smithsonian physical tables, Volume
+  71:

+
+   
+   
+  
<table>
+ <caption>Specification values: <b>Steel</b>, <b>Castings</b>,
+ Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.</caption>
+ <thead>
+  <tr>
+   <th rowspan=2>Grade.</th>
+   <th rowspan=2>Yield Point.</th>
+   <th colspan=2>Ultimate tensile strength</th>
+   <th rowspan=2>Per cent elong. 50.8mm or 2 in.</th>
+   <th rowspan=2>Per cent reduct. area.</th>
+  </tr>
+  <tr>
+   <th>kg/mm<sup>2</sup></th>
+   <th>lb/in<sup>2</sup></th>
+  </tr>
+ </thead>
+ <tbody>
+  <tr>
+   <td>Hard</td>
+   <td>0.45 ultimate</td>
+   <td>56.2</td>
+   <td>80,000</td>
+   <td>15</td>
+   <td>20</td>
+  </tr>
+  <tr>
+   <td>Medium</td>
+   <td>0.45 ultimate</td>
+   <td>49.2</td>
+   <td>70,000</td>
+   <td>18</td>
+   <td>25</td>
+  </tr>
+  <tr>
+   <td>Soft</td>
+   <td>0.45 ultimate</td>
+   <td>42.2</td>
+   <td>60,000</td>
+   <td>22</td>
+   <td>30</td>
+  </tr>
+ </tbody>
+</table>

+
+  
This table could look like this:

+
+  
+   
+     
+     
+     
+     
+    
+     
+    
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+    
Specification values: Steel, Castings,
+   Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.
Grade.Yield Point.Ultimate tensile strengthPer cent elong. 50.8 mm or 2 in.Per cent reduct. area.
kg/mm2lb/in2
Hard0.45 ultimate56.280,0001520
Medium0.45 ultimate49.270,0001825
Soft0.45 ultimate42.260,0002230
The following shows how one might mark up the gross margin table
+  on page 46 of Apple, Inc's 10-K filing for fiscal year 2008:

+
+  
<table>
+ <thead>
+  <tr>
+   <th>
+   <th>2008
+   <th>2007
+   <th>2006
+ <tbody>
+  <tr>
+   <th>Net sales
+   <td>$ 32,479
+   <td>$ 24,006
+   <td>$ 19,315
+  <tr>
+   <th>Cost of sales
+   <td>  21,334
+   <td>  15,852
+   <td>  13,717
+ <tbody>
+  <tr>
+   <th>Gross margin
+   <td>$ 11,145
+   <td>$  8,154
+   <td>$  5,598
+ <tfoot>
+  <tr>
+   <th>Gross margin percentage
+   <td>34.3%
+   <td>34.0%
+   <td>29.0%
+</table>

+
+
+  
This table could look like this:

+
+  

+     2008
+     2007
+     2006
+   
Net sales
+     $ 32,479
+     $ 24,006
+     $ 19,315
+    
Cost of sales
+       21,334
+       15,852
+       13,717
+   
Gross margin
+     $ 11,145
+     $  8,154
+     $  5,598
+   
Gross margin percentage
+     34.3%
+     34.0%
+     29.0%
+  
The following shows how one might mark up the operating expenses
+  table from lower on the same page of that document:

+
+  
<table>
+ <colgroup> <col>
+ <colgroup> <col> <col> <col>
+ <thead>
+  <tr> <th> <th>2008 <th>2007 <th>2006
+ <tbody>
+  <tr> <th scope=rowgroup> Research and development
+       <td> $ 1,109 <td> $ 782 <td> $ 712
+  <tr> <th scope=row> Percentage of net sales
+       <td> 3.4% <td> 3.3% <td> 3.7%
+ <tbody>
+  <tr> <th scope=rowgroup> Selling, general, and administrative
+       <td> $ 3,761 <td> $ 2,963 <td> $ 2,433
+  <tr> <th scope=row> Percentage of net sales
+       <td> 11.6% <td> 12.3% <td> 12.6%
+</table>

+
+  
This table could look like this:

+
+  
 2008 2007 2006
+   
 Research and development
+          $ 1,109  $ 782  $ 712
+    
 Percentage of net sales
+          3.4%  3.3%  3.7%
+   
 Selling, general, and administrative
+          $ 3,761  $ 2,963  $ 2,433
+    
 Percentage of net sales
+          11.6%  12.3%  12.6%
+  
4.10 Forms

+
+  
4.10.1 Introduction

+
+  
This section is non-normative.

+
+  
Forms allow unscripted client-server interaction: given a form, a
+  user can provide data, submit it to the server, and have the server
+  act on it accordingly (e.g. returning the results of a search or
+  calculation). The elements used in forms can also be used for user
+  interaction with no associated submission mechanism, in conjunction
+  with scripts.

+
+  
Writing a form consists of several steps, which can be performed
+  in any order: writing the user interface, implementing the
+  server-side processing, and configuring the user interface to
+  communicate with the server.

+
+
+  
4.10.1.1 Writing a form's user interface

+
+  
This section is non-normative.

+
+  
For the purposes of this brief introduction, we will create a
+  pizza ordering form.

+
+  
Any form starts with a form element, inside which
+  are placed the controls. Most controls are represented by the
+  input element, which by default provides a one-line
+  text field. To label a control, the label element is
+  used; the label text and the control itself go inside the
+  label element. Each part of a form is considered a
+  paragraph, and is typically separated from other parts
+  using p elements. Putting this together, here is how
+  one might ask for the customer's name:

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+</form>

+
+  
To let the user select the size of the pizza, we can use a set of
+  radio buttons. Radio buttons also use the input
+  element, this time with a type
+  attribute with the value radio. To make the radio
+  buttons work as a group, they are given a common name using the
+  name attribute. To group a batch
+  of controls together, such as, in this case, the radio buttons, one
+  can use the fieldset element. The title of such a group
+  of controls is given by the first element in the
+  fieldset, which has to be a legend
+  element.

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+</form>

+
+  
Changes from the previous step are highlighted.

+
+  
To pick toppings, we can use checkboxes. These use the
+  input element with a type attribute with the value checkbox:

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox> Bacon </label></p>
+  <p><label> <input type=checkbox> Extra Cheese </label></p>
+  <p><label> <input type=checkbox> Onion </label></p>
+  <p><label> <input type=checkbox> Mushroom </label></p>
+ </fieldset>
+</form>

+
+  
The pizzeria for which this form is being written is always
+  making mistakes, so it needs a way to contact the customer. For this
+  purpose, we can use form controls specifically for telephone numbers
+  (input elements with their type attribute set to tel) and e-mail addresses
+  (input elements with their type attribute set to email):

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <p><label>Telephone: <input type=tel></label></p>
+ <p><label>E-mail address: <input type=email></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox> Bacon </label></p>
+  <p><label> <input type=checkbox> Extra Cheese </label></p>
+  <p><label> <input type=checkbox> Onion </label></p>
+  <p><label> <input type=checkbox> Mushroom </label></p>
+ </fieldset>
+</form>

+
+  
We can use an input element with its type attribute set to time to ask for a delivery
+  time. Many of these form controls have attributes to control exactly
+  what values can be specified; in this case, three attributes of
+  particular interest are min,
+  max, and step. These set the minimum time, the
+  maximum time, and the interval between allowed values (in
+  seconds). This pizzeria only delivers between 11am and 9pm, and
+  doesn't promise anything better than 15 minute increments, which we
+  can mark up as follows:

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <p><label>Telephone: <input type=tel></label></p>
+ <p><label>E-mail address: <input type=email></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox> Bacon </label></p>
+  <p><label> <input type=checkbox> Extra Cheese </label></p>
+  <p><label> <input type=checkbox> Onion </label></p>
+  <p><label> <input type=checkbox> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
+</form>

+
+  
The textarea element can be used to provide a
+  free-form text field. In this instance, we are going to use it to
+  provide a space for the customer to give delivery instructions:

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <p><label>Telephone: <input type=tel></label></p>
+ <p><label>E-mail address: <input type=email></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox> Bacon </label></p>
+  <p><label> <input type=checkbox> Extra Cheese </label></p>
+  <p><label> <input type=checkbox> Onion </label></p>
+  <p><label> <input type=checkbox> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
+ <p><label>Delivery instructions: <textarea></textarea></label></p>
+</form>

+
+  
Finally, to make the form submittable we use the
+  button element:

+
+  
<form>
+ <p><label>Customer name: <input></label></p>
+ <p><label>Telephone: <input type=tel></label></p>
+ <p><label>E-mail address: <input type=email></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size> Small </label></p>
+  <p><label> <input type=radio name=size> Medium </label></p>
+  <p><label> <input type=radio name=size> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox> Bacon </label></p>
+  <p><label> <input type=checkbox> Extra Cheese </label></p>
+  <p><label> <input type=checkbox> Onion </label></p>
+  <p><label> <input type=checkbox> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
+ <p><label>Delivery instructions: <textarea></textarea></label></p>
+ <p><button>Submit order</button><p>
+</form>

+
+
+  
4.10.1.2 Implementing the server-side processing for a form

+
+  
This section is non-normative.

+
+  
The exact details for writing a server-side processor are out of
+  scope for this specification. For the purposes of this introduction,
+  we will assume that the script at https://pizza.example.com/order.cgi is configured to
+  accept submissions using the application/x-www-form-urlencoded
+  format, expecting the following parameters sent in an HTTP POST
+  body:

+
+  
custname

+   
Customer's name

+
+   
custtel

+   
Customer's telephone number

+
+   
custemail

+   
Customer's e-mail address

+
+   
size

+   
The pizza size, either small, medium, or large

+
+   
toppings

+   
The topping, specified once for each selected topping, with the allowed values being bacon, cheese, onion, and mushroom

+
+   
delivery

+   
The requested delivery time

+
+   
comments

+   
The delivery instructions

+
+  
4.10.1.3 Configuring a form to communicate with a server

+
+  
This section is non-normative.

+
+  
Form submissions are exposed to servers in a variety of ways,
+  most commonly as HTTP GET or POST requests. To specify the exact
+  method used, the method
+  attribute is specified on the form element. This
+  doesn't specify how the form data is encoded, though; to specify
+  that, you use the enctype
+  attribute. You also have to specify the URL of the
+  service that will handle the submitted data, using the action attribute.

+
+  
For each form control you want submitted, you then have to give a
+  name that will be used to refer to the data in the submission. We
+  already specified the name for the group of radio buttons; the same
+  attribute (name) also specifies
+  the submission name. Radio buttons can be distinguished from each
+  other in the submission by giving them different values, using the
+  value attribute.

+
+  
Multiple controls can have the same name; for example, here we
+  give all the checkboxes the same name, and the server distinguishes
+  which checkbox was checked by seeing which values are submitted with
+  that name — like the radio buttons, they are also given unique
+  values with the value
+  attribute.

+
+  
Given the settings in the previous section, this all becomes:

+
+  
<form method="post"
+      enctype="application/x-www-form-urlencoded"
+      action="https://pizza.example.com/order.cgi">
+ <p><label>Customer name: <input name="custname"></label></p>
+ <p><label>Telephone: <input type=tel name="custtel"></label></p>
+ <p><label>E-mail address: <input type=email name="custemail"></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size value="small"> Small </label></p>
+  <p><label> <input type=radio name=size value="medium"> Medium </label></p>
+  <p><label> <input type=radio name=size value="large"> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
+  <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
+  <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
+  <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery"></label></p>
+ <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p>
+ <p><button>Submit order</button><p>
+</form>

+
+  
For example, if the customer entered "Denise Lawrence" as their
+  name, "555-321-8642" as their telephone number, did not specify an
+  e-mail address, asked for a medium-sized pizza, selected the Extra
+  Cheese and Mushroom toppings, entered a delivery time of 7pm, and
+  left the delivery instructions text field blank, the user agent
+  would submit the following to the online Web service:

+
+  
custname=Denise+Lawrence&custtel=555-321-8624&custemail=&size=medium&topping=cheese&topping=mushroom&delivery=19%3A00&comments=

+
+
+
+  
4.10.1.4 Client-side form validation

+
+  
This section is non-normative.

+
+  
Forms can be annotated in such a way that the user agent will
+  check the user's input before the form is submitted. The server
+  still has to verify the input is valid (since hostile users can
+  easily bypass the form validation), but it allows the user to avoid
+  the wait incurred by having the server be the sole checker of the
+  user's input.

+
+  
The simplest annotation is the required attribute, which can be
+  specified on input elements to indicate that the form
+  is not to be submitted until a value is given. By adding this
+  attribute to the customer name and delivery time fields, we allow
+  the user agent to notify the user when the user submits the form
+  without filling in those fields:

+
+  
<form method="post"
+      enctype="application/x-www-form-urlencoded"
+      action="https://pizza.example.com/order.cgi">
+ <p><label>Customer name: <input name="custname" required></label></p>
+ <p><label>Telephone: <input type=tel name="custtel"></label></p>
+ <p><label>E-mail address: <input type=email name="custemail"></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size value="small"> Small </label></p>
+  <p><label> <input type=radio name=size value="medium"> Medium </label></p>
+  <p><label> <input type=radio name=size value="large"> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
+  <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
+  <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
+  <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
+ <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p>
+ <p><button>Submit order</button><p>
+</form>

+
+  
It is also possible to limit the length of the input, using the
+  maxlength attribute. By
+  adding this to the textarea element, we can limit users
+  to 1000 characters, preventing them from writing huge essays to the
+  busy delivery drivers instead of staying focused and to the
+  point:

+
+  
<form method="post"
+      enctype="application/x-www-form-urlencoded"
+      action="https://pizza.example.com/order.cgi">
+ <p><label>Customer name: <input name="custname" required></label></p>
+ <p><label>Telephone: <input type=tel name="custtel"></label></p>
+ <p><label>E-mail address: <input type=email name="custemail"></label></p>
+ <fieldset>
+  <legend> Pizza Size </legend>
+  <p><label> <input type=radio name=size value="small"> Small </label></p>
+  <p><label> <input type=radio name=size value="medium"> Medium </label></p>
+  <p><label> <input type=radio name=size value="large"> Large </label></p>
+ </fieldset>
+ <fieldset>
+  <legend> Pizza Toppings </legend>
+  <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
+  <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
+  <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
+  <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
+ </fieldset>
+ <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
+ <p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p>
+ <p><button>Submit order</button><p>
+</form>

+
+
+
+
+  
4.10.2 Categories

+
+  
Mostly for historical reasons, elements in this section fall into
+  several overlapping (but subtly different) categories in addition to
+  the usual ones like flow content, phrasing
+  content, and interactive content.

+
+  
A number of the elements are form-associated elements, which means they can have a
+  form owner and, to expose this, have a form content attribute with a matching
+  form IDL attribute.

+
+  
+  
The form-associated
+  elements fall into several subcategories:

+
+  
Listed elements

+
+   

+
+    
Denotes elements that are listed in the form.elements
+    and fieldset.elements APIs.

+
+    
+    

+
+   
Labelable elements

+
+   

+
+    
Denotes elements that can be associated with label
+    elements.

+
+    
+    

+
+   
Submittable elements

+
+   

+
+    
Denotes elements that can be used for constructing the form data
+    set when a form element is submitted.

+
+    
+    

+
+   
Resettable elements

+
+   

+
+    
Denotes elements that can be affected when a form
+    element is reset.

+
+    
+    

+
+  
In addition, some submittable
+  elements can be, depending on their attributes, buttons. The prose below defines when
+  an element is a button. Some buttons are specifically submit buttons.

+
+  
The object element is also a
+  form-associated element and can, with the use of a
+  suitable plugin, partake in form
+  submission.

+
+
+  
4.10.3 The form element

+
+  
Categories

+   
Flow content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Flow content, but with no form element descendants.

+   
Content attributes:

+   
Global attributes

+   
accept-charset

+   
action

+   
autocomplete

+   
enctype

+   
method

+   
name

+   
novalidate

+   
target

+   
DOM interface:

+   

+
[OverrideBuiltins]
+interface HTMLFormElement : HTMLElement {
+           attribute DOMString acceptCharset;
+           attribute DOMString action;
+           attribute DOMString autocomplete;
+           attribute DOMString enctype;
+           attribute DOMString method;
+           attribute DOMString name;
+           attribute boolean noValidate;
+           attribute DOMString target;
+
+  readonly attribute HTMLFormControlsCollection elements;
+  readonly attribute long length;
+  caller getter any item(in unsigned long index);
+  caller getter any namedItem(in DOMString name);
+
+  void submit();
+  void reset();
+  boolean checkValidity();
+
+  void dispatchFormInput();
+  void dispatchFormChange();
+};

+   

+  
The form element represents a
+  collection of form-associated
+  elements, some of which can represent editable values that
+  can be submitted to a server for processing.

+
+  
The accept-charset
+  attribute gives the character encodings that are to be used for the
+  submission. If specified, the value must be an ordered set of
+  unique space-separated tokens, and each token must be an
+  ASCII case-insensitive match for the preferred
+  MIME name of an ASCII-compatible character
+  encoding. [IANACHARSET]

+
+  
The name attribute
+  represents the form's name within the forms collection. The value must
+  not be the empty string, and the value must be unique amongst the
+  form elements in the forms collection that it is in, if
+  any.

+
+  
The autocomplete
+  attribute is an enumerated attribute. The attribute has
+  two states. The on
+  keyword maps to the on state, and the
+  off keyword maps to
+  the off
+  state. The attribute may also be omitted. The missing value
+  default is the on state. The off state indicates
+  that by default, input elements in the form will have
+  their resulting autocompletion state set to off; the on state indicates
+  that by default, input elements in the form will have
+  their resulting autocompletion state set to on.

+
+  
The action, enctype, method, novalidate, and target attributes are attributes
+  for form submission.

+
+  
form . elements

+
+   

+
+    
Returns an HTMLCollection of the form controls in
+    the form (excluding image buttons for historical reasons).

+
+   

+
+   
form . length

+
+   

+
+    
Returns the number of form controls in the form (excluding
+    image buttons for historical reasons).

+
+   

+
+   
element = form . item(index)

+   
form[index]

+   
form(index)

+
+   

+
+    
Returns the indexth element in the form
+    (excluding image buttons for historical reasons).

+
+   

+
+   
element = form . namedItem(name)

+   
form[name]

+   
form(name)

+
+   

+
+    
Returns the form control in the form with the given ID or name (excluding image buttons for
+    historical reasons).

+
+    
Once an element has been referenced using a particular name,
+    that name will continue being available as a way to reference that
+    element in this method, even if the element's actual ID or name changes, for as long as the
+    element remains in the Document.

+
+    
If there are multiple matching items, then a
+    NodeList object containing all those elements is
+    returned.

+
+    
Returns null if no element with that ID or name could be found.

+
+   

+
+   
form . submit()

+
+   

+
+    
Submits the form.

+
+   

+
+   
form . reset()

+
+   

+
+    
Resets the form.

+
+   

+
+   
form . checkValidity()

+
+   

+
+    
Returns true if the form's controls are all valid; otherwise,
+    returns false.

+
+   

+
+   
form . dispatchFormInput()

+
+   

+
+    
Dispatches a forminput event at all the form controls.

+
+   

+
+   
form . dispatchFormChange()

+
+   

+
+    
Dispatches a formchange event at all the form controls.

+
+   

+
+  

+
+  
The autocomplete and
+  name IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  
The acceptCharset IDL
+  attribute must reflect the accept-charset content
+  attribute.

+
+  
The elements
+  IDL attribute must return an HTMLFormControlsCollection
+  rooted at the Document node, whose filter matches listed elements whose form
+  owner is the form element, with the exception of
+  input elements whose type attribute is in the Image Button state, which must,
+  for historical reasons, be excluded from this particular
+  collection.

+
+  
The length IDL
+  attribute must return the number of nodes represented by the elements collection.

+
+  
The
+  indices of the supported indexed properties at any
+  instant are the indices supported by the object returned by the
+  elements attribute at that
+  instant.

+
+  
The item(index) method must return the value
+  returned by the method of the same name on the elements collection, when invoked
+  with the same argument.

+
+  
Each form element has a mapping of names to elements
+  called the past names map. It is used to persist names of
+  controls even when they change names.

+
+  
The names of the supported named properties are the
+  union of the names currently supported by the object returned by the
+  elements attribute, and the
+  names currently in the past names map.

+
+  
The namedItem(name) method, when called, must run the
+  following steps:

+
+  
  1. 
+
+    
    If name is one of the names of the
+    supported named properties of the object returned by the
+    elements attribute, then
+    run these substeps:
    
+
+    
    1. Let candidate be the object returned
+     by the namedItem()
+     method on the object returned by the elements attribute when passed
+     the name argument.
      2. 
+
+     
    2. If candidate is an element, then add a
+     mapping from name to candidate in the form element's
+     past names map, replacing the previous entry with
+     the same name, if any.
      3. 
+
+     
    3. Return candidate and abort these
+     steps.
      4. 
+
+    
    2. 
+
+   
  2. Otherwise, name is the name of one of
+   the entries in the form element's past names
+   map: return the object associated with name in that map.
    3. 
+
+  
If an element listed in the form element's past
+  names map is removed from the Document, then its
+  entries must be removed from the map.

+
+  
+
+  
The submit()
+  method, when invoked, must submit the form
+  element from the form element itself, with the scripted-submit flag set.

+
+  
The reset()
+  method, when invoked, must run the following steps:

+
+  
  1. If the form element is marked as locked for
+   reset, then abort these steps.
    2. 
+
+   
  2. Mark the form element as locked for
+   reset.
    3. 
+
+   
  3. Reset the
+   form element.
    4. 
+
+   
  4. Unmark the form element as locked for
+   reset.
    5. 
+
+  
If the checkValidity()
+  method is invoked, the user agent must statically validate the
+  constraints of the form element, and return true
+  if the constraint validation return a positive result, and
+  false if it returned a negative result.

+
+  
If the dispatchFormInput()
+  method is invoked, the user agent must broadcast forminput events from the
+  form element.

+
+  
If the dispatchFormChange()
+  method is invoked, the user agent must broadcast formchange events from the
+  form element.

+
+  

+
+  

+
+   
This example shows two search forms:

+
+   
<form action="http://www.google.com/search" method="get">
+ <label>Google: <input type="search" name="q"></label> <input type="submit" value="Search...">
+</form>
+<form action="http://www.bing.com/search" method="get">
+ <label>Bing: <input type="search" name="q"></label> <input type="submit" value="Search...">
+</form>

+
+  

+
+
+
+
+  
4.10.4 The fieldset element

+
+  
Categories

+   
Flow content.

+   
Sectioning root.

+   
Listed form-associated element.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Optionally a legend element, followed by flow content.

+   
Content attributes:

+   
Global attributes

+   
disabled

+   
form

+   
name

+   
DOM interface:

+   

+
interface HTMLFieldSetElement : HTMLElement {
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString name;
+
+  readonly attribute DOMString type;
+
+  readonly attribute HTMLFormControlsCollection elements;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+};

+   

+  
The fieldset element represents a set
+  of form controls optionally grouped under a common name.

+
+  
The name of the group is given by the first legend
+  element that is a child of the fieldset element, if
+  any. The remainder of the descendants form the group.

+
+  
The disabled
+  attribute, when specified, causes all the form control descendants
+  of the fieldset element, excluding those that are
+  descendants of the fieldset element's first
+  legend element child, if any, to be disabled.

+
+  
The form attribute is used to
+  explicitly associate the fieldset element with its
+  form owner. The name
+  attribute represents the element's name.

+
+  
fieldset . type

+
+   

+
+    
Returns the string "fieldset".

+
+   

+
+   
fieldset . elements

+
+   

+
+    
Returns an HTMLCollection of the form controls in
+    the element.

+
+   

+
+  

+
+  
The disabled IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  
The type IDL
+  attribute must return the string "fieldset".

+
+  
The elements IDL
+  attribute must return an HTMLFormControlsCollection
+  rooted at the fieldset element, whose filter matches
+  listed elements.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  form and name IDL attributes are part of the
+  element's forms API.

+
+  
Constraint validation: fieldset
+  elements are always barred from constraint
+  validation.

+
+  

+
+  

+
+   
The following snippet shows a fieldset with a checkbox in the
+   legend that controls whether or not the fieldset is enabled. The
+   contents of the fieldset consist of two required text fields and an
+   optional year/month control.

+
+   
<fieldset name="clubfields" disabled>
+ <legend> <label>
+  <input type=checkbox name=club onchange="form.clubfields.disabled = !checked">
+  Use Club Card
+ </label> </legend>
+ <p><label>Name on card: <input name=clubname required></label></p>
+ <p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p>
+ <p><label>Expiry date: <input name=clubexp type=month></label></p>
+</fieldset>

+
+  

+
+
+  
4.10.5 The legend element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the first child of a fieldset element.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+    
interface HTMLLegendElement : HTMLElement {
+  readonly attribute HTMLFormElement form;
+};

+   

+  
The legend element represents a caption
+  for the rest of the contents of the legend element's
+  parent fieldset element, if
+  any.

+
+  
legend . form

+
+   

+
+    
Returns the element's form element, if any, or
+    null otherwise.

+
+   

+
+  

+
+  
The form IDL
+  attribute's behavior depends on whether the legend
+  element is in a fieldset element or not. If the
+  legend has a fieldset element as its
+  parent, then the form IDL
+  attribute must return the same value as the form IDL attribute on that
+  fieldset element. Otherwise, it must return null.

+
+  

+
+
+
+  
4.10.6 The label element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but with no descendant labelable form-associated elements unless it is the element's labeled control, and no descendant label elements.

+   
Content attributes:

+   
Global attributes

+   
form

+   
for

+   
DOM interface:

+   

+
interface HTMLLabelElement : HTMLElement {
+  readonly attribute HTMLFormElement form;
+           attribute DOMString htmlFor;
+  readonly attribute HTMLElement control;
+};

+   

+  
The label represents a caption in a
+  user interface. The caption can be associated with a specific form
+  control, known as the label
+  element's labeled control, either using for attribute, or by putting the form
+  control inside the label element itself.

+
+  

+
+  
Except where otherwise specified by the following rules, a
+  label element has no labeled control.

+
+  

+
+  
The for attribute
+  may be specified to indicate a form control with which the caption
+  is to be associated. If the attribute is specified, the attribute's
+  value must be the ID of a labelable
+  form-associated element in the same Document as
+  the label element. If the attribute
+  is specified and there is an element in the Document
+  whose ID is equal to the value of the for attribute, and the first such
+  element is a labelable form-associated
+  element, then that element is the label
+  element's labeled control.

+
+  

+
+  
If the for attribute is not
+  specified, but the label element has a labelable form-associated element
+  descendant, then the first such descendant in tree
+  order is the label element's labeled
+  control.

+
+  
The label element's exact default presentation and
+  behavior, in particular what its activation behavior
+  might be, if anything, should match the platform's label
+  behavior.

+
+  
+
+  

+
+   
For example, on platforms where clicking a checkbox label checks
+   the checkbox, clicking the label in the following
+   snippet could trigger the user agent to run synthetic click
+   activation steps on the input element, as if
+   the element itself had been triggered by the user:

+
+   
<label><input type=checkbox name=lost> Lost</label>

+
+   
On other platforms, the behavior might be just to focus the
+   control, or do nothing.

+
+  

+
+  

+
+  
label . control

+
+   

+
+    
Returns the form control that is associated with this element.

+
+   

+
+  
The form attribute is used to
+  explicitly associate the label element with its
+  form owner.

+
+  

+
+  
The htmlFor IDL
+  attribute must reflect the for content attribute.

+
+  
The control IDL
+  attribute must return the label element's labeled
+  control, if any, or null if there isn't one.

+
+  

+
+  
control . labels

+
+   

+
+    
Returns a NodeList of all the label
+    elements that the form control is associated with.

+
+   

+
+  

+
+  
Labelable form-associated
+  elements have a NodeList object associated with
+  them that represents the list of label elements, in
+  tree order, whose labeled control is the
+  element in question. The labels IDL attribute of
+  labelable form-associated
+  elements, on getting, must return that NodeList
+  object.

+
+  
The form IDL attribute is part
+  of the element's forms API.

+
+  

+
+  

+
+   
The following example shows three form controls each with a
+   label, two of which have small text showing the right format for
+   users to use.

+
+   
<p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p>
+<p><label>Age: <input name=age type=number min=0></label></p>
+<p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p>

+
+  

+
+
+  
4.10.7 The input element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
If the type attribute is not in the Hidden state: Interactive content.

+   
Listed, labelable, submittable, and resettable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
accept

+   
alt

+   
autocomplete

+   
autofocus

+   
checked

+   
disabled

+   
form

+   
formaction

+   
formenctype

+   
formmethod

+   
formnovalidate

+   
formtarget

+   
height

+   
list

+   
max

+   
maxlength

+   
min

+   
multiple

+   
name

+   
pattern

+   
placeholder

+   
readonly

+   
required

+   
size

+   
src

+   
step

+   
type

+   
value

+   
width

+   
DOM interface:

+   

+
interface HTMLInputElement : HTMLElement {
+           attribute DOMString accept;
+           attribute DOMString alt;
+           attribute DOMString autocomplete;
+           attribute boolean autofocus;
+           attribute boolean defaultChecked;
+           attribute boolean checked;
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+  readonly attribute FileList files;
+           attribute DOMString formAction;
+           attribute DOMString formEnctype;
+           attribute DOMString formMethod;
+           attribute boolean formNoValidate;
+           attribute DOMString formTarget;
+           attribute DOMString height;
+           attribute boolean indeterminate;
+  readonly attribute HTMLElement list;
+           attribute DOMString max;
+           attribute long maxLength;
+           attribute DOMString min;
+           attribute boolean multiple;
+           attribute DOMString name;
+           attribute DOMString pattern;
+           attribute DOMString placeholder;
+           attribute boolean readOnly;
+           attribute boolean required;
+           attribute unsigned long size;
+           attribute DOMString src;
+           attribute DOMString step;
+           attribute DOMString type;
+           attribute DOMString defaultValue;
+           attribute DOMString value;
+           attribute Date valueAsDate;
+           attribute double valueAsNumber;
+  readonly attribute HTMLOptionElement selectedOption;
+           attribute DOMString width;
+
+  void stepUp(in optional long n);
+  void stepDown(in optional long n);
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+
+  void select();
+           attribute unsigned long selectionStart;
+           attribute unsigned long selectionEnd;
+  void setSelectionRange(in unsigned long start, in unsigned long end);
+};

+   

+  
The input element represents a typed data field,
+  usually with a form control to allow the user to edit the data.

+
+  
The type
+  attribute controls the data type (and associated control) of the
+  element. It is an enumerated attribute. The following
+  table lists the keywords and states for the attribute — the
+  keywords in the left column map to the states in the cell in the
+  second column on the same row as the keyword.

+
+  
 Keyword
+      State
+      Data type
+      Control type
+   
 hidden
+      Hidden
+      An arbitrary string
+      n/a
+    
 text
+      Text
+      Text with no line breaks
+      Text field
+    
 search
+      Search
+      Text with no line breaks
+      Search field
+    
 tel
+      Telephone
+      Text with no line breaks
+      A text field
+    
 url
+      URL
+      An absolute IRI
+      A text field
+    
 email
+      E-mail
+      An e-mail address or list of e-mail addresses
+      A text field
+    
 password
+      Password
+      Text with no line breaks (sensitive information)
+      Text field that obscures data entry
+    
 datetime
+      Date and Time
+      A date and time (year, month, day, hour, minute, second, fraction of a second) with the time zone set to UTC
+      A date and time control
+    
 date
+      Date
+      A date (year, month, day) with no time zone
+      A date control
+    
 month
+      Month
+      A date consisting of a year and a month with no time zone
+      A month control
+    
 week
+      Week
+      A date consisting of a week-year number and a week number with no time zone
+      A week control
+    
 time
+      Time
+      A time (hour, minute, seconds, fractional seconds) with no time zone
+      A time control
+    
 datetime-local
+      Local Date and Time
+      A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone
+      A date and time control
+    
 number
+      Number
+      A numerical value
+      A text field or spinner control
+    
 range
+      Range
+      A numerical value, with the extra semantic that the exact value is not important
+      A slider control or similar
+    
 color
+      Color
+      An sRGB color with 8-bit red, green, and blue components
+      A color well
+    
 checkbox
+      Checkbox
+      A set of zero or more values from a predefined list
+      A checkbox
+    
 radio
+      Radio Button
+      An enumerated value
+      A radio button
+    
 file
+      File Upload
+      Zero or more files each with a MIME type and optionally a file name
+      A label and a button
+    
 submit
+      Submit Button
+      An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission
+      A button
+    
 image
+      Image Button
+      A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission
+      Either a clickable image, or a button
+    
 reset
+      Reset Button
+      n/a
+      A button
+    
 button
+      Button
+      n/a
+      A button
+  
The missing value default is the Text state.

+
+  
Which of the accept, alt, autocomplete, checked, formaction, formenctype, formmethod, formnovalidate, formtarget, height, list, max, maxlength, min, multiple, pattern, placeholder, readonly, required, size, src, step, and width content attributes, the checked, files, valueAsDate, valueAsNumber, list, and selectedOption IDL
+  attributes, the select() method, the selectionStart and
+  selectionEnd
+  IDL attributes, the setSelectionRange()
+  method, the stepUp() and
+  stepDown() methods, and the
+  input and change events apply to an
+  input element depends on the state of its type attribute.  The following table
+  is non-normative and summarizes which of
+  those content attributes, IDL attributes, methods, and events apply
+  to each state:

+
+  

+      Hidden
+      Text,
+          Search,
+          URL,
+          Telephone
+      E-mail
+      Password
+      Date and Time,
+          Date,
+          Month,
+          Week,
+          Time
+      Local Date and Time,
+          Number
+      Range
+      Color
+      Checkbox,
+          Radio Button
+      File Upload
+      Submit Button
+      Image Button
+      Reset Button,
+          Button
+
+   
Content attributes
+
+    
 accept
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      Yes     
+      · 
+      · 
+      · 
+
+
+    
 alt
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      Yes     
+      · 
+
+
+    
 autocomplete
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 checked
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      Yes     
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 formaction
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      Yes     
+      Yes     
+      · 
+
+
+    
 formenctype
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      Yes     
+      Yes     
+      · 
+
+
+    
 formmethod
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      Yes     
+      Yes     
+      · 
+
+
+    
 formnovalidate
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      Yes     
+      Yes     
+      · 
+
+
+    
 formtarget
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      Yes     
+      Yes     
+      · 
+
+
+    
 height
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      Yes     
+      · 
+
+
+    
 list
+      · 
+      Yes     
+
+
+      Yes     
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 max
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 maxlength
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 min
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 multiple
+      · 
+      · 
+
+
+      Yes     
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      Yes     
+      · 
+      · 
+      · 
+
+
+    
 pattern
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 placeholder
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 readonly
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      Yes     
+
+
+
+
+      Yes     
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 required
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      Yes     
+
+
+
+
+      Yes     
+
+      · 
+      · 
+      Yes     
+
+      Yes     
+      · 
+      · 
+      · 
+
+
+    
 size
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 src
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      Yes     
+      · 
+
+
+    
 step
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 width
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      Yes     
+      · 
+
+
+   
IDL attributes and methods
+
+    
 checked
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      Yes     
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 files
+      · 
+      · 
+
+
+      · 
+      · 
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      Yes     
+      · 
+      · 
+      · 
+
+
+    
 value
+      default 
+      value 
+
+
+      value 
+      value 
+      value 
+
+
+
+
+      value 
+
+      value 
+      value 
+      default/on 
+
+      filename 
+      default 
+      default 
+      default 
+
+
+    
 valueAsDate
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 valueAsNumber
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 list
+      · 
+      Yes     
+
+
+      Yes     
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 selectedOption
+      · 
+      Yes     
+
+
+      Yes     
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 select()
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 selectionStart
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 selectionEnd
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 setSelectionRange()
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      · 
+
+
+
+
+      · 
+
+      · 
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 stepDown()
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 stepUp()
+      · 
+      · 
+
+
+      · 
+      · 
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      · 
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+   
Events
+
+    
 input event
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      · 
+
+      · 
+      · 
+      · 
+      · 
+
+
+    
 change event
+      · 
+      Yes     
+
+
+      Yes     
+      Yes     
+      Yes     
+
+
+
+
+      Yes     
+
+      Yes     
+      Yes     
+      Yes     
+
+      Yes     
+      · 
+      · 
+      · 
+
+
+  

+
+  
When an input element's type attribute changes state, and
+  when the element is first created, the element's rendering and
+  behavior must change to the new state's accordingly and the
+  value sanitization algorithm, if one is defined for the
+  type attribute's new state,
+  must be invoked.

+
+  
Each input element has a value, which is exposed by the value IDL attribute. Some states
+  define an algorithm
+  to convert a string to a number, an algorithm to convert a
+  number to a string, an algorithm to convert a
+  string to a Date object, and an algorithm to convert a
+  Date object to a string, which are used by
+  max,
+  min,
+  step,
+  valueAsDate,
+  valueAsNumber,
+  stepDown(), and
+  stepUp().

+
+  
Each input element has a boolean dirty value flag. When
+  it is true, the element is said to have a dirty value. The
+  dirty value flag
+  must be initially set to false when the element is created, and must
+  be set to true whenever the user interacts with the control in a way
+  that changes the value.

+
+  

+
+  
The value
+  content attribute gives the default value of the input
+  element. When the value content attribute is added,
+  set, or removed, if the control does not have a dirty value, the user agent
+  must set the value of the
+  element to the value of the value content attribute, if there is
+  one, or the empty string otherwise, and then run the current
+  value sanitization algorithm, if one is
+  defined.

+
+  

+
+  
Each input element has a checkedness, which is exposed by
+  the checked IDL
+  attribute.

+
+  
Each input element has a boolean dirty checkedness
+  flag. When it is true, the element is said to have a dirty
+  checkedness. The dirty checkedness
+  flag must be initially set to false when the element is
+  created, and must be set to true whenever the user interacts with
+  the control in a way that changes the checkedness.

+
+  

+
+  
The checked
+  content attribute is a boolean attribute that gives the
+  default checkedness of the
+  input element. When the checked content attribute is
+  added, if the control does not have dirty checkedness, the user
+  agent must set the checkedness of the element to
+  true; when the checked
+  content attribute is removed, if the control does not have dirty checkedness, the user
+  agent must set the checkedness of the element to
+  false.

+
+  

+
+  
The reset
+  algorithm for input elements is to set the dirty value flag and
+  dirty checkedness
+  flag back to false, set the value of the element to the value of
+  the value content attribute,
+  if there is one, or the empty string otherwise, set the checkedness of the element to true
+  if the element has a checked
+  content attribute and false if it does not, and then invoke the
+  value sanitization algorithm, if the type attribute's current state
+  defines one.

+
+  
Each input element is either mutable or immutable. Except where
+  otherwise specified, an input element is always mutable. Similarly, except where
+  otherwise specified, the user agent should not allow the user to
+  modify the element's value or
+  checkedness.

+
+  
When an input element is disabled, it is immutable.

+
+  
When an input element does not have a
+  Document node as one of its ancestors (i.e. when it is
+  not in the document), it is immutable.
 
+
+  
The readonly attribute can also in
+  some cases (e.g. for the Date state, but not the Checkbox state) make an
+  input element immutable.

+
+  
When an input element is cloned, the element's value, dirty value flag,
+  checkedness, and dirty checkedness
+  flag must be propagated to the clone when it is created.

+
+  

+
+  
The form attribute is used to
+  explicitly associate the input element with its
+  form owner. The name
+  attribute represents the element's name. The disabled attribute is used to make
+  the control non-interactive and to prevent its value from being
+  submitted. The autofocus
+  attribute controls focus.

+
+  

+
+  
The indeterminate IDL
+  attribute must initially be set to false. On getting, it must return
+  the last value it was set to. On setting, it must be set to the new
+  value. It has no effect except for changing the appearance of checkbox controls.

+
+  
The accept, alt, autocomplete, max, min, multiple, pattern, placeholder, required, size, src, step, and type IDL attributes must
+  reflect the respective content attributes of the same
+  name. The maxLength IDL
+  attribute must reflect the maxlength content attribute,
+  limited to only non-negative numbers. The readOnly IDL attribute
+  must reflect the readonly content attribute. The
+  defaultChecked
+  IDL attribute must reflect the checked content attribute. The
+  defaultValue
+  IDL attribute must reflect the value content attribute.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The select(), selectionStart,
+  selectionEnd,
+  and setSelectionRange()
+  methods and attributes expose the element's text selection. The
+  autofocus, disabled, form, and name IDL attributes are part of the
+  element's forms API.

+
+  

+
+
+
+  
4.10.7.1 States of the type attribute

+
+
+  
4.10.7.1.1 Hidden state

+
+  

+
+  
When an input element's type attribute is in the Hidden state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a value
+  that is not intended to be examined or manipulated by the user.

+
+  

+
+  
Constraint validation: If an input
+  element's type attribute is in
+  the Hidden state, it is
+  barred from constraint validation.

+
+  

+
+  
If the name attribute is
+  present and has a value that is a case-sensitive match
+  for the string "_charset_", then the element's
+  value attribute must be
+  omitted.

+
+  

+
+   
The
+   value
+   IDL attribute applies to this element and is
+   in mode default.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input and change events do not apply.

+
+  

+
+
+  
4.10.7.1.2 Text state and Search state

+
+  
+
+  

+
+  
When an input element's type attribute is in the Text state or the Search state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a one line
+  plain text edit control for the element's value.

+
+  
The difference between the Text state and the Search state is primarily
+  stylistic: on platforms where search fields are distinguished from
+  regular text fields, the Search state might result in
+  an appearance consistent with the platform's search fields rather
+  than appearing like a regular text field.

+
+  

+
+  
If the element is mutable,
+  its value should be editable
+  by the user. User agents must not allow users to insert U+000A LINE
+  FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the
+  element's value.

+  

+
+  
The value attribute, if
+  specified, must have a value that contains no U+000A LINE FEED (LF)
+  or U+000D CARRIAGE RETURN (CR) characters.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: Strip line breaks from the value.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   maxlength,
+   pattern,
+   placeholder,
+   readonly,
+   required, and
+   size content attributes;
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd, and
+   value IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   max,
+   min,
+   multiple,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+  

+
+
+  
4.10.7.1.3 Telephone state

+
+  

+
+  
When an input element's type attribute is in the Telephone state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a control
+  for editing a telephone number given in the element's value.

+
+  

+
+  
If the element is mutable,
+  its value should be editable
+  by the user. User agents may change the punctuation of values that the user enters. User
+  agents must not allow users to insert U+000A LINE FEED (LF) or
+  U+000D CARRIAGE RETURN (CR) characters into the element's value.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that contains no U+000A LINE FEED (LF)
+  or U+000D CARRIAGE RETURN (CR) characters.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: Strip line breaks from the value.

+
+  

+
+  
Unlike the URL and E-mail types, the Telephone type does not enforce a
+  particular syntax. This is intentional; in practice, telephone
+  number fields tend to be free-form fields, because there are a wide
+  variety of valid phone numbers. Systems that need to enforce a
+  particular format are encouraged to use the pattern attribute or the setCustomValidity() method
+  to hook into the client-side validation mechanism.

+
+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   maxlength,
+   pattern,
+   placeholder,
+   readonly,
+   required, and
+   size content attributes;
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd, and
+   value IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   max,
+   min,
+   multiple,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+  

+
+
+  
4.10.7.1.4 URL state

+
+  

+
+  
When an input element's type attribute is in the URL state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for editing a single absolute URL given in the
+  element's value.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the URL represented
+  by its value. User agents may
+  allow the user to set the value to a string that is not a
+  valid absolute URL, but
+  may also or instead automatically escape characters entered by the
+  user so that the value is
+  always a valid absolute
+  URL (even if that isn't the actual value seen and edited by
+  the user in the interface). User agents should allow the user to set
+  the value to the empty
+  string. User agents must not allow users to insert U+000A LINE FEED
+  (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid URL potentially
+  surrounded by spaces that is also an absolute
+  URL.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: Strip line breaks from the value, then strip leading and
+  trailing whitespace from the value.

+
+  
Constraint validation: While the value of the element is not a valid absolute URL, the
+  element is suffering from a type mismatch.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   maxlength,
+   pattern,
+   placeholder,
+   readonly,
+   required, and
+   size content attributes;
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd, and
+   value IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   max,
+   min,
+   multiple,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+  

+
+  

+
+   
If a document contained the following markup:

+
+   
<input type="url" name="location" list="urls">
+<datalist id="urls">
+ <option label="MIME: Format of Internet Message Bodies" value="http://www.ietf.org/rfc/rfc2045">
+ <option label="HTML 4.01 Specification" value="http://www.w3.org/TR/html4/">
+ <option label="Form Controls" value="http://www.w3.org/TR/xforms/slice8.html#ui-commonelems-hint">
+ <option label="Scalable Vector Graphics (SVG) 1.1 Specification" value="http://www.w3.org/TR/SVG/">
+ <option label="Feature Sets - SVG 1.1 - 20030114" value="http://www.w3.org/TR/SVG/feature.html">
+ <option label="The Single UNIX Specification, Version 3" value="http://www.unix-systems.org/version3/">
+</datalist>
+

+
+   
...and the user had typed "www.w3", and the user
+   agent had also found that the user had visited
+   http://www.w3.org/Consortium/#membership and
+   http://www.w3.org/TR/XForms/ in the recent past, then
+   the rendering might look like this:

+
+   
A text box with an icon on the left followed by the text "www.w3" and a cursor, with a drop down button on the right hand side; with, below, a drop down box containing a list of six URIs on the left, with the first four having grayed out labels on the right; and a scroll bar to the right of the drow down box, indicating further values are available.

+
+   
The first four URIs in this sample consist of the four URIs in
+   the author-specified list that match the text the user has entered,
+   sorted lexically. Note how the UA is using the knowledge that the
+   values are URIs to allow the user to omit the scheme part and
+   perform intelligent matching on the domain name.

+
+   
The last two URIs (and probably many more, given the scrollbar's
+   indications of more values being available) are the matches from
+   the user agent's session history data. This data is not made
+   available to the page DOM. In this particular case, the UA has no
+   titles to provide for those values.

+
+  

+
+
+  
4.10.7.1.5 E-mail state

+
+  

+
+  
When an input element's type attribute is in the E-mail state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for editing a list of e-mail addresses given in the element's value.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the e-mail addresses
+  represented by its value. If
+  the multiple attribute is
+  specified, then the user agent should allow the user to select or
+  provide multiple addresses; otherwise, the user agent should act in
+  a manner consistent with expecting the user to provide a single
+  e-mail address. User agents may allow the user to set the value to a string that is not a
+  valid e-mail address list. User agents should allow the
+  user to set the value to the
+  empty string. User agents must not allow users to insert U+000A LINE
+  FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value. User agents may transform the
+  value for display and editing
+  (e.g. converting punycode in the value to IDN in the display and vice
+  versa).

+
+  

+
+  
If the multiple
+  attribute is specified on the element, then the value attribute, if specified, must
+  have a value that is a valid e-mail address list;
+  otherwise, the value
+  attribute, if specified, must have a value that is a single
+  valid e-mail address.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: Strip line breaks from the value.

+
+  
Constraint validation: If the multiple attribute is specified
+  on the element, then, while the value of the element is not a
+  valid e-mail address list, the element is
+  suffering from a type mismatch; otherwise, while the
+  value of the element is not a
+  single valid e-mail address, the element is
+  suffering from a type mismatch.

+
+  

+
+  
A valid e-mail address list is a set of
+  comma-separated tokens, where each token is itself a
+  valid e-mail address. To obtain the
+  list of tokens from a valid e-mail address list, the
+  user agent must split the
+  string on commas.

+
+  
A valid e-mail address is a string that matches the
+  ABNF production 1*( atext / "." ) "@" ldh-str 1*( "." ldh-str )
+  where atext is defined in RFC 5322 section
+  3.2.3, and ldh-str is defined in RFC 1034
+  section 3.5. [ABNF] [RFC5322] [RFC1034]
 
+
+  
This requirement is a willful violation
+  of RFC 5322, which defines a syntax for e-mail addresses that is
+  simultaneously too strict (before the "@" character), too vague
+  (after the "@" character), and too lax (allowing comments, white
+  space characters, and quoted strings in manners unfamiliar to most
+  users) to be of practical use here.

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required, and
+   size content attributes;
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd, and
+   value IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   max,
+   min,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+  

+
+
+  
4.10.7.1.6 Password state

+
+  

+
+  
When an input element's type attribute is in the Password state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a one line
+  plain text edit control for the element's value. The user agent should obscure
+  the value so that people other than the user cannot see it.

+
+  

+
+  
If the element is mutable,
+  its value should be editable
+  by the user. User agents must not allow users to insert U+000A LINE
+  FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that contains no U+000A LINE FEED (LF)
+  or U+000D CARRIAGE RETURN (CR) characters.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: Strip line breaks from the value.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   maxlength,
+   pattern,
+   placeholder,
+   readonly,
+   required, and
+   size content attributes;
+   selectionStart,
+   selectionEnd, and
+   value IDL attributes;
+   select(), and
+   setSelectionRange() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   min,
+   multiple,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+  

+
+
+  
4.10.7.1.7 Date and Time state

+
+  

+
+  
When an input element's type attribute is in the Date and Time state, the
+  rules in this section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  specific global date and
+  time. User agents may display the date and
+  time in whatever time zone is appropriate for the user.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the global date and time represented by
+  its value, as obtained by
+  parsing a global
+  date and time from it. User agents must not allow the user to
+  set the value to a string that
+  is not a valid global date and time string expressed in
+  UTC, though user agents may allow the user to set and view the time
+  in another time zone and silently translate the time to and from the
+  UTC time zone in the value. If
+  the user agent provides a user interface for selecting a global date and time, then the value must be set to a valid
+  global date and time string expressed in UTC representing the
+  user's selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid global date and
+  time string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is a valid global date and time string,
+  then adjust the time so that the value represents the same point in
+  time but expressed in the UTC time zone, otherwise, set it to the
+  empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid global date and
+  time string. The max
+  attribute, if specified, must have a value that is a valid
+  global date and time string.

+
+  
The step attribute is
+  expressed in seconds. The step scale factor is 1000
+  (which converts the seconds to milliseconds, as used in the other
+  algorithms). The default step is 60
+  seconds.

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest global date and time for which the
+  element would not suffer from a step mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing a global date and time from input results in an error, then return an error;
+  otherwise, return the number of milliseconds elapsed from midnight
+  UTC on the morning of 1970-01-01 (the time represented by the value
+  "1970-01-01T00:00:00.0Z") to the parsed global date and time, ignoring leap
+  seconds.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid global date and time
+  string expressed in UTC that represents the global date and time that is input milliseconds after midnight UTC on the morning
+  of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z").

+
+  
The algorithm to convert a
+  string to a Date object, given a string input, is as follows: If parsing a global date and time
+  from input results in an error, then return an
+  error; otherwise, return a Date object representing the
+  parsed global date and time,
+  expressed in UTC.

+
+  
The algorithm to convert a
+  Date object to a string, given a
+  Date object input, is as
+  follows: Return a valid global date and time
+  string expressed in UTC that represents the global date and time that is
+  represented by input.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsDate,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart, and
+   selectionEnd IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+  

+
+   
The following fragment shows part of a calendar application. A
+   user can specify a date and time for a meeting (in his local time
+   zone, probably, though the user agent can allow the user to change
+   that), and since the submitted data includes the time-zone offset,
+   the application can ensure that the meeting is shown at the correct
+   time regardless of the time zones used by all the participants.

+
+   
<fieldset>
+ <legend>Add Meeting</legend>
+ <p><label>Meeting name: <input type=text name="meeting.label"></label>
+ <p><label>Meeting time: <input type=datetime name="meeting.start"></label>
+</fieldset>

+
+   
Had the application used the datetime-local type
+   instead, the calendar application would have also had to explicitly
+   determine which time zone the user intended.

+
+  

+
+
+  
4.10.7.1.8 Date state

+
+  

+
+  
When an input element's type attribute is in the Date state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  specific date.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the date represented by its value, as obtained by parsing a date from it. User
+  agents must not allow the user to set the value to a string that is not a
+  valid date string. If the user agent provides a user
+  interface for selecting a date,
+  then the value must be set to
+  a valid date string representing the user's
+  selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid date
+  string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid date string, then set it
+  to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid date
+  string. The max
+  attribute, if specified, must have a value that is a valid
+  date string.

+
+  
The step attribute is
+  expressed in days. The step scale factor is
+  86,400,000 (which converts the days to milliseconds, as used in the
+  other algorithms). The default step is 1 day.

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest date for which the element would not
+  suffer from a step
+  mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing
+  a date from input results in an error,
+  then return an error; otherwise, return the number of milliseconds
+  elapsed from midnight UTC on the morning of 1970-01-01 (the time
+  represented by the value "1970-01-01T00:00:00.0Z") to midnight UTC on the
+  morning of the parsed date,
+  ignoring leap seconds.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid date string that
+  represents the date that, in UTC,
+  is current input milliseconds after midnight UTC
+  on the morning of 1970-01-01 (the time represented by the value
+  "1970-01-01T00:00:00.0Z").

+
+  
The algorithm to convert a
+  string to a Date object, given a string input, is as follows: If parsing a date from input
+  results in an error, then return an error; otherwise, return a
+  Date object representing midnight UTC on the morning of
+  the parsed date.

+
+  
The algorithm to convert a
+  Date object to a string, given a
+  Date object input, is as
+  follows: Return a valid date string that
+  represents the date current at the
+  time represented by input in the UTC
+  time zone.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsDate,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   selectionStart, and
+   selectionEnd IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+
+  
4.10.7.1.9 Month state

+
+  

+
+  
When an input element's type attribute is in the Month state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  specific month.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the month represented by its value, as obtained by parsing a month from it. User
+  agents must not allow the user to set the value to a string that is not a
+  valid month string. If the user agent provides a user
+  interface for selecting a month,
+  then the value must be set to
+  a valid month string representing the user's
+  selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid month
+  string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid month string, then set it
+  to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid month
+  string. The max
+  attribute, if specified, must have a value that is a valid
+  month string.

+
+  
The step attribute is
+  expressed in months. The step scale factor is 1
+  (there is no conversion needed as the algorithms use months).
+  The default step is
+  1 month.

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest month for which the element would not
+  suffer from a step
+  mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing a month from input
+  results in an error, then return an error; otherwise, return the
+  number of months between January 1970 and the parsed month.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid month string
+  that represents the month that
+  has input months between it and January
+  1970.

+
+  
+
+  
The algorithm to convert a
+  string to a Date object, given a string input, is as follows: If parsing a month from input results in an error, then return an error;
+  otherwise, return a Date object representing midnight
+  UTC on the morning of the first day of the parsed month.

+
+  
The algorithm to convert a
+  Date object to a string, given a
+  Date object input, is as
+  follows: Return a valid month string that
+  represents the month current at
+  the time represented by input in the UTC
+  time zone.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsDate,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart, and
+   selectionEnd IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+
+  
4.10.7.1.10 Week state

+
+  

+
+  
When an input element's type attribute is in the Week state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  specific week.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the week represented by its value, as obtained by parsing a week from it. User
+  agents must not allow the user to set the value to a string that is not a
+  valid week string. If the user agent provides a user
+  interface for selecting a week,
+  then the value must be set to
+  a valid week string representing the user's
+  selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid week
+  string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid week string, then set it
+  to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid week
+  string. The max
+  attribute, if specified, must have a value that is a valid
+  week string.

+
+  
The step attribute is
+  expressed in weeks. The step scale factor is
+  604,800,000 (which converts the weeks to milliseconds, as used in
+  the other algorithms). The default step is 1
+  week. The default step base is
+  −259,200,000 (the start of week 1970-W01).

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest week for which the element would not
+  suffer from a step
+  mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing
+  a week string from input results in an
+  error, then return an error; otherwise, return the number of
+  milliseconds elapsed from midnight UTC on the morning of 1970-01-01
+  (the time represented by the value "1970-01-01T00:00:00.0Z") to midnight UTC on the
+  morning of the Monday of the parsed week, ignoring leap seconds.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid week string that
+  represents the week that, in UTC,
+  is current input milliseconds after midnight UTC
+  on the morning of 1970-01-01 (the time represented by the value
+  "1970-01-01T00:00:00.0Z").

+
+  
The algorithm to convert a
+  string to a Date object, given a string input, is as follows: If parsing a week from input
+  results in an error, then return an error; otherwise, return a
+  Date object representing midnight UTC on the morning of
+  the Monday of the parsed week.

+
+  
The algorithm to convert a
+  Date object to a string, given a
+  Date object input, is as
+  follows: Return a valid week string that
+  represents the week current at the
+  time represented by input in the UTC
+  time zone.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsDate,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart, and
+   selectionEnd IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+
+  
4.10.7.1.11 Time state

+
+  
+
+  

+
+  
When an input element's type attribute is in the Time state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  specific time.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the time represented by its value, as obtained by parsing a time from it. User
+  agents must not allow the user to set the value to a string that is not a
+  valid time string. If the user agent provides a user
+  interface for selecting a time,
+  then the value must be set to
+  a valid time string representing the user's
+  selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid time
+  string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid time string, then set it
+  to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid time
+  string. The max
+  attribute, if specified, must have a value that is a valid
+  time string.

+
+  
The step attribute is
+  expressed in seconds. The step scale factor is 1000
+  (which converts the seconds to milliseconds, as used in the other
+  algorithms). The default step is 60
+  seconds.

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest time for which the element would not
+  suffer from a step
+  mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing
+  a time from input results in an error,
+  then return an error; otherwise, return the number of milliseconds
+  elapsed from midnight to the parsed time on a day with no time changes.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid time string that
+  represents the time that is input milliseconds after midnight on a day with no
+  time changes.

+
+  
The algorithm to convert a
+  string to a Date object, given a string input, is as follows: If parsing a time from input
+  results in an error, then return an error; otherwise, return a
+  Date object representing the parsed time in UTC on 1970-01-01.

+
+  
The algorithm to convert a
+  Date object to a string, given a
+  Date object input, is as
+  follows: Return a valid time string that
+  represents the UTC time component
+  that is represented by input.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsDate,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart, and
+   selectionEnd IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+
+  
4.10.7.1.12 Local Date and Time state

+
+  

+
+  
When an input element's type attribute is in the Local Date and Time
+  state, the rules in this section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  local date and time,
+  with no time-zone offset information.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the date and time represented by
+  its value, as obtained by
+  parsing a date and
+  time from it. User agents must not allow the user to set the
+  value to a string that is not
+  a valid local date and time string. If the user agent
+  provides a user interface for selecting a local date and time, then the
+  value must be set to a
+  valid local date and time string representing the
+  user's selection. User agents should allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid local date and
+  time string.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid local date and time
+  string, then set it to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid local date and
+  time string. The max
+  attribute, if specified, must have a value that is a valid
+  local date and time string.

+
+  
The step attribute is
+  expressed in seconds. The step scale factor is 1000
+  (which converts the seconds to milliseconds, as used in the other
+  algorithms). The default step is 60
+  seconds.

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest local date and time for which
+  the element would not suffer from a step mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If parsing a date and time from input results in an error, then return an error;
+  otherwise, return the number of milliseconds elapsed from midnight
+  on the morning of 1970-01-01 (the time represented by the value
+  "1970-01-01T00:00:00.0") to the parsed local date and time, ignoring
+  leap seconds.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid local date and time
+  string that represents the date and time that is input milliseconds after midnight on the morning of
+  1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0").

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart,
+   selectionEnd, and
+   valueAsDate IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+  

+
+   
The following example shows part of a flight booking
+   application. The application uses an input element
+   with its type attribute set to
+   datetime-local,
+   and it then interprets the given date and time in the time zone of
+   the selected airport.

+
+   
<fieldset>
+ <legend>Destination</legend>
+ <p><label>Airport: <input type=text name=to list=airports></label></p>
+ <p><label>Departure time: <input type=datetime-local name=totime step=3600></label></p>
+</fieldset>
+<datalist id=airports>
+ <option value=ATL label="Atlanta">
+ <option value=MEM label="Memphis">
+ <option value=LHR label="London Heathrow">
+ <option value=LAX label="Los Angeles">
+ <option value=FRA label="Frankfurt">
+</datalist>

+
+   
If the application instead used the datetime type, then the
+   user would have to work out the time-zone conversions himself,
+   which is clearly not a good user experience!

+
+  

+
+
+  
4.10.7.1.13 Number state

+
+  

+
+  
When an input element's type attribute is in the Number state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  number.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the number
+  represented by its value, as
+  obtained from applying the rules for parsing floating point
+  number values to it. User agents must not allow the user to
+  set the value to a string that
+  is not a valid floating point number. If the user agent
+  provides a user interface for selecting a number, then the value must be set to the best representation of the number representing the user's
+  selection as a floating point number. User agents should
+  allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid floating point
+  number.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid floating point number,
+  then set it to the empty string instead.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid floating point
+  number. The max
+  attribute, if specified, must have a value that is a valid
+  floating point number.

+
+  
The step scale factor is
+  1. The default
+  step is 1 (allowing only integers, unless the min attribute has a non-integer
+  value).

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent may round the element's value to the nearest number for
+  which the element would not suffer from a step mismatch.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If applying the rules for parsing
+  floating point number values to input
+  results in an error, then return an error; otherwise, return the
+  resulting number.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid floating point
+  number that represents input.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min,
+   readonly,
+   required, and
+   step content attributes;
+   list,
+   value,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart,
+   selectionEnd, and
+   valueAsDate IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+
+  
4.10.7.1.14 Range state

+
+  

+
+  
When an input element's type attribute is in the Range state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a control
+  for setting the element's value to a string representing a
+  number, but with the caveat that the exact value is not important,
+  letting UAs provide a simpler interface than they do for the Number state.

+
+  

+
+  
In this state, the range and step constraints are
+  enforced even during user input, and there is no way to set the
+  value to the empty string.

+
+  
If the element is mutable,
+  the user agent should allow the user to change the number
+  represented by its value, as
+  obtained from applying the rules for parsing floating point
+  number values to it. User agents must not allow the user to
+  set the value to a string that
+  is not a valid floating point number. If the user agent
+  provides a user interface for selecting a number, then the value must be set to a best representation of the number representing the user's
+  selection as a floating point number. User agents must not
+  allow the user to set the value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid floating point
+  number.
 
+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is not a valid floating point number,
+  then set it to a valid floating point number that
+  represents the default value.

+
+  

+
+  
The min attribute, if
+  specified, must have a value that is a valid floating point
+  number. The default
+  minimum is 0. The max
+  attribute, if specified, must have a value that is a valid
+  floating point number. The default maximum is 100.

+
+  
The default
+  value is the minimum
+  plus half the difference between the minimum and the maximum, unless the maximum is less than the minimum, in which case the default value is
+  the minimum.

+
+  

+
+  
When the element is suffering from an
+  underflow, the user agent must set the element's value to a valid floating point
+  number that represents the minimum.

+
+  
When the element is suffering from an overflow,
+  if the maximum is not less
+  than the minimum, the user
+  agent must set the element's value to a valid floating point
+  number that represents the maximum.

+
+  

+
+  
The step scale factor is
+  1. The default
+  step is 1 (allowing only integers, unless the min attribute has a non-integer
+  value).

+
+  

+
+  
When the element is suffering from a step mismatch,
+  the user agent must round the element's value to the nearest number for
+  which the element would not suffer from a step mismatch, and which is greater
+  than or equal to the minimum,
+  and, if the maximum is not
+  less than the minimum, which
+  is less than or equal to the maximum.

+
+  
The algorithm to convert a
+  string to a number, given a string input,
+  is as follows: If applying the rules for parsing
+  floating point number values to input
+  results in an error, then return an error; otherwise, return the
+  resulting number.

+
+  
The algorithm to convert a
+  number to a string, given a number input,
+  is as follows: Return a valid floating point
+  number that represents input.

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete,
+   list,
+   max,
+   min, and
+   step content attributes;
+   list,
+   value,
+   valueAsNumber, and
+   selectedOption IDL attributes;
+   stepDown() and
+   stepUp() methods.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart,
+   selectionEnd, and
+   valueAsDate IDL attributes;
+   select() and
+   setSelectionRange() methods.

+
+  

+
+  

+
+   
Here is an example of a range control using an autocomplete list
+   with the list attribute. This
+   could be useful if there are values along the full range of the
+   control that are especially important, such as preconfigured light
+   levels or typical speed limits in a range control used as a speed
+   control. The following markup fragment:

+
+   
<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers">
+<datalist id="powers">
+ <option value="0">
+ <option value="-30">
+ <option value="30">
+ <option value="+50">
+</datalist>
+

+
+   
...with the following style sheet applied:

+
+   
input { height: 75px; width: 49px; background: #D5CCBB; color: black; }

+
+   
...might render as:

+
+   
A vertical slider control whose primary color is black and whose background color is beige, with the slider having five tick marks, one long one at each extremity, and three short ones clustered around the midpoint.
Note how the UA determined the orientation of the control from
+   the ratio of the style-sheet-specified height and width properties.
+   The colors were similiarly derived from the style sheet. The tick
+   marks, however, were derived from the markup. In particular, the
+   step attribute has not
+   affected the placement of tick marks, the UA deciding to only use
+   the author-specified completion values and then adding longer tick
+   marks at the extremes.

+
+   
Note also how the invalid value +50 was
+   completely ignored.

+
+  

+
+  

+
+   
For another example, consider the following markup fragment:

+
+   
<input name=x type=range min=100 max=700 step=9.09090909 value=509.090909>

+
+   
A user agent could display in a variety of ways, for instance:

+
+   
As a dial.

+
+   
Or, alternatively, for instance:

+
+   
As a long horizontal slider with tick marks.

+
+   
The user agent could pick which one to display based on the
+   dimensions given in the style sheet. This would allow it to
+   maintain the same resolution for the tick marks, despite the
+   differences in width.

+
+  

+
+
+
+  
4.10.7.1.15 Color state

+
+  

+
+  
When an input element's type attribute is in the Color state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a color
+  well control, for setting the element's value to a string representing a
+  simple color.

+
+  

+
+  
In this state, there is always a color picked, and
+  there is no way to set the value to the empty string.

+
+  
If the element is mutable,
+  the user agent should allow the user to change the color represented
+  by its value, as obtained from
+  applying the rules for parsing simple color values to
+  it. User agents must not allow the user to set the value to a string that is not a
+  valid lowercase simple color. If the user agent
+  provides a user interface for selecting a color, then the value must be set to the result of
+  using the rules for serializing simple color values to
+  the user's selection. User agents must not allow the user to set the
+  value to the empty string.

+
+  

+
+  
The value attribute, if
+  specified, must have a value that is a valid simple
+  color.

+
+  

+
+  
The value sanitization algorithm is as
+  follows: If the value
+  of the element is a valid simple color, then set it to
+  the value of the element
+  converted to ASCII lowercase; otherwise, set it to the string
+  "#000000".

+
+  

+
+  

+
+   
The following common input element content
+   attributes, IDL attributes, and methods apply to the element:
+   autocomplete and
+   list content attributes;
+   list,
+   value, and
+   selectedOption IDL attributes.

+
+   
The value IDL attribute is
+   in mode value.

+
+   
The input and change events apply.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   maxlength,
+   max,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+  

+
+
+  
4.10.7.1.16 Checkbox state

+
+  

+
+  
When an input element's type attribute is in the Checkbox state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a
+  two-state control that represents the element's checkedness state. If the
+  element's checkedness state
+  is true, the control represents a positive selection, and if it is
+  false, a negative selection. If the element's indeterminate IDL attribute
+  is set to true, then the control's selection should be obscured as
+  if the control was in a third, indeterminate, state.

+
+  
The control is never a true tri-state control, even
+  if the element's indeterminate IDL attribute
+  is set to true. The indeterminate IDL attribute
+  only gives the appearance of a third state.

+
+  

+
+  
If the element is mutable,
+  then: The pre-click activation steps consist of setting
+  the element's checkedness to
+  its opposite value (i.e. true if it is false, false if it is true),
+  and of setting the element's indeterminate IDL attribute
+  to false. The canceled activation steps consist of
+  setting the checkedness and
+  the element's indeterminate IDL attribute
+  back to the values they had before the pre-click activation
+  steps were run. The activation behavior is to
+  fire a simple event that bubbles named change at the element, then broadcast formchange events at the
+  element's form owner.

+
+  
Constraint validation: If the element is required and its checkedness is false, then the
+  element is suffering from being missing.

+
+  

+
+  
input . indeterminate [ = value ]

+
+   

+
+    
When set, overrides the rendering of checkbox controls so that
+    the current value is not visible.

+
+   

+
+  

+
+   
The following common input element content
+   attributes and IDL attributes apply to the element:
+   checked, and
+   required content attributes;
+   checked and
+   value IDL attributes.

+
+   
The value IDL attribute is
+   in mode default/on.

+
+   
The change event applies.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input event does not apply.

+
+  

+
+
+
+  
4.10.7.1.17 Radio Button state

+
+  

+
+  
When an input element's type attribute is in the Radio Button state, the rules
+  in this section apply.

+
+  

+
+  
The input element represents a control
+  that, when used in conjunction with other input
+  elements, forms a radio button group in which only one
+  control can have its checkedness state set to true. If
+  the element's checkedness
+  state is true, the control represents the selected control in the
+  group, and if it is false, it indicates a control in the group that
+  is not selected.

+
+  
The radio button group that contains an
+  input element a also contains all
+  the other input elements b that
+  fulfill all of the following conditions:

+
+  
A document must not contain an input element whose
+  radio button group contains only that element.

+
+  

+
+  
When any of the following events occur, if the element's checkedness state is true after
+  the event, the checkedness state of all the
+  other elements in the same radio button group must be set to
+  false:

+
+  
  • The element's checkedness state is set to
+   true (for whatever reason).
    • 
+
+   
  • The element's name
+   attribute is added, removed, or changes value.
    • 
+
+   
  • The element's form owner changes.
    • 
+
+  
If the element is mutable,
+  then: The pre-click activation steps consist of setting
+  the element's checkedness to
+  true. The canceled activation steps consist of setting
+  the element's checkedness to
+  false. The activation behavior is to fire a
+  simple event that bubbles named change at the element, then broadcast formchange events at the
+  element's form owner.

+
+  
Constraint validation: If the element is required and all of the
+  input elements in the radio button group have a
+  checkedness that is
+  false, then the element is suffering from being
+  missing.

+
+  

+
+  
If none of the radio buttons in a radio button
+  group are checked when they are inserted into the document,
+  then they will all be initially unchecked in the interface, until
+  such time as one of them is checked (either by the user or by
+  script).

+
+  

+
+   
The following common input element content
+   attributes and IDL attributes apply to the element:
+   checked and
+   required content attributes;
+   checked and
+   value IDL attributes.

+
+   
The value IDL attribute is
+   in mode default/on.

+
+   
The change event applies.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input event does not apply.

+
+  

+
+
+
+  
4.10.7.1.18 File Upload state

+
+  
+
+  

+
+  
When an input element's type attribute is in the File Upload state, the rules in this
+  section apply.

+
+  

+
+  
The input element represents a list of
+  selected files,
+  each file consisting of a file name, a file type, and a file body
+  (the contents of the file).

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to change the files on the
+  list, e.g. adding or removing files. Files can be from the
+  filesystem or created on the fly, e.g. a picture taken from a camera
+  connected to the user's device.

+
+  
Constraint validation: If the element is required and the list of selected files is
+  empty, then the element is suffering from being
+  missing.

+
+  
Unless the multiple
+  attribute is set, there must be no more than one file in the list of
+  selected
+  files.

+
+  

+
+  
The accept
+  attribute may be specified to provide user agents with a hint of
+  what file types the server will be able to accept.

+
+  
If specified, the attribute must consist of a set of
+  comma-separated tokens, each of which must be an ASCII
+  case-insensitive match for one of the following:

+
+  
The string audio/*

+
+   
Indicates that sound files are accepted.

+
+   
The string video/*

+
+   
Indicates that video files are accepted.

+
+   
The string image/*

+
+   
Indicates that image files are accepted.

+
+   
A valid MIME type with no parameters

+
+   
Indicates that files of the specified type are accepted.

+
+  
The tokens must not be ASCII case-insensitive
+  matches for any of the other tokens (i.e. duplicates are not
+  allowed). To obtain the list of tokens from the
+  attribute, the user agent must split the attribute value on commas.

+
+  

+
+  
User agents should prevent the user from selecting files that are
+  not accepted by one (or more) of these tokens.

+
+  

+
+  

+
+   
For historical reasons, the value IDL attribute prefixes the
+   filename with the string "C:\fakepath\". Some
+   legacy user agents actually included the full path (which was a
+   security vulnerability). As a result of this, obtaining the
+   filename from the value IDL
+   attribute in a backwards-compatible way is non-trivial. The
+   following function extracts the filename in a suitably compatible
+   manner:

+
+   
function extractFilename(path) {
+  var x;
+  x = path.lastIndexOf('\\');
+  if (x >= 0) // Windows-based path
+    return path.substr(x+1);
+  x = path.lastIndexOf('/');
+  if (x >= 0) // Unix-based path
+    return path.substr(x+1);
+  return path; // just the filename
+}

+
+   
This can be used as follows:

+
+   
<p><input type=file name=image onchange="updateFilename(this.value)"></p>
+<p>The name of the file you picked is: <span id="filename">(none)</span></p>
+<script>
+ function updateFilename(path) {
+   var name = extractFilename(path);
+   document.getElementById('filename').textContent = name;
+ }
+</script>

+
+   
+
+  

+
+  

+
+   
The following common input element content
+   attributes apply to the element:
+
+   
The following common input element content
+   attributes and IDL attributes apply to the element:
+   accept,
+   multiple, and
+   required;
+   files and
+   value IDL attributes.

+
+   
The value IDL attribute is
+   in mode filename.

+
+   
The change event applies.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   alt,
+   autocomplete,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   pattern,
+   placeholder,
+   readonly,
+   size,
+   src,
+   step, and
+   width.

+
+   
The element's value
+   attribute must be omitted.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input event does not apply.

+
+  

+
+
+
+  
4.10.7.1.19 Submit Button state

+
+  

+
+  
When an input element's type attribute is in the Submit Button state, the rules
+  in this section apply.

+
+  

+
+  
The input element represents a button
+  that, when activated, submits the form. If the
+  element has a value attribute,
+  the button's label must be the value of that attribute; otherwise,
+  it must be an implementation-defined string that means "Submit" or
+  some such. The element is a button, specifically a submit button.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to activate the element.

+
+  
The element's activation behavior, if the element
+  has a form owner, is to submit the form
+  owner from the input element; otherwise, it is
+  to do nothing.

+
+  

+
+  
The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes
+  for form submission.

+
+  
The formnovalidate attribute can
+  be used to make submit buttons that do not trigger the constraint
+  validation.

+
+  

+
+   
The following common input element content
+   attributes and IDL attributes apply to the element:
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate, and
+   formtarget content attributes;
+   value IDL attribute.

+
+   
The value IDL attribute is
+   in mode default.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   checked,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input and change events do not apply.

+
+  

+
+
+  
4.10.7.1.20 Image Button state

+
+  

+
+  
When an input element's type attribute is in the Image Button state, the rules
+  in this section apply.

+
+  

+
+  
The input element represents either an
+  image from which a user can select a coordinate and submit the form,
+  or alternatively a button from which the user can submit the
+  form. The element is a button,
+  specifically a submit
+  button.

+
+  
The image is given by the src attribute. The src attribute must be present, and
+  must contain a valid non-empty URL potentially surrounded by
+  spaces referencing a non-interactive, optionally animated,
+  image resource that is neither paged nor scripted.

+
+  

+
+  
When any of the following events occur, unless the user agent
+  cannot support images, or its support for images has been disabled,
+  or the user agent only fetches elements on demand, or the src attribute's value is the empty
+  string, the user agent must resolve the value of the src attribute, relative to the
+  element, and if that is successful, must fetch the
+  resulting absolute URL:
  
+
+  
  • The input element's type attribute is first set to the
+   Image Button state
+   (possibly when the element is first created), and the src attribute is present.
    • 
+
+   
  • The input element's type attribute is changed back to
+   the Image Button state,
+   and the src attribute is
+   present, and its value has changed since the last time the type attribute was in the Image Button state.
    • 
+
+   
  • The input element's type attribute is in the Image Button state, and the
+   src attribute is set or
+   changed.
    • 
+
+  
Fetching the image must delay the load event of the
+  element's document until the task
+  that is queued by the
+  networking task source once the resource has been fetched (defined below) has been run.

+
+  
If the image was successfully obtained, with no network errors,
+  and the image's type is a supported image type, and the image is a
+  valid image of that type, then the image is said to be available. If this is true
+  before the image is completely downloaded, each task that is queued by the networking task source while
+  the image is being fetched must update
+  the presentation of the image appropriately.

+
+  
The user agents should apply the image sniffing rules to determine the type
+  of the image, with the image's associated
+  Content-Type headers giving the official
+  type. If these rules are not applied, then the type of the
+  image must be the type given by the image's associated Content-Type headers.

+
+  
User agents must not support non-image resources with the
+  input element. User agents must not run executable code
+  embedded in the image resource. User agents must only display the
+  first page of a multipage resource. User agents must not allow the
+  resource to act in an interactive fashion, but should honor any
+  animation in the resource.

+
+  
The task that is queued by the networking task
+  source once the resource has been fetched, must, if the download was successful
+  and the image is available,
+  queue a task to fire a simple event named
+  load at the input
+  element; and otherwise, if the fetching process fails without a
+  response from the remote server, or completes but the image is not a
+  valid or supported image, queue a task to fire a
+  simple event named error on
+  the input element.

+
+  

+
+  
The alt attribute
+  provides the textual label for the alternative button for users and
+  user agents who cannot use the image. The alt attribute must also be present,
+  and must contain a non-empty string.

+
+  
The input element supports dimension
+  attributes.

+
+  

+
+  
If the src attribute is set,
+  and the image is available and
+  the user agent is configured to display that image, then: The
+  element represents a control for selecting a coordinate from
+  the image specified by the src
+  attribute; if the element is mutable, the user agent should
+  allow the user to select this coordinate. The
+  activation behavior in this case consists of taking the
+  user's selected coordinate, and
+  then, if the element has a form owner, submitting the input
+  element's form owner from the input
+  element. If the user activates the control without explicitly
+  selecting a coordinate, then the coordinate (0,0) must be
+  assumed.

+
+  
Otherwise, the element represents a submit button
+  whose label is given by the value of the alt attribute; if the element is mutable, the user agent should
+  allow the user to activate the button. The activation
+  behavior in this case consists of setting the selected
+  coordinate to (0,0), and then, if the element has a
+  form owner, submitting the input
+  element's form owner from the input
+  element.

+
+  
The selected
+  coordinate must consist of an x-component
+  and a y-component. The coordinates represent the
+  position relative to the edge of the image, with the coordinate
+  space having the positive x direction to the
+  right, and the positive y direction
+  downwards.

+
+  
The x-component must be a valid
+  integer representing a number x in the
+  range −(borderleft+paddingleft) ≤ x ≤ width+borderright+paddingright, where width
+  is the rendered width of the image, borderleft is the width of the border on the left of
+  the image, paddingleft is
+  the width of the padding on the left of the image, borderright is the width of the
+  border on the right of the image, and paddingright is the width of the padding on the right
+  of the image, with all dimensions given in CSS pixels.

+
+  
The y-component must be a valid
+  integer representing a number y in the
+  range −(bordertop+paddingtop) ≤ y ≤ height+borderbottom+paddingbottom, where height
+  is the rendered height of the image, bordertop is the width of the border above the image,
+  paddingtop is the width of
+  the padding above the image, borderbottom is the width of the border below the
+  image, and paddingbottom is
+  the width of the padding below the image, with all dimensions given
+  in CSS pixels.

+
+  
Where a border or padding is missing, its width is zero CSS
+  pixels.

+
+  

+
+  
The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes
+  for form submission.

+
+  

+
+   
The following common input element content
+   attributes and IDL attributes apply to the element:
+   alt,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   src, and
+   width content attributes;
+   value IDL attribute.

+
+   
The value IDL attribute is
+   in mode default.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   autocomplete,
+   checked,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size, and
+   step.

+
+   
The element's value
+   attribute must be omitted.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input and change events do not apply.

+
+  

+
+  
Many aspects of this state's behavior are similar to
+  the behavior of the img element. Readers are encouraged
+  to read that section, where many of the same requirements are
+  described in more detail.

+
+
+
+  
4.10.7.1.21 Reset Button state

+
+  

+
+  
When an input element's type attribute is in the Reset Button state, the rules
+  in this section apply.

+
+  

+
+  
The input element represents a button
+  that, when activated, resets the form. If the
+  element has a value attribute,
+  the button's label must be the value of that attribute; otherwise,
+  it must be an implementation-defined string that means "Reset" or
+  some such. The element is a button.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to activate the element.

+
+  
The element's activation behavior, if the element
+  has a form owner, is to reset the form owner;
+  otherwise, it is to do nothing.

+
+  
Constraint validation: The element is
+  barred from constraint validation.

+
+  

+
+  

+
+   
The value IDL attribute
+   applies to this element and is in mode default.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input and change events do not apply.

+
+  

+
+
+  
4.10.7.1.22 Button state

+
+  

+
+  
When an input element's type attribute is in the Button state, the rules in
+  this section apply.

+
+  

+
+  
The input element represents a button
+  with no default behavior. If the element has a
+  value attribute, the button's
+  label must be the value of that attribute; otherwise, it must be the
+  empty string. The element is a button.

+
+  

+
+  
If the element is mutable,
+  the user agent should allow the user to activate the element. The
+  element's activation behavior is to do nothing.

+
+  
Constraint validation: The element is
+  barred from constraint validation.

+
+  

+
+  

+
+   
The value IDL attribute
+   applies to this element and is in mode default.

+
+   
The following content attributes must not be specified and do not
+   apply to the element:
+   accept,
+   alt,
+   autocomplete,
+   checked,
+   formaction,
+   formenctype,
+   formmethod,
+   formnovalidate,
+   formtarget,
+   height,
+   list,
+   max,
+   maxlength,
+   min,
+   multiple,
+   pattern,
+   placeholder,
+   readonly,
+   required,
+   size,
+   src,
+   step, and
+   width.

+
+   
The following IDL attributes and methods do not apply to the
+   element:
+   checked,
+   files,
+   list,
+   selectedOption,
+   selectionStart,
+   selectionEnd,
+   valueAsDate, and
+   valueAsNumber IDL attributes;
+   select(),
+   setSelectionRange(),
+   stepDown(), and
+   stepUp() methods.

+
+   
The input and change events do not apply.

+
+  

+
+
+
+  
4.10.7.2 Common input element attributes

+
+  

+
+  
These attributes only apply to an input element if
+  its type attribute is in a
+  state whose definition declares that the attribute applies. When an
+  attribute doesn't apply to an input element, user
+  agents must ignore the attribute, regardless of the
+  requirements and definitions below.

+
+  

+
+
+  
4.10.7.2.1 The autocomplete attribute

+
+  
User agents sometimes have features for helping users fill forms
+  in, for example prefilling the user's address based on earlier user
+  input.

+
+  
The autocomplete
+  attribute is an enumerated attribute. The attribute has
+  three states. The on
+  keyword maps to the on state, and the
+  off keyword maps to
+  the off
+  state. The attribute may also be omitted. The missing value
+  default is the default
+  state.

+
+  
The off
+  state indicates either that the control's input data is particularly
+  sensitive (for example the activation code for a nuclear weapon); or
+  that it is a value that will never be reused (for example a
+  one-time-key for a bank login) and the user will therefore have to
+  explicitly enter the data each time, instead of being able to rely
+  on the UA to prefill the value for him; or that the document
+  provides its own autocomplete mechanism and does not want the user
+  agent to provide autocompletion values.

+
+  
Conversely, the on state indicates
+  that the value is not particularly sensitive and the user can expect
+  to be able to rely on his user agent to remember values he has
+  entered for that control.

+
+  
The default state
+  indicates that the user agent is to use the autocomplete attribute on the
+  element's form owner instead. (By default, the autocomplete attribute of
+  form elements is in the on state.)

+
+  

+
+  
Each input element has a resulting
+  autocompletion state, which is either on or off.

+
+  
When an input element is in one of the following
+  conditions, the input element's resulting
+  autocompletion state is on; otherwise, the
+  input element's resulting autocompletion
+  state is off:

+
+  
When an input element's resulting
+  autocompletion state is on, the user agent
+  may store the value entered by the user so that if the user returns
+  to the page, the UA can prefill the form. Otherwise, the user agent
+  should not remember the control's value, and should not offer past
+  values to the user.

+
+  
In addition, if the resulting autocompletion state
+  is off, values are
+  reset when traversing the
+  history.

+
+  
The autocompletion mechanism must be implemented by the user
+  agent acting as if the user had modified the element's value, and must be done at a time
+  where the element is mutable
+  (e.g. just after the element has been inserted into the document, or
+  when the user agent stops
+  parsing).

+
+  

+
+  

+
+   
Banks frequently do not want UAs to prefill login
+   information:

+
+   
<p><label>Account: <input type="text" name="ac" autocomplete="off"></label></p>
+<p><label>PIN: <input type="password" name="pin" autocomplete="off"></label></p>

+
+  

+
+  

+
+  
A user agent may allow the user to override the resulting
+  autocompletion state and set it to always on,
+  always allowing values to be remembered and prefilled), or always off, never remembering values. However, the ability to
+  override the resulting autocompletion state to on should not be trivially accessible, as there are
+  significant security implications for the user if all values are
+  always remembered, regardless of the site's preferences.

+
+  

+
+
+
+  
4.10.7.2.2 The list attribute

+
+  
The list
+  attribute is used to identify an element that lists predefined
+  options suggested to the user.

+
+  
If present, its value must be the ID of a datalist
+  element in the same document.

+
+  

+
+  
The suggestions source
+  element is the first element in the document in tree
+  order to have an ID equal to the value of the list attribute, if that element is a
+  datalist element. If there is no list attribute, or if there is no
+  element with that ID, or if the first element with that ID is not a
+  datalist element, then there is no suggestions source element.

+
+  
If there is a suggestions source
+  element, then, when the user agent is allowing the user to
+  edit the input element's value, the user agent should offer
+  the suggestions represented by the suggestions source element to the
+  user in a manner suitable for the type of control used. The user
+  agent may use the suggestion's label to identify the suggestion
+  if appropriate. If the user selects a suggestion, then the
+  input element's value must be set to the selected
+  suggestion's value, as if
+  the user had written that value himself.

+
+  
User agents must filter the suggestions to hide suggestions that
+  the user would not be allowed to enter as the input
+  element's value, and should
+  filter the suggestions to hide suggestions that would cause the
+  element to not satisfy its
+  constraints.

+
+  
If the list attribute does
+  not apply, there is no suggestions
+  source element.

+
+  

+
+  

+
+   
This URL field offers some suggestions.

+
+   
<label>Homepage: <input name=hp type=url list=hpurls></label>
+<datalist id=hpurls>
+ <option value="http://www.google.com/" label="Google">
+ <option value="http://www.reddit.com/" label="Reddit">
+</datalist>

+
+   
Other URLs from the user's history might show also; this is up
+   to the user agent.

+
+  

+
+  

+
+   
This example demonstrates how to design a form that uses the
+   autocompletion list feature while still degrading usefully in
+   legacy user agents.

+
+   
If the autocompletion list is merely an aid, and is not
+   important to the content, then simply using a datalist
+   element with children option elements is enough. To
+   prevent the values from being rendered in legacy user agents, they
+   should be placed inside the value attribute instead of
+   inline.

+
+   
<p>
+ <label>
+  Enter a breed:
+  <input type="text" name="breed" list="breeds">
+  <datalist id="breeds">
+   <option value="Abyssinian">
+   <option value="Alpaca">
+   <!-- ... -->
+  </datalist>
+ </label>
+</p>

+
+   
However, if the values need to be shown in legacy UAs, then
+   fallback content can be placed inside the datalist
+   element, as follows:

+
+   
<p>
+ <label>
+  Enter a breed:
+  <input type="text" name="breed" list="breeds">
+ </label>
+ <datalist id="breeds">
+  <label>
+   or select one from the list:
+   <select name="breed">
+    <option value=""> (none selected)
+    <option>Abyssinian
+    <option>Alpaca
+    <!-- ... -->
+   </select>
+  </label>
+ </datalist>
+</p>
+

+
+   
The fallback content will only be shown in UAs that don't
+   support datalist. The options, on the other hand, will
+   be detected by all UAs, even though they are not direct children of
+   the datalist element.

+
+   
Note that if an option element used in a
+   datalist is selected, it will be selected
+   by default by legacy UAs (because it affects the
+   select), but it will not have any effect on the
+   input element in UAs that support
+   datalist.

+
+  

+
+
+
+  
4.10.7.2.3 The readonly attribute

+
+  
The readonly
+  attribute is a boolean attribute that controls whether
+  or not the use can edit the form control. When
+  specified, the element is immutable.

+
+  

+
+  
Constraint validation: If the readonly attribute is specified
+  on an input element, the element is barred from
+  constraint validation.

+
+  

+
+  

+
+   
In the following example, the existing product identifiers
+   cannot be modified, but they are still displayed as part of the
+   form, for consistency with the row representing a new product
+   (where the identifier is not yet filled in).

+
+   
<form action="products.cgi" method=post enctype="multipart/form-data">
+ <table>
+  <tr> <th> Product ID <th> Product name <th> Price <th> Action
+  <tr>
+   <td> <input readonly name="1.pid" value="H412">
+   <td> <input required name="1.pname" value="Floor lamp Ulke">
+   <td> $<input required type=number min=0 step=0.01 name="1.pprice" value="49.99">
+   <td> <button formnovalidate name="action" value="delete:1">Delete</button>
+  <tr>
+   <td> <input readonly name="2.pid" value="FG28">
+   <td> <input required name="2.pname" value="Table lamp Ulke">
+   <td> $<input required type=number min=0 step=0.01 name="2.pprice" value="24.99">
+   <td> <button formnovalidate name="action" value="delete:2">Delete</button>
+  <tr>
+   <td> <input required name="3.pid" value="" pattern="[A-Z0-9]+">
+   <td> <input required name="3.pname" value="">
+   <td> $<input required type=number min=0 step=0.01 name="3.pprice" value="">
+   <td> <button formnovalidate name="action" value="delete:3">Delete</button>
+ </table>
+ <p> <button formnovalidate name="action" value="add">Add</button> </p>
+ <p> <button name="action" value="update">Save</button> </p>
+</form>

+
+  

+
+
+
+  
4.10.7.2.4 The size attribute

+
+  
The size
+  attribute gives the number of characters that, in a visual
+  rendering, the user agent is to allow the user to see while editing
+  the element's value.

+
+  
The size attribute, if
+  specified, must have a value that is a valid non-negative
+  integer greater than zero.

+
+  

+
+  
If the attribute is present, then its value must be parsed using
+  the rules for parsing non-negative integers, and if the
+  result is a number greater than zero, then the user agent should
+  ensure that at least that many characters are visible.

+
+  
The size IDL attribute is
+  limited to only non-negative numbers greater than
+  zero.

+
+  

+
+
+
+  
4.10.7.2.5 The required attribute

+
+  
The required
+  attribute is a boolean attribute. When specified, the
+  element is required.

+
+  

+
+  
Constraint validation: If the element is required, and its value IDL attribute applies and is in
+  the mode value, and the
+  element is mutable, and the
+  element's value is the empty
+  string, then the element is suffering from being
+  missing.

+
+  

+
+  

+
+   
The following form has two required fields, one for an e-mail
+   address and one for a password. It also has a third field that is
+   only considerd valid if the user types the same password in the
+   password field and this third field.

+
+   
<h1>Create new account</h1>
+<form action="/newaccount" method=post>
+ <p>
+  <label for="username">E-mail address:</label>
+  <input id="username" type=email required name=un>
+ <p>
+  <label for="password1">Password:</label>
+  <input id="password1" type=password required name=up>
+ <p>
+  <label for="password2">Confirm password:</label>
+  <input id="password2" type=password onforminput="setCustomValidity(value != password1.value ? 'Passwords do not match.' : '')">
+ <p>
+  <input type=submit value="Create account">
+</form>

+
+  

+
+
+  
4.10.7.2.6 The multiple attribute

+
+  
The multiple
+  attribute is a boolean attribute that indicates whether
+  the user is to be allowed to specify more than one value.

+
+  

+
+   
The following extract shows how an e-mail client's "Cc" field
+   could accept multiple e-mail addresses.

+
+   
<label>Cc: <input type=email multiple name=cc></label>

+
+   
If the user had, amongst many friends in his user contacts
+   database, two friends "Arthur Dent" (with address
+   "art@example.net") and "Adam Josh" (with address
+   "adamjosh@example.net"), then, after the user has typed "a", the
+   user agent might suggest these two e-mail addresses to the
+   user.

+
+   

+
+   
The page could also link in the user's contacts database from the site:

+
+   
<label>Cc: <input type=email multiple name=cc list=contacts></label>
+...
+<datalist id="contacts">
+ <option value="hedral@damowmow.com">
+ <option value="pillar@example.com">
+ <option value="astrophy@cute.example">
+ <option value="astronomy@science.example.org">
+</datalist>

+
+   
Suppose the user had entered "bob@example.net" into this text
+   field, and then started typing a second e-mail address starting
+   with "a". The user agent might show both the two friends mentioned
+   earlier, as well as the "astrophy" and "astronomy" values given in
+   the datalist element.

+
+   

+
+  

+
+  

+
+   
The following extract shows how an e-mail client's "Attachments"
+   field could accept multiple files for upload.

+
+   
<label>Attachments: <input type=file multiple name=att></label>

+
+  

+
+
+  
4.10.7.2.7 The maxlength attribute

+
+  
The maxlength
+  attribute, when it applies, is a form control maxlength attribute
+  controlled by the input element's dirty value
+  flag.

+
+  
If the input element has a maximum allowed
+  value length, then the code-point length of the
+  value of the element's value
+  attribute must be equal to or less than the element's maximum
+  allowed value length.

+
+  

+
+   
The following extract shows how a messaging client's text entry
+   could be arbitrarily restricted to a fixed number of characters,
+   thus forcing any conversion through this medium to be terse and
+   discouraging intelligent discourse.

+
+   
What are you doing? <input name=status maxlength=140>

+
+  

+
+
+
+  
4.10.7.2.8 The pattern attribute

+
+  
The pattern
+  attribute specifies a regular expression against which the control's
+  value is to be checked.

+
+  
If specified, the attribute's value must match the JavaScript Pattern production. [ECMA262]

+
+  

+
+  
Constraint validation: If the element's value is not the empty string, and
+  the element's pattern
+  attribute is specified and the attribute's value, when compiled as a
+  JavaScript regular expression with the global,
+  ignoreCase, and multiline flags disabled (see ECMA262
+  Edition 5, sections 15.10.7.2 through 15.10.7.4), compiles
+  successfully but the resulting regular expression does not match the
+  entirety of the element's value, then the element is
+  suffering from a pattern mismatch. [ECMA262]

+
+  
This implies that the regular expression language
+  used for this attribute is the same as that used in JavaScript,
+  except that the pattern
+  attribute must match the entire value, not just any subset (somewhat
+  as if it implied a ^(?: at the start of the
+  pattern and a )$ at the end).

+
+  

+
+  
When an input element has a pattern attribute specified,
+  authors should include a title
+  attribute to give a description of the pattern. User agents may use
+  the contents of this attribute, if it is present, when informing the
+  user that the pattern is not matched, or at any other suitable time,
+  such as in a tooltip or read out by assistive technology when the
+  control gains focus.

+
+  

+   
For example, the following snippet:

+   
<label> Part number:
+ <input pattern="[0-9][A-Z]{3}" name="part"
+        title="A part number is a digit followed by three uppercase letters."/>
+</label>

+   
...could cause the UA to display an alert such as:

+   
A part number is a digit followed by three uppercase letters.
+You cannot complete this form until the field is correct.

+  

+
+  
When a control has a pattern attribute, the title attribute, if used, must describe
+  the pattern.  Additional information could also be included, so long
+  as it assists the user in filling in the control. Otherwise,
+  assistive technology would be impaired.

+
+  
For instance, if the title attribute contained
+  the caption of the control, assistive technology could end up saying
+  something like The text you have entered does not match the
+  required pattern. Birthday, which is not useful.

+
+  
UAs may still show the title in non-error situations
+  (for example, as a tooltip when hovering over the control), so
+  authors should be careful not to word titles as if an
+  error has necessarily occurred.

+
+
+
+  
4.10.7.2.9 The min and max attributes

+
+  
The min and max attributes indicate
+  the allowed range of values for the element.

+
+  

+
+  
Their syntax is defined by the section that defines the type attribute's current state.

+
+  
If the element has a min
+  attribute, and the result of applying the algorithm to convert a
+  string to a number to the value of the min attribute is a number, then that
+  number is the element's minimum; otherwise, if the type attribute's current state
+  defines a default
+  minimum, then that is the minimum; otherwise, the element has
+  no minimum.

+
+  
Constraint validation: When the element has a
+  minimum, and the result of
+  applying the algorithm to convert a
+  string to a number to the string given by the element's value is a number, and the number
+  obtained from that algorithm is less than the minimum, the element is
+  suffering from an underflow.

+
+  
The min attribute also
+  defines the step
+  base.

+
+  
If the element has a max
+  attribute, and the result of applying the algorithm to convert a
+  string to a number to the value of the max attribute is a number, then that
+  number is the element's maximum; otherwise, if the type attribute's current state
+  defines a default
+  maximum, then that is the maximum; otherwise, the element has
+  no maximum.

+
+  
Constraint validation: When the element has a
+  maximum, and the result of
+  applying the algorithm to convert a
+  string to a number to the string given by the element's value is a number, and the number
+  obtained from that algorithm is more than the maximum, the element is
+  suffering from an overflow.

+
+  

+
+  
The max attribute's value
+  (the maximum) must not be
+  less than the min attribute's
+  value (its minimum).

+
+  

+
+  
If an element has a maximum that is less than its minimum, then so long as the element
+  has a value, it will either be
+  suffering from an underflow or suffering from an
+  overflow.

+
+  

+
+  

+
+   
The following date control limits input to dates that are before
+   the 1980s:

+
+   
<input name=bday type=date max="1979-12-31">

+
+  

+
+  

+
+   
The following number control limits input to whole numbers
+   greater than zero:

+
+   
<input name=quantity required type=number min=1 value=1>

+
+  

+
+
+  
4.10.7.2.10 The step attribute

+
+  
The step
+  attribute indicates the granularity that is expected (and required)
+  of the value, by limiting the
+  allowed values. The section that defines the
+  type attribute's current state
+  also defines the default
+  step, the step scale
+  factor, and in some cases the default step base,
+  which are used in processing the attribute as described
+  below.

+
+  
The step attribute, if
+  specified, must either have a value that is a valid floating
+  point number that parses to a number that is greater than
+  zero, or must have a value that is an ASCII
+  case-insensitive match for the string "any".

+
+  

+
+  
The attribute provides the allowed value step for the element,
+  as follows:

+
+  
  1. If the attribute is absent, then the allowed value step is the default step multiplied
+   by the step scale
+   factor.
    2. 
+
+   
  2. Otherwise, if the attribute's value is an ASCII
+   case-insensitive match for the string "any", then there is no allowed value step.
    3. 
+
+   
  3. Otherwise, if the rules for parsing floating point number
+   values, when they are applied to the attribute's value,
+   return an error, zero, or a number less than zero, then the allowed value step is the default step multiplied
+   by the step scale
+   factor.
    4. 
+
+   
  4. Otherwise, the allowed value
+   step is the number returned by the rules for parsing
+   floating point number values when they are applied to the
+   attribute's value, multiplied by the step scale factor.
    5. 
+
+  
The step base is the
+  result of applying the algorithm to convert a
+  string to a number to the value of the min attribute, unless the element does
+  not have a min attribute
+  specified or the result of applying that algorithm is an error, in
+  which case the step base
+  is the default step
+  base, if one is defined, or zero, if not.

+
+  
Constraint validation: When the element has an
+  allowed value step, and the
+  result of applying the algorithm to convert a
+  string to a number to the string given by the element's value is a number, and that
+  number subtracted from the step
+  base is not an integral multiple of the allowed value step, the element is
+  suffering from a step mismatch.

+
+  

+
+  

+
+   
The following range control only accepts values in the range
+   0..1, and allows 256 steps in that range:

+
+   
<input name=opacity type=range min=0 max=1 step=0.00392156863>

+
+  

+
+  

+
+   
The following control allows any time in the day to be selected,
+   with any accuracy (e.g. thousandth-of-a-second accuracy or
+   more):

+
+   
<input name=favtime type=time step=any>

+
+   
Normally, time controls are limited to an accuracy of one
+   minute.

+
+  

+
+
+
+
+  
4.10.7.2.11 The placeholder attribute

+
+  
+
+  
The placeholder
+  attribute represents a short hint (a word or short phrase)
+  intended to aid the user with data entry. A hint could be a sample
+  value or a brief description of the expected format. The attribute,
+  if specified, must have a value that contains no U+000A LINE FEED
+  (LF) or U+000D CARRIAGE RETURN (CR) characters.

+
+  
For a longer hint or other advisory text, the title attribute is more appropriate.

+
+  
The placeholder
+  attribute should not be used as an alternative to a
+  label.

+
+  

+
+  
User agents should present this hint to the user, after having
+  stripped line breaks from it,
+  when the element's value is
+  the empty string and the control is not focused (e.g. by displaying
+  it inside a blank unfocused control).

+
+  

+
+  

+
+   
Here is an example of a mail configuration user interface that
+   uses the placeholder
+   attribute:

+
+   
<fieldset>
+ <legend>Mail Account</legend>
+ <p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p>
+ <p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p>
+ <p><label>Password: <input type="password" name="password"></label></p>
+ <p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p>
+</fieldset>

+
+  

+
+
+
+  
4.10.7.3 Common input element APIs

+
+  
input . value [ = value ]

+
+   

+
+    
Returns the current value
+    of the form control.

+
+    
Can be set, to change the value.

+
+    
Throws an INVALID_STATE_ERR exception if it is
+    set to any value other than the empty string when the control is a
+    file upload control.

+
+   

+
+   
input . checked [ = value ]

+
+   

+
+    
Returns the current checkedness of the form
+    control.

+
+    
Can be set, to change the checkedness.

+
+   

+
+   
input . files

+
+   

+
+    
Returns a FileList object listing the selected files of
+    the form control.

+
+    
Throws an INVALID_STATE_ERR exception if the
+    control isn't a file control.

+
+   

+
+   
input . valueAsDate [ = value ]

+
+   

+
+    
Returns a Date object representing the form
+    control's value, if
+    applicable; otherwise, returns null.

+
+    
Can be set, to change the value.

+
+    
Throws an INVALID_STATE_ERR exception if the
+    control isn't date- or time-based.

+
+   

+
+   
input . valueAsNumber [ = value ]

+
+   

+
+    
Returns a number representing the form control's value, if applicable; otherwise,
+    returns null.

+
+    
Can be set, to change the value.

+
+    
Throws an INVALID_STATE_ERR exception if the
+    control is neither date- or time-based nor numeric.

+
+   

+
+   
input . stepUp( [ n ] )

+   
input . stepDown( [ n ] )

+
+   

+
+    
Changes the form control's value by the value given in the
+    step attribute, multiplied by
+    n. The default is 1.

+
+    
Throws INVALID_STATE_ERR exception if the control
+    is neither date- or time-based nor numeric, if the step attribute's value is "any", if the current value could not be parsed, or if
+    stepping in the given direction by the given amount would take the
+    value out of range.

+
+   

+
+   
input . list

+
+   

+
+    
Returns the datalist element indicated by the
+    list attribute.

+
+   

+
+   
input . selectedOption

+
+   

+
+    
Returns the option element from the
+    datalist element indicated by the list attribute that matches the
+    form control's value.

+
+   

+
+  

+
+  
The value IDL
+  attribute allows scripts to manipulate the value of an input
+  element. The attribute is in one of the following modes, which
+  define its behavior:

+
+  
value
+
+   
On getting, it must return the current value of the element. On setting,
+   it must set the element's value to the new value, set the
+   element's dirty value
+   flag to true, and then invoke the value sanitization
+   algorithm, if the element's type attribute's current state
+   defines one.

+
+   
default
+
+   
On getting, if the element has a value attribute, it must return
+   that attribute's value; otherwise, it must return the empty
+   string. On setting, it must set the element's value attribute to the new
+   value.

+
+   
default/on
+
+   
On getting, if the element has a value attribute, it must return
+   that attribute's value; otherwise, it must return the string "on". On setting, it must set the element's value attribute to the new
+   value.

+
+   
filename
+
+   
On getting, it must return the string "C:\fakepath\" followed by the filename of the first
+   file in the list of selected files, if
+   any, or the empty string if the list is empty. On setting, if the
+   new value is the empty string, it must empty the list of selected files;
+   otherwise, it must throw an INVALID_STATE_ERR
+   exception.

+
+  
The checked IDL
+  attribute allows scripts to manipulate the checkedness of an
+  input element. On getting, it must return the current
+  checkedness of the element;
+  and on setting, it must set the element's checkedness to the new value and
+  set the element's dirty checkedness
+  flag to true.

+
+  
The files IDL
+  attribute allows scripts to access the element's selected files. On
+  getting, if the IDL attribute applies, it must return a
+  FileList object that represents the current selected files. The
+  same object must be returned until the list of selected files
+  changes. If the IDL attribute does not apply, then it must instead
+  throw an INVALID_STATE_ERR exception. [FILEAPI]

+
+  
The valueAsDate IDL
+  attribute represents the value of the element, interpreted
+  as a date.

+
+  
On getting, if the valueAsDate attribute does not
+  apply, as defined for the input element's type attribute's current state, then
+  return null. Otherwise, run the algorithm to convert a
+  string to a Date object defined for that state;
+  if the algorithm returned a Date object, then return
+  it, otherwise, return null.

+
+  
On setting, if the valueAsDate attribute does not
+  apply, as defined for the input element's type attribute's current state, then
+  throw an INVALID_STATE_ERR exception; otherwise, if
+  the new value is null, then set the value of the element to the empty
+  string; otherwise, run the algorithm to convert a
+  Date object to a string, as defined for that
+  state, on the new value, and set the value of the element to resulting
+  string.

+
+  
The valueAsNumber IDL
+  attribute represents the value
+  of the element, interpreted as a number.

+
+  
On getting, if the valueAsNumber attribute does
+  not apply, as defined for the input element's type attribute's current state, then
+  return a Not-a-Number (NaN) value. Otherwise, if the valueAsDate
+  attribute applies, run the algorithm to convert a
+  string to a Date object defined for that state;
+  if the algorithm returned a Date object, then return
+  the time value of the object (the number of milliseconds from
+  midnight UTC the morning of 1970-01-01 to the time represented by
+  the Date object), otherwise, return a Not-a-Number
+  (NaN) value. Otherwise, run the algorithm to convert a
+  string to a number defined for that state; if the algorithm
+  returned a number, then return it, otherwise, return a Not-a-Number
+  (NaN) value.

+
+  
On setting, if the valueAsNumber attribute does
+  not apply, as defined for the input element's type attribute's current state, then
+  throw an INVALID_STATE_ERR exception. Otherwise, if
+  the valueAsDate
+  attribute applies, run the algorithm to convert a
+  Date object to a string defined for that state,
+  passing it a Date object whose time value is the
+  new value, and set the value
+  of the element to resulting string. Otherwise, run the algorithm to convert a
+  number to a string, as defined for that state, on the new
+  value, and set the value of
+  the element to resulting string.

+
+  
The stepDown(n) and stepUp(n) methods, when invoked, must run the
+  following algorithm:

+
+  
  1. If the stepDown() and
+   stepUp() methods do not
+   apply, as defined for the input element's type attribute's current state, then
+   throw an INVALID_STATE_ERR exception, and abort these
+   steps.
    2. 
+
+   
  2. If the element has no allowed value step, then throw an
+   INVALID_STATE_ERR exception, and abort these
+   steps.
    3. 
+
+   
  3. If applying the algorithm to convert a
+   string to a number to the string given by the element's
+   value results in an error,
+   then throw an INVALID_STATE_ERR exception, and abort
+   these steps; otherwise, let value be the result
+   of that algorithm.
    4. 
+
+   
  4. Let n be the argument, or 1 if the
+   argument was omitted.
    5. 
+
+   
  5. Let delta be the allowed value step multiplied by
+   n.
    6. 
+
+   
  6. If the method invoked was the stepDown() method, negate delta.
    7. 
+
+   
  7. Let value be the result of adding delta to value.
    8. 
+   
  8. If the element has a minimum, and the value is less than that minimum, then throw a
+   INVALID_STATE_ERR exception.
    9. 
+
+   
  9. If the element has a maximum, and the value is greater than that maximum, then throw a
+   INVALID_STATE_ERR exception.
    10. 
+
+   
  10. Let value as string be the result of
+   running the algorithm to convert a
+   number to a string, as defined for the input
+   element's type attribute's
+   current state, on value.
    11. 
+
+   
  11. Set the value of the
+   element to value as string.
    12. 
+
+  
The list IDL
+  attribute must return the current suggestions source element, if
+  any, or null otherwise.

+
+  
The selectedOption
+  IDL attribute must return the first option element, in
+  tree order, to be a child of the suggestions source element and
+  whose value matches the
+  input element's value, if any. If there is no suggestions source element, or if
+  it contains no matching option element, then the selectedOption attribute
+  must return null.

+
+  

+
+
+  

+
+  
4.10.7.4 Common event behaviors

+
+  
When the input
+  event applies, any time the user causes the element's value to change, the user agent must
+  queue a task to fire a simple event that
+  bubbles named input at the
+  input element, then broadcast forminput events at the
+  input element's form owner. User agents
+  may wait for a suitable break in the user's interaction before
+  queuing the task; for example, a user agent could wait for the user
+  to have not hit a key for 100ms, so as to only fire the event when
+  the user pauses, instead of continuously for each keystroke.

+  
+
+  
Examples of a user changing the element's value would include the user typing
+  into a text field, pasting a new value into the field, or undoing an
+  edit in that field. Some user interactions do not cause changes to
+  the value, e.g. hitting the "delete" key in an empty text field, or
+  replacing some text in the field with text from the clipboard that
+  happens to be exactly the same text.

+
+  
When the change event applies,
+  if the element does not have an activation behavior
+  defined but uses a user interface that involves an explicit commit
+  action, then any time the user commits a change to the element's
+  value or list of selected files, the
+  user agent must queue a task to fire a simple
+  event that bubbles named change at the input
+  element, then broadcast formchange events at the
+  input element's form owner.

+
+  
An example of a user interface with a commit
+  action would be a File
+  Upload control that consists of a single button that brings
+  up a file selection dialog: when the dialog is closed, if that the
+  file selection
+  changed as a result, then the user has committed a new file selection.

+
+  
Another example of a user interface with a commit
+  action would be a Date
+  control that allows both text-based user input and user selection
+  from a drop-down calendar: while text input might not have an
+  explicit commit step, selecting a date from the drop down calendar
+  and then dismissing the drop down would be a commit action.

+
+  
When the user agent changes the element's value on behalf of the user (e.g. as
+  part of a form prefilling feature), the user agent must follow these
+  steps:

+
+  
  1. If the input event
+   applies, queue a task to fire a simple
+   event that bubbles named input at the input
+   element.
    2. 
+
+   
  2. If the input event
+   applies, broadcast forminput events at the
+   input element's form owner.
    3. 
+
+   
  3. If the change event
+   applies, queue a task to fire a simple
+   event that bubbles named change at the input
+   element.
    4. 
+
+   
  4. If the change event
+   applies, broadcast formchange events at the
+   input element's form owner.
    5. 
+
+  
In addition, when the change event applies, change events can also be fired as part
+  of the element's activation behavior and as part of the
+  unfocusing steps.

+
+  
The task source for these tasks is the user interaction task
+  source.

+
+  

+
+
+
+  
4.10.8 The button element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Listed, labelable, and submittable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but there must be no interactive content descendant.

+   
Content attributes:

+   
Global attributes

+   
autofocus

+   
disabled

+   
form

+   
formaction

+   
formenctype

+   
formmethod

+   
formnovalidate

+   
formtarget

+   
name

+   
type

+   
value

+   
DOM interface:

+   

+
interface HTMLButtonElement : HTMLElement {
+           attribute boolean autofocus;
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString formAction;
+           attribute DOMString formEnctype;
+           attribute DOMString formMethod;
+           attribute DOMString formNoValidate;
+           attribute DOMString formTarget;
+           attribute DOMString name;
+           attribute DOMString type;
+           attribute DOMString value;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+};

+   

+  
The button element represents a
+  button. If the element is not disabled, then the user agent
+  should allow the user to activate the button.

+
+  
The element is a button.

+
+  
The type
+  attribute controls the behavior of the button when it is activated.
+  It is an enumerated attribute. The following table
+  lists the keywords and states for the attribute — the keywords
+  in the left column map to the states in the cell in the second
+  column on the same row as the keyword.

+
+  
 Keyword
+      State
+      Brief description
+   
submit
+     Submit Button
+     Submits the form.
+    
reset
+     Reset Button
+     Resets the form.
+    
button
+     Button
+     Does nothing.
+  
The missing value default is the Submit Button
+  state.

+
+  
If the type attribute is in
+  the Submit Button
+  state, the element is specifically a submit button.

+
+  

+
+  
Constraint validation: If the type attribute is in the Reset Button state or
+  the Button state,
+  the element is barred from constraint validation.

+
+  
If the element is not disabled, the activation
+  behavior of the button element is to run the
+  steps defined in the following list for the current state of the
+  element's type attribute.

+
+  
 Submit Button 

+
+   
If the element has a form owner, the element
+   must submit the form
+   owner from the button element.

+
+   
 Reset Button 

+
+   
If the element has a form owner, the element
+   must reset the form
+   owner.

+
+   
 Button
+
+   
Do nothing.

+
+  

+
+  
The form attribute is used to
+  explicitly associate the button element with its
+  form owner. The name
+  attribute represents the element's name. The disabled attribute is used to make
+  the control non-interactive and to prevent its value from being
+  submitted. The autofocus
+  attribute controls focus. The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are
+  attributes for form submission.

+
+  
The formnovalidate attribute can
+  be used to make submit buttons that do not trigger the constraint
+  validation.

+
+  
The formaction, formenctype, formmethod, formnovalidate, and formtarget must not be specified
+  if the element's type
+  attribute is not in the Submit Button
+  state.

+
+  
The value
+  attribute gives the element's value for the purposes of form
+  submission. The element's value is the value of the element's
+  value attribute, if there is
+  one, or the empty string otherwise.

+
+  
A button (and its value) is only included in the
+  form submission if the button itself was used to initiate the form
+  submission.

+
+  

+
+  
The value and
+  type IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the
+  element's forms API.

+
+  

+
+  

+
+   
The following button is labeled "Show hint" and pops up a dialog
+   box when activated:

+
+   
<button type=button
+        onclick="alert('This 15-20 minute piece was composed by George Gershwin.')">
+ Show hint
+</button>

+
+  

+
+
+
+
+  
4.10.9 The select element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Listed, labelable, submittable, and resettable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Zero or more option or optgroup elements.

+   
Content attributes:

+   
Global attributes

+   
autofocus

+   
disabled

+   
form

+   
multiple

+   
name

+   
size

+   
DOM interface:

+   

+
interface HTMLSelectElement : HTMLElement {
+           attribute boolean autofocus;
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute boolean multiple;
+           attribute DOMString name;
+           attribute unsigned long size;
+
+  readonly attribute DOMString type;
+
+  readonly attribute HTMLOptionsCollection options;
+           attribute unsigned long length;
+  caller getter any item(in unsigned long index);
+  caller getter any namedItem(in DOMString name);
+  void add(in HTMLElement element, in optional HTMLElement before);
+  void add(in HTMLElement element, in long before);
+  void remove(in long index);
+
+  readonly attribute HTMLCollection selectedOptions;
+           attribute long selectedIndex;
+           attribute DOMString value;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+};

+   

+  
The select element represents a control for
+  selecting amongst a set of options.

+
+  
The multiple
+  attribute is a boolean attribute. If the attribute is
+  present, then the select element
+  represents a control for selecting zero or more options
+  from the list of
+  options. If the attribute is absent, then the
+  select element represents a control for
+  selecting a single option from the list of options.

+
+  
The list of options
+  for a select element consists of all the
+  option element children of the select
+  element, and all the option element children of all the
+  optgroup element children of the select
+  element, in tree order.

+
+  
The size
+  attribute gives the number of options to show to the user. The size attribute, if specified, must
+  have a value that is a valid non-negative integer
+  greater than zero. If the multiple attribute is present,
+  then the size attribute's
+  default value is 4. If the multiple attribute is absent,
+  then the size attribute's
+  default value is 1.

+
+  

+
+  
The display size of a
+  select element is the result of applying the
+  rules for parsing non-negative integers to the value of
+  element's size attribute, if it
+  has one and parsing it is successful. If applying those rules to the
+  attribute's value is not successful, or if the size attribute is absent, the
+  element's display size is
+  the default value of the attribute.

+
+  
If the multiple
+  attribute is absent, and the element is not disabled, then the user agent
+  should allow the user to pick an option element in its
+  list of options that
+  is itself not disabled. Upon this
+  option element being picked (either through a click, or
+  through unfocusing the element after changing its value, or through
+  a menu command, or through any
+  other mechanism), and before the relevant user interaction event
+   is queued (e.g. before the
+  click event), the user agent must
+  set the selectedness of the
+  picked option element to true and then queue a
+  task to fire a simple event that bubbles named
+  change at the select
+  element, using the user interaction task source as the
+  task source, then broadcast formchange events at the
+  element's form owner.

+
+  
If the multiple
+  attribute is absent, whenever an option element in the
+  select element's list of options has its
+  selectedness set to
+  true, and whenever an option element with its selectedness set to true
+  is added to the select element's list of options, the user
+  agent must set the selectedness of all the
+  other option element in its list of options to
+  false.

+
+  
If the multiple
+  attribute is absent and the element's display size is greater than 1,
+  then the user agent should also allow the user to request that the
+  option whose selectedness is true, if
+  any, be unselected. Upon this request being conveyed to the user
+  agent, and before the relevant user interaction event  is queued (e.g. before the click event), the user agent must set the
+  selectedness of
+  that option element to false and then queue a
+  task to fire a simple event that bubbles named
+  change at the select
+  element, using the user interaction task source as the
+  task source, then broadcast formchange events at the
+  element's form owner.

+
+  
If the multiple
+  attribute is absent and the element's display size is 1, then whenever
+  there are no option elements in the select
+  element's list of
+  options that have their selectedness set to true,
+  the user agent must set the selectedness of the first
+  option element in the list of options in
+  tree order that is not disabled, if any, to
+  true.

+
+  
If the multiple
+  attribute is present, and the element is not disabled, then the user agent
+  should allow the user to toggle the selectedness of the
+  option elements in its list of options that are
+  themselves not disabled
+  (either through a click, or through a menu command, or any other
+  mechanism). Upon the selectedness of one or
+  more option elements being changed by the user, and
+  before the relevant user interaction event  is queued (e.g. before a related click event), the user agent must
+  queue a task to fire a simple event that
+  bubbles named change at the
+  select element, using the user interaction task
+  source as the task source, then broadcast formchange events at the
+  element's form owner.

+
+  
The reset
+  algorithm for select elements is to go through
+  all the option elements in the element's list of options, and set
+  their selectedness
+  to true if the option element has a selected attribute, and false
+  otherwise.

+
+  

+
+  
The form attribute is used to
+  explicitly associate the select element with its
+  form owner. The name
+  attribute represents the element's name. The disabled attribute is used to make
+  the control non-interactive and to prevent its value from being
+  submitted. The autofocus
+  attribute controls focus.

+
+  
select . type

+
+   

+
+    
Returns "select-multiple" if the element
+    has a multiple
+    attribute, and "select-one"
+    otherwise.

+
+   

+
+   
select . options

+
+   

+
+    
Returns an HTMLOptionsCollection of the list of options.

+
+   

+
+   
select . length [ = value ]

+   

+    
Returns the number of elements in the list of options.

+    
When set to a smaller number, truncates the number of option elements in the select.

+    
When set to a greater number, adds new blank option elements to the select.

+   

+
+   
element = select . item(index)

+   
select[index]

+   
select(index)

+   

+    
Returns the item with index index from the list of options. The items are sorted in tree order.

+    
Returns null if index is out of range.

+   

+
+   
element = select . namedItem(name)

+   
select[name]

+   
select(name)

+   

+    
Returns the item with ID or name name from the list of options.

+    
If there are multiple matching items, then a NodeList object containing all those elements is returned.

+    
Returns null if no element with that ID could be found.

+   

+
+   
select . add(element [, before ])

+   

+    
Inserts element before the node given by before.

+    
The before argument can be a number, in
+    which case element is inserted before the item
+    with that number, or an element from the list of options, in
+    which case element is inserted before that
+    element.

+    
If before is omitted, null, or a number out
+    of range, then element will be added at the
+    end of the list.

+    
This method will throw a HIERARCHY_REQUEST_ERR
+    exception if element is an ancestor of the
+    element into which it is to be inserted. If element is not an option or
+    optgroup element, then the method does nothing.

+   

+
+   
select . selectedOptions

+
+   

+
+    
Returns an HTMLCollection of the list of options that are
+    selected.

+
+   

+
+   
select . selectedIndex [ = value ]

+
+   

+
+    
Returns the index of the first selected item, if any, or
+    −1 if there is no selected item.

+
+    
Can be set, to change the selection.

+
+   

+
+   
select . value [ = value ]

+
+   

+
+    
Returns the value of the
+    first selected item, if any, or the empty string if there is no
+    selected item.

+
+    
Can be set, to change the selection.

+
+   

+
+  

+
+  
The type IDL
+  attribute, on getting, must return the string "select-one" if the multiple attribute is absent,
+  and the string "select-multiple" if the multiple attribute is
+  present.

+
+  
The options
+  IDL attribute must return an HTMLOptionsCollection
+  rooted at the select node, whose filter matches the
+  elements in the list of
+  options.

+
+  
The options collection is
+  also mirrored on the HTMLSelectElement object. The
+  indices of the supported indexed properties at any
+  instant are the indices supported by the object returned by the
+  options attribute at that
+  instant. The names of the supported named properties at
+  any instant are the names supported by the object returned by the
+  options attribute at that
+  instant.

+
+  
The length IDL
+  attribute must return the number of nodes represented by the options collection. On setting, it
+  must act like the attribute of the same name on the options collection.

+
+  
The item(index) method must return the value
+  returned by the method of the same name on the options collection, when invoked
+  with the same argument.

+
+  
The namedItem(name) method must return the value
+  returned by the method of the same name on the options collection, when invoked
+  with the same argument.

+
+  
Similarly, the add() and remove() methods must
+  act like their namesake methods on that same options collection.

+
+  
The selectedOptions
+  IDL attribute must return an HTMLCollection rooted at
+  the select node, whose filter matches the elements in
+  the list of options
+  that have their selectedness set to
+  true.

+
+  
The selectedIndex
+  IDL attribute, on getting, must return the index of the first
+  option element in the list of options in
+  tree order that has its selectedness set to true,
+  if any. If there isn't one, then it must return −1.

+
+  
On setting, the selectedIndex attribute must
+  set the selectedness of all the
+  option elements in the list of options to false,
+  and then the option element in the list of options whose
+  index is the given new
+  value, if any, must have its selectedness set to
+  true.

+
+  
The value IDL
+  attribute, on getting, must return the value of the first
+  option element in the list of options in
+  tree order that has its selectedness set to true,
+  if any. If there isn't one, then it must return the empty
+  string.

+
+  
On setting, the value
+  attribute must set the selectedness of all the
+  option elements in the list of options to false,
+  and then first the option element in the list of options, in
+  tree order, whose value is equal to the given new
+  value, if any, must have its selectedness set to
+  true.

+
+  
The multiple
+  and size IDL
+  attributes must reflect the respective content
+  attributes of the same name. The size IDL attribute limited to
+  only non-negative numbers greater than zero.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the
+  element's forms API.

+
+  

+
+  

+
+   
The following example shows how a select element
+   can be used to offer the user with a set of options from which the
+   user can select a single option. The default option is
+   preselected.

+
+   
<p>
+ <label for="unittype">Select unit type:</label>
+ <select id="unittype" name="unittype">
+  <option value="1"> Miner </option>
+  <option value="2"> Puffer </option>
+  <option value="3" selected> Snipey </option>
+  <option value="4"> Max </option>
+  <option value="5"> Firebot </option>
+ </select>
+</p>

+
+  

+
+  

+
+   
Here, the user is offered a set of options from which he can
+   select any number. By default, all five options are selected.

+
+   
<p>
+ <label for="allowedunits">Select unit types to enable on this map:</label>
+ <select id="allowedunits" name="allowedunits" multiple>
+  <option value="1" selected> Miner </option>
+  <option value="2" selected> Puffer </option>
+  <option value="3" selected> Snipey </option>
+  <option value="4" selected> Max </option>
+  <option value="5" selected> Firebot </option>
+ </select>
+</p>

+
+  

+
+
+
+  
4.10.10 The datalist element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Either: phrasing content.

+   
Or: Zero or more option elements.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   

+
interface HTMLDataListElement : HTMLElement {
+  readonly attribute HTMLCollection options;
+};

+   

+  
The datalist element represents a set of
+  option elements that represent predefined options for
+  other controls. The contents of the element represents fallback
+  content for legacy user agents, intermixed with option
+  elements that represent the predefined options. In the rendering,
+  the datalist element represents
+  nothing and it, along with its children, should
+  be hidden.

+
+  
The datalist element is hooked up to an
+  input element using the list attribute on the
+  input element. 

+
+  
Each option element that is a descendant of the
+  datalist element, that is not disabled, and whose value is a string that isn't the
+  empty string, represents a suggestion. Each suggestion has a value and a label.
+
+  
datalist . options

+
+   

+    
Returns an HTMLCollection of the options elements of the table.

+   

+
+  

+
+  
The options
+  IDL attribute must return an HTMLCollection rooted at
+  the datalist node, whose filter matches
+  option elements.

+
+  
Constraint validation: If an element has a
+  datalist element ancestor, it is barred from
+  constraint validation.

+
+  

+
+
+  
4.10.11 The optgroup element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a select element.

+   
Content model:

+   
Zero or more option elements.

+   
Content attributes:

+   
Global attributes

+   
disabled

+   
label

+   
DOM interface:

+   

+
interface HTMLOptGroupElement : HTMLElement {
+           attribute boolean disabled;
+           attribute DOMString label;
+};

+   

+  
The optgroup element represents a group of
+  option elements with a common label.

+
+  
The element's group of option elements consists of
+  the option elements that are children of the
+  optgroup element.

+
+  

+
+  
When showing option elements in select
+  elements, user agents should show the option elements
+  of such groups as being related to each other and separate from
+  other option elements.

+
+  

+
+  
The disabled attribute
+  is a boolean attribute and can be used to disable a group of
+  option elements together.

+
+  
The label
+  attribute must be specified. Its value gives the name of the group,
+  for the purposes of the user interface. User
+  agents should use this attribute's value when labelling the group of
+  option elements in a select
+  element.

+
+  

+
+  
The disabled and label attributes must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+  

+
+   
The following snippet shows how a set of lessons from three
+   courses could be offered in a select drop-down
+   widget:

+
+   
<form action="courseselector.dll" method="get">
+ <p>Which course would you like to watch today?
+ <p><label>Course:
+  <select name="c">
+   <optgroup label="8.01 Physics I: Classical Mechanics">
+    <option value="8.01.1">Lecture 01: Powers of Ten
+    <option value="8.01.2">Lecture 02: 1D Kinematics
+    <option value="8.01.3">Lecture 03: Vectors
+   <optgroup label="8.02 Electricity and Magnestism">
+    <option value="8.02.1">Lecture 01: What holds our world together?
+    <option value="8.02.2">Lecture 02: Electric Field
+    <option value="8.02.3">Lecture 03: Electric Flux
+   <optgroup label="8.03 Physics III: Vibrations and Waves">
+    <option value="8.03.1">Lecture 01: Periodic Phenomenon
+    <option value="8.03.2">Lecture 02: Beats
+    <option value="8.03.3">Lecture 03: Forced Oscillations with Damping
+  </select>
+ </label>
+ <p><input type=submit value="▶ Play">
+</form>

+
+  

+
+
+
+  
4.10.12 The option element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As a child of a select element.

+   
As a child of a datalist element.

+   
As a child of an optgroup element.

+   
Content model:

+   
Text.

+   
Content attributes:

+   
Global attributes

+   
disabled

+   
label

+   
selected

+   
value

+   
DOM interface:

+   

+
[NamedConstructor=Option(),
+ NamedConstructor=Option(in DOMString text),
+ NamedConstructor=Option(in DOMString text, in DOMString value),
+ NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected),
+ NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected, in boolean selected)]
+interface HTMLOptionElement : HTMLElement {
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString label;
+           attribute boolean defaultSelected;
+           attribute boolean selected;
+           attribute DOMString value;
+
+           attribute DOMString text;
+  readonly attribute long index;
+};

+   

+  
The option element represents an option
+  in a select element or as part of a list of suggestions
+  in a datalist element.

+
+  
The disabled
+  attribute is a boolean attribute. An
+  option element is disabled if its disabled attribute is present or
+  if it is a child of an optgroup element whose disabled attribute is
+  present.

+
+  

+
+  
An option element that is disabled must prevent any click events that are queued on the user interaction task
+  source from being dispatched on the element.

+
+  

+
+  
The label
+  attribute provides a label for element. The label of an option
+  element is the value of the label attribute, if there is one,
+  or the textContent of the element, if there isn't.

+
+  
The value
+  attribute provides a value for element. The value of an option
+  element is the value of the value attribute, if there is one,
+  or the textContent of the element, if there isn't.

+
+  
The selected
+  attribute represents the default selectedness of the
+  element.

+
+  

+
+  
The selectedness
+  of an option element is a boolean state, initially
+  false. If the element is disabled, then the element's
+  selectedness is
+  always false and cannot be set to true. Except where otherwise
+  specified, when the element is created, its selectedness must be set
+  to true if the element has a selected attribute. Whenever an
+  option element's selected attribute is added, its
+  selectedness must
+  be set to true.

+
+  
The Option()
+  constructor with three or fewer arguments overrides the initial
+  state of the selectedness state to
+  always be false even if the third argument is true (implying that a
+  selected attribute is to
+  be set). The fourth argument can be used to explicitly set the
+  initial selectedness state when
+  using the constructor.

+
+  

+
+  
A select element whose multiple attribute is not
+  specified must not have more than one descendant option
+  element with its selected
+  attribute set.

+
+  

+
+  
An option element's index is the number of
+  option element that are in the same list of options but that
+  come before it in tree order. If the
+  option element is not in a list of options, then the
+  option element's index is zero.

+
+  

+
+  
option . selected

+
+   

+
+    
Returns true if the element is selected, and false otherwise.

+
+   

+
+   
option . index

+
+   

+
+    
Returns the index of the element in its select
+    element's options
+    list.

+
+   

+
+   
option . form

+
+   

+
+    
Returns the element's form element, if any, or
+    null otherwise.

+
+   

+
+   
option . text

+
+   

+
+    
Same as textContent.

+
+   

+
+   
option = new Option( [ text [, value [, defaultSelected [, selected ] ] ] ] )

+
+   

+
+    
Returns a new option element.

+
+    
The text argument sets the contents of the element.

+    
The value argument sets the value attribute.

+    
The defaultSelected argument sets the selected attribute.

+    
The selected argument sets whether or not the element is selected. If it is omitted, even if the defaultSelected argument is true, the element is not selected.

+
+   

+
+  

+
+  
The disabled
+  and label IDL
+  attributes must reflect the respective content
+  attributes of the same name. The defaultSelected
+  IDL attribute must reflect the selected content attribute.

+
+  
The value IDL
+  attribute, on getting, must return the value of the element's value content attribute, if it has
+  one, or else the value of the element's textContent IDL
+  attribute. On setting, the element's value content attribute must be set
+  to the new value.

+
+  
The selected
+  IDL attribute must return true if the element's selectedness is true, and
+  false otherwise.

+
+  
The index IDL
+  attribute must return the element's index.

+
+  
The text IDL
+  attribute, on getting, must return the same value as the
+  textContent IDL attribute on the element, and on
+  setting, must act as if the textContent IDL attribute
+  on the element had been set to the new value.

+
+  
The form IDL
+  attribute's behavior depends on whether the option
+  element is in a select element or not. If the
+  option has a select element as its parent,
+  or has a colgroup element as its parent and that
+  colgroup element has a select element as
+  its parent, then the form IDL
+  attribute must return the same value as the form IDL attribute on that
+  select element. Otherwise, it must return null.

+
+  
Several constructors are provided for creating
+  HTMLOptionElement objects (in addition to the factory
+  methods from DOM Core such as createElement()): Option(), Option(text), Option(text, value), Option(text, value, defaultSelected), and Option(text, value, defaultSelected, selected). When invoked as constructors,
+  these must return a new HTMLOptionElement object (a new
+  option element). If the text
+  argument is present, the new object must have as its only child a
+  Node with node type TEXT_NODE (3)
+  whose data is the value of that argument. If the value argument is present, the new object must have a
+  value attribute set with the
+  value of the argument as its value. If the defaultSelected argument is present and true, the new
+  object must have a selected attribute set with no
+  value. If the selected argument is present and
+  true, the new object must have its selectedness set to true;
+  otherwise the fourth argument is absent or false, and the selectedness must be set
+  to false, even if the defaultSelected argument
+  is present and true. The element's document must be the active
+  document of the browsing context of the
+  Window object on which the interface object of the
+  invoked constructor is found.

+
+  

+
+
+
+  
4.10.13 The textarea element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Listed, labelable, submittable, and resettable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Text.

+   
Content attributes:

+   
Global attributes

+   
autofocus

+   
cols

+   
disabled

+   
form

+   
maxlength

+   
name

+   
placeholder

+   
readonly

+   
required

+   
rows

+   
wrap

+   
DOM interface:

+   

+
interface HTMLTextAreaElement : HTMLElement {
+           attribute boolean autofocus;
+           attribute unsigned long cols;
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute long maxLength;
+           attribute DOMString name;
+           attribute DOMString placeholder;
+           attribute boolean readOnly;
+           attribute boolean required;
+           attribute unsigned long rows;
+           attribute DOMString wrap;
+
+  readonly attribute DOMString type;
+           attribute DOMString defaultValue;
+           attribute DOMString value;
+  readonly attribute unsigned long textLength;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+
+  void select();
+           attribute unsigned long selectionStart;
+           attribute unsigned long selectionEnd;
+  void setSelectionRange(in unsigned long start, in unsigned long end);
+};

+   

+  
The textarea element represents a
+  multiline plain text edit control for the
+  element's raw
+  value. The contents of the control represent the
+  control's default value.

+
+  

+
+  
The raw value of
+  a textarea control must be initially the empty
+  string.

+
+  

+
+  
The readonly attribute
+  is a boolean attribute used to control whether the text
+  can be edited by the user or not.

+
+  

+
+  
Constraint validation: If the readonly attribute is
+  specified on a textarea element, the element is
+  barred from constraint validation.

+
+  
A textarea element is mutable if it is neither
+  disabled nor has a readonly attribute
+  specified.

+
+  
When a textarea is mutable, its raw value should be
+  editable by the user. Any time the user causes the element's raw value to change, the
+  user agent must queue a task to fire a simple
+  event that bubbles named input at the textarea
+  element, then broadcast forminput events at the
+  textarea element's form owner. User agents
+  may wait for a suitable break in the user's interaction before
+  queuing the task; for example, a user agent could wait for the user
+  to have not hit a key for 100ms, so as to only fire the event when
+  the user pauses, instead of continuously for each keystroke.

+  
+
+  
A textarea element has a dirty value flag, which must be
+  initially set to false, and must be set to true whenever the user
+  interacts with the control in a way that changes the raw value.

+
+  
When the textarea element's textContent
+  IDL attribute changes value, if the element's dirty value flag is false,
+  then the element's raw
+  value must be set to the value of the element's
+  textContent IDL attribute.

+
+  
The reset
+  algorithm for textarea elements is to set the
+  element's value to
+  the value of the element's textContent IDL
+  attribute.

+
+  

+
+  
The cols
+  attribute specifies the expected maximum number of characters per
+  line. If the cols attribute
+  is specified, its value must be a valid non-negative
+  integer greater than zero. If applying the
+  rules for parsing non-negative integers to the
+  attribute's value results in a number greater than zero, then the
+  element's character
+  width is that value; otherwise, it is 20.

+
+  

+
+  
The user agent may use the textarea element's character width as a hint to
+  the user as to how many characters the server prefers per line
+  (e.g. for visual user agents by making the width of the control be
+  that many characters). In visual renderings, the user agent should
+  wrap the user's input in the rendering so that each line is no wider
+  than this number of characters.

+
+  

+
+  
The rows
+  attribute specifies the number of lines to show. If the rows attribute is specified, its
+  value must be a valid non-negative integer greater than
+  zero. If applying the rules for parsing
+  non-negative integers to the attribute's value results in a
+  number greater than zero, then the element's character height is that
+  value; otherwise, it is 2.

+
+  

+
+  
Visual user agents should set the height of the control to the
+  number of lines given by character height.

+
+  

+
+  
The wrap
+  attribute is an enumerated attribute with two keywords
+  and states: the soft keyword
+  which maps to the Soft state, and the
+  hard keyword
+  which maps to the Hard state. The
+  missing value default is the Soft state.

+
+  
If the element's wrap
+  attribute is in the Hard state, the cols attribute must be
+  specified.

+
+  
+
+  

+
+  
The element's value is
+  defined to be the element's raw value with the
+  following transformation applied:

+
+  
  1. Replace every occurrence of a U+000D CARRIAGE RETURN (CR)
+   character not followed by a U+000A LINE FEED (LF) character, and
+   every occurrence of a U+000A LINE FEED (LF) character not preceded
+   by a U+000D CARRIAGE RETURN (CR) character, by a two-character
+   string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED
+   (CRLF) character pair.
    2. 
+
+   
  2. If the element's wrap attribute is in the Hard state, insert
+   U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs
+   into the string using a UA-defined algorithm so that each line has
+   no more than character
+   width characters. For the purposes of this requirement,
+   lines are delimited by the start of the string, the end of the
+   string, and U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF)
+   character pairs.
    3. 
+
+  

+
+  
The maxlength
+  attribute is a form control maxlength attribute controlled by the
+  textarea element's dirty value flag.

+
+  
If the textarea element has a maximum allowed
+  value length, then the element's children must be such that
+  the code-point length of the value of the element's
+  textContent IDL attribute is equal to or less than the
+  element's maximum allowed value length.

+
+  
The required attribute
+  is a boolean attribute. When specified, the user will
+  be required to enter a value before submitting the form.

+
+  

+
+  
Constraint validation: If the element has its
+  required attribute
+  specified, and the element is mutable, and the element's
+  value is the empty string,
+  then the element is suffering from being missing.

+
+  

+
+
+  
+
+  
The placeholder
+  attribute represents a hint (a word or short phrase) intended to aid
+  the user with data entry. A hint could be a sample value or a brief
+  description of the expected format. The attribute, if specified,
+  must have a value that contains no U+000A LINE FEED (LF) or U+000D
+  CARRIAGE RETURN (CR) characters.

+
+  
For a longer hint or other advisory text, the title attribute is more appropriate.

+
+  
The placeholder
+  attribute should not be used as an alternative to a
+  label.

+
+  

+
+  
User agents should present this hint to the user, after having
+  stripped line breaks from it,
+  when the element's value is
+  the empty string and the control is not focused (e.g. by displaying
+  it inside a blank unfocused control).

+
+  

+
+
+  
The form attribute is used to
+  explicitly associate the textarea element with its
+  form owner. The name
+  attribute represents the element's name. The disabled attribute is used to make
+  the control non-interactive and to prevent its value from being
+  submitted. The autofocus
+  attribute controls focus.

+
+  
textarea . type

+
+   

+
+    
Returns the string "textarea".

+
+   

+
+   
textarea . value

+
+   

+
+    
Returns the current value of the element.

+
+    
Can be set, to change the value.

+
+   

+
+  

+
+  
The cols, placeholder,
+  required, rows, and wrap attributes must
+  reflect the respective content attributes of the same
+  name. The cols and rows attributes are limited
+  to only non-negative numbers greater than zero. The maxLength IDL
+  attribute must reflect the maxlength content attribute,
+  limited to only non-negative numbers. The readOnly IDL
+  attribute must reflect the readonly content
+  attribute.

+
+  
The type IDL
+  attribute must return the value "textarea".

+
+  
The defaultValue
+  IDL attribute must act like the element's textContent
+  IDL attribute.

+
+  
The value
+  attribute must, on getting, return the element's raw value; on setting, it
+  must set the element's raw
+  value to the new value.

+
+  
The textLength IDL
+  attribute must return the code-point length of the
+  element's value.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The select(), selectionStart,
+  selectionEnd,
+  and setSelectionRange()
+  methods and attributes expose the element's text selection. The
+  autofocus, disabled, form, and name IDL attributes are part of the
+  element's forms API.

+
+  

+
+  

+
+   
Here is an example of a textarea being used for
+   unrestricted free-form text input in a form:

+
+   
<p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p>

+
+  

+
+
+
+  
4.10.14 The keygen element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Listed, labelable, submittable, and resettable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
autofocus

+   
challenge

+   
disabled

+   
form

+   
keytype

+   
name

+   
DOM interface:

+   

+
interface HTMLKeygenElement : HTMLElement {
+           attribute boolean autofocus;
+           attribute DOMString challenge;
+           attribute boolean disabled;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString keytype;
+           attribute DOMString name;
+
+  readonly attribute DOMString type;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+};

+   

+  
The keygen element represents a key
+  pair generator control. When the control's form is submitted, the
+  private key is stored in the local keystore, and the public key is
+  packaged and sent to the server.

+
+  
The challenge attribute
+  may be specified. Its value will be packaged with the submitted
+  key.

+
+  
The keytype
+  attribute is an enumerated attribute. The following
+  table lists the keywords and states for the attribute — the
+  keywords in the left column map to the states listed in the cell in
+  the second column on the same row as the keyword. User agents are
+  not required to support these values, and must only recognize values
+  whose corresponding algorithms they support.

+
+  
 Keyword  State
+   
 rsa
+      RSA
+
+  
The invalid value default state is the unknown state. The missing value default state
+  is the RSA state, if it is supported, or the unknown state otherwise.

+
+  
This specification does not specify what key types
+  user agents are to support — it is possible for a user agent
+  to not support any key types at all.

+
+  

+
+  
The user agent may expose a user interface for each
+  keygen element to allow the user to configure settings
+  of the element's key pair generator, e.g. the key length.

+
+  
The reset
+  algorithm for keygen elements is to set these
+  various configuration settings back to their defaults.

+
+  
The element's value is the
+  string returned from the following algorithm:

+
+  
  1. 
+
+    
    Use the appropriate step from the following list:
    
+
+    
    If the keytype
+     attribute is in the RSA state
    
+
+     
    
+
+      
    Generate an RSA key pair using the settings given by the
+      user, if appropriate, using the md5WithRSAEncryption RSA signature algorithm
+      (the signature algorithm with MD5 and the RSA encryption
+      algorithm) referenced in section 2.2.1 ("RSA Signature
+      Algorithm") of RFC 3279, and defined in RFC 2313. [RFC3279] [RFC2313]
    
+
+     
    
+
+     
    Otherwise, the keytype attribute is in the unknown state
    
+
+     
    
+
+      
    The given key type is not supported. Return the empty string
+      and abort this algorithm.
    
+
+     
    
+
+    
    Let private key be the generated private key.
    
+
+    
    Let public key be the generated public key.
    
+
+    
    Let signature algorithm be the selected
+    signature algorithm.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the element has a challenge attribute, then let
+    challenge be that attribute's value.
+    Otherwise, let challenge be the empty
+    string.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Let algorithm be an ASN.1 AlgorithmIdentifier structure as defined by
+    RFC 5280, with the algorithm field giving the
+    ASN.1 OID used to identify signature
+    algorithm, using the OIDs defined in section 2.2 ("Signature
+    Algorithms") of RFC 3279, and the parameters
+    field set up as required by RFC 3279 for AlgorithmIdentifier structures for that
+    algorithm. [X690] [RFC5280] [RFC3279]
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Let spki be an ASN.1 SubjectPublicKeyInfo structure as defined by
+    RFC 5280, with the algorithm field set to the
+    algorithm structure from the previous step,
+    and the subjectPublicKey field set to the
+    BIT STRING value resulting from ASN.1 DER encoding the public key. [X690] [RFC5280]
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Let publicKeyAndChallenge be an ASN.1
+    PublicKeyAndChallenge structure as defined below,
+    with the spki field set to the spki structure from the previous step, and the
+    challenge field set to the string challenge obtained earlier. [X690]
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Let signature be the BIT STRING value
+    resulting from ASN.1 DER encoding the signature generated by
+    applying the signature algorithm to the byte
+    string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure, using private key as the signing key. [X690]
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Let signedPublicKeyAndChallenge be an ASN.1
+    SignedPublicKeyAndChallenge structure as defined
+    below, with the publicKeyAndChallenge field
+    set to the publicKeyAndChallenge structure,
+    the signatureAlgorithm field set to the algorithm structure, and the signature field set to the BIT STRING signature from the previous step. [X690]
    
+
+   
    8. 
+
+   
  8. 
+
+    
    Return the result of base64 encoding the result of ASN.1 DER
+    encoding the signedPublicKeyAndChallenge
+    structure. [RFC3548] [X690]
    
+
+   
    9. 
+
+  
The data objects used by the above algorithm are defined as
+  follows. These definitions use the same "ASN.1-like" syntax defined
+  by RFC 5280. [RFC5280]

+
+  
PublicKeyAndChallenge ::= SEQUENCE {
+    spki SubjectPublicKeyInfo,
+    challenge IA5STRING
+}
+
+SignedPublicKeyAndChallenge ::= SEQUENCE {
+    publicKeyAndChallenge PublicKeyAndChallenge,
+    signatureAlgorithm AlgorithmIdentifier,
+    signature BIT STRING
+}

+
+  
Constraint validation: The keygen
+  element is barred from constraint validation.

+
+  

+
+  
The form attribute is used to
+  explicitly associate the keygen element with its
+  form owner. The name
+  attribute represents the element's name. The disabled attribute is used to make
+  the control non-interactive and to prevent its value from being
+  submitted. The autofocus
+  attribute controls focus.

+
+  
keygen . type

+
+   

+
+    
Returns the string "keygen".

+
+   

+
+  

+
+  
The challenge IDL
+  attribute must reflect the content attributes of the
+  same name.

+
+  
The keytype
+  IDL attribute must reflect the content attributes of
+  the same name, limited to only known values.

+
+  
The type IDL
+  attribute must return the value "keygen".

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the
+  element's forms API.

+
+  

+
+  
This specification does not specify how the private
+  key generated is to be used. It is expected that after receiving the
+  SignedPublicKeyAndChallenge (SPKAC) structure, the
+  server will generate a client certificate and offer it back to the
+  user for download; this certificate, once downloaded and stored in
+  the key store along with the private key, can then be used to
+  authenticate to services that use SSL and certificate
+  authentication.

+
+  
+
+  

+
+   
To generate a key pair, add the private key to the user's key
+   store, and submit the public key to the server, markup such as the
+   following can be used:

+
+   
<form action="processkey.cgi" method="post" enctype="multipart/form-data">
+ <p><keygen name="key"></p>
+ <p><input type=submit value="Submit key..."></p>
+</form>

+
+   
The server will then receive a form submission with a packaged
+   RSA public key as the value of "key". This
+   can then be used for various purposes, such as generating a client
+   certificate, as mentioned above.

+
+  

+
+
+
+  
4.10.15 The output element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Listed, labelable, and resettable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
for

+   
form

+   
name

+   
DOM interface:

+   

+
interface HTMLOutputElement : HTMLElement {
+  [PutForwards=value] readonly attribute DOMSettableTokenList htmlFor;
+  readonly attribute HTMLFormElement form;
+           attribute DOMString name;
+
+  readonly attribute DOMString type;
+           attribute DOMString defaultValue;
+           attribute DOMString value;
+
+  readonly attribute boolean willValidate;
+  readonly attribute ValidityState validity;
+  readonly attribute DOMString validationMessage;
+  boolean checkValidity();
+  void setCustomValidity(in DOMString error);
+
+  readonly attribute NodeList labels;
+};

+   

+  
The output element represents the result of a
+  calculation.

+
+  
The for content
+  attribute allows an explicit relationship to be made between the
+  result of a calculation and the elements that represent the values
+  that went into the calculation or that otherwise influenced the
+  calculation. The for attribute,
+  if specified, must contain a string consisting of an unordered
+  set of unique space-separated tokens, each of which must have
+  the value of an ID of an element in the same
+  Document.

+
+  
The form attribute is used to
+  explicitly associate the output element with its
+  form owner. The name
+  attribute represents the element's name.

+
+  

+
+  
The element has a value mode
+  flag which is either value or default. Initially, the
+  value mode flag must be set
+  to default.

+
+  
The element also has a default value. Initially,
+  the default value
+  must be the empty string.

+
+  
When the value mode flag
+  is in mode default, the
+  contents of the element represent both the value of the element and
+  its default
+  value. When the value mode
+  flag is in mode value, the contents of the
+  element represent the value of the element only, and the default value is only
+  accessible using the defaultValue IDL
+  attribute.

+
+  
Whenever the element's descendants are changed in any way, if the
+  value mode flag is in mode
+  default, the element's
+  default value must
+  be set to the value of the element's textContent IDL
+  attribute.

+
+  
The reset
+  algorithm for output elements is to set the
+  element's value mode flag
+  to default and then to
+  set the element's textContent IDL attribute to the
+  value of the element's default value (thus
+  replacing the element's child nodes).

+
+  

+
+  
output . value [ = value ]

+
+   

+
+    
Returns the element's current value.

+
+    
Can be set, to change the value.

+
+   

+
+   
output . defaultValue [ = value ]

+
+   

+
+    
Returns the element's current default value.

+
+    
Can be set, to change the default value.

+
+   

+
+   
output . type

+
+   

+
+    
Returns the string "output".

+
+   

+
+  

+
+  
The value IDL
+  attribute must act like the element's textContent IDL
+  attribute, except that on setting, in addition, before the child
+  nodes are changed, the element's value mode flag must be set to value.

+
+  
The defaultValue IDL
+  attribute, on getting, must return the element's default value. On
+  setting, the attribute must set the element's default value, and, if
+  the element's value mode
+  flag is in the mode default, set the element's
+  textContent IDL attribute as well.

+
+  
The type
+  attribute must return the string "output".

+
+  
The htmlFor
+  IDL attribute must reflect the for content attribute.

+
+  
The willValidate, validity, and validationMessage
+  attributes, and the checkValidity() and setCustomValidity()
+  methods, are part of the constraint validation API. The
+  labels attribute provides a list
+  of the element's labels. The form and name IDL attributes are part of the
+  element's forms API.

+
+  
Constraint validation: output
+  elements are always barred from constraint
+  validation.

+
+  

+
+  

+
+   
A simple calculator could use output for its
+   display of calculated results:

+
+   
<form onsubmit="return false">
+ <input name=a type=number step=any> +
+ <input name=b type=number step=any> =
+ <output onforminput="value = a.valueAsNumber + b.valueAsNumber"></output>
+</form>

+
+  

+
+
+
+  
4.10.16 The progress element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Labelable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but there must be no progress element descendants.

+   
Content attributes:

+   
Global attributes

+   
value

+   
max

+   
form

+   
DOM interface:

+   

+
interface HTMLProgressElement : HTMLElement {
+           attribute float value;
+           attribute float max;
+  readonly attribute float position;
+  readonly attribute HTMLFormElement form;
+  readonly attribute NodeList labels;
+};

+   

+  
The progress element represents the
+  completion progress of a task. The progress is either indeterminate,
+  indicating that progress is being made but that it is not clear how
+  much more work remains to be done before the task is complete
+  (e.g. because the task is waiting for a remote host to respond), or
+  the progress is a number in the range zero to a maximum, giving the
+  fraction of work that has so far been completed.

+
+  
There are two attributes that determine the current task
+  completion represented by the element.

+
+  
The value
+  attribute specifies how much of the task has been completed, and the
+  max attribute
+  specifies how much work the task requires in total. The units are
+  arbitrary and not specified.

+
+  
Authors are encouraged to also include the current value and the
+  maximum value inline as text inside the element, so that the
+  progress is made available to users of legacy user agents.

+
+  

+   
Here is a snippet of a Web application that shows the progress
+   of some automated task:

+   
<section>
+ <h2>Task Progress</h2>
+ <p>Progress: <progress id="p" max=100><span>0</span>%</progress></p>
+ <script>
+  var progressBar = document.getElementById('p');
+  function updateProgress(newValue) {
+    progressBar.value = newValue;
+    progressBar.getElementsByTagName('span')[0].textContent = newValue;
+  }
+ </script>
+</section>

+   
(The updateProgress() method in this example would
+   be called by some other code on the page to update the actual
+   progress bar as the task progressed.)

+  

+
+  
The value and max attributes, when present, must
+  have values that are valid
+  floating point numbers. The value attribute, if present, must
+  have a value equal to or greater than zero, and less than or equal
+  to the value of the max
+  attribute, if present, or 1.0, otherwise. The max attribute, if present, must
+  have a value greater than zero.

+
+  
The progress element is the wrong
+  element to use for something that is just a gauge, as opposed to
+  task progress. For instance, indicating disk space usage using
+  progress would be inappropriate. Instead, the
+  meter element is available for such use cases.

+
+  

+
+  
User agent requirements: If the value attribute is omitted, then
+  the progress bar is an indeterminate progress bar. Otherwise, it is
+  a determinate progress bar.

+
+  
If the progress bar is a determinate progress bar and the element
+  has a max attribute, the user
+  agent must parse the max
+  attribute's value according to the rules for parsing floating
+  point number values. If this does not result in an error, and
+  if the parsed value is greater than zero, then the maximum value of
+  the progress bar is that value. Otherwise, if the element has no
+  max attribute, or if it has
+  one but parsing it resulted in an error, or if the parsed value was
+  less than or equal to zero, then the maximum value of the progress
+  bar is 1.0.

+
+  
If the progress bar is a determinate progress bar, user agents
+  must parse the value
+  attribute's value according to the rules for parsing floating
+  point number values. If this does not result in an error, and
+  if the parsed value is less than the maximum value and greater than
+  zero, then the current value of the progress bar is that parsed
+  value. Otherwise, if the parsed value was greater than or equal to
+  the maximum value, then the current value of the progress bar is the
+  maximum value of the progress bar. Otherwise, if parsing the value attribute's value resulted
+  in an error, or a number less than or equal to zero, then the
+  current value of the progress bar is zero.

+
+  
UA requirements for showing the progress bar:
+  When representing a progress element to the user, the
+  UA should indicate whether it is a determinate or indeterminate
+  progress bar, and in the former case, should indicate the relative
+  position of the current value relative to the maximum value.

+
+  
The max and value IDL attributes
+  must reflect the respective content attributes of the
+  same name. When the relevant content attributes are absent, the IDL
+  attributes must return zero.

+
+  
The form attribute is used to
+  explicitly associate the progress element with its
+  form owner.

+
+  

+
+  
progress . position

+
+   

+
+    
For a determinate progress bar (one with known current and
+    maximum values), returns the result of dividing the current value
+    by the maximum value.

+
+    
For an indeterminate progress bar, returns −1.

+
+  

+
+  
If the progress bar is an indeterminate progress bar, then the
+  position IDL
+  attribute must return −1. Otherwise, it must return the result of
+  dividing the current value by the maximum value.

+
+  
The labels attribute provides
+  a list of the element's labels. The form IDL attribute is part of the
+  element's forms API.

+
+  

+
+
+
+  
4.10.17 The meter element

+  
+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Labelable form-associated element.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Phrasing content, but there must be no meter element descendants.

+   
Content attributes:

+   
Global attributes

+   
value

+   
min

+   
max

+   
low

+   
high

+   
optimum

+   
form

+   
DOM interface:

+   

+
interface HTMLMeterElement : HTMLElement {
+           attribute float value;
+           attribute float min;
+           attribute float max;
+           attribute float low;
+           attribute float high;
+           attribute float optimum;
+  readonly attribute HTMLFormElement form;
+  readonly attribute NodeList labels;
+};

+   

+  
The meter element represents a scalar
+  measurement within a known range, or a fractional value; for example
+  disk usage, the relevance of a query result, or the fraction of a
+  voting population to have selected a particular candidate.

+
+  
This is also known as a gauge.

+
+  
The meter element should not be used to
+  indicate progress (as in a progress bar). For that role, HTML
+  provides a separate progress element.

+
+  
The meter element also does not
+  represent a scalar value of arbitrary range — for example, it
+  would be wrong to use this to report a weight, or height, unless
+  there is a known maximum value.

+
+  
There are six attributes that determine the semantics of the
+  gauge represented by the element.

+
+  
The min attribute
+  specifies the lower bound of the range, and the max attribute specifies
+  the upper bound. The value attribute
+  specifies the value to have the gauge indicate as the "measured"
+  value.

+
+  
The other three attributes can be used to segment the gauge's
+  range into "low", "medium", and "high" parts, and to indicate which
+  part of the gauge is the "optimum" part. The low attribute specifies
+  the range that is considered to be the "low" part, and the high attribute specifies
+  the range that is considered to be the "high" part. The optimum attribute
+  gives the position that is "optimum"; if that is higher than the
+  "high" value  then this indicates that the higher the value, the
+  better; if it's lower than the "low" mark then it indicates that
+  lower values are better, and naturally if it is in between then it
+  indicates that neither high nor low values are good.

+
+  
Authoring
+  requirements: The value attribute must be
+  specified. The value, min, low, high, max, and optimum attributes, when present,
+  must have values that are valid floating point numbers.

+
+  
In addition, the attributes' values are further constrained:

+
+  
Let value be the value attribute's number.

+
+  
If the min attribute
+  attribute is specified, then let minimum be that
+  attribute's value; otherwise, let it be zero.

+
+  
If the max attribute
+  attribute is specified, then let maximum be that
+  attribute's value; otherwise, let it be 1.0.

+
+  
The following inequalities must hold, as applicable:

+
+  
  • minimum ≤ value ≤ maximum
    • 
+   
  • minimum ≤ low ≤ maximum (if low is specified)
    • 
+   
  • minimum ≤ high ≤ maximum (if high is specified)
    • 
+   
  • minimum ≤ optimum ≤ maximum (if optimum is specified)
    • 
+   
  • low ≤ high (if both low and high are specified)
    • 
+  
If no minimum or maximum is specified, then the
+  range is assumed to be 0..1, and the value thus has to be within
+  that range.

+
+  
Authors are encouraged to include a textual representation of the
+  gauge's state in the element's contents, for users of user agents
+  that do not support the meter element.

+
+  

+
+   
The following examples show three gauges that would all be
+   three-quarters full:

+
+   
Storage space usage: <meter value=6 max=8>6 blocks used (out of 8 total)</meter>
+Voter turnout: <meter value=0.75><img alt="75%" src="graph75.png"></meter>
+Tickets sold: <meter min="0" max="100" value="75"></meter>

+
+   
The following example is incorrect use of the element, because
+   it doesn't give a range (and since the default maximum is 1, both
+   of the gauges would end up looking maxed out):

+
+   
<p>The grapefruit pie had a radius of <meter value=12>12cm</meter>
+and a height of <meter value=2>2cm</meter>.</p> <!-- BAD! -->

+
+   
Instead, one would either not include the meter element, or use
+   the meter element with a defined range to give the dimensions in
+   context compared to other pies:

+
+   
<p>The grapefruit pie had a radius of 12cm and a height of
+2cm.</p>
+<dl>
+ <dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter>
+ <dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter>
+</dl>

+
+  

+
+  
There is no explicit way to specify units in the
+  meter element, but the units may be specified in the
+  title attribute in free-form text.

+
+  

+
+   
The example above could be extended to mention the units:

+
+   
<dl>
+ <dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter>
+ <dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter>
+</dl>

+
+  

+
+  

+
+  
User agent requirements: User agents must parse
+  the min, max, value, low, high, and optimum attributes using the
+  rules for parsing floating point number values.

+
+  
User agents must then use all these numbers to obtain values for
+  six points on the gauge, as follows. (The order in which these are
+  evaluated is important, as some of the values refer to earlier
+  ones.)

+
+  
The minimum value

+
+   

+    
If the min attribute is
+    specified and a value could be parsed out of it, then the minimum
+    value is that value. Otherwise, the minimum value is zero.

+   

+
+   
The maximum value

+
+   

+
+    
If the max attribute is
+    specified and a value could be parsed out of it, the maximum value
+    is that value. Otherwise, the maximum value is 1.0.

+
+    
If the maximum value would be less than the minimum value, then
+    the maximum value is actually the same as the minimum value.

+
+   

+
+   
The actual value

+
+   

+
+    
If the value attribute is
+    specified and a value could be parsed out of it, then that value
+    is the actual value. Otherwise, the actual value is zero.

+
+    
If the actual value would be less than the minimum value, then
+    the actual value is actually the same as the minimum value.

+
+    
If, on the other hand, the actual value would be greater than
+    the maximum value, then the actual value is the maximum value.

+
+   

+
+   
The low boundary

+
+   

+
+    
If the low attribute is
+    specified and a value could be parsed out of it, then the low
+    boundary is that value. Otherwise, the low boundary is the same as
+    the minimum value.

+
+    
If the low boundary is then less than the minimum value, then
+    the low boundary is actually the same as the minimum
+    value. Similarly, if the low boundary is greater than the maximum
+    value, then it is actually the maximum value instead.

+
+   

+
+   
The high boundary

+
+   

+
+    
If the high attribute is
+    specified and a value could be parsed out of it, then the high
+    boundary is that value. Otherwise, the high boundary is the same
+    as the maximum value.

+
+    
If the high boundary is then less than the low boundary, then
+    the high boundary is actually the same as the low
+    boundary. Similarly, if the high boundary is greater than the
+    maximum value, then it is actually the maximum value instead.

+
+   

+
+   
The optimum point

+
+   

+
+    
If the optimum
+    attribute is specified and a value could be parsed out of it, then
+    the optimum point is that value. Otherwise, the optimum point is
+    the midpoint between the minimum value and the maximum value.

+
+    
If the optimum point is then less than the minimum value, then
+    the optimum point is actually the same as the minimum
+    value. Similarly, if the optimum point is greater than the maximum
+    value, then it is actually the maximum value instead.

+
+   

+
+  
All of which will result in the following inequalities all being
+  true:

+
+  
  • minimum value ≤ actual value ≤ maximum value
    • 
+   
  • minimum value ≤ low boundary ≤ high boundary ≤ maximum value
    • 
+   
  • minimum value ≤ optimum point ≤ maximum value
    • 
+  
UA requirements for regions of the gauge: If the
+  optimum point is equal to the low boundary or the high boundary, or
+  anywhere in between them, then the region between the low and high
+  boundaries of the gauge must be treated as the optimum region, and
+  the low and high parts, if any, must be treated as
+  suboptimal. Otherwise, if the optimum point is less than the low
+  boundary, then the region between the minimum value and the low
+  boundary must be treated as the optimum region, the region between
+  the low boundary and the high boundary must be treated as a
+  suboptimal region, and the region between the high boundary and the
+  maximum value must be treated as an even less good region. Finally,
+  if the optimum point is higher than the high boundary, then the
+  situation is reversed; the region between the high boundary and the
+  maximum value must be treated as the optimum region, the region
+  between the high boundary and the low boundary must be treated as a
+  suboptimal region, and the remaining region between the low boundary
+  and the minimum value must be treated as an even less good
+  region.

+
+  
UA requirements for showing the gauge: When
+  representing a meter element to the user, the UA should
+  indicate the relative position of the actual value to the minimum
+  and maximum values, and the relationship between the actual value
+  and the three regions of the gauge.

+
+  

+
+  

+   
The following markup:

+   
<h3>Suggested groups</h3>
+<menu type="toolbar">
+ <a href="?cmd=hsg" onclick="hideSuggestedGroups()">Hide suggested groups</a>
+</menu>
+<ul>
+ <li>
+  <p><a href="/group/comp.infosystems.www.authoring.stylesheets/view">comp.infosystems.www.authoring.stylesheets</a> -
+     <a href="/group/comp.infosystems.www.authoring.stylesheets/subscribe">join</a></p>
+  <p>Group description: <strong>Layout/presentation on the WWW.</strong></p>
+  <p><meter value="0.5">Moderate activity,</meter> Usenet, 618 subscribers</p>
+ </li>
+ <li>
+  <p><a href="/group/netscape.public.mozilla.xpinstall/view">netscape.public.mozilla.xpinstall</a> -
+     <a href="/group/netscape.public.mozilla.xpinstall/subscribe">join</a></p>
+  <p>Group description: <strong>Mozilla XPInstall discussion.</strong></p>
+  <p><meter value="0.25">Low activity,</meter> Usenet, 22 subscribers</p>
+ </li>
+ <li>
+  <p><a href="/group/mozilla.dev.general/view">mozilla.dev.general</a> -
+     <a href="/group/mozilla.dev.general/subscribe">join</a></p>
+  <p><meter value="0.25">Low activity,</meter> Usenet, 66 subscribers</p>
+ </li>
+</ul>

+   
Might be rendered as follows:

+   
With the <meter> elements rendered as inline green bars of varying lengths.

+  

+
+  
User agents may combine the value of
+  the title attribute and the other
+  attributes to provide context-sensitive help or inline text
+  detailing the actual values.

+
+  

+   
For example, the following snippet:

+   
<meter min=0 max=60 value=23.2 title=seconds></meter>

+   
...might cause the user agent to display a gauge with a tooltip
+   saying "Value: 23.2 out of 60." on one line and "seconds" on a
+   second line.

+  

+
+  
The form attribute is used to
+  explicitly associate the meter element with its
+  form owner.

+
+  

+
+  
The min, max, value, low, high, and optimum IDL attributes
+  must reflect the respective content attributes of the
+  same name. When the relevant content attributes are absent, the IDL
+  attributes must return zero.

+
+  
The labels attribute provides
+  a list of the element's labels. The form IDL attribute is part of the
+  element's forms API.

+
+  

+
+  

+
+   
The following example shows how a gauge could fall back to
+   localized or pretty-printed text.

+
+   
<p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used
+out of 233 257 824 bytes available</meter></p>

+
+  

+
+
+
+
+  
4.10.18 Association of controls and forms

+
+  
A form-associated element can have a relationship
+  with a form element, which is called the element's
+  form owner. If a form-associated element is
+  not associated with a form element, its form
+  owner is said to be null.

+
+  
A form-associated element is, by default, associated
+  with its nearest ancestor form element (as described below), but may have a form attribute specified to
+  override this.

+
+  
If a form-associated element has a form attribute specified, then its
+  value must be the ID of a form element in the element's
+  owner Document.

+
+  

+
+  
When a form-associated element is created, its
+  form owner must be initialized to null (no owner).

+
+  
When a form-associated element is to be associated with a form, its
+  form owner must be set to that form.

+
+  
When a form-associated element's ancestor chain
+  changes, e.g. because it or one of its ancestors was inserted or removed from a
+  Document, then the user agent must reset the form
+  owner of that element.

+
+  
When a form-associated element's form attribute is added, removed, or
+  has its value changed, then the user agent must reset the form
+  owner of that element.

+
+  
When a form-associated element has a form attribute and the ID of any of the
+  elements in the Document changes, then the user agent
+  must reset the form owner of that form-associated
+  element.

+
+  
When a form-associated element has a form attribute and an element with an
+  ID is inserted
+  into or removed from the Document, then the
+  user agent must reset the form owner of that
+  form-associated element.

+
+  
When the user agent is to reset the form owner of a
+  form-associated element, it must run the following
+  steps:

+
+  
  1. If the element's form owner is not null, and
+   the element's form content
+   attribute is not present, and the element's form owner
+   is its nearest form element ancestor after the change
+   to the ancestor chain, then do nothing, and abort these
+   steps.
    2. 
+
+   
  2. Let the element's form owner be null.
    3. 
+
+   
  3. 
+
+    
    If the element has a form
+    content attribute, then run these substeps:
    
+
+    
    1. If the first element in the
+     Document to have an ID that is case-sensitively equal to the
+     element's form content
+     attribute's value is a form element, then associate the
+     form-associated element with that form
+     element.
      2. 
+
+     
    2. Abort the "reset the form owner" steps.
      3. 
+
+    
    4. 
+
+   
  4. Otherwise, if the form-associated element in
+   question has an ancestor form element, then associate the
+   form-associated element with the nearest such ancestor
+   form element.
    5. 
+
+   
  5. Otherwise, the element is left unassociated.
    6. 
+
+  

+
+   
In the following non-conforming snippet:

+
+   
...
+ <form id="a">
+  <div id="b"></div>
+ </form>
+ <script>
+  document.getElementById('b').innerHTML =
+     '<table><tr><td><form id="c"><input id="d"></table>' +
+     '<input id="e">';
+ </script>
+...

+
+   
The form owner of "d" would be the inner nested
+   form "c", while the form owner of "e" would be the
+   outer form "a".

+
+   
This is because despite the association of "e" with "c" in the
+   HTML parser, when the innerHTML algorithm moves the nodes
+   from the temporary document to the "b" element, the nodes see their
+   ancestor chain change, and thus all the "magic" associations done
+   by the parser are reset to normal ancestor associations.

+
+   
This example is a non-conforming document, though, as it is a
+   violation of the content models to nest form
+   elements.

+
+  

+
+  

+
+  
element . form

+
+   

+
+    
Returns the element's form owner.

+
+    
Returns null if there isn't one.

+
+   

+
+  

+
+  
Form-associated
+  elements have a form IDL attribute, which,
+  on getting, must return the element's form owner, or
+  null if there isn't one.

+
+  

+
+
+
+  
4.10.19 Attributes common to form controls

+
+  
4.10.19.1 Naming form controls

+
+  
The name content
+  attribute gives the name of the form control, as used in form
+  submission and in the form element's elements object. If the attribute
+  is specified, its value must not be the empty string.

+
+  

+
+  
The name IDL
+  attribute must reflect the name content attribute.

+
+  

+
+
+  
4.10.19.2 Enabling and disabling form controls

+
+  
The disabled
+  content attribute is a boolean attribute.

+
+  
A form control is disabled
+  if its disabled attribute is
+  set, or if it is a descendant of a fieldset element
+  whose disabled attribute
+  is set and is not a descendant of that
+  fieldset element's first legend element
+  child, if any.

+
+  

+
+  
A form control that is disabled must prevent any click events that are queued on the user interaction task
+  source from being dispatched on the element.

+
+  
Constraint validation: If an element is disabled, it is barred from
+  constraint validation.

+
+  
The disabled IDL
+  attribute must reflect the disabled content attribute.

+
+  

+
+
+
+  

+
+  
4.10.19.3 A form control's value

+
+  
Form controls have a value
+  and a checkedness. (The latter
+  is only used by input elements.) These are used to
+  describe how the user interacts with the control.

+
+  

+
+
+
+  
4.10.19.4 Autofocusing a form control

+
+  
+
+  
The autofocus
+  content attribute allows the user to indicate that a control is to
+  be focused as soon as the page is loaded, allowing the user to just
+  start typing without having to manually focus the main control.

+
+  
The autofocus attribute is
+  a boolean attribute.

+
+  
There must not be more than one element in the document with the
+  autofocus attribute
+  specified.

+
+  

+
+  
Whenever an element with the autofocus attribute specified is
+  inserted into a
+  document whose browsing context did not have the
+  sandboxed automatic features browsing context flag set
+  when the Document was created, the user agent should
+  queue a task that checks to see if the element is
+  focusable, and if so, runs the focusing
+  steps for that element. User agents may also change the
+  scrolling position of the document, or perform some other action
+  that brings the element to the user's attention. The task
+  source for this task is the DOM manipulation task
+  source.

+
+  
User agents may ignore this attribute if the user has indicated
+  (for example, by starting to type in a form control) that he does
+  not wish focus to be changed.

+
+  
Focusing the control does not imply that the user
+  agent must focus the browser window if it has lost focus.

+
+  
The autofocus
+  IDL attribute must reflect the content attribute of the
+  same name.

+
+  

+
+  

+   
In the following snippet, the text control would be focused when
+   the document was loaded.

+   
<input maxlength="256" name="q" value="" autofocus>
+<input type="submit" value="Search">

+  

+
+
+  
4.10.19.5 Limiting user input length

+
+  
A form control maxlength attribute, controlled by a dirty value flag declares a limit on the number of
+  characters a user can input.

+
+  
If an element has its form
+  control maxlength attribute specified,
+  the attribute's value must be a valid non-negative
+  integer. If the attribute is specified and applying the
+  rules for parsing non-negative integers to its value
+  results in a number, then that number is the element's maximum
+  allowed value length. If the attribute is omitted or parsing
+  its value results in an error, then there is no maximum
+  allowed value length.

+
+  

+
+  
Constraint validation: If an element has a
+  maximum allowed value length, and its dirty value flag is true, and the code-point
+  length of the element's value is greater than the element's
+  maximum allowed value length, then the element is
+  suffering from being too long.

+
+  
User agents may prevent the user from causing the element's value to be set to a value whose
+  code-point length is greater than the element's
+  maximum allowed value length.

+
+  

+
+
+
+  
4.10.19.6 Form submission

+
+  
Attributes for form submission can be specified both
+  on form elements and on submit buttons (elements that
+  represent buttons that submit forms, e.g. an input
+  element whose type attribute is
+  in the Submit Button
+  state).
+
+  
The attributes for form submission that may be
+  specified on form elements are action, enctype, method, novalidate, and target.

+
+  
The corresponding attributes for form submission
+  that may be specified on submit
+  buttons are formaction, formenctype, formmethod, formnovalidate, and formtarget. When omitted, they
+  default to the values given on the corresponding attributes on the
+  form element.

+
+  
The action and
+  formaction
+  content attributes, if specified, must have a value that is a
+  valid URL potentially surrounded by spaces.

+
+  
The action of an element is
+  the value of the element's formaction attribute, if the
+  element is a submit
+  button and has such an attribute, or the value of its
+  form owner's action
+  attribute, if it has one, or else the empty string.

+
+  
The method and
+  formmethod
+  content attributes are enumerated
+  attributes with the following keywords and states:

+
+  
  • The keyword GET, mapping
+   to the state GET, indicating
+   the HTTP GET method.
    • 
+
+   
  • The keyword POST, mapping
+   to the state POST, indicating
+   the HTTP POST method.
    • 
+
+   
  • The keyword PUT, mapping
+   to the state PUT, indicating
+   the HTTP PUT method.
    • 
+
+   
  • The keyword DELETE, mapping
+   to the state DELETE, indicating
+   the HTTP DELETE method.
    • 
+
+  
The missing value default for these attributes is the
+  GET state.

+
+  
The method of an element is
+  one of those four states. If the element is a submit button and has a formmethod attribute, then the
+  element's method is that
+  attribute's state; otherwise, it is the form owner's
+  method attribute's state.

+
+  
The enctype and
+  formenctype
+  content attributes are enumerated
+  attributes with the following keywords and states:

+
+  
  • The "application/x-www-form-urlencoded" keyword and corresponding state.
    • 
+   
  • The "multipart/form-data" keyword and corresponding state.
    • 
+   
  • The "text/plain" keyword and corresponding state.
    • 
+  
The missing value default for these attributes is the
+  application/x-www-form-urlencoded
+  state.

+
+  
The enctype of an element
+  is one of those three states. If the element is a submit button and has a formenctype attribute, then the
+  element's enctype is that
+  attribute's state; otherwise, it is the form owner's
+  enctype attribute's state.

+
+  
The target and
+  formtarget
+  content attributes, if specified, must have values that are valid browsing
+  context names or keywords.

+
+  
The target of an element is
+  the value of the element's formtarget attribute, if the
+  element is a submit
+  button and has such an attribute; or the value of its
+  form owner's target
+  attribute, if it has such an attribute; or, if one of the
+  child nodes of the head element is a
+  base element with a target attribute, then the value of
+  the target attribute of the
+  first such base element; or, if there is no such
+  element, the empty string.
 
+
+  
The novalidate
+  and formnovalidate
+  content attributes are boolean
+  attributes. If present, they indicate that the form is not to
+  be validated during submission.

+
+  
The no-validate state of
+  an element is true if the element is a submit button and the element's
+  formnovalidate attribute
+  is present, or if the element's form owner's novalidate attribute is present,
+  and false otherwise.

+
+  

+
+   
This attribute is useful to include "save" buttons on forms that
+   have validation constraints, to allow users to save their progress
+   even though they haven't fully entered the data in the form. The
+   following example shows a simple form that has two required
+   fields. There are three buttons: one to submit the form, which
+   requires both fields to be filled in; one to save the form so that
+   the user can come back and fill it in later; and one to cancel the
+   form altogether.

+
+   
<form action="editor.cgi" method="post">
+ <p><label>Name: <input required name=fn></label></p>
+ <p><label>Essay: <textarea name=essay></textarea></label></p>
+ <p><input type=submit name=submit value="Submit essay"></p>
+ <p><input type=submit formnovalidate name=save value="Save essay"></p>
+ <p><input type=submit formnovalidate name=cancel value="Cancel"></p>
+</form>

+
+  

+
+  

+
+  
The action, method, enctype, and target IDL attributes must
+  reflect the respective content attributes of the same
+  name. The noValidate IDL
+  attribute must reflect the novalidate content attribute.  The
+  formAction IDL
+  attribute must reflect the formaction content attribute. The
+  formEnctype IDL
+  attribute must reflect the formenctype content attribute.
+  The formMethod IDL
+  attribute must reflect the formmethod content attribute. The
+  formNoValidate
+  IDL attribute must reflect the formnovalidate content
+  attribute. The formTarget IDL
+  attribute must reflect the formtarget content attribute.
+
+  

+
+
+
+  
4.10.20 Constraints

+
+  
4.10.20.1 Definitions

+
+  

+
+  
A listed form-associated
+  element is a candidate for constraint validation
+  except when a condition has barred the element from constraint
+  validation. (For example, an element is barred from
+  constraint validation if it is an output or
+  fieldset element.)

+
+  
An element can have a custom validity error message
+  defined. Initially, an element must have its custom validity
+  error message set to the empty string. When its value is not
+  the empty string, the element is suffering from a custom
+  error. It can be set using the setCustomValidity()
+  method. The user agent should use the custom validity error
+  message when alerting the user to the problem with the
+  control.

+
+  
An element can be constrained in various ways. The following is
+  the list of validity states that a form control can be
+  in, making the control invalid for the purposes of constraint
+  validation. (The definitions below are non-normative; other parts of
+  this specification define more precisely when each state applies or
+  does not.)

+
+  
 Suffering from being missing 

+
+   
 
When a control has no value but has a required attribute (input required, textarea
+   required). 

+
+   
 Suffering from a type mismatch 

+
+   
 
When a control that allows arbitrary user
+   input has a value that is not
+   in the correct syntax (E-mail, URL). 

+
+   
 Suffering from a pattern mismatch 

+
+   
 
When a control has a value that doesn't satisfy the
+   pattern attribute.

+
+   
 Suffering from being too long 

+
+   
 
When a control has a value that is too long for the
+   form control maxlength attribute (input
+   maxlength,
+   textarea maxlength). 

+
+   
 Suffering from an underflow 

+
+   
 
When a control has a value that is too low for the min attribute.

+
+   
 Suffering from an overflow 

+
+   
 
When a control has a value that is too high for the
+   max attribute.

+
+   
 Suffering from a step mismatch 

+
+   
 
When a control has a value that doesn't fit the rules
+   given by the step
+   attribute.

+
+   
 Suffering from a custom error 

+
+   
 
When a control's custom validity error
+   message (as set by the element's setCustomValidity()
+   method) is not the empty string.
 

+
+  
An element can still suffer from these states even
+  when the element is disabled; thus these states can
+  be represented in the DOM even if validating the form during
+  submission wouldn't indicate a problem to the user.

+
+  
An element satisfies its
+  constraints if it is not suffering from any of the above
+  validity states.

+
+  

+
+
+
+  

+
+  
4.10.20.2 Constraint validation

+
+  
When the user agent is required to statically validate the
+  constraints of form element form, it must run the following steps, which return
+  either a positive result (all the controls in the form are
+  valid) or a negative result (there are invalid controls)
+  along with a (possibly empty) list of elements that are invalid and
+  for which no script has claimed responsibility:

+
+  
  1. Let controls be a list of all the submittable elements whose
+   form owner is form, in tree
+   order.
    2. 
+
+   
  2. Let invalid controls be an initially
+   empty list of elements.
    3. 
+
+   
  3. 
+
+    
    For each element field in controls, in tree order, run the
+    following substeps:
    
+
+    
    1. If field is not a candidate for
+     constraint validation, then move on to the next
+     element.
      2. 
+
+     
    2. Otherwise, if field satisfies its constraints, then
+     move on to the next element.
      3. 
+
+     
    3. Otherwise, add field to invalid controls.
      4. 
+
+    
    4. 
+
+   
  4. If invalid controls is empty, then
+   return a positive result and abort these steps.
    5. 
+
+   
  5. Let unhandled invalid controls be an
+   initially empty list of elements.
    6. 
+
+   
  6. 
+
+    
    For each element field in invalid controls, if any, in tree
+    order, run the following substeps:
    
+
+    
    1. Fire a simple event named invalid that is cancelable at field.
      2. 
+
+     
    2. If the event was not canceled, then add field to unhandled invalid
+     controls.
      3. 
+
+    
    7. 
+
+   
  7. Return a negative result with the list of elements in
+   the unhandled invalid controls list.
    8. 
+
+  
If a user agent is to interactively validate the
+  constraints of form element form, then the user agent must run the following
+  steps:

+
+  
  1. Statically validate the constraints of form, and let unhandled invalid
+   controls be the list of elements returned if the result was
+   negative.
    2. 
+
+   
  2. If the result was positive, then return that result
+   and abort these steps.
    3. 
+
+   
  3. Report the problems with the constraints of at least one of
+   the elements given in unhandled invalid
+   controls to the user. User agents may focus one of those
+   elements in the process, by running the focusing steps
+   for that element, and may change the scrolling position of the
+   document, or perform some other action that brings the element to
+   the user's attention. User agents may report more than one
+   constraint violation. User agents may coalesce related constraint
+   violation reports if appropriate (e.g. if multiple radio buttons in
+   a group are marked as
+   required, only one error need be reported). If one of the controls
+   is not being rendered (e.g. it has the hidden attribute set) then user agents
+   may report a script error.
    4. 
+
+   
  4. Return a negative result.
    5. 
+
+  

+
+
+
+  
4.10.20.3 The constraint validation API

+
+  
element . willValidate

+
+   

+
+    
Returns true if the element will be validated when the form is submitted; false otherwise.

+
+   

+
+   
element . setCustomValidity(message)

+
+   

+
+    
Sets a custom error, so that the element would fail to
+    validate. The given message is the message to be shown to the user
+    when reporting the problem to the user.

+
+    
If the argument is the empty string, clears the custom error.

+
+   

+
+   
element . validity . valueMissing

+
+   

+
+    
Returns true if the element has no value but is a required field; false otherwise.

+
+   

+
+   
element . validity . typeMismatch

+
+   

+
+    
Returns true if the element's value is not in the correct syntax; false otherwise.

+
+   

+
+   
element . validity . patternMismatch

+
+   

+
+    
Returns true if the element's value doesn't match the provided pattern; false otherwise.

+
+   

+
+   
element . validity . tooLong

+
+   

+
+    
Returns true if the element's value is longer than the provided maximum length; false otherwise.

+
+   

+
+   
element . validity . rangeUnderflow

+
+   

+
+    
Returns true if the element's value is lower than the provided minimum; false otherwise.

+
+   

+
+   
element . validity . rangeOverflow

+
+   

+
+    
Returns true if the element's value is higher than the provided maximum; false otherwise.

+
+   

+
+   
element . validity . stepMismatch

+
+   

+
+    
Returns true if the element's value doesn't fit the rules given by the step attribute; false otherwise.

+
+   

+
+   
element . validity . customError

+
+   

+
+    
Returns true if the element has a custom error; false otherwise.

+
+   

+
+   
element . validity . valid

+
+   

+
+    
Returns true if the element's value has no validity problems; false otherwise.

+
+   

+
+   
valid = element . checkValidity()

+
+   

+
+    
Returns true if the element's value has no validity problems;
+    false otherwise. Fires an invalid event at the element in the
+    latter case.

+
+   

+
+   
element . validationMessage

+
+   

+
+    
Returns the error message that would be shown to the user if
+    the element was to be checked for validity.

+
+   

+
+  

+
+  
The willValidate
+  attribute must return true if an element is a candidate for
+  constraint validation, and false otherwise (i.e. false if any
+  conditions are barring it from constraint validation).

+
+  
The setCustomValidity(message), when invoked, must set the
+  custom validity error message to the value of the given
+  message argument.

+
+  

+
+  

+
+   
In the following example, a script checks the value of a form
+   control each time it is edited, and whenever it is not a valid
+   value, uses the setCustomValidity() method
+   to set an appropriate message.

+
+   
<label>Feeling: <input name=f type="text" oninput="check(this)"></label>
+<script>
+ function check(input) {
+   if (input.value == "good" ||
+       input.value == "fine" ||
+       input.value == "tired") {
+     input.setCustomValidity('"' + input.value + '" is not a feeling.');
+   } else {
+     // input is fine -- reset the error message
+     input.setCustomValidity('');
+   }
+ }
+</script>

+
+  

+
+  

+
+  
The validity
+  attribute must return a ValidityState object that
+  represents the validity states of the element. This
+  object is live, and the same object must be returned
+  each time the element's validity attribute is retrieved.

+
+
interface ValidityState {
+  readonly attribute boolean valueMissing;
+  readonly attribute boolean typeMismatch;
+  readonly attribute boolean patternMismatch;
+  readonly attribute boolean tooLong;
+  readonly attribute boolean rangeUnderflow;
+  readonly attribute boolean rangeOverflow;
+  readonly attribute boolean stepMismatch;
+  readonly attribute boolean customError;
+  readonly attribute boolean valid;
+};

+
+  
A ValidityState object has the following
+  attributes. On getting, they must return true if the corresponding
+  condition given in the following list is true, and false
+  otherwise.

+
+  
valueMissing

+   
 
The control is suffering from being missing.
 

+
+   
typeMismatch

+   
 
The control is suffering from a type mismatch.
 

+
+   
patternMismatch

+   
 
The control is suffering from a pattern mismatch.
 

+
+   
tooLong

+   
 
The control is suffering from being too long.
 

+
+   
rangeUnderflow

+   
 
The control is suffering from an underflow.
 

+
+   
rangeOverflow

+   
 
The control is suffering from an overflow.
 

+
+   
stepMismatch

+   
 
The control is suffering from a step mismatch.
 

+
+   
customError

+   
 
The control is suffering from a custom error.
 

+
+   
valid

+   
 
None of the other conditions are true.
 

+
+  
When the checkValidity()
+  method is invoked, if the element is a candidate for
+  constraint validation and does not satisfy its constraints, the user
+  agent must fire a simple event named invalid that is cancelable (but in this
+  case has no default action) at the element and return
+  false. Otherwise, it must only return true without doing anything
+  else.

+
+  
The validationMessage
+  attribute must return the empty string if the element is not a
+  candidate for constraint validation or if it is one but
+  it satisfies its constraints;
+  otherwise, it must return a suitably localized message that the user
+  agent would show the user if this were the only form control with a
+  validity constraint problem. If the user agent would not actually
+  show a textual message in such a situation (e.g. it would show a
+  graphical cue instead), then the attribute must return a suitably
+  localized message that expresses (one or more of) the validity
+  constraint(s) that the control does not satisfy. If the element is a
+  candidate for constraint validation and is
+  suffering from a custom error, then the custom
+  validity error message should be present in the return
+  value.

+
+  

+
+
+  
4.10.20.4 Security

+
+  
Servers should not rely on client-side
+  validation. Client-side validation can be intentionally bypassed by
+  hostile users, and unintentionally bypassed by users of older user
+  agents or automated tools that do not implement these features. The
+  constraint validation features are only intended to improve the user
+  experience, not to provide any kind of security mechanism.

+
+
+
+
+  
4.10.21 Form submission

+
+  

+
+  
4.10.21.1 Introduction

+
+  

+
+  
This section is non-normative.

+
+  
When forms are submitted, the data in the form is converted into
+  the form specified by the enctype, and then sent to the
+  destination specified by the action using the given method.

+
+  
For example, take the following form:

+
+  
<form action="/find.cgi" method=get>
+ <input type=text name=t>
+ <input type=search name=q>
+ <input type=submit>
+</form>

+
+  
If the user types in "cats" in the first field and "fur" in the
+  second, and then hits the submit button, then the user agent will
+  load /find.cgi?t=cats&q=fur.

+
+  
On the other hand, consider this form:

+
+  
<form action="/find.cgi" method=post enctype="multipart/form-data">
+ <input type=text name=t>
+ <input type=search name=q>
+ <input type=submit>
+</form>

+
+  
Given the same user input, the result on submission is quite
+  different: the user agent instead does an HTTP POST to the given
+  URL, with as the entity body something like the following text:

+
+  
------kYFrd4jNJEgCervE
+Content-Disposition: form-data; name="t"
+
+cats
+------kYFrd4jNJEgCervE
+Content-Disposition: form-data; name="q"
+
+fur
+------kYFrd4jNJEgCervE--

+
+
+
+  

+
+  
4.10.21.2 Implicit submission

+
+  
User agents may establish a button in each form as being the
+  form's default button. This should be the first submit button in tree
+  order whose form owner is that form
+  element, but user agents may pick another button if another would be
+  more appropriate for the platform. If the platform supports letting
+  the user submit a form implicitly (for example, on some platforms
+  hitting the "enter" key while a text field is focused implicitly
+  submits the form), then doing so must cause the form's default
+  button's activation behavior, if any, to be
+  run.

+
+  
Consequently, if the default button is
+  disabled, the form is not
+  submitted when such an implicit submission mechanism is used. (A
+  button has no activation behavior when disabled.)

+
+  
If the form has no submit
+  button, then the implicit submission mechanism must just
+  submit the
+  form element from the form element
+  itself.

+
+  

+
+
+  

+
+  
4.10.21.3 Form submission algorithm

+
+  
When a form form is submitted from an element submitter (typically a button), optionally with a
+  scripted-submit flag set, the user agent must
+  run the following steps:

+
+  
  1. If form is in
+   a Document that has no associated browsing
+   context or whose browsing context had its
+   sandboxed forms browsing context flag set when the
+   Document was created, then abort these steps without
+   doing anything.
    2. 
+
+   
  2. If form is already being submitted
+   (i.e. the form was submitted again while processing
+   the events fired from the next two steps, probably from a script
+   redundantly calling the submit() method on form), then abort these steps. This doesn't affect
+   the earlier instance of this algorithm.
    3. 
+
+   
+
+   
  3. If the scripted-submit flag is not set,
+   and the submitter element's no-validate state is false,
+   then interactively validate the constraints of form and examine the result: if the result is
+   negative (the constraint validation concluded that there were
+   invalid fields and probably informed the user of this) then abort
+   these steps.
    4. 
+
+   
  4. If the scripted-submit flag is not set,
+   then fire a simple event that is cancelable named
+   submit, at form. If the event's default action is prevented
+   (i.e. if the event is canceled) then abort these steps. Otherwise,
+   continue (effectively the default action is to perform the
+   submission).
    5. 
+
+   
+
+   
+
+   
  5. Let controls be a list of all the submittable elements whose
+   form owner is form, in tree
+   order.
    6. 
+
+   
  6. Let the form data set be a list of
+   name-value-type tuples, initially empty.
    7. 
+
+   
  7. 
+
+    
    Constructing the form data set. For each
+    element field in controls,
+    in tree order, run the following substeps:
    
+
+    
    1. 
+
+      
      If any of the following conditions are met, then skip these
+      substeps for this element:
      
+
+      
      • The field element has a
+       datalist element ancestor.
        • 
+
+       
      • The field element is disabled.
        • 
+
+       
      • The field element is a button but it is not submitter.
        • 
+
+       
      • The field element is an
+       input element whose type attribute is in the Checkbox state and
+       whose checkedness is
+       false.
        • 
+
+       
      • The field element is an
+       input element whose type attribute is in the Radio Button state and
+       whose checkedness is
+       false.
        • 
+
+       
      • The field element is not an
+       input element whose type attribute is in the Image Button state, and
+       either the field element does not have a
+       name attribute specified, or
+       its name attribute's value is
+       the empty string.
        • 
+
+       
      • The field element is an
+       object element that is not using a
+       plugin.
        • 
+
+      
      Otherwise, process field as follows:
      
+
+     
      2. 
+
+     
    2. Let type be the value of the type IDL attribute of field.
      3.  
+
+     
    3. 
+
+      
      If the field element is an
+      input element whose type attribute is in the Image Button state,
+      then run these further nested substeps:
      
+
+      
      1. If the field element has an name attribute specified and value
+       is not the empty string, let name be that
+       value followed by a single U+002E FULL STOP character
+       (.). Otherwise, let name be the empty
+       string.
        2. 
+
+       
      2. Let namex be the
+       string consisting of the concatenation of name and a single U+0078 LATIN SMALL LETTER X
+       character (x).
        3. 
+
+       
      3. Let namey be the
+       string consisting of the concatenation of name and a single U+0079 LATIN SMALL LETTER Y
+       character (y).
        4. 
+
+       
      4. The field element is submitter, and before this algorithm was invoked
+       the user indicated a
+       coordinate. Let x be the x-component of the coordinate selected by the
+       user, and let y be the y-component of the coordinate selected by the
+       user.
        5. 
+
+       
      5. Append an entry in the form data set
+       with the name namex,
+       the value x, and the type type.
        6. 
+
+       
      6. Append an entry in the form data set
+       with the name namey and
+       the value y, and the type type.
        7. 
+
+       
      7. Skip the remaining substeps for this element: if there
+       are any more elements in controls, return
+       to the top of the constructing the form data
+       set step, otherwise, jump to the next step in the overall
+       form submission algorithm.
        8. 
+
+      
      4. 
+
+     
    4. Let name be the value of the field element's name attribute.
      5. 
+
+     
    5. If the field element is a
+     select element, then for each option
+     element in the select element whose selectedness is true,
+     append an entry in the form data set with the
+     name as the name, the value of the
+     option element as the value, and type as the type.
      6. 
+
+     
    6. 
+
+      
      Otherwise, if the field element is an
+      input element whose type attribute is in the Checkbox state or the
+      Radio Button state,
+      then run these further nested substeps:
      
+
+      
      1. If the field element has a value attribute specified, then
+       let value be the value of that attribute;
+       otherwise, let value be the string
+       "on".
        2. 
+
+       
      2. Append an entry in the form data set
+       with name as the name, value as the value, and type
+       as the type.
        3. 
+
+      
      7. 
+
+     
    7. Otherwise, if the field element is an
+     input element whose type attribute is in the File Upload state, then for
+     each file selected in the
+     input element, append an entry in the form data set with the name as
+     the name, the file (consisting of the name, the type, and the
+     body) as the value, and type as the type. If
+     there are no selected files,
+     then append an entry in the form data set
+     with the name as the name, the empty string
+     as the value, and application/octet-stream
+     as the type.
      8. 
+     
+
+     
    8. Otherwise, if the field element is an
+     object element: try to obtain a form submission
+     value from the plugin,
+     and if that is successful, append an entry in the form data set with name as the
+     name, the returned form submission value as the value, and the
+     string "object" as the type.
      9. 
+
+     
    9. Otherwise, append an entry in the form data
+     set with name as the name, the value of the field element as the value, and type as the type.
      10. 
+
+    
    8. 
+
+   
  8. Let action be the submitter element's action.
    9. 
+
+   
  9. 
+
+    
    If action is the empty string, let action be the document's address.
    
+
+    
    This step is a willful violation of
+    RFC 3986, which would require base URL processing here. This
+    violation is motivated by a desire for compatibility with legacy
+    content. [RFC3986]
    
+
+    
+
+   
    10. 
+
+   
  10. Resolve the
+   URL action, relative to the submitter element. If this fails, abort these
+   steps. Otherwise, let action be the resulting
+   absolute URL.
    11. 
+
+   
  11. Let scheme be the <scheme> of the resulting
+   absolute URL.
    12. 
+
+   
  12. Let enctype be the submitter element's enctype.
    13. 
+
+   
  13. Let method be the submitter element's method.
    14. 
+
+   
  14. Let target be the submitter element's target.
    15. 
+
+   
  15. 
+
+    
    Select the appropriate row in the table below based on the
+    value of scheme as given by the first cell of
+    each row. Then, select the appropriate cell on that row based on
+    the value of method as given in the first cell
+    of each column. Then, jump to the steps named in that cell and
+    defined below the table.
    
+
+    
    
+       GET
+       POST
+       PUT
+       DELETE
+     
     http
+       Mutate action
+       Submit as entity body
+       Submit as entity body
+       Delete action
+     
     https
+       Mutate action
+       Submit as entity body
+       Submit as entity body
+       Delete action
+     
     ftp
+       Get action
+       Get action
+       Get action
+       Get action
+     
     javascript
+       Get action
+       Get action
+       Get action
+       Get action
+     
     data
+       Get action
+       Post to data:
+       Put to data:
+       Get action
+     
     mailto
+       Mail with headers
+       Mail as body
+       Mail with headers
+       Mail with headers
+    
    If scheme is not one of those listed in
+    this table, then the behavior is not defined by this
+    specification. User agents should, in the absence of another
+    specification defining this, act in a manner analogous to that
+    defined in this specification for similar schemes.
    
+
+    
    The behaviors are as follows:
    
+
+    
    Mutate action
+     
    
+
+      
    Let query be the result of encoding the
+      form data set using the application/x-www-form-urlencoded encoding
+      algorithm, interpreted as a US-ASCII string.
    
+
+      
+
+      
    Let destination be a new URL
+      that is equal to the action except that its
+      <query> component is
+      replaced by query (adding a U+003F QUESTION
+      MARK character (?) if appropriate).
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to destination. If target browsing context was newly created for
+      this purpose by the steps above, then it must be navigated with
+      replacement enabled.
    
+
+     
    
+
+     
    Submit as entity body
+     
    
+
+      
    Let entity body be the result of encoding
+      the form data set using the
+      appropriate form encoding algorithm.
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Let MIME type be determined as
+      follows:
    
+
+      
    If enctype is application/x-www-form-urlencoded
    
+
+       
    Let MIME type be "application/x-www-form-urlencoded".
    
+
+       
    If enctype is multipart/form-data
    
+
+       
    Let MIME type be "multipart/form-data".
    
+
+       
    If enctype is text/plain
    
+
+       
    Let MIME type be "text/plain".
    
+
+      
    If method is anything but GET or POST,
+      and the origin of action is not
+      the same origin as that of the form
+      element's Document, then abort these steps.
    
+      
+
+      
    Otherwise, navigate target
+      browsing context to action using the
+      HTTP method given by method and with entity body as the entity body, of type MIME type. If target browsing
+      context was newly created for this purpose by the steps
+      above, then it must be navigated with replacement
+      enabled.
    
+
+     
    
+
+     
    Delete action
+     
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    If the origin of action is
+      not the same origin as that of the
+      form element's Document, then abort
+      these steps.
     
+
+      
    Otherwise, navigate target
+      browsing context to action using the
+      DELETE method. If target browsing context
+      was newly created for this purpose by the steps above, then it
+      must be navigated with replacement enabled.
    
+
+     
    
+
+     
    Get action
+     
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to action. If target browsing context was newly created for
+      this purpose by the steps above, then it must be navigated with
+      replacement enabled.
    
+
+     
    
+
+     
    Post to data:
+     
    
+
+      
    Let data be the result of encoding the
+      form data set using the appropriate
+      form encoding algorithm.
    
+
+      
    If action contains the string "%%%%" (four U+0025 PERCENT SIGN characters),
+      then %-escape all bytes in data that, if
+      interpreted as US-ASCII, do not match the unreserved production in the URI Generic Syntax,
+      and then, treating the result as a US-ASCII string, further
+      %-escape all the U+0025 PERCENT SIGN characters in the resulting
+      string and replace the first occurrence of "%%%%" in action with the
+      resulting double-escaped string. [RFC3986]
    
+
+      
    Otherwise, if action contains the string
+      "%%" (two U+0025 PERCENT SIGN characters
+      in a row, but not four), then %-escape all characters in data that, if interpreted as US-ASCII, do not
+      match the unreserved production in the URI
+      Generic Syntax, and then, treating the result as a US-ASCII
+      string, replace the first occurrence of "%%" in action with the
+      resulting escaped string. [RFC3986]
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to the potentially modified action. If target browsing
+      context was newly created for this purpose by the steps
+      above, then it must be navigated with replacement
+      enabled.
    
+
+     
    
+
+     
    Put to data:
+     
    
+
+      
    Let data be the result of encoding the
+      form data set using the appropriate
+      form encoding algorithm.
    
+
+      
    Let MIME type be determined as
+      follows:
    
+
+      
    If enctype is application/x-www-form-urlencoded
    
+
+       
    Let MIME type be "application/x-www-form-urlencoded".
    
+
+       
    If enctype is multipart/form-data
    
+
+       
    Let MIME type be "multipart/form-data".
    
+
+       
    If enctype is text/plain
    
+
+       
    Let MIME type be "text/plain".
    
+
+      
    Let destination be the result of
+      concatenating the following:
    
+
+      
    1. The string "data:".
      2. 
+
+       
    2. The value of MIME type.
      3. 
+
+       
    3. The string ";base64,".
      4. 
+
+       
    4. A base-64 encoded representation of data. [RFC2045]
      5. 
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to destination. If target browsing context was newly created for
+      this purpose by the steps above, then it must be navigated with
+      replacement enabled.
    
+
+     
    
+
+     
    Mail with headers
+     
    
+
+      
    Let headers be the resulting encoding the
+      form data set using the application/x-www-form-urlencoded encoding
+      algorithm, interpreted as a US-ASCII string.
    
+
+      
    Replace occurrences of U+002B PLUS SIGN characters (+) in
+      headers with the string "%20".
    
+
+      
    Let destination consist of all the
+      characters from the first character in action to the character immediately before the
+      first U+003F QUESTION MARK character (?), if any, or the end of
+      the string if there are none.
    
+
+      
    Append a single U+003F QUESTION MARK character (?) to destination.
    
+
+      
    Append headers to destination.
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to destination. If target browsing context was newly created for
+      this purpose by the steps above, then it must be navigated with
+      replacement enabled.
    
+
+     
    
+
+     
    Mail as body
+     
    
+
+      
    Let body be the resulting encoding the
+      form data set using the appropriate
+      form encoding algorithm and then %-escaping all the bytes
+      in the resulting byte string that, when interpreted as US-ASCII,
+      do not match the unreserved production in
+      the URI Generic Syntax. [RFC3986]
    
+
+      
    Let destination have the same value as
+      action.
    
+
+      
    If destination does not contain a U+003F
+      QUESTION MARK character (?), append a single U+003F QUESTION
+      MARK character (?) to destination. Otherwise, append a single U+0026
+      AMPERSAND character (&).
    
+
+      
    Append the string "body=" to destination.
    
+
+      
    Append body, interpreted as a US-ASCII
+      string, to destination.
    
+
+      
    Let target browsing context be the
+      form submission target browsing context.
    
+
+      
    Navigate target browsing
+      context to destination. If target browsing context was newly created for
+      this purpose by the steps above, then it must be navigated with
+      replacement enabled.
    
+
+     
    
+
+    
    The form submission target browsing context is
+    obtained, when needed by the behaviors described above, as
+    follows: If the user indicated a specific browsing
+    context to use when submitting the form, then that is the
+    target browsing context. Otherwise, apply the rules for
+    choosing a browsing context given a browsing context name
+    using target as the name and the
+    browsing context of form as the
+    context in which the algorithm is executed; the resulting
+    browsing context is the target browsing context.
    
+
+    
    The appropriate form encoding algorithm is
+    determined as follows:
    
+
+    
    If enctype is application/x-www-form-urlencoded
    
+
+     
    Use the application/x-www-form-urlencoded encoding
+     algorithm.
    
+
+     
    If enctype is multipart/form-data
    
+
+     
    Use the multipart/form-data encoding
+     algorithm.
    
+
+     
    If enctype is text/plain
    
+
+     
    Use the text/plain encoding
+     algorithm.
    
+
+    
    16. 
+
+  

+
+
+  

+
+  
4.10.21.4 URL-encoded form data

+
+  
The application/x-www-form-urlencoded encoding
+  algorithm is as follows:

+
+  
  1. Let result be the empty string.
    2. 
+
+   
  2. 
+
+    
    If the form element has an accept-charset attribute,
+    then, taking into account the characters found in the form data set's names and values, and the character
+    encodings supported by the user agent, select a character encoding
+    from the list given in the form's accept-charset attribute
+    that is an ASCII-compatible character encoding. If
+    none of the encodings are supported, then let the selected
+    character encoding be UTF-8.
    
+
+    
    Otherwise, if the document's character encoding is
+    an ASCII-compatible character encoding, then that is
+    the selected character encoding.
    
+
+    
    Otherwise, let the selected character encoding be UTF-8.
    
+
+   
    3. 
+
+   
  3. Let charset be the preferred MIME
+   name of the selected character encoding.
    4. 
+
+   
  4. 
+
+    
    For each entry in the form data set,
+    perform these substeps:
    
+
+    
    1. If the entry's name is "_charset_"
+     and its type is "hidden", replace its value
+     with charset.
      2. 
+
+     
    2. If the entry's type is "file",
+     replace its value with the file's filename only.
      3. 
+
+     
    3. For each character in the entry's name and value that
+     cannot be expressed using the selected character encoding,
+     replace the character by a string consisting of a U+0026
+     AMPERSAND character (&), a U+0023 NUMBER SIGN character (#),
+     one or more characters in the range U+0030 DIGIT ZERO (0) to
+     U+0039 DIGIT NINE (9) representing the Unicode code point of the
+     character in base ten, and finally a U+003B SEMICOLON character
+     (;).
      4. 
+
+     
    4. 
+
+      
      For each character in the entry's name and value, apply the
+      appropriate subsubsteps from the following list:
      
+
+      
      The character is a U+0020 SPACE character
      
+
+       
      Replace the character with a single U+002B PLUS SIGN
+       character (+).
      
+
+
+       
+
+       
      If the character isn't in the range U+0020, U+002A,
+       U+002D, U+002E, U+0030 to U+0039, U+0041 to U+005A, U+005F,
+       U+0061 to U+007A
      
+
+       
      
+
+        
      Replace the character with a string formed as follows:
      
+
+        
      1. Let s be an empty string.
        2. 
+
+         
      2. 
+
+          
        For each byte b of the character when
+          expressed in the selected character encoding in turn, run
+          the appropriate subsubsubstep from the list below:
        
+
+          
        If the byte is in the range 0x20, 0x2A, 0x2D, 0x2E,
+           0x30 to 0x39, 0x41 to 0x5A, 0x5F, 0x61 to 0x7A
        
+
+           
        Append to s the Unicode
+           character with the codepoint equal to the byte.
        
+
+           
        Otherwise
        
+
+           
        Append to the string a U+0025 PERCENT SIGN character
+           (%) followed by two characters in the ranges U+0030 DIGIT
+           ZERO (0) to U+0039 DIGIT NINE (9) and U+0041 LATIN CAPITAL
+           LETTER A to U+0046 LATIN CAPITAL LETTER F representing the
+           hexadecimal value of the byte (zero-padded if
+           necessary).
        
+
+          
        3. 
+
+        
      
+
+       
      Otherwise
      
+
+       
      Leave the character as is.
      
+
+      
      5. 
+
+     
    5. If the entry's name is "isindex",
+     its type is "text", and this is the first
+     entry in the form data set, then append the
+     value to result and skip the rest of the
+     substeps for this entry, moving on to the next entry, if any, or
+     the next step in the overall algorithm otherwise.
      6. 
+
+     
    6. If this is not the first entry, append a single U+0026
+     AMPERSAND character (&) to result.
      7. 
+
+     
    7. Append the entry's name to result.
      8. 
+
+     
    8. Append a single U+003D EQUALS SIGN character (=) to result.
      9. 
+
+     
    9. Append the entry's value to result.
      10. 
+
+    
    5. 
+
+   
  5. Encode result as US-ASCII and return the
+   resulting byte stream.
    6. 
+
+  

+
+
+
+  

+
+  
4.10.21.5 Multipart form data

+
+  
The multipart/form-data encoding
+  algorithm is to encode the form data set
+  using the rules described by RFC2388, Returning Values from
+  Forms: multipart/form-data, and return
+  the resulting byte stream. [RFC2388]

+
+  
Each entry in the form data set is a
+  field, the name of the entry is the field name and the
+  value of the entry is the field value, unless the entry's
+  name is "_charset_" and its type is "hidden", in which case the field value is the
+  character encoding used by the aforementioned algorithm to encode
+  the value of the field.

+
+  
The order of parts must be the same as the order of fields in the
+  form data set. Multiple entries with the same
+  name must be treated as distinct fields.

+
+  

+
+
+
+  

+
+  
4.10.21.6 Plain text form data

+
+  
The text/plain encoding
+  algorithm is as follows:

+
+  
  1. Let result be the empty string.
    2. 
+
+   
  2. 
+
+    
+
+    
    If the form element has an accept-charset attribute,
+    then, taking into account the characters found in the form data set's names and values, and the character
+    encodings supported by the user agent, select a character encoding
+    from the list given in the form's accept-charset
+    attribute. If none of the encodings are supported, then let the
+    selected character encoding be UTF-8.
    
+
+    
    Otherwise, the selected character encoding is the
+    document's character encoding.
    
+
+   
    3. 
+
+   
  3. Let charset be the preferred MIME
+   name of the selected character encoding.
    4. 
+
+   
  4. If the entry's name is "_charset_" and
+   its type is "hidden", replace its value with
+   charset.
    5. 
+
+   
  5. If the entry's type is "file", replace
+   its value with the file's filename only.
    6. 
+
+   
  6. 
+
+    
    For each entry in the form data set,
+    perform these substeps:
    
+
+    
    1. Append the entry's name to result.
      2. 
+
+     
    2. Append a single U+003D EQUALS SIGN character (=) to result.
      3. 
+
+     
    3. Append the entry's value to result.
      4. 
+
+     
    4. Append a U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF)
+     character pair to result.
      5. 
+
+    
    7. 
+
+   
  7. Encode result using the selected
+   character encoding and return the resulting byte stream.
    8. 
+
+  

+
+
+
+  

+
+  
4.10.22 Resetting a form

+
+  
When a form form is reset, the user agent must
+  fire a simple event named reset, that is cancelable, at form, and then, if that event is not canceled, must
+  invoke the reset
+  algorithm of each resettable elements whose form
+  owner is form, and broadcast formchange events from form.

+
+  
Each resettable element
+  defines its own reset
+  algorithm. Changes made to form controls as part of these
+  algorithms do not count as changes caused by the user (and thus,
+  e.g., do not cause input events to
+  fire).

+
+  

+
+
+
+  

+
+  
4.10.23 Event dispatch

+
+  
When the user agent is to broadcast forminput events or
+  broadcast formchange
+  events from a form element form, it must run the following steps:

+
+  
  1. Let controls be a list of all the resettable elements whose form
+   owner is form.
    2. 
+
+   
  2. If the user agent was to broadcast forminput events, let event name be forminput. Otherwise the user agent
+   was to broadcast formchange events; let event name be formchange.
    3. 
+
+   
  3. For each element in controls, in
+   tree order, fire a simple event named
+   event name at the element.
    4. 
+
+  

+
+
+  
4.11 Interactive elements

+
+  
4.11.1 The details element

+
+  
Categories

+   
Flow content.

+   
Sectioning root.

+   
Interactive content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
One summary element followed by flow content.

+   
Content attributes:

+   
Global attributes

+   
open

+   
DOM interface:

+   

+
interface HTMLDetailsElement : HTMLElement {
+           attribute boolean open;
+};

+   

+  
The details element represents a
+  disclosure widget from which the user can obtain additional
+  information or controls.

+
+  
The details element is not appropriate
+  for footnotes. Please see the section on
+  footnotes for details on how to mark up footnotes.

+
+  
The first summary element
+  child of the element, if any, represents the summary or
+  legend of the details. If there is no child
+  summary element, the user agent should provide its own
+  legend (e.g. "Details").

+
+  
The open
+  content attribute is a boolean attribute. If present,
+  it indicates that the details are to be shown to the user. If the
+  attribute is absent, the details are not to be shown.

+
+  

+
+  
If the attribute is removed, then the details should be
+  hidden. If the attribute is added, the details should be shown.

+
+  
The user agent should allow the user to request that the details
+  be shown or hidden. To honor a request for the details to be shown,
+  the user agent must set the open attribute on the element to
+  the value open. To honor a request for the
+  details to be hidden, the user agent must remove the open attribute from the
+  element.

+
+  
The open
+  attribute must reflect the open content attribute.

+
+  

+
+  

+
+   
The following example shows the details element
+   being used to hide technical details in a progress report.

+
+   
<section class="progress window">
+ <h1>Copying "Really Achieving Your Childhood Dreams"</h1>
+ <details>
+  <summary>Copying... <progress max="375505392" value="97543282"></progress> 25%</summary>
+  <dl>
+   <dt>Transfer rate:</dt> <dd>452KB/s</dd>
+   <dt>Local filename:</dt> <dd>/home/rpausch/raycd.m4v</dd>
+   <dt>Remote filename:</dt> <dd>/var/www/lectures/raycd.m4v</dd>
+   <dt>Duration:</dt> <dd>01:16:27</dd>
+   <dt>Color profile:</dt> <dd>SD (6-1-6)</dd>
+   <dt>Dimensions:</dt> <dd>320×240</dd>
+  </dl>
+ </details>
+</section>

+
+  

+
+  

+
+   
The following shows how a details element can be
+   used to hide some controls by default:

+
+   
<details>
+ <summary>Name & Extension:</summary>
+ <p><input type=text name=fn value="Pillar Magazine.pdf">
+ <p><label><input type=checkbox name=ext checked> Hide extension</label>
+</details>

+
+   
One could use this in conjuction with other details
+   in a list to allow the user to collapse a set of fields down to a
+   small set of headings, with the ability to open each one.

+
+   

+
+   
In these examples, the summary really just summarises what the
+   controls can change, and not the actual values, which is less than
+   ideal.

+
+  

+
+
+  
4.11.2 The summary element

+
+  
Categories

+   
None.

+   
Contexts in which this element may be used:

+   
As the first child of a details element.

+   
Content model:

+   
Phrasing content.

+   
Content attributes:

+   
Global attributes

+   
DOM interface:

+   
Uses HTMLElement.

+  
The summary element represents a
+  summary, caption, or legend for the rest of the contents of the
+  summary element's parent details
+  element, if any.

+
+
+
+
+
+  
4.11.3 The command element

+
+  
Categories

+   
Metadata content.

+   
Flow content.

+   
Phrasing content.

+   
Contexts in which this element may be used:

+   
Where metadata content is expected.

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
type

+   
label

+   
icon

+   
disabled

+   
checked

+   
radiogroup

+   
+   
Also, the title attribute has special semantics on this element.

+   
DOM interface:

+   

+
interface HTMLCommandElement : HTMLElement {
+           attribute DOMString type;
+           attribute DOMString label;
+           attribute DOMString icon;
+           attribute boolean disabled;
+           attribute boolean checked;
+           attribute DOMString radiogroup;
+};

+   

+  
The command element represents a command that the user
+  can invoke.

+
+  
The type
+  attribute indicates the kind of command: either a normal command
+  with an associated action, or a state or option that can be toggled,
+  or a selection of one item from a list of items.

+
+  
The attribute is an enumerated attribute with three
+  keywords and states. The "command"
+  keyword maps to the Command state, the
+  "checkbox"
+  keyword maps to the Checkbox state, and
+  the "radio"
+  keyword maps to the Radio state. The
+  missing value default is the Command state.

+
+  
The Command state

+
+   
The element represents a normal command with an associated action.

+
+   
The Checkbox state

+
+   
The element represents a state or option that can be toggled.

+
+   
The Radio state

+
+   
The element represents a selection of one item from a list of items.

+
+  
The label
+  attribute gives the name of the command, as shown to the user. The
+  label attribute must be
+  specified and must have a value that is not the empty string.

+
+  
The title
+  attribute gives a hint describing the command, which might be shown
+  to the user to help him.

+
+  
The icon
+  attribute gives a picture that represents the command. If the
+  attribute is specified, the attribute's value must contain a
+  valid non-empty URL potentially surrounded by
+  spaces. To obtain the absolute
+  URL of the icon when the attribute's value is not the empty
+  string, the attribute's value must be resolved relative to the element. When the attribute is
+  absent, or its value is the empty string, or resolving its value fails, there is no icon.

+  
+
+  
The disabled attribute
+  is a boolean attribute that, if present, indicates that
+  the command is not available in the current state.

+
+  
The distinction between disabled and hidden is subtle. A command would be
+  disabled if, in the same context, it could be enabled if only
+  certain aspects of the situation were changed. A command would be
+  marked as hidden if, in that situation, the command will never be
+  enabled. For example, in the context menu for a water faucet, the
+  command "open" might be disabled if the faucet is already open, but
+  the command "eat" would be marked hidden since the faucet could
+  never be eaten.

+
+  
The checked
+  attribute is a boolean attribute that, if present,
+  indicates that the command is selected. The attribute must be
+  omitted unless the type
+  attribute is in either the Checkbox state or
+  the Radio
+  state.

+
+  
The radiogroup
+  attribute gives the name of the group of commands that will be
+  toggled when the command itself is toggled, for commands whose type attribute has the value "radio". The scope of the name is the child list of
+  the parent element. The attribute must be omitted unless the type attribute is in the Radio state.

+
+
+
+  

+
+  
The type, label, icon, disabled, checked, and radiogroup
+  IDL attributes must reflect the respective content
+  attributes of the same name.

+
+  
The element's activation behavior depends on the
+  value of the type attribute
+  of the element, as follows:

+
+  
If the type attribute is
+   in the Checkbox state

+
+   
If the element has a checked attribute, the UA must
+   remove that attribute. Otherwise, the UA must add a checked attribute, with the
+   literal value checked. The UA must then
+   fire a click event at the
+   element.

+
+
+   
If the type attribute is
+   in the Radio state

+
+   
If the element has a parent, then the UA must walk the list
+   of child nodes of that parent element, and for each node that is a
+   command element, if that element has a radiogroup attribute whose
+   value exactly matches the current element's (treating missing radiogroup attributes as if
+   they were the empty string), and has a checked attribute, must remove
+   that attribute.

+
+   
Then, the element's checked attribute attribute
+   must be set to the literal value checked and
+   the user agent must fire a click
+   event at the element.

+
+
+   
Otherwise

+
+   
The element has no activation behavior.

+
+  
Firing a synthetic click event at the element does not cause
+  any of the actions described above to happen.

+
+  
+
+  

+
+  
command elements are not rendered
+  unless they form part of a menu.

+
+  

+
+   
Here is an example of a toolbar with three buttons that let the
+   user toggle between left, center, and right alignment. One could
+   imagine such a toolbar as part of a text editor. The toolbar also
+   has a separator followed by another button labeled "Publish",
+   though that button is disabled.

+
+   
<menu type="toolbar">
+ <command type="radio" radiogroup="alignment" checked="checked"
+          label="Left" icon="icons/alL.png" onclick="setAlign('left')">
+ <command type="radio" radiogroup="alignment"
+          label="Center" icon="icons/alC.png" onclick="setAlign('center')">
+ <command type="radio" radiogroup="alignment"
+          label="Right" icon="icons/alR.png" onclick="setAlign('right')">
+ <hr>
+ <command type="command" disabled
+          label="Publish" icon="icons/pub.png" onclick="publish()">
+</menu>

+
+  

+
+
+
+  
+
+  
Categories

+   
Flow content.

+   
If the element's type attribute is in the toolbar state: Interactive content.

+   
Contexts in which this element may be used:

+   
Where flow content is expected.

+   
Content model:

+   
Either: Zero or more li elements.

+   
Or: Flow content.

+   
Content attributes:

+   
Global attributes

+   
type

+   
label

+   
DOM interface:

+   

+
interface HTMLMenuElement : HTMLElement {
+           attribute DOMString type;
+           attribute DOMString label;
+};

+  
The menu element represents a list of commands.

+
+  
+
+  
The type attribute
+  is an enumerated attribute indicating the kind of menu
+  being declared. The attribute has three states. The context keyword maps to the
+  context menu state, in which
+  the element is declaring a context menu. The toolbar keyword maps to the
+  toolbar state, in which the
+  element is declaring a toolbar. The attribute may also be
+  omitted. The missing value default is the list state, which indicates that the element is merely
+  a list of commands that is neither declaring a context menu nor
+  defining a toolbar.

+
+  
If a menu element's type attribute is in the context menu state, then the
+  element represents the commands of a context menu, and
+  the user can only interact with the commands if that context menu is
+  activated.

+
+  
If a menu element's type attribute is in the toolbar state, then the element
+  represents a list of active commands that the user can
+  immediately interact with.

+
+  
If a menu element's type attribute is in the list state, then the element either
+  represents an unordered list of items (each represented
+  by an li element), each of which represents a command
+  that the user can perform or activate, or, if the element has no
+  li element children, flow content
+  describing available commands.

+
+  
The label
+  attribute gives the label of the menu. It is used by user agents to
+  display nested menus in the UI. For example, a context menu
+  containing another menu would use the nested menu's label attribute for the submenu's
+  menu label.

+
+  

+
+  
The type and label IDL attributes must
+  reflect the respective content attributes of the same
+  name.

+
+  

+
+
+
+  
+
+  
This section is non-normative.

+
+  
The menu element is used to define context menus and
+  toolbars.

+
+  
For example, the following represents a toolbar with three menu
+  buttons on it, each of which has a dropdown menu with a series of
+  options:

+
+  
<menu type="toolbar">
+ <li>
+  <menu label="File">
+   <button type="button" onclick="fnew()">New...</button>
+   <button type="button" onclick="fopen()">Open...</button>
+   <button type="button" onclick="fsave()">Save</button>
+   <button type="button" onclick="fsaveas()">Save as...</button>
+  </menu>
+ </li>
+ <li>
+  <menu label="Edit">
+   <button type="button" onclick="ecopy()">Copy</button>
+   <button type="button" onclick="ecut()">Cut</button>
+   <button type="button" onclick="epaste()">Paste</button>
+  </menu>
+ </li>
+ <li>
+  <menu label="Help">
+   <li><a href="help.html">Help</a></li>
+   <li><a href="about.html">About</a></li>
+  </menu>
+ </li>
+</menu>

+
+  
In a supporting user agent, this might look like this:

+
+  
A toolbar with three buttons, labeled 'File', 'Edit', and 'Help'; where if you select the 'Edit' button you get a drop-down menu with three more options, 'Copy', 'Cut', and 'Paste'.

+
+  
In a legacy user agent, the above would look like a bulleted list
+  with three items, the first of which has four buttons, the second of
+  which has three, and the third of which has two nested bullet points
+  with two items consisting of links.

+
+  
The following implements a similar toolbar, with a single button
+  whose values, when selected, redirect the user to Web sites.

+
+  
<form action="redirect.cgi">
+ <menu type="toolbar">
+  <label for="goto">Go to...</label>
+  <menu label="Go">
+   <select id="goto">
+    <option value="" selected="selected"> Select site: </option>
+    <option value="http://www.apple.com/"> Apple </option>
+    <option value="http://www.mozilla.org/"> Mozilla </option>
+    <option value="http://www.opera.com/"> Opera </option>
+   </select>
+   <span><input type="submit" value="Go"></span>
+  </menu>
+ </menu>
+</form>

+
+  
The behavior in supporting user agents is similar to the example
+  above, but here the legacy behavior consists of a single
+  select element with a submit button. The submit button
+  doesn't appear in the toolbar, because it is not a direct child of
+  the menu element or of its li
+  children.

+
+
+
+  

+
+  
4.11.4.2 Building menus and toolbars

+
+  
A menu (or toolbar) consists of a list of zero or more of the
+  following components:

+
+  
  • Commands, which can be marked as default commands
    • 
+   
  • Separators
    • 
+   
  • Other menus (which allows the list to be nested)
    • 
+  
The list corresponding to a particular menu element
+  is built by iterating over its child nodes. For each child node in
+  tree order, the required behavior depends on what the
+  node is, as follows:

+
+  
An element that defines a command

+
+   
Append the command to the menu, respecting its facets. 

+
+
+   
An hr element

+   
An option element that has a value attribute set to the empty
+   string, and has a disabled attribute, and whose
+   textContent consists of a string of one or more
+   hyphens (U+002D HYPHEN-MINUS)

+
+   
Append a separator to the menu.

+
+
+   
An li element

+   
A label element

+
+   
Iterate over the children of the element.

+
+
+   
A menu element with no label attribute

+   
A select element

+
+   
Append a separator to the menu, then iterate over the children
+   of the menu or select element, then
+   append another separator.

+
+   
+
+
+   
A menu element with a label attribute

+   
An optgroup element with a label attribute

+
+   
Append a submenu to the menu, using the value of the element's
+   label attribute as the label of the menu. The
+   submenu must be constructed by taking the element and creating a
+   new menu for it using the complete process described in this
+   section.

+
+
+   
Any other node

+
+   
Ignore the node.

+
+  
Once all the nodes have been processed as described above, the
+  user agent must the post-process the menu as follows:

+
+  
  1. Except for separators, any menu item with no label, or whose
+   label is the empty string, must be removed.
    2. 
+
+   
  2. Any sequence of two or more separators in a row must be
+   collapsed to a single separator.
    3. 
+
+   
  3. Any separator at the start or end of the menu must be
+   removed.
    4. 
+
+  

+
+
+
+
+  
4.11.4.3 Context menus

+
+  
The contextmenu
+  attribute gives the element's context
+  menu. The value must be the ID of a menu element
+  in the DOM. If the node that would be obtained by
+  the invoking the getElementById() method
+  using the attribute's value as the only argument is null or not a
+  menu element, then the element has no assigned context
+  menu. Otherwise, the element's assigned context menu is the element
+  so identified.

+
+  

+
+  
When an element's context menu is requested (e.g. by the user
+  right-clicking the element, or pressing a context menu key), the UA
+  must fire a simple event named contextmenu that bubbles and is
+  cancelable at the element for which the menu was requested.

+
+  
Typically, therefore, the firing of the contextmenu event will be the
+  default action of a mouseup or keyup event. The exact sequence of events
+  is UA-dependent, as it will vary based on platform conventions.

+
+  
The default action of the contextmenu event depends on
+  whether the element or one of its ancestors has a context menu
+  assigned (using the contextmenu attribute) or not. If
+  there is no context menu assigned, the default action must be for
+  the user agent to show its default context menu, if it has one.

+
+  
If the element or one of its ancestors does have a
+  context menu assigned, then the user agent must fire a simple
+  event named show at the
+  menu element of the context menu of the nearest
+  ancestor (including the element itself) with one assigned.

+  
+
+  
The default action of this event is that the user agent
+  must show a context menu built from the menu element.

+
+  
The user agent may also provide access to its default context
+  menu, if any, with the context menu shown. For example, it could
+  merge the menu items from the two menus together, or provide the
+  page's context menu as a submenu of the default menu.

+
+  
If the user dismisses the menu without making a selection,
+  nothing in particular happens.

+
+  
If the user selects a menu item that represents a command, then the UA must invoke
+  that command's Action.

+
+  
Context menus must not, while being shown, reflect changes in the
+  DOM; they are constructed as the default action of the show event and must remain as constructed
+  until dismissed.

+
+  
User agents may provide means for bypassing the context menu
+  processing model, ensuring that the user can always access the UA's
+  default context menus. For example, the user agent could handle
+  right-clicks that have the Shift key depressed in such a way that it
+  does not fire the contextmenu
+  event and instead always shows the default context menu.

+
+  
The contextMenu
+  attribute must reflect the contextmenu content attribute.

+
+  

+
+  

+
+   
Here is an example of a context menu for an input control:

+
+   
<form name="npc">
+ <label>Character name: <input name=char type=text contextmenu=namemenu required></label>
+ <menu type=context id=namemenu>
+  <command label="Pick random name" onclick="document.forms.npc.elements.char.value = getRandomName()">
+  <command label="Prefill other fields based on name" onclick="prefillFields(document.forms.npc.elements.char.value)">
+ </menu>
+</form>

+
+   
This adds to items to the control's context menu, one called
+   "Pick random name", and one called "Prefill other fields based on
+   name". They invoke scripts that are not shown in the example
+   above.

+
+  

+
+
+
+  

+
+  
4.11.4.4 Toolbars

+
+  
When a menu element has a type attribute in the toolbar state, then the user agent
+  must build the
+  menu for that menu element, and use the result in the
+  rendering.

+
+  
The user agent must reflect changes made to the
+  menu's DOM, by immediately rebuilding the menu.

+
+  

+
+
+
+  
4.11.5 Commands

+
+  
A command is the abstraction
+  behind menu items, buttons, and links.

+
+  
Commands are defined to have the following
+  facets:

+
+  
Type

+
+   
The kind of command: "command", meaning it is a normal command;
+   "radio", meaning that triggering the command will, amongst other
+   things, set the Checked
+   State to true (and probably uncheck some other commands); or
+   "checkbox", meaning that triggering the command will, amongst other
+   things, toggle the value of the Checked State.

+
+   
ID

+
+   
The name of the command, for referring to the command from the
+   markup or from script. If a command has no ID, it is an
+   anonymous command.

+
+   
Label

+
+   
The name of the command as seen by the user.

+
+   
Hint

+
+   
A helpful or descriptive string that can be shown to the
+   user.

+
+   
Icon

+
+   
An absolute URL identifying a graphical image that
+   represents the action. A command might not have an Icon.
 
+
+   
Access Key

+
+   
A key combination selected by the user agent that triggers the
+   command. A command might not have an Access Key.

+
+   
Hidden State

+
+   
Whether the command is hidden or not (basically, whether it
+   should be shown in menus).

+
+   
Disabled State

+
+   
Whether the command is relevant and can be triggered or not.

+
+   
Checked State

+
+   
Whether the command is checked or not.

+
+   
Action

+
+   
The actual effect that triggering the command will have. This
+   could be a scripted event handler, a URL to which to
+   navigate, or a form submission.

+
+
+
+  
These facets are exposed on elements using the command
+  API:

+
+  
element . commandType

+
+   

+
+    
Exposes the Type facet of the command.

+
+   

+
+   
element . id

+
+   

+
+    
Exposes the ID facet of the command.

+
+   

+
+   
element . label

+
+   

+
+    
Exposes the Label facet of the command.

+
+   

+
+   
element . title

+
+   

+
+    
Exposes the Hint facet of the command.

+
+   

+
+   
element . icon

+
+   

+
+    
Exposes the Icon facet of the command.

+
+   

+
+   
element . accessKeyLabel

+
+   

+
+    
Exposes the Access Key facet of the command.

+
+   

+
+   
element . hidden

+
+   

+
+    
Exposes the Hidden State facet of the command.

+
+   

+
+   
element . disabled

+
+   

+
+    
Exposes the Disabled State facet of the command.

+
+   

+
+   
element . checked

+
+   

+
+    
Exposes the Checked State facet of the command.

+
+   

+
+   
element . click()

+
+   

+
+    
Triggers the Action of the command.

+
+   

+
+
+
+  

+
+  
The commandType
+  attribute must return a string whose value is either "command", "radio", or "checkbox", depending on whether the Type of the command defined by the
+  element is "command", "radio", or "checkbox" respectively. If the
+  element does not define a command, it must return null.

+
+  
The label
+  attribute must return the command's Label, or null if the element
+  does not define a command or does not specify a Label. This attribute will be
+  shadowed by the label IDL attribute on
+  various elements.

+
+  
The icon
+  attribute must return the absolute URL of the command's
+  Icon. If the element does
+  not specify an icon, or if the element does not define a command,
+  then the attribute must return null. This attribute will be shadowed
+  by the icon IDL attribute on
+  command elements.

+
+  
The disabled
+  attribute must return true if the command's Disabled State is that
+  the command is disabled, and false if the command is not
+  disabled. This attribute is not affected by the command's Hidden State. If the
+  element does not define a command, the attribute must return
+  false. This attribute will be shadowed by the disabled IDL attribute on various elements.

+
+  
The checked attribute
+  must return true if the command's Checked State is that the
+  command is checked, and false if it is that the command is not
+  checked. If the element does not define a command, the attribute
+  must return false. This attribute will be shadowed by the checked IDL attribute on input and
+  command elements.

+
+
+
+  
The ID facet
+  is exposed by the id IDL attribute,
+  the Hint facet is exposed by
+  the title IDL attribute, the AccessKey facet is exposed by
+  the accessKeyLabel IDL
+  attribute, and the Hidden
+  State facet is exposed by the hidden IDL attribute.

+
+  

+
+  
document . commands

+   

+    
Returns an HTMLCollection of the elements in the
+    Document that define commands and have IDs.

+   

+
+  

+
+  
The commands attribute
+  of the document's HTMLDocument interface must return an
+  HTMLCollection rooted at the Document
+  node, whose filter matches only elements that define commands and have IDs.

+
+  

+
+  
User agents may expose the commands whose Hidden State facet is false
+  (visible), e.g. in the user agent's menu bar. User agents are
+  encouraged to do this especially for commands that have Access Keys, as a way to
+  advertise those keys to the user.

+
+
+  

+
+  
4.11.5.1 Using the a element to define a command

+
+  
An a element with an href attribute defines a command.

+
+  
The Type of the command
+  is "command".

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  is the string given by the element's textContent IDL
+  attribute.

+
+  
The Hint of the command
+  is the value of the title attribute
+  of the element. If the attribute is not present, the Hint is the empty string.

+
+  
The Icon of the command
+  is the absolute URL obtained from resolving the value of the src attribute of the first
+  img element descendant of the element, relative to that
+  element, if there is such an element and resolving its attribute is
+  successful. Otherwise, there is no Icon for the command.

+
+  
The AccessKey of the
+  command is the element's assigned access key, if
+  any.

+
+  
The Hidden State
+  of the command is true (hidden) if the element has a hidden attribute, and false
+  otherwise.

+
+  
The Disabled
+  State facet of the command is always false. (The command is
+  always enabled.)

+
+  
The Checked State
+  of the command is always false. (The command is never checked.)

+
+  
The Action of the
+  command is to fire a click event at the element.

+
+
+  
4.11.5.2 Using the button element to define a command

+
+  
A button element always defines a command.

+
+  
The Type, ID, Label, Hint, Icon, Access Key, Hidden State, Checked State, and Action facets of the command are
+  determined as for a
+  elements (see the previous section).

+
+  
The Disabled
+  State of the command mirrors the disabled state of the button.

+
+
+  
4.11.5.3 Using the input element to define a command

+
+  
An input element whose type attribute is in one of the Submit Button, Reset Button, Image Button, Button, Radio Button, or Checkbox states defines a command.

+
+  
The Type of the command
+  is "radio" if the type
+  attribute is in the Radio
+  Button state, "checkbox" if the type attribute is in the Checkbox state, and
+  "command" otherwise.

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  depends on the Type of the command:

+
+  
If the Type is "command",
+  then it is the string given by the value attribute, if any, and a
+  UA-dependent, locale-dependent value that the UA uses to label the
+  button itself if the attribute is absent.

+
+  
Otherwise, the Type is
+  "radio" or "checkbox". If the element is a labeled
+  control, the textContent of the first
+  label element in tree order whose
+  labeled control is the element in question is the Label (in DOM terms, this is the
+  string given by element.labels[0].textContent). Otherwise,
+  the value of the value
+  attribute, if present, is the Label. Otherwise, the Label is the empty string.

+
+  
The Hint of the command
+  is the value of the title attribute
+  of the input element. If the attribute is not present, the
+  Hint is the empty
+  string.

+
+  
If the element's type
+  attribute is in the Image
+  Button state, and the element has a src attribute, and that attribute's
+  value can be successfully resolved relative to the element, then the Icon of the command is the
+  absolute URL obtained from resolving that attribute
+  that way. Otherwise, there is no Icon for the command.

+
+  
The AccessKey of the
+  command is the element's assigned access key, if
+  any.

+
+  
The Hidden State
+  of the command is true (hidden) if the element has a hidden attribute, and false
+  otherwise.

+
+  
The Disabled
+  State of the command mirrors the disabled state of the
+  control.

+
+  
The Checked State
+  of the command is true if the command is of Type "radio" or "checkbox" and the
+  element is checked
+  attribute, and false otherwise.

+
+  
The Action of the
+  command, if the element has a defined activation
+  behavior, is to run synthetic click activation
+  steps on the element. Otherwise, it is just to fire a
+  click event at the
+  element.

+
+
+  
4.11.5.4 Using the option element to define a command

+
+  
An option element with an ancestor
+  select element and either no value attribute or a value attribute that is not the
+  empty string defines a
+  command.

+
+  
The Type of the command
+  is "radio" if the option's nearest ancestor
+  select element has no multiple attribute, and
+  "checkbox" if it does.

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  is the value of the option element's label attribute, if there is one,
+  or the value of the option element's
+  textContent IDL attribute if there isn't.

+
+  
The Hint of the command
+  is the string given by the element's title attribute, if any, and the empty
+  string if the attribute is absent.

+
+  
There is no Icon for the
+  command.

+
+  
The AccessKey of the
+  command is the element's assigned access key, if
+  any.

+
+  
The Hidden State
+  of the command is true (hidden) if the element has a hidden attribute, and false
+  otherwise.

+
+  
The Disabled
+  State of the command is true (disabled) if the element is
+  disabled or if its
+  nearest ancestor select element is disabled, and false
+  otherwise.

+
+  
The Checked State
+  of the command is true (checked) if the element's selectedness is true, and
+  false otherwise.

+
+  
The Action of the
+  command depends on its Type. If the command is of Type "radio" then it must pick the option
+  element. Otherwise, it must toggle the option
+  element.

+
+
+  
4.11.5.5 Using the command element to define
+  a command

+
+  
A command element defines a command.

+
+  
The Type of the command
+  is "radio" if the command's type attribute is
+  "radio", "checkbox" if the attribute's value is
+  "checkbox", and "command" otherwise.

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  is the value of the element's label attribute, if there is one,
+  or the empty string if it doesn't.

+
+  
The Hint of the command
+  is the string given by the element's title attribute, if any, and the
+  empty string if the attribute is absent.

+
+  
The Icon for the command
+  is the absolute URL obtained from resolving the value of the element's icon attribute, relative to the
+  element, if it has such an attribute and resolving it is
+  successful. Otherwise, there is no Icon for the command.

+
+  
The AccessKey of the
+  command is the element's assigned access key, if
+  any.

+
+  
The Hidden State
+  of the command is true (hidden) if the element has a hidden attribute, and false
+  otherwise.

+
+  
The Disabled
+  State of the command is true (disabled) if the element has a
+  disabled attribute, and
+  false otherwise.

+
+  
The Checked State
+  of the command is true (checked) if the element has a checked attribute, and false
+  otherwise.

+
+  
The Action of the
+  command, if the element has a defined activation
+  behavior, is to run synthetic click activation
+  steps on the element. Otherwise, it is just to fire a
+  click event at the
+  element.

+
+
+
+
+
+  
4.11.5.6 Using the accesskey attribute on a label element to define a command

+
+  
A label element that has an assigned access
+  key and a labeled control and whose
+  labeled control defines a
+  command, itself defines a
+  command.

+
+  
The Type of the command
+  is "command".

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  is the string given by the element's textContent IDL
+  attribute.

+
+  
The Hint of the command
+  is the value of the title attribute
+  of the element.

+
+  
There is no Icon for the
+  command.

+
+  
The AccessKey of the
+  command is the element's assigned access key.

+
+  
The Hidden State,
+  Disabled State, and
+  Action facets of the
+  command are the same as the respective facets of the element's
+  labeled control.

+
+  
The Checked State
+  of the command is always false. (The command is never checked.)

+
+
+
+  
4.11.5.7 Using the accesskey attribute on a legend element to define a command

+
+  
A legend element that has an assigned access
+  key and is a child of a fieldset element that
+  has a descendant that is not a descendant of the legend
+  element and is neither a label element nor a
+  legend element but that defines a command, itself defines a command.

+
+  
The Type of the command
+  is "command".

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  is the string given by the element's textContent IDL
+  attribute.

+
+  
The Hint of the command
+  is the value of the title attribute
+  of the element.

+
+  
There is no Icon for the
+  command.

+
+  
The AccessKey of the
+  command is the element's assigned access key.

+
+  
The Hidden State,
+  Disabled State, and
+  Action facets of the
+  command are the same as the respective facets of the first element
+  in tree order that is a descendant of the parent of the
+  legend element that defines a command but is not a
+  descendant of the legend element and is neither a
+  label nor a legend element.

+
+  
The Checked State
+  of the command is always false. (The command is never checked.)

+
+
+
+  
4.11.5.8 Using the accesskey attribute to define a command on other elements

+
+  
An element that has an assigned access key defines a command.

+
+  
If one of the other sections that define elements that define commands define that this
+  element defines a command, then
+  that section applies to this element, and this section does
+  not. Otherwise, this section applies to that element.

+
+  
The Type of the command
+  is "command".

+
+  
The ID of the command is
+  the value of the id attribute of the
+  element, if the attribute is present and not empty. Otherwise the
+  command is an anonymous command.

+
+  
The Label of the command
+  depends on the element. If the element is a labeled
+  control, the textContent of the first
+  label element in tree order whose
+  labeled control is the element in question is the Label (in DOM terms, this is the
+  string given by element.labels[0].textContent). Otherwise, the
+  Label is the
+  textContent of the element itself.

+
+  
The Hint of the command
+  is the value of the title attribute
+  of the element. If the attribute is not present, the Hint is the empty string.

+
+  
There is no Icon for the
+  command.

+
+  
The AccessKey of the
+  command is the element's assigned access key.

+
+  
The Hidden State
+  of the command is true (hidden) if the element has a hidden attribute, and false
+  otherwise.

+
+  
The Disabled
+  State facet of the command is always false. (The command is
+  always enabled.)

+
+  
The Checked State
+  of the command is always false. (The command is never checked.)

+
+  
The Action of the
+  command is to run the following steps:

+
+  
  1. If the element is focusable, run the
+   focusing steps for the element.
    2. 
+
+   
  2. If the element has a defined activation behavior,
+   run synthetic click activation steps on the
+   element.
    3. 
+
+   
  3. Otherwise, if the element does not have a defined
+   activation behavior, fire a click event at the element.
    4. 
+
+  

+
+
+
+
+  
4.11.6 The device element

+
+  
Categories

+   
Flow content.

+   
Phrasing content.

+   
Interactive content.

+   
Contexts in which this element may be used:

+   
Where phrasing content is expected.

+   
Content model:

+   
Empty.

+   
Content attributes:

+   
Global attributes

+   
type

+   
DOM interface:

+   

+
interface HTMLDeviceElement : HTMLElement {
+           attribute DOMString type;
+  readonly attribute any data;
+};

+  
The device element represents a device selector, to
+  allow the user to give the page access to a device, for example a
+  video camera.

+
+  
The type
+  attribute allows the author to specify which kind of device the page
+  would like access to. The attribute is an enumerated
+  attribute with the keywords given in the first column of the
+  following table, and their corresponding states given in the cell in
+  second column of the same row.

+
+  
RS232 is only included below to give an idea of where
+  we could go with this. Should we instead just make this only
+  useful for audiovisual streams? Unless there are compelling
+  reasons, we probably should not be this generic. So far, the reasons
+  aren't that compelling.

+
+  
Keyword
+     State
+     Device description
+     Examples
+   
media
+     Media
+     Stream of audio and/or video data.
+     A webcam.
+    
fs
+     File system
+     File system.
+     A USB-connected media player.
+    
rs232
+     RS232
+     RS232 device.
+     A serial port.
+  
processing model: 'change' event fires once user
+  selects a new device; .data is set to new Stream, LocalFS, or RS232
+  object as appropriate.

+
+  

+
+   
<p>To start chatting, select a video camera: <device type=media onchange="update(this.data)"></p>
+<video autoplay></video>
+<script>
+ function update(stream) {
+   document.getElementsByTagName('video')[0].src = stream.url;
+ }
+</script>

+
+  

+
+
+  
4.11.6.1 Stream API

+
+  
The Stream interface is used to represent
+  streams.

+
+  
interface Stream {
+  readonly attribute DOMString url;
+  StreamRecorder record();
+};

+
+  
The url attribute
+  must return a File URN representing the
+  stream. [FILEAPI]

+
+  
For audio and video streams, the stream must be in a format
+  supported by the user agent for use in audio and
+  video elements.

+
+  
This will be pinned down to a specific codec.

+
+  
When the record() method is
+  invoked, the user agent must return a new
+  StreamRecorder object associated with the stream.

+
+  
interface StreamRecorder {
+  File stop();
+};

+
+  
The stop() method
+  must return a new File object representing the data
+  that was streamed between the creation of the
+  StreamRecorder object and the invocation of the stop() method. [FILEAPI]

+
+  
For audio and video streams, the file must be in a format
+  supported by the user agent for use in audio and
+  video elements.

+
+  
This again will be pinned down to a specific codec.

+
+
+  
4.11.6.2 Peer-to-peer connections

+
+  
This section will be moved to a more appropriate
+  location in due course; it is here currently to keep it near the
+  device element to allow reviewers to look at it.

+
+  
[Constructor(in DOMString serverConfiguration)]
+interface ConnectionPeer {
+  void sendText(in DOMString text);
+  attribute Function ontext; // receiving
+
+  void sendBitmap(in HTMLImageElement image);
+  attribute Function onbitmap; // receiving
+
+  void sendFile(in File file);
+  attribute Function onfile; // receiving
+
+  void addStream(in Stream stream);
+  void removeStream(in Stream stream);
+  readonly attribute Stream[] localStreams;
+  readonly attribute Stream[] remoteStreams;
+  attribute Function onstream; // receiving
+
+  void getLocalConfiguration(in ConnectionPeerConfigurationCallback callback); // maybe this should be in the constructor
+  void addRemoteConfiguration(in DOMString configuration);
+  void close(); // disconnects and stops listening
+
+  attribute Function onconnect;
+  attribute Function onerror;
+  attribute Function ondisconnect;
+};
+
+[Callback=FunctionOnly, NoInterfaceObject]
+interface ConnectionPeerConfigurationCallback {
+  void handleEvent(in ConnectionPeer server, in DOMString configuration);
+};

+
+  
...

+
+  

+
+   
This relies on some currently hypothetical other standard to
+   define:

+
+   
  • The format of server configuration strings.
+    
  • The format of client configuration strings.
+    
  • The protocols that clients use to talk to third-party servers mentioned in the server configuration strings.
+    
  • The protocols that clients use to talk to each other.
+   

+
+  

+
+   
When two peers decide they are going to set up a connection to
+   each other, they both go through these steps. The serverConfig
+   comes from a third-party server they can use to get things like
+   their public IP address or to set up NAT traversal. They also have
+   to send their respective configuration to each other using the same
+   out-of-band mechanism they used to establish that they were going
+   to communicate in the first place.

+
+   
var serverConfig = ...; // configuration string obtained from server
+// contains details such as the IP address of a server that can speak some
+// protocol to help the client determine its public IP address, route packets
+// if necessary, etc.
+
+var local = new ConnectionPeer(serverConfig);
+local.getLocalConfiguration(function (configuration) {
+  if (configuration != '') {
+    ...; // send configuration to other peer using out-of-band mechanism
+  } else {
+    // we've exhausted our options; wait for connection
+  }
+});
+
+function ... (configuration) {
+  // called whenever we get configuration information out-of-band
+  local.addRemoteConfiguration(configuration);
+}
+
+local.onconnect = function (event) {
+  // we are connected!
+  local.sendText('Hello');
+  local.addStream(...); // send video
+  local.onstream = function (event) {
+    // receive video
+    // (videoElement is some <video> element)
+    if (local.remoteStreams.length > 0)
+      videoElement.src = local.remoteStreams[0].url;
+  };
+};

+
+  

+
+  
To prevent network sniffing from allowing a
+  fourth party to establish a connection to a peer using the
+  information sent out-of-band to the other peer and thus spoofing the
+  client, the configuration information should always be transmitted
+  using an encrypted connection.

+
+
+
+
+
+
+  
+
+
+  
+
+  
The a, area, and link
+  elements can, in certain situations described in the definitions of
+  those elements, represent hyperlinks.

+
+  
The href
+  attribute on a and area elements must have
+  a value that is a valid URL potentially surrounded by
+  spaces. This URL is the destination
+  resource of the hyperlink.

+
+  
The href
+  attribute on a and area elements is not
+  required; when those elements do not have href attributes they do not
+  represent hyperlinks.

+
+  
The href
+  attribute on the link element is required (and
+  has to be a valid non-empty URL), but whether
+  a link element represents a hyperlink or not depends on
+  the value of the rel attribute of
+  that element.

+
+  
The target
+  attribute, if present, must be a valid browsing context name
+  or keyword. It gives the name of the browsing
+  context that will be used. User agents use
+  this name when following hyperlinks.

+
+
+  
The ping attribute, if
+  present, gives the URLs of the resources that are interested in
+  being notified if the user follows the hyperlink. The value must be
+  a set of space-separated tokens, each of which must be
+  a valid non-empty URL. The value is
+  used by the user agent for hyperlink
+  auditing.

+
+
+  
For a and area elements that represent
+  hyperlinks, the relationship between the document containing the
+  hyperlink and the destination resource indicated by the hyperlink is
+  given by the value of the element's rel attribute, which
+  must be a set of space-separated tokens. The allowed values and their meanings are defined
+  below. The rel attribute has
+  no default value. If the attribute is omitted or if none of the
+  values in the attribute are recognized by the user agent, then the
+  document has no particular relationship with the destination
+  resource other than there being a hyperlink between the two.

+
+  
The media
+  attribute describes for which media the target document was
+  designed. It is purely advisory. The value must be a valid
+  media query. The default, if the media attribute is omitted, is
+  "all".

+
+  
The hreflang
+  attribute on hyperlink elements, if present, gives the language of
+  the linked resource. It is purely advisory. The value must be a
+  valid BCP 47 language tag. [BCP47]
+  User agents must not consider this attribute
+  authoritative — upon fetching the resource, user agents must
+  use only language information associated with the resource to
+  determine its language, not metadata included in the link to the
+  resource.

+
+  
The type
+  attribute, if present, gives the MIME type of the
+  linked resource. It is purely advisory. The value must be a
+  valid MIME type. User agents must
+  not consider the type
+  attribute authoritative — upon fetching the resource, user
+  agents must not use metadata included in the link to the resource to
+  determine its type.

+
+
+  

+
+  
+
+  
When a user follows a hyperlink, the user agent must
+  resolve the URL
+  given by the href attribute
+  of that hyperlink, relative to the hyperlink element, and if that is
+  successful, must navigate a browsing
+  context to the resulting absolute URL. In the
+  case of server-side image maps, the URL of the hyperlink must
+  further have its hyperlink suffix appended to it.

+
+  
If resolving the
+  URL fails, the user agent may report the error to the
+  user in a user-agent-specific manner, may navigate to an error page
+  to report the error, or may ignore the error and do nothing.

+
+  
If the user indicated a specific browsing context
+  when following the hyperlink, or if the user agent is configured to
+  follow hyperlinks by navigating a particular browsing context, then
+  that must be the browsing context that is
+  navigated.

+
+  
Otherwise, if the hyperlink element is an a or
+  area element that has a target attribute, then the
+  browsing context that is navigated must be chosen by
+  applying the rules for choosing a browsing context given a
+  browsing context name, using the value of the target attribute as the
+  browsing context name. If these rules result in the creation of a
+  new browsing context, it must be navigated with
+  replacement enabled.

+
+  
Otherwise, if the hyperlink element is a sidebar hyperlink and the user
+  agent implements a feature that can be considered a secondary
+  browsing context, such a secondary browsing context may be selected
+  as the browsing context to be navigated.

+
+  
Otherwise, if the hyperlink element is an a or
+  area element with no target attribute, but one of
+  the child nodes of the head element is a
+  base element with a target attribute, then the browsing
+  context that is navigated must be chosen by applying the rules
+  for choosing a browsing context given a browsing context name,
+  using the value of the target
+  attribute of the first such base element as the
+  browsing context name. If these rules result in the creation of a
+  new browsing context, it must be navigated with
+  replacement enabled.

+
+  
Otherwise, the browsing context that must be navigated is the
+  same browsing context as the one which the hyperlink element itself
+  is in.

+
+  
The navigation must be done with the browsing
+  context that contains the Document object with
+  which the hyperlink's element in question is associated as the
+  source browsing context.

+
+  

+
+
+
+  

+
+  
+
+  
If an a or area hyperlink element has a
+  ping attribute, and the
+  user follows the hyperlink, and the hyperlink's URL can
+  be resolved, relative to the
+  hyperlink element, without failure, then the user agent must take
+  the ping attribute's value,
+  split that string on
+  spaces, resolve each
+  resulting token relative to the hyperlink element, and then should
+  send a request (as described below) to each of the resulting absolute URLs. (Tokens that fail to
+  resolve are ignored.) This may be done in parallel with the primary
+  request, and is independent of the result of that request.

+
+  
User agents should allow the user to adjust this behavior, for
+  example in conjunction with a setting that disables the sending of
+  HTTP Referer (sic) headers. Based
+  on the user's preferences, UAs may either ignore the
+  ping attribute altogether,
+  or selectively ignore URLs in the list (e.g. ignoring any
+  third-party URLs).

+
+  
For URLs that are HTTP URLs, the requests must be performed by
+  fetching the specified URLs using the
+  POST method, with an entity body with the MIME type
+  text/ping consisting of the four-character string
+  "PING", from the origin of the
+  Document containing the hyperlink.  All relevant cookie and HTTP
+  authentication headers must be included in the request. Which other
+  headers are required depends on the URLs involved.

+
+  
If both the address
+   of the Document object containing the hyperlink being
+   audited and the ping URL have the same origin

+
+   
The request must include a Ping-From HTTP header with, as its
+   value, the address of
+   the document containing the hyperlink, and a Ping-To HTTP header with, as its value,
+   the address of the absolute URL of the target of the
+   hyperlink. The request must not include a Referer (sic) HTTP header. 

+
+   
Otherwise, if the origins are different, but the document
+   containing the hyperlink being audited was not retrieved over an
+   encrypted connection

+
+   
The request must include a Referer (sic) HTTP header with, as its
+   value, the current
+   address of the document containing the hyperlink, a Ping-From HTTP header with the same
+   value, and a Ping-To HTTP header
+   with, as its value, the address of the target of the
+   hyperlink.

+
+   
Otherwise, the origins are different and the document
+   containing the hyperlink being audited was retrieved over an
+   encrypted connection

+
+   
The request must include a Ping-To HTTP header with, as its value,
+   the address of the target of the hyperlink. The request must
+   neither include a Referer (sic)
+   HTTP header nor include a Ping-From HTTP header.

+
+  
To save bandwidth, implementors might also wish to
+  consider omitting optional headers such as Accept from
+  these requests.

+
+  
User agents must, unless otherwise specified by the user, honor
+  the HTTP headers (including, in particular, redirects and HTTP
+  cookie headers), but must ignore any entity bodies returned in the
+  responses. User agents may close the connection prematurely once
+  they start receiving an entity body. [COOKIES]

+
+  
For URLs that are not HTTP URLs, the requests must be performed
+  by fetching the specified URL normally,
+  and discarding the results.

+
+  
When the ping attribute is
+  present, user agents should clearly indicate to the user that
+  following the hyperlink will also cause secondary requests to be
+  sent in the background, possibly including listing the actual target
+  URLs.

+
+  
For example, a visual user agent could include
+  the hostnames of the target ping URLs along with the hyperlink's
+  actual URL in a status bar or tooltip.

+
+  

+
+  

+
+   
The ping attribute is redundant
+   with pre-existing technologies like HTTP redirects and JavaScript
+   in allowing Web pages to track which off-site links are most
+   popular or allowing advertisers to track click-through rates.

+
+   
However, the ping attribute
+   provides these advantages to the user over those alternatives:

+
+   
  • It allows the user to see the final target URL
+    unobscured.
    • 
+
+    
  • It allows the UA to inform the user about the out-of-band
+    notifications.
    • 
+
+    
  • It allows the user to disable the notifications without losing
+    the underlying link functionality.
    • 
+
+    
  • It allows the UA to optimize the use of available network
+    bandwidth so that the target page loads faster.
    • 
+
+   
Thus, while it is possible to track users without this feature,
+   authors are encouraged to use the ping attribute so that the user
+   agent can make the user experience more transparent.

+
+  

+
+  
+
+
+
+
+  
4.12.3 Link types

+
+  
The following table summarizes the link types that are defined by
+  this specification. This table is non-normative; the actual
+  definitions for the link types are given in the next few
+  sections.

+
+  
In this section, the term referenced document refers to
+  the resource identified by the element representing the link, and
+  the term current document refers to the resource within
+  which the element representing the link finds itself.

+
+  

+
+  
To determine which link types apply to a link,
+  a, or area element, the element's rel attribute must be split on spaces. The resulting tokens are the link
+  types that apply to that element.

+
+  

+
+  
Except where otherwise specified, a keyword must not be specified
+  more than once per rel
+  attribute.

+
+  
The link types that contain no U+003A COLON characters (:),
+  including all those defined in this specification, are ASCII
+  case-insensitive values, and must be
+  compared as such.

+
+  
Thus, rel="next" is the
+  same as rel="NEXT".

+
+  
+     
+     
+    
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
+     
+     
+     
+    
Link typeEffect on...Brief description
linka and area
alternate HyperlinkHyperlinkGives alternate representations of the current document.
archivesHyperlinkHyperlinkProvides a link to a collection of records, documents, or other materials of historical interest.
authorHyperlinkHyperlinkGives a link to the current document's author.
bookmark not allowedHyperlinkGives the permalink for the nearest ancestor section.
external not allowedHyperlinkIndicates that the referenced document is not part of the same site as the current document.
firstHyperlinkHyperlinkIndicates that the current document is a part of a series, and that the first document in the series is the referenced document.
helpHyperlinkHyperlinkProvides a link to context-sensitive help.
icon External Resourcenot allowedImports an icon to represent the current document.
index HyperlinkHyperlinkGives a link to the document that provides a table of contents or index listing the current document.
lastHyperlinkHyperlinkIndicates that the current document is a part of a series, and that the last document in the series is the referenced document.
license HyperlinkHyperlinkIndicates that the main content of the current document is covered by the copyright license described by the referenced document.
nextHyperlinkHyperlinkIndicates that the current document is a part of a series, and that the next document in the series is the referenced document.
nofollow not allowedHyperlinkIndicates that the current document's original author or publisher does not endorse the referenced document.
noreferrernot allowedHyperlinkRequires that the user agent not send an HTTP Referer (sic) header if the user follows the hyperlink.
pingbackExternal Resourcenot allowedGives the address of the pingback server that handles pingbacks to the current document.
prefetchExternal Resourcenot allowedSpecifies that the target resource should be preemptively cached.
prev HyperlinkHyperlinkIndicates that the current document is a part of a series, and that the previous document in the series is the referenced document.
search HyperlinkHyperlinkGives a link to a resource that can be used to search through the current document and its related pages.
stylesheet External Resourcenot allowedImports a stylesheet.
sidebar HyperlinkHyperlinkSpecifies that the referenced document, if retrieved, is intended to be shown in the browser's sidebar (if it has one).
tag HyperlinkHyperlinkGives a tag (identified by the given address) that applies to the current document.
upHyperlinkHyperlinkProvides a link to a document giving the context for the current document.

+
+  
Some of the types described below list synonyms for these
+  values. These are to be handled as
+  specified by user agents, but must not be used in
+  documents.

+
+  

+
+  
+
+
+  
+
+  
The alternate keyword may be
+  used with link, a, and area
+  elements.

+
+  
The meaning of this keyword depends on the values of the other
+  attributes.

+
+  
If the element is a link element and the rel attribute also contains the
+   keyword stylesheet

+
+   

+
+    
The alternate keyword
+    modifies the meaning of the stylesheet keyword in the way
+    described for that keyword. The alternate keyword does not create a
+    link of its own.

+
+   

+
+
+   
The alternate keyword is
+   used with the type
+   attribute set to the value application/rss+xml or the value application/atom+xml

+
+   

+
+    
The link is a hyperlink
+    referencing a syndication feed (though not necessarily syndicating
+    exactly the same content as the current page).

+
+    

+
+    
The first link, a, or area
+    element in the document (in tree order) with the alternate keyword used with the type attribute set to the value
+    application/rss+xml or the value application/atom+xml must be treated as the default
+    syndication feed for the purposes of feed autodiscovery.

+
+    

+     
The following link element gives the syndication
+     feed for the current page:

+     
<link rel="alternate" type="application/atom+xml" href="data.xml">

+     
The following extract offers various different syndication
+     feeds:

+     
<p>You can access the planets database using Atom feeds:</p>
+<ul>
+ <li><a href="recently-visited-planets.xml" rel="alternate" type="application/atom+xml">Recently Visited Planets</a></li>
+ <li><a href="known-bad-planets.xml" rel="alternate" type="application/atom+xml">Known Bad Planets</a></li>
+ <li><a href="unexplored-planets.xml" rel="alternate" type="application/atom+xml">Unexplored Planets</a></li>
+</ul>

+    

+
+    

+
+   

+
+
+   
Otherwise

+
+   

+
+    
The link is a hyperlink
+    referencing an alternate representation of the current
+    document.

+
+    
The nature of the referenced document is given by the media, hreflang, and type attributes.

+
+    
If the alternate keyword is
+    used with the media
+    attribute, it indicates that the referenced document is intended for
+    use with the media specified.

+
+    
If the alternate keyword is
+    used with the hreflang
+    attribute, and that attribute's value differs from the root
+    element's language, it indicates that the
+    referenced document is a translation.

+
+    
If the alternate keyword is
+    used with the type
+    attribute, it indicates that the referenced document is a
+    reformulation of the current document in the specified format.

+
+    
The media, hreflang, and type attributes can be combined
+    when specified with the alternate
+    keyword.

+
+    

+
+     
For example, the following link is a French translation that
+     uses the PDF format:

+
+     
<link rel=alternate type=application/pdf hreflang=fr href=manual-fr>

+
+    

+
+    
This relationship is transitive — that is, if a document
+    links to two other documents with the link type "alternate", then, in addition to
+    implying that those documents are alternative representations of
+    the first document, it is also implying that those two documents
+    are alternative representations of each other.

+
+   

+
+  

+
+  
The archives keyword may be
+  used with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The archives keyword indicates
+  that the referenced document describes a collection of records,
+  documents, or other materials of historical interest.

+
+  
A blog's index page could link to an index of the
+  blog's past posts with rel="archives".

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keyword "archive" like the
+  archives keyword.

+
+  

+
+
+  
+
+  
The author keyword may be
+  used with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
For a and area elements, the author keyword indicates that the
+  referenced document provides further information about the author of
+  the nearest article element ancestor of the element
+  defining the hyperlink, if there is one, or of the page as a whole,
+  otherwise.

+
+  
For link elements, the author keyword indicates that the
+  referenced document provides further information about the author
+  for the page as a whole.

+
+  
The "referenced document" can be, and often is, a
+  mailto: URL giving the e-mail address of the
+  author. [MAILTO]

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat link, a, and
+  area elements that have a rev
+  attribute with the value "made" as having the author keyword specified as a link
+  relationship.

+
+  

+
+
+  
+
+  
The bookmark keyword may be
+  used with a and area elements.

+
+  
The bookmark keyword gives a
+  permalink for the nearest ancestor article element of
+  the linking element in question, or of the section the linking element is most
+  closely associated with, if there are no ancestor
+  article elements.

+
+  

+   
The following snippet has three permalinks. A user agent could
+   determine which permalink applies to which part of the spec by
+   looking at where the permalinks are given.

+   
 ...
+ <body>
+  <h1>Example of permalinks</h1>
+  <div id="a">
+   <h2>First example</h2>
+   <p><a href="a.html" rel="bookmark">This</a> permalink applies to
+   only the content from the first H2 to the second H2. The DIV isn't
+   exactly that section, but it roughly corresponds to it.</p>
+  </div>
+  <h2>Second example</h2>
+  <article id="b">
+   <p><a href="b.html" rel="bookmark">This</a> permalink applies to
+   the outer ARTICLE element (which could be, e.g., a blog post).</p>
+   <article id="c">
+    <p><a href="c.html" rel="bookmark">This</a> permalink applies to
+    the inner ARTICLE element (which could be, e.g., a blog comment).</p>
+   </article>
+  </article>
+ </body>
+ ...

+  

+
+
+
+
+  
+
+  
The external keyword may be
+  used with a and area elements.

+
+  
The external keyword indicates
+  that the link is leading to a document that is not part of the site
+  that the current document forms a part of.

+
+
+  
+
+  
The help keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
For a and area elements, the help keyword indicates that the referenced
+  document provides further help information for the parent of the
+  element defining the hyperlink, and its children.

+
+  

+
+   
In the following example, the form control has associated
+   context-sensitive help. The user agent could use this information,
+   for example, displaying the referenced document if the user presses
+   the "Help" or "F1" key.

+
+   
 <p><label> Topic: <input name=topic> <a href="help/topic.html" rel="help">(Help)</a></label></p>

+
+  

+
+  
For link elements, the help keyword indicates that the referenced
+  document provides help for the page as a whole.

+
+
+  
4.12.3.7 Link type "icon"

+
+  
The icon keyword may be used with
+  link elements, for which it creates an external resource link.

+
+  

+
+  
The specified resource is an icon representing the page or site,
+  and should be used by the user agent when representing the page in
+  the user interface.

+
+  

+
+  
Icons could be auditory icons, visual icons, or other kinds of
+  icons. If multiple icons are provided, the user
+  agent must select the most appropriate icon according to the type, media, and sizes attributes. If there are
+  multiple equally appropriate icons, user agents must use the last
+  one declared in tree order. If the user agent tries to
+  use an icon but that icon is determined, upon closer examination, to
+  in fact be inappropriate (e.g. because it uses an unsupported
+  format), then the user agent must try the next-most-appropriate icon
+  as determined by the attributes.

+
+  

+
+  
There is no default type for resources given by the icon keyword. However, for the purposes of
+  determining the type of the
+  resource, user agents must expect the resource to be an image.

+
+  

+
+  
The sizes
+  attribute gives the sizes of icons for visual media.

+
+  
If specified, the attribute must have a value that is an
+  unordered set of unique space-separated tokens. The
+  values must all be either any or a value that consists of
+  two valid non-negative
+  integers that do not have a leading U+0030 DIGIT ZERO (0)
+  character and that are separated by a single U+0078 LATIN SMALL
+  LETTER X character (x).

+
+  
The keywords represent icon sizes.

+
+  

+
+  
To parse and process the attribute's value, the user agent must
+  first split the attribute's
+  value on spaces, and must then parse each resulting keyword
+  to determine what it represents.

+
+  

+
+  
The any keyword
+  represents that the resource contains a scalable icon, e.g. as
+  provided by an SVG image.

+
+  

+
+  
Other keywords must be further parsed as follows to determine
+  what they represent:

+
+  
  • If the keyword doesn't contain exactly one U+0078 LATIN
+   SMALL LETTER X character (x), then this keyword doesn't represent
+   anything. Abort these steps for that keyword.
    • 
+
+   
  • Let width string be the string before
+   the "x".
    • 
+
+   
  • Let height string be the string after the
+   "x".
    • 
+
+   
  • If either width string or height string start with a U+0030 DIGIT ZERO (0)
+   character or contain any characters other than characters in the
+   range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then this
+   keyword doesn't represent anything. Abort these steps for that
+   keyword.
    • 
+
+   
  • Apply the rules for parsing non-negative
+   integers to width string to obtain width.
    • 
+
+   
  • Apply the rules for parsing non-negative
+   integers to height string to obtain height.
    • 
+
+   
  • The keyword represents that the resource contains a bitmap
+   icon with a width of width device pixels and a
+   height of height device pixels.
    • 
+
+  

+
+  
The keywords specified on the sizes attribute must not represent
+  icon sizes that are not actually available in the linked
+  resource.

+
+  

+
+  
If the attribute is not specified, then the user agent must
+  assume that the given icon is appropriate, but less appropriate than
+  an icon of a known and appropriate size.

+
+  

+
+  

+
+   
The following snippet shows the top part of an application with
+   several icons.

+
+   
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>lsForums — Inbox</title>
+  <link rel=icon href=favicon.png sizes="16x16" type="image/png">
+  <link rel=icon href=windows.ico sizes="32x32 48x48" type="image/vnd.microsoft.icon">
+  <link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768">
+  <link rel=icon href=iphone.png sizes="59x60" type="image/png">
+  <link rel=icon href=gnome.svg sizes="any" type="image/svg+xml">
+  <link rel=stylesheet href=lsforums.css>
+  <script src=lsforums.js></script>
+  <meta name=application-name content="lsForums">
+ </head>
+ <body>
+  ...

+
+  

+
+
+  
+
+  
The license keyword may be used
+  with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The license keyword indicates
+  that the referenced document provides the copyright license terms
+  under which the main content of the current document is
+  provided.

+
+  
This specification does not specify how to distinguish between
+  the main content of a document and content that is not deemed to be
+  part of that main content. The distinction should be made clear to
+  the user.

+
+  

+
+   
Consider a photo sharing site. A page on that site might
+   describe and show a photograph, and the page might be marked up as
+   follows:

+
+   
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Exampl Pictures: Kissat</title>
+  <link rel="stylesheet" href="/style/default">
+ </head>
+ <body>
+  <h1>Kissat</h1>
+  <nav>
+   <a href="../">Return to photo index</a>
+  </nav>
+  <figure>
+   <img src="/pix/39627052_fd8dcd98b5.jpg">
+   <figcaption>Kissat</figcaption>
+  </figure>
+  <p>One of them has six toes!</p>
+  <p><small><a rel="license" href="http://www.opensource.org/licenses/mit-license.php">MIT Licensed</a></small></p>
+  <footer>
+   <a href="/">Home</a> | <a href="../">Photo index</a>
+   <p><small>© copyright 2009 Exampl Pictures. All Rights Reserved.</small></p>
+  </footer>
+ </body>
+</html>

+
+   
In this case the license
+   applies to just the photo (the main content of the document), not
+   the whole document. In particular not the design of the page
+   itself, which is covered by the copyright given at the bottom of
+   the document. This could be made clearer in the styling
+   (e.g. making the license link prominently positioned near the
+   photograph, while having the page copyright in light small text at
+   the foot of the page.

+
+  

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keyword "copyright" like
+  the license keyword.

+
+  

+
+
+  
+
+  
The nofollow keyword may be
+  used with a and area elements.

+
+  
The nofollow keyword indicates
+  that the link is not endorsed by the original author or publisher of
+  the page, or that the link to the referenced document was included
+  primarily because of a commercial relationship between people
+  affiliated with the two pages.

+
+
+  
+
+  
The noreferrer keyword may be
+  used with a and area elements.

+
+  
It indicates that no referrer information is to be leaked when
+  following the link.

+
+  

+
+  
If a user agent follows a link defined by an a or
+  area element that has the noreferrer keyword, the user agent
+  must not include a Referer (sic)
+  HTTP header (or
+  equivalent for other protocols) in the request.

+
+  
This keyword also causes the opener attribute to remain null if the
+  hyperlink creates a new browsing context.

+
+  

+
+  
+
+
+  
+
+  
The pingback keyword may be
+  used with link elements, for which it creates an external resource link.

+
+  
For the semantics of the pingback keyword, see the Pingback 1.0
+  specification. [PINGBACK]

+
+
+  
+
+  
The prefetch keyword may be
+  used with link elements, for which it creates an external resource link.

+
+  
The prefetch keyword indicates
+  that preemptively fetching and caching the specified resource is
+  likely to be beneficial, as it is highly likely that the user will
+  require this resource.

+
+  
There is no default type for resources given by the prefetch keyword.

+
+
+  
+
+  
The search keyword may be used
+  with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The search keyword indicates that
+  the referenced document provides an interface specifically for
+  searching the document and its related resources.

+
+  
OpenSearch description documents can be used with
+  link elements and the search link type to enable user agents to
+  autodiscover search interfaces. [OPENSEARCH]

+
+
+  
+
+  
The stylesheet keyword may be
+  used with link elements, for which it creates an external resource link that
+  contributes to the styling processing model.

+
+  
The specified resource is a resource that describes how to
+  present the document. Exactly how the resource is to be processed
+  depends on the actual type of the resource.

+
+  
If the alternate keyword is
+  also specified on the link element, then the link
+  is an alternative stylesheet; in this case, the title attribute must be specified on the
+  link element, with a non-empty value.

+
+  
The default type for resources given by the stylesheet keyword is text/css.

+
+  

+
+  
Quirk: If the document has been set to
+  quirks mode and the Content-Type metadata of the external
+  resource is not a supported style sheet type, the user agent must
+  instead assume it to be text/css.

+
+  

+
+
+  
+
+  
The sidebar keyword may be used
+  with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The sidebar keyword indicates
+  that the referenced document, if retrieved, is intended to be shown
+  in a secondary browsing context (if possible), instead
+  of in the current browsing context.

+
+  
A hyperlink element with the sidebar keyword specified is a sidebar hyperlink.

+
+
+  
+
+  
The tag keyword may be used
+  with link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The tag keyword indicates that the
+  tag that the referenced document represents applies to the
+  current document.

+
+  
Since it indicates that the tag applies to the
+  current document, it would be inappropriate to use this keyword
+  in the markup of a tag cloud, which lists
+  the popular tag across a set of pages.

+
+
+  
+
+  
Some documents form part of a hierarchical structure of
+  documents.

+
+  
A hierarchical structure of documents is one where each document
+  can have various subdocuments. The document of which a document is a
+  subdocument is said to be the document's parent. A document
+  with no parent forms the top of the hierarchy.

+
+  
A document may be part of multiple hierarchies.

+
+
+  
+
+  
The index keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The index keyword indicates that
+  the document is part of a hierarchical structure, and that the link
+  is leading to the document that is the top of the hierarchy. It
+  conveys more information when used with the up keyword (q.v.).

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keywords "top", "contents", and "toc" like the
+  index keyword.

+
+  

+
+
+  
+
+  
The up keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The up keyword indicates that the
+  document is part of a hierarchical structure, and that the link is
+  leading to a document that is an ancestor of the current
+  document.

+
+  
The up keyword may be repeated within
+  a rel attribute to indicate
+  the hierarchical distance from the current document to the
+  referenced document. If it occurs only once, then the link is
+  leading to the current document's parent; each additional occurrence
+  of the keyword represents one further level. If the index keyword is also present, then the
+  number of up keywords is the depth of
+  the current page relative to the top of the hierarchy. Only one link
+  is created for the set of one or more up
+  keywords and, if present, the index
+  keyword.

+
+  
If the page is part of multiple hierarchies, then they should be
+  described in different paragraphs. User agents
+  must scope any interpretation of the up
+  and index keywords together
+  indicating the depth of the hierarchy to the paragraph
+  in which the link finds itself, if any, or to the document
+  otherwise.

+
+  

+
+  
When two links have both the up and
+  index keywords specified together in
+  the same scope and contradict each other by having a different
+  number of up keywords, the link with the
+  greater number of up keywords must be
+  taken as giving the depth of the document.

+
+  

+
+  

+
+   
This can be used to mark up a navigation style sometimes known
+   as bread crumbs. In the following example, the current page can be
+   reached via two paths.

+
+   
<nav>
+ <p>
+  <a href="/" rel="index up up up">Main</a> >
+  <a href="/products/" rel="up up">Products</a> >
+  <a href="/products/dishwashers/" rel="up">Dishwashers</a> >
+  <a>Second hand</a>
+ </p>
+ <p>
+  <a href="/" rel="index up up">Main</a> >
+  <a href="/second-hand/" rel="up">Second hand</a> >
+  <a>Dishwashers</a>
+ </p>
+</nav>

+
+  

+
+  
The relList IDL
+  attribute (e.g. on the a element) does not currently
+  represent multiple up keywords (the
+  interface hides duplicates).

+
+
+  
+
+  
Some documents form part of a sequence of documents.

+
+  
A sequence of documents is one where each document can have a
+  previous sibling and a next sibling. A document
+  with no previous sibling is the start of its sequence, a document
+  with no next sibling is the end of its sequence.

+
+  
A document may be part of multiple sequences.

+
+
+  
+
+  
The first keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The first keyword indicates that
+  the document is part of a sequence, and that the link is leading to
+  the document that is the first logical document in the sequence.

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keywords "begin" and
+  "start" like the first keyword.

+
+  

+
+
+  
+
+  
The last keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The last keyword indicates that the
+  document is part of a sequence, and that the link is leading to the
+  document that is the last logical document in the sequence.

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keyword "end" like the
+  last keyword.

+
+  

+
+
+  
+
+  
The next keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The next keyword indicates that the
+  document is part of a sequence, and that the link is leading to the
+  document that is the next logical document in the sequence.

+
+
+  
+
+  
The prev keyword may be used with
+  link, a, and area
+  elements. For link elements, it creates a hyperlink.

+
+  
The prev keyword indicates that the
+  document is part of a sequence, and that the link is leading to the
+  document that is the previous logical document in the sequence.

+
+  

+
+  
Synonyms: For historical reasons, user agents
+  must also treat the keyword "previous" like
+  the prev keyword.

+
+  

+
+
+  
+
+  
Extensions to the predefined
+  set of link types may be registered in the WHATWG Wiki
+  RelExtensions page. [WHATWGWIKI]

+
+  
Anyone is free to edit the WHATWG Wiki RelExtensions page at any
+  time to add a type. Extension types must be specified with the
+  following information:

+
+  
Keyword

+
+   

+
+    
The actual value being defined. The value should not be
+    confusingly similar to any other defined value (e.g. differing
+    only in case).

+
+    
If the value contains a U+003A COLON character (:), it must
+    also be an absolute URL.

+
+   

+
+
+   
Effect on... link

+
+   

+
+    
One of the following:

+
+    
not allowed

+
+     
The keyword is not allowed to be specified on
+     link elements.

+
+     
Hyperlink

+
+     
The keyword may be specified on a link element;
+     it creates a hyperlink
+     link.

+
+     
External Resource

+
+     
The keyword may be specified on a link element;
+     it creates a external
+     resource link.

+
+    

+
+
+   
Effect on... a and area

+
+   

+
+    
One of the following:

+
+    
not allowed

+
+     
The keyword is not allowed to be specified on a
+     and area elements.

+
+     
Hyperlink

+
+     
The keyword may be specified on a and
+     area elements.

+
+    

+
+
+   
Brief description

+
+   
A short non-normative description of what the keyword's
+   meaning is.

+
+
+   
Specification

+
+   
A link to a more detailed description of the keyword's
+   semantics and requirements. It could be another page on the Wiki,
+   or a link to an external page.

+
+
+   
Synonyms

+
+   
A list of other keyword values that have exactly the same
+   processing requirements. Authors should not use the values defined
+   to be synonyms, they are only intended to allow user agents to
+   support legacy content. Anyone may remove synonyms that are not
+   used in practice; only names that need to be processed as synonyms
+   for compatibility with legacy content are to be registered in this
+   way.

+
+
+   
Status

+
+   

+
+    
One of the following:

+
+    
Proposed

+
+     
The keyword has not received wide peer review and
+     approval. Someone has proposed it and is, or soon will be, using
+     it.

+
+     
Ratified

+
+     
The keyword has received wide peer review and approval. It
+     has a specification that unambiguously defines how to handle
+     pages that use the keyword, including when they use it in
+     incorrect ways.

+
+     
Discontinued

+
+     
The keyword has received wide peer review and it has been
+     found wanting. Existing pages are using this keyword, but new
+     pages should avoid it. The "brief description" and
+     "specification" entries will give details of what authors should
+     use instead, if anything.

+
+    
If a keyword is found to be redundant with existing values, it
+    should be removed and listed as a synonym for the existing
+    value.

+
+    
If a keyword is registered in the "proposed" state for a
+    period of a month or more without being used or specified, then it
+    may be removed from the registry.

+
+    
If a keyword is added with the "proposed" status and found to
+    be redundant with existing values, it should be removed and listed
+    as a synonym for the existing value. If a keyword is added with
+    the "proposed" status and found to be harmful, then it should be
+    changed to "discontinued" status.

+
+    
Anyone can change the status at any time, but should only do so
+    in accordance with the definitions above.

+
+   

+
+  

+
+  
Conformance checkers must use the information given on the WHATWG
+  Wiki RelExtensions page to establish if a value is allowed or not:
+  values defined in this specification or marked as "proposed" or
+  "ratified" must be accepted when used on the elements for which they
+  apply as described in the "Effect on..." field, whereas values
+  marked as "discontinued" or not listed in either this specification
+  or on the aforementioned page must be rejected as invalid.
+  Conformance checkers may cache this information (e.g. for
+  performance reasons or to avoid the use of unreliable network
+  connectivity).

+
+  
When an author uses a new type not defined by either this
+  specification or the Wiki page, conformance checkers should offer to
+  add the value to the Wiki, with the details described above, with
+  the "proposed" status.

+
+  

+
+  
Types defined as extensions in the WHATWG Wiki
+  RelExtensions page with the status "proposed" or "ratified" may
+  be used with the rel attribute on
+  link, a, and area elements in
+  accordance to the "Effect on..." field. [WHATWGWIKI]

+
+
+  
4.13 Common idioms without dedicated elements

+
+  
4.13.1 Tag clouds

+
+  
This specification does not define any markup
+  specifically for marking up lists of keywords that apply to a group
+  of pages (also known as tag clouds). In general, authors are
+  encouraged to either mark up such lists using ul
+  elements with explicit inline counts that are then hidden and turned
+  into a presentational effect using a style sheet, or to use SVG.

+
+  

+
+   
Here, three tags are included in a short tag cloud:

+
+   
<style>
+@media screen, print, handheld, tv {
+  /* should be ignored by non-visual browsers */
+  .tag-cloud > li > span { display: none; }
+  .tag-cloud > li { display: inline; }
+  .tag-cloud-1 { font-size: 0.7em; }
+  .tag-cloud-2 { font-size: 0.9em; }
+  .tag-cloud-3 { font-size: 1.1em; }
+  .tag-cloud-4 { font-size: 1.3em; }
+  .tag-cloud-5 { font-size: 1.5em; }
+}
+</style>
+...
+<ul class="tag-cloud">
+ <li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span>
+ <li class="tag-cloud-2"><a title="6 instances"  href="/t/kiwi">kiwi</a> <span>(rare)</span>
+ <li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span>
+</ul>

+
+   
The actual frequency of each tag is given using the title attribute. A CSS style sheet is
+   provided to convert the markup into a cloud of differently-sized
+   words, but for user agents that do not support CSS or are not
+   visual, the markup contains annotations like "(popular)" or
+   "(rare)" to categorize the various tags by frequency, thus enabling
+   all users to benefit from the information.

+
+   
The ul element is used (rather than
+   ol) because the order is not particularly important:
+   while the list is in fact ordered alphabetically, it would convey
+   the same information if ordered by, say, the length of the tag.

+
+   
The tag rel-keyword is not used
+   on these a elements because they do not represent tags
+   that apply to the page itself; they are just part of an index
+   listing the tags themselves.

+
+  

+
+
+  
4.13.2 Conversations

+
+  
+
+  
This specification does not define a specific element for marking
+  up conversations, meeting minutes, chat transcripts, dialogues in
+  screenplays, instant message logs, and other situations where
+  different players take turns in discourse.

+
+  
Instead, authors are encouraged to mark up conversations using
+  p elements and punctuation. Authors who need to mark
+  the speaker for styling purposes are encouraged to use
+  span or b. Paragraphs with their text
+  wrapped in the i element can be used for marking up
+  stage directions.

+
+  

+
+   
This example demonstrates this using an extract from Abbot and
+   Costello's famous sketch, Who's on first:

+
+
<p> Costello: Look, you gotta first baseman?
+<p> Abbott: Certainly.
+<p> Costello: Who's playing first?
+<p> Abbott: That's right.
+<p> Costello becomes exasperated.
+<p> Costello: When you pay off the first baseman every month, who gets the money?
+<p> Abbott: Every dollar of it.

+
+  

+
+  

+
+   
The following extract shows how an IM conversation log could be
+   marked up.

+
+   
<p> <time>14:22</time> <b>egof</b> I'm not that nerdy, I've only seen 30% of the star trek episodes
+<p> <time>14:23</time> <b>kaj</b> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy
+<p> <time>14:23</time> <b>egof</b> it's unarguably
+<p> <time>14:23</time> <i>* kaj blinks</i>
+<p> <time>14:24</time> <b>kaj</b> you are not helping your case

+   
+
+  

+
+
+  
4.13.3 Footnotes

+
+  
HTML does not have a dedicated mechanism for marking up
+  footnotes. Here are the recommended alternatives.

+
+  
For short inline annotations, the title attribute should be used.

+
+  

+
+   
In this example, two parts of a dialogue are annotated with
+   footnote-like content using the title attribute.

+
+   
<p> <b>Customer</b>: Hello! I wish to register a complaint. Hello. Miss?
+<p> <b>Shopkeeper</b>: <span title="Colloquial pronunciation of 'What do you'"
+>Watcha</span> mean, miss?
+<p> <b>Customer</b>: Uh, I'm sorry, I have a cold. I wish to make a complaint.
+<p> <b>Shopkeeper</b>: Sorry, <span title="This is, of course, a lie.">we're
+closing for lunch</span>.

+
+  

+
+  
For longer annotations, the a element should be
+  used, pointing to an element later in the document. The convention
+  is that the contents of the link be a number in square brackets.

+
+  

+
+   
In this example, a footnote in the dialogue links to a paragraph
+   below the dialogue. The paragraph then reciprocally links back to the
+   dialogue, allowing the user to return to the location of the
+   footnote.

+
+   
<p> Announcer: Number 16: The <i>hand</i>.
+<p> Interviewer: Good evening. I have with me in the studio tonight
+Mr Norman St John Polevaulter, who for the past few years has been
+contradicting people. Mr Polevaulter, why <em>do</em> you
+contradict people?
+<p> Norman: I don't. <sup><a href="#fn1" id="r1">[1]</a></sup>
+<p> Interviewer: You told me you did!
+...
+<section>
+ <p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie,
+ but paradoxically if it were true he could not say so without
+ contradicting the interviewer and thus making it false.</p>
+</section>

+
+  

+
+  
For side notes, longer annotations that apply to entire sections
+  of the text rather than just specific words or sentences, the
+  aside element should be used.

+
+  

+
+   
In this example, a sidebar is given after a dialogue, giving it
+   some context.

+
+   
<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
+<p> <span class="speaker">Shopkeeper</span>: I'm sorry?
+<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
+<p> <span class="speaker">Shopkeeper</span>: No no no, this's'a tobacconist's.
+<aside>
+ <p>In 1970, the British Empire lay in ruins, and foreign
+ nationalists frequented the streets — many of them Hungarians
+ (not the streets — the foreign nationals). Sadly, Alexander
+ Yalt has been publishing incompetently-written phrase books.
+</aside>

+
+  

+
+  
For figures or tables, footnotes can be included in the relevant
+  figcaption or caption element, or in
+  surrounding prose.

+
+  

+
+   
In this example, a  table has cells with footnotes
+   that are given in prose. A figure element is used to
+   give a single legend to the combination of the table and its
+   footnotes.

+
+   
<figure>
+ <figcaption>Table 1. Alternative activities for knights.</figcaption>
+ <table>
+  <tr>
+   <th> Activity
+   <th> Location
+   <th> Cost
+  <tr>
+   <td> Dance
+   <td> Wherever possible
+   <td> £0<sup><a href="#fn1">1</a></sup>
+  <tr>
+   <td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup>
+   <td> Undisclosed
+   <td> Undisclosed
+  <tr>
+   <td> Dining<sup><a href="#fn3">3</a></sup>
+   <td> Camelot
+   <td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup>
+ </table>
+ <p id="fn1">1. Assumed.</p>
+ <p id="fn2">2. Footwork impeccable.</p>
+ <p id="fn3">3. Quality described as "well".</p>
+ <p id="fn4">4. A lot.</p>
+</figure>

+
+  

+
+
+
+  

+
+  
4.14 Matching HTML elements using selectors

+
+  
4.14.1 Case-sensitivity

+
+  
Attribute and element names of HTML
+  elements in HTML documents must be treated as
+  ASCII case-insensitive.

+
+  
Classes from the class attribute
+  of HTML elements in documents that are in quirks
+  mode must be treated as ASCII
+  case-insensitive.

+
+  
Attribute selectors on an HTML
+  element in an HTML
+  document must treat the values of attributes with
+  the following names as ASCII case-insensitive:

+
+  
+  
+  
  • accept
+   
  • accept-charset
+   
  • align
+   
  • alink
+   
  • axis
+   
  • bgcolor
+   
  • charset
+   
  • checked
+   
  • clear
+   
  • codetype
+   
  • color
+   
  • compact
+   
  • declare
+   
  • defer
+   
  • dir
+   
  • direction 
+   
  • disabled
+   
  • enctype
+   
  • face
+   
  • frame
+   
  • hreflang
+   
  • http-equiv
+   
  • lang
+   
  • language
+   
  • link
+   
  • media
+   
  • method
+   
  • multiple
+   
  • nohref
+   
  • noresize
+   
  • noshade
+   
  • nowrap
+   
  • readonly
+   
  • rel
+   
  • rev
+   
  • rules
+   
  • scope
+   
  • scrolling
+   
  • selected
+   
  • shape
+   
  • target
+   
  • text
+   
  • type
+   
  • valign
+   
  • valuetype
+   
  • vlink
+  
All other attribute values on HTML elements must be
+  treated as case-sensitive.

+
+
+  
4.14.2 Pseudo-classes

+
+  
There are a number of dynamic selectors that can be used with
+  HTML. This section defines when these selectors match HTML
+  elements.

+
+  
:link

+   
:visited

+
+   

+
+    
All a elements that have an href attribute, all
+    area elements that have an href attribute, and all
+    link elements that have an href attribute, must match one of
+    :link and :visited.

+
+   

+
+
+   
:active

+
+   

+
+    
The :active pseudo-class
+    must match the following elements between the time the user begins
+    to activate the element and the time the user stops activating
+    the element:

+
+    
For example, if the user is using a keyboard to
+    push a button element by pressing the space bar, the
+    element would match this pseudo-class in between the time that the
+    element received the keydown
+    event and the time the element received the keyup event.

+
+   

+
+
+   
:enabled

+
+   

+
+    
The :enabled pseudo-class
+    must match the following elements:

+
+    

+
+
+   
:disabled

+
+   

+
+    
The :disabled
+    pseudo-class must match the following elements:

+
+    

+
+
+   
:checked

+
+   

+
+    
The :checked pseudo-class
+    must match the following elements:

+
+    

+
+
+   
:indeterminate

+
+   

+
+    
The :indeterminate
+    pseudo-class must match input elements whose type attribute is in the Checkbox state and whose
+    indeterminate IDL
+    attribute is set to true.

+
+   

+
+
+   
:default

+
+   

+
+    
The :default pseudo-class
+    must match the following elements:

+
+    

+
+
+   
:valid

+
+   

+
+    
The :valid pseudo-class
+    must match all elements that are candidates for constraint validation
+    and that satisfy their
+    constraints.

+
+   

+
+
+   
:invalid

+
+   

+
+    
The :invalid pseudo-class
+    must match all elements that are candidates for constraint validation
+    but that do not satisfy their
+    constraints.

+
+   

+
+
+   
:in-range

+
+   

+
+    
The :in-range
+    pseudo-class must match all elements that are candidates for
+    constraint validation and that are neither suffering
+    from an underflow nor suffering from an
+    overflow.

+
+   

+
+
+   
:out-of-range

+
+   

+
+    
The :out-of-range
+    pseudo-class must match all elements that are candidates for
+    constraint validation and that are suffering from an
+    underflow or suffering from an overflow.

+
+   

+
+
+   
:required

+
+   

+
+    
The :required
+    pseudo-class must match the following elements:

+
+    

+
+
+   
:optional

+
+   

+
+    
The :optional
+    pseudo-class must match the following elements:

+
+    

+
+
+   
:read-only

+   
:read-write

+
+   

+
+    
The :read-write
+    pseudo-class must match the following elements:

+
+    
The :read-only
+    pseudo-class must match all other HTML elements.

+
+   

+
+  
Another section of this specification defines the
+  target element used with the :target pseudo-class.

+
+  
This specification does not define when an element
+  matches the :hover, :focus, or :lang() dynamic pseudo-classes, as
+  those are all defined in sufficient detail in a language-agnostic
+  fashion in the Selectors specification. [SELECTORS]

+
+  

+
+
+
+
+  

+
+  
5 Microdata

+
+
+
+
+  
5.1 Introduction

+
+  
5.1.1 Overview

+
+  
This section is non-normative.

+
+  
Sometimes, it is desirable to annotate content with specific
+  machine-readable labels, e.g. to allow generic scripts to provide
+  services that are customised to the page, or to enable content from
+  a variety of cooperating authors to be processed by a single script
+  in a consistent manner.

+
+  
For this purpose, authors can use the microdata features
+  described in this section. Microdata allows nested groups of
+  name-value pairs to be added to documents, in parallel with the
+  existing content.

+
+
+
+  
5.1.2 The basic syntax

+
+  
This section is non-normative.

+
+  
At a high level, microdata consists of a group of name-value
+  pairs. The groups are called items, and each name-value pair is a
+  property. Items and properties are represented by regular
+  elements.

+
+  
To create an item, the itemscope attribute is used.

+
+  
To add a property to an item, the itemprop attribute is used on one of
+  the item's descendants.

+
+  

+
+   
Here there are two items, each of which has the property "name":

+
+   
<div itemscope>
+ <p>My name is <span itemprop="name">Elizabeth</span>.</p>
+</div>
+
+<div itemscope>
+ <p>My name is <span itemprop="name">Daniel</span>.</p>
+</div>

+
+  

+
+  
Properties generally have values that are strings.

+
+  

+
+   
Here the item has three properties:

+
+   
<div itemscope>
+ <p>My name is <span itemprop="name">Neil</span>.</p>
+ <p>My band is called <span itemprop="band">Four Parts Water</span>.</p>
+ <p>I am <span itemprop="nationality">British</span>.</p>
+</div>

+
+  

+
+  
Properties can also have values that are URLs. This is achieved using the a
+  element and its href
+  attribute, the img element and its src attribute, or other elements that
+  link to or embed external resources.

+
+  

+
+   
In this example, the item has one property, "image", whose value
+   is a URL:

+
+   
<div itemscope>
+ <img itemprop="image" src="google-logo.png" alt="Google">
+</div>

+
+  

+
+  
Properties can also have values that are dates, times, or dates
+  and times. This is achieved using the time element and
+  its datetime attribute.

+
+  

+
+   
In this example, the item has one property,
+   "birthday", whose value is a date:

+
+   
<div itemscope>
+ I was born on <time itemprop="birthday" datetime="2009-05-10">May 10th 2009</time>.
+</div>

+
+  

+
+  
Properties can also themselves be groups of name-value pairs, by
+  putting the itemscope attribute
+  on the element that declares the property.

+
+  
Items that are not part of others are called top-level
+  microdata items.

+
+  

+
+   
In this example, the outer item represents a person, and the
+   inner one represents a band:

+
+   
<div itemscope>
+ <p>Name: <span itemprop="name">Amanda</span></p>
+ <p>Band: <span itemprop="band" itemscope> <span itemprop="name">Jazz Band</span> (<span itemprop="size">12</span> players)</span></p>
+</div>

+
+   
The outer item here has two properties, "name" and
+   "band". The "name" is "Amanda", and the
+   "band" is an item in its own right, with two
+   properties, "name" and "size". The
+   "name" of the band is "Jazz Band", and the
+   "size" is "12".

+
+   
The outer item in this example is a top-level microdata
+   item.

+
+  

+
+  
Properties that are not descendants of the element with the itemscope attribute can be associated
+  with the item using the itemref attribute. This attribute takes
+  a list of IDs of elements to crawl in addition to crawling the
+  children of the element with the itemscope attribute.

+
+  

+
+   
This example is the same as the previous one, but all the
+   properties are separated from their items:

+
+   
<div itemscope id="amanda" itemref="a b"></div>
+<p id="a">Name: <span itemprop="name">Amanda</span></p>
+<div id="b" itemprop="band" itemscope itemref="c"></div>
+<div id="c">
+ <p>Band: <span itemprop="name">Jazz Band</span></p>
+ <p>Size: <span itemprop="size">12</span> players</p>
+</div>

+
+   
This gives the same result as the previous example. The first
+   item has two properties, "name", set to "Amanda", and "band", set
+   to another item. That second item has two further properties,
+   "name", set to "Jazz Band", and "size", set to "12".

+
+  

+
+  
An item can have multiple
+  properties with the same name and different values.

+
+  

+
+   
This example describes an ice cream, with two flavors:

+
+   
<div itemscope>
+ <p>Flavors in my favorite ice cream:</p>
+ <ul>
+  <li itemprop="flavor">Lemon sorbet</li>
+  <li itemprop="flavor">Apricot sorbet</li>
+ </ul>
+</div>

+
+   
This thus results in an item with two properties, both
+   "flavor", having the values "Lemon sorbet" and "Apricot
+   sorbet".

+
+  

+
+  
An element introducing a property can also introduce multiple
+  properties at once, to avoid duplication when some of the properties
+  have the same value.

+
+  

+
+   
Here we see an item with two properties,
+   "favorite-color" and "favorite-fruit", both
+   set to the value "orange":

+
+   
<div itemscope>
+ <span itemprop="favorite-color favorite-fruit">orange</span>
+</div>

+
+  

+
+  
It's important to note that there is no relationship between the
+  microdata and the content of the document where the microdata is
+  marked up.

+
+  

+
+   
There is no semantic difference, for instance, between the
+   following two examples:

+
+   
<figure>
+ <img src="castle.jpeg">
+ <figcaption><span itemscope><span itemprop="name">The Castle</span></span> (1986)</figcaption>
+</figure>

+
+   
<span itemscope><meta itemprop="name" content="The Castle"></span>
+<figure>
+ <img src="castle.jpeg">
+ <figcaption>The Castle (1986)</figcaption>
+</figure>

+
+   
Both have a figure with a caption, and both, completely
+   unrelated to the figure, have an item with a name-value pair with
+   the name "name" and the value "The Castle". The only
+   difference is that if the user drags the caption out of the
+   document, in the former case, the item will be included in the
+   drag-and-drop data. In neither case is the image in any way
+   associated with the item.

+
+  

+
+
+  
5.1.3 Typed items

+
+  
This section is non-normative.

+
+  
The examples in the previous section show how information could
+  be marked up on a page that doesn't expect its microdata to be
+  re-used. Microdata is most useful, though, when it is used in
+  contexts where other authors and readers are able to cooperate to
+  make new uses of the markup.

+
+  
For this purpose, it is necessary to give each item a type, such as
+  "http://example.com/person", or "http://example.org/cat", or
+  "http://band.example.net/". Types are identified as URLs.

+
+  
The type for an item is given
+  as the value of an itemtype
+  attribute on the same element as the itemscope attribute.

+
+  

+
+   
Here, the item is "http://example.org/animals#cat":

+
+
<section itemscope itemtype="http://example.org/animals#cat">
+ <h1 itemprop="name">Hedral</h1>
+ <p itemprop="desc">Hedral is a male american domestic
+ shorthair, with a fluffy black fur with white paws and belly.</p>
+ <img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
+</section>

+
+   
In this example the "http://example.org/animals#cat" item has three
+   properties, a "name" ("Hedral"), a "desc" ("Hedral is..."), and an
+   "img" ("hedral.jpeg").

+
+  

+
+  
An item can only have one type. The type gives the context for
+  the properties, thus defining a vocabulary: a property named "class"
+  given for an item with the type "http://census.example/person" might
+  refer to the economic class of an individual, while a property named
+  "class" given for an item with the type "http://example.com/school/teacher"
+  might refer to the classroom a teacher has been assigned.

+
+
+  
5.1.4 Global identifiers for items

+
+  
This section is non-normative.

+
+  
Sometimes, an item gives
+  information about a topic that has a global identifier. For example,
+  books can be identified by their ISBN number.

+
+  
Vocabularies (as identified by the itemtype attribute) can be designed
+  such that items get associated
+  with their global identifier in an unambiguous way by expressing the
+  global identifiers as URLs given in an
+  itemid attribute.

+
+  
The exact meaning of the URLs given in
+  itemid attributes depends on the
+  vocabulary used.

+
+  

+
+   
Here, an item is talking about a particular book:

+
+
<dl itemscope
+    itemtype="http://vocab.example.net/book"
+    itemid="urn:isbn:0-330-34032-8">
+ <dt>Title
+ <dd itemprop="title">The Reality Dysfunction
+ <dt>Author
+ <dd itemprop="author">Peter F. Hamilton
+ <dt>Publication date
+ <dd><time itemprop="pubdate" datetime="1996-01-26">26 January 1996</time>
+</dl>

+
+   
The "http://vocab.example.net/book"
+   vocabulary in this example would define that the itemid attribute takes a urn: URL pointing to the ISBN of the
+   book.

+
+  

+
+  
+
+
+
+  
5.1.5 Selecting names when defining vocabularies

+
+  
This section is non-normative.

+
+  
Using microdata means using a vocabulary. For some purposes, an
+  ad-hoc vocabulary is adequate. For others, a vocabulary will need to
+  be designed. Where possible, authors are encouraged to re-use
+  existing vocabularies, as this makes content re-use easier.

+
+  
When designing new vocabularies, identifiers can be created
+  either using URLs, or, for properties, as
+  plain words (with no dots or colons). For URLs, conflicts with other
+  vocabularies can be avoided by only using identifiers that
+  correspond to pages that the author has control over.

+
+  

+
+   
For instance, if Jon and Adam both write content at example.com, at http://example.com/~jon/... and http://example.com/~adam/... respectively, then
+   they could select identifiers of the form
+   "http://example.com/~jon/name" and "http://example.com/~adam/name"
+   respectively.

+
+  

+
+  
Properties whose names are just plain words can only be used
+  within the context of the types for which they are intended;
+  properties named using URLs can be reused in items of any type. If
+  an item has no type, and is not part of another item, then if its
+  properties have names that are just plain words, they are not
+  intended to be globally unique, and are instead only intended for
+  limited use. Generally speaking, authors are encouraged to use
+  either properties with globally unique names (URLs) or ensure that
+  their items are typed.

+
+  

+
+   
Here, an item is an "http://example.org/animals#cat", and most of the
+   properties have names that are words defined in the context of that
+   type. There are also a few additional properties whose names come
+   from other vocabularies.

+
+
<section itemscope itemtype="http://example.org/animals#cat">
+ <h1 itemprop="name http://example.com/fn">Hedral</h1>
+ <p itemprop="desc">Hedral is a male american domestic
+ shorthair, with a fluffy <span
+ itemprop="http://example.com/color">black</span> fur with <span
+ itemprop="http://example.com/color">white</span> paws and belly.</p>
+ <img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
+</section>

+
+   
This example has one item with the type "http://example.org/animals#cat"
+   and the following properties:

+
+   
Property
+      Value
+    
name
+      Hedral
+     
http://example.com/fn
+      Hedral
+     
desc
+      Hedral is a male american domestic shorthair, with a fluffy black fur with white paws and belly.
+     
http://example.com/color
+      black
+     
http://example.com/color
+      white
+     
img
+      .../hedral.jpeg
+   

+
+
+
+  
5.1.6 Using the microdata DOM API

+
+  
This section is non-normative.

+
+  
The microdata becomes even more useful when scripts can use it to
+  expose information to the user, for example offering it in a form
+  that can be used by other applications.

+
+  
The document.getItems(typeNames) method provides access to the
+  top-level microdata items. It returns a
+  NodeList containing the items with the specified types,
+  or all types if no argument is specified.

+
+  
Each item is represented in the
+  DOM by the element on which the relevant itemscope attribute is found. These
+  elements have their element.itemScope IDL attribute set to
+  true.

+
+  
The type of items can be
+  obtained using the element.itemType IDL attribute on the
+  element with the itemscope
+  attribute.

+
+  

+
+   
This sample shows how the getItems() method can be used
+   to obtain a list of all the top-level microdata items of one type
+   given in the document:

+
+   
var cats = document.getItems("http://example.com/feline");

+
+  

+
+  
Once an element representing an item has been obtained, its properties
+  can be extracted using the properties IDL attribute. This
+  attribute returns an HTMLPropertiesCollection, which can
+  be enumerated to go through each element that adds one or more
+  properties to the item. It can also be indexed by name, which will
+  return an object with a list of the elements that add properties
+  with that name.

+
+  
Each element that adds a property also has a itemValue IDL attribute that returns
+  its value.

+
+  

+
+   
This sample gets the first item of type "http://example.net/user" and
+   then pops up an alert using the "name" property from
+   that item.

+
+   
var user = document.getItems('http://example.net/user')[0];
+alert('Hello ' + user.properties['name'][0].content + '!');

+
+  

+
+  
The HTMLPropertiesCollection object, when indexed by
+  name in this way, actually returns a PropertyNodeList
+  object with all the matching properties. The
+  PropertyNodeList object can be used to obtain all the
+  values at once using its values attribute, which
+  returns an array of all the values.

+
+  

+
+   
In an earlier example, a "http://example.org/animals#cat" item had two
+   "http://example.com/color" values. This script looks up the first such
+   item and then lists all its values.

+
+   
var cat = document.getItems('http://example.org/animals#cat')[0];
+var colors = cat.properties['http://example.com/color'].values;
+var result;
+if (colors.length == 0) {
+  result = 'Color unknown.';
+} else if (colors.length == 1) {
+  result = 'Color: ' + colors[0];
+} else {
+  result = 'Colors:';
+  for (var i = 0; i < colors.length; i += 1)
+    result += ' ' + colors[i];
+}

+
+  

+
+  
It's also possible to get a list of all the property
+  names using the object's names IDL
+  attribute.

+
+  

+
+   
This example creates a big list with a nested list for each item
+   on the page, each with of all the property names used in that
+   item.

+
+   
var outer = document.createElement('ul');
+var items = document.getItems();
+for (var item = 0; item < items.length; item += 1) {
+  var itemLi = document.createElement('li');
+  var inner = document.createElement('ul');
+  for (var name = 0; name < items[item].properties.names.length; name += 1) {
+    var propLi = document.createElement('li');
+    propLi.appendChild(document.createTextNode(items[item].properties.names[name]));
+    inner.appendChild(propLi);
+  }
+  itemLi.appendChild(inner);
+  outer.appendChild(itemLi);
+}
+document.body.appendChild(outer);

+
+   
If faced with the following from an earlier example:

+
+   
<section itemscope itemtype="http://example.org/animals#cat">
+ <h1 itemprop="name http://example.com/fn">Hedral</h1>
+ <p itemprop="desc">Hedral is a male american domestic
+ shorthair, with a fluffy <span
+ itemprop="http://example.com/color">black</span> fur with <span
+ itemprop="http://example.com/color">white</span> paws and belly.</p>
+ <img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
+</section>

+
+   
...it would result in the following output:

+
+   
  • 
+     
    • name
      • 
+      
    • http://example.com/fn
      • 
+      
    • desc
      • 
+      
    • http://example.com/color
      • 
+      
    • img
      • 
+     
    • 
+   
(The duplicate occurrence of "http://example.com/color" is not included
+   in the list.)

+
+  

+
+
+  
5.2 Encoding microdata

+
+
+
+  
5.2.1 The microdata model

+
+  
The microdata model consists of groups of name-value pairs known
+  as items.

+
+  
Each group is known as an item. Each item can have an item type,
+  a global identifier (if the item type
+  supports global
+  identifiers for its items), and a list of name-value
+  pairs. Each name in the name-value pair is known as a property, and each property has one or more
+  values. Each value is either a string or itself a group of
+  name-value pairs (an item).

+
+  
An item is said to be a
+  typed item when either it has an item type,
+  or it is the value of a property of a typed item. The
+  relevant type for a typed item is the item's item type, if it has
+  one, or else is the relevant type of the item for which it is a property's value.

+
+
+
+  
5.2.2 Items

+
+  
Every HTML element may have an
+  itemscope attribute
+  specified. The itemscope
+  attribute is a boolean attribute.

+
+  
An element with the itemscope
+  attribute specified creates a new item, a group of name-value pairs.

+
+  
Elements with an itemscope
+  attribute may have an itemtype attribute
+  specified, to give the item type of the item.

+
+  
The itemtype attribute, if
+  specified, must have a value that is a valid URL that
+  is an absolute URL for which the string "http://www.w3.org/1999/xhtml/microdata#" is not a
+  prefix match.
 
+
+  
The item type of an item is the value of its element's itemtype attribute, if it has one and
+  its value is not the empty string. If the itemtype attribute is missing or its
+  value is the empty string, the item is said to have no item
+  type.

+
+  
The item type must be a type defined in an applicable
+  specification.

+
+  

+
+   
Except if otherwise specified by that specification, the
+   URL given as the item type should not be
+   automatically dereferenced.

+
+   
A specification could define that its item
+   type can be derefenced to provide the user with help
+   information, for example. In fact, vocabulary authors are
+   encouraged to provide useful information at the given
+   URL.

+
+   
Item types are opaque
+   identifiers, and user agents must not dereference unknown item types, or otherwise deconstruct them,
+   in order to determine how to process items that use them.

+
+  

+
+  
The itemtype attribute must
+  not be specified on elements that do not have an itemscope attribute specified.

+
+  
Elements with an itemscope
+  attribute and an itemtype
+  attribute that references a vocabulary that is defined to
+  support global identifiers for items may also have an
+  itemid attribute
+  specified, to give a global identifier for the item, so that it can be related to other
+  items on pages elsewhere on the
+  Web.

+
+  
The itemid attribute, if
+  specified, must have a value that is a valid URL potentially
+  surrounded by spaces.

+
+  
The global identifier of an item is the value of its element's itemid attribute, if it has one, resolved relative to the element on
+  which the attribute is specified. If the itemid attribute is missing or if
+  resolving it fails, it is said to have no global
+  identifier.

+
+  
The itemid attribute must not be
+  specified on elements that do not have both an itemscope attribute and an itemtype attribute specified, and must
+  not be specified on elements with an itemscope attribute whose itemtype attribute specifies a
+  vocabulary that does not support global identifiers for
+  items, as defined by that vocabulary's specification.

+
+  
Elements with an itemscope
+  attribute may have an itemref attribute specified,
+  to give a list of additional elements to crawl to find the
+  name-value pairs of the item.

+
+  
The itemref attribute, if
+  specified, must have a value that is an unordered set of
+  unique space-separated tokens consisting of IDs of elements in the same home
+  subtree.

+
+  
The itemref attribute must not
+  be specified on elements that do not have an itemscope attribute specified.

+
+
+  
5.2.3 Names: the itemprop attribute

+
+  
Every HTML element may have an
+  itemprop attribute specified, if
+  doing so adds a
+  property to one or more items (as defined below).

+
+  
The itemprop attribute, if
+  specified, must have a value that is an unordered set of
+  unique space-separated tokens representing the names of the
+  name-value pairs that it adds. The attribute's value must have at
+  least one token.

+
+  
Each token must be either:

+
+  
  • A valid URL that is an absolute URL
+   for which the string "http://www.w3.org/1999/xhtml/microdata#" is not a
+   prefix match, or
    • 
+
+   
  • If the item is a typed item: a defined
+   property name allowed in this situation according to the
+   specification that defines the relevant type for the
+   item, or
    • 
+
+   
  • If the item is not a typed item: a string that
+   contains no U+002E FULL STOP characters (.) and no U+003A COLON
+   characters (:).
    • 
+
+  
When an element with an itemprop attribute adds a property to multiple items, the requirement above regarding
+  the tokens applies for each item
+  individually.

+
+  
+
+  
The property names of an element are the tokens that
+  the element's itemprop attribute
+  is found to contain when its value is split on spaces, with the order preserved but with
+  duplicates removed (leaving only the first occurrence of each
+  name).

+
+  
Within an item, the properties
+  are unordered with respect to each other, except for properties with
+  the same name, which are ordered in the order they are given by the
+  algorithm that defines the properties of an item.

+
+  

+
+   
In the following example, the "a" property has the values "1"
+   and "2", in that order, but whether the "a" property comes
+   before the "b" property or not is not important:

+
+   
<div itemscope>
+ <p itemprop="a">1</p>
+ <p itemprop="a">2</p>
+ <p itemprop="b">test</p>
+</div>

+
+   
Thus, the following is equivalent:

+
+   
<div itemscope>
+ <p itemprop="b">test</p>
+ <p itemprop="a">1</p>
+ <p itemprop="a">2</p>
+</div>

+
+   
As is the following:

+
+   
<div itemscope>
+ <p itemprop="a">1</p>
+ <p itemprop="b">test</p>
+ <p itemprop="a">2</p>
+</div>

+
+   
And the following:

+
+   
<div itemscope itemref="x">
+ <p itemprop="b">test</p>
+ <p itemprop="a">2</p>
+</div>
+<div id="x">
+ <p itemprop="a">1</p>
+</div>
+

+
+  

+
+
+
+  
5.2.4 Values

+
+  
The property value of a
+  name-value pair added by an element with an itemprop attribute depends on the
+  element, as follows:

+
+  
If the element also has an itemscope attribute

+
+   
The value is the item
+   created by the element.

+
+
+   
If the element is a meta element

+
+   
The value is the value of the element's content attribute, if any, or the empty
+   string if there is no such attribute.

+
+
+   
If the element is an audio, embed,
+   iframe, img, source, or
+   video element

+
+   
The value is the absolute URL that results from
+   resolving the value of the
+   element's src attribute relative to the
+   element at the time the attribute is set, or the empty string if
+   there is no such attribute or if resolving it results in an error.

+
+
+   
If the element is an a, area, or
+   link element

+
+   
The value is the absolute URL that results from
+   resolving the value of the
+   element's href attribute relative to the
+   element at the time the attribute is set, or the empty string if
+   there is no such attribute or if resolving it results in an error.

+
+
+   
If the element is an object element

+
+   
The value is the absolute URL that results from
+   resolving the value of the
+   element's data attribute relative to the
+   element at the time the attribute is set, or the empty string if
+   there is no such attribute or if resolving it results in an error.

+
+
+   
If the element is a time element with a datetime attribute

+
+   
The value is the value of the element's datetime attribute.

+
+
+   
Otherwise

+
+   
The value is the element's
+   textContent.

+
+  
The URL property elements are the a,
+  area, audio, embed,
+  iframe, img, link,
+  object, source, and video
+  elements.

+
+  
If a property's value
+  is an absolute URL, the property must be specified
+  using a URL property
+  element.

+
+  
If a property's value
+  represents a date, time, or global date and time, the property
+  must be specified using the datetime attribute of a
+  time element.

+
+
+  
5.2.5 Associating names with items

+
+  
To find the properties of an item defined by the
+  element root, the user agent must try to
+  crawl the properties of the element root, with an empty list as the value of memory: if this fails, then the properties of the item defined by
+  the element root is an empty list; otherwise, it
+  is the returned list.

+
+  
To crawl the properties of an element root with a list memory, the user
+  agent must run the following steps. These steps either fail or
+  return a list with a count of errors. The count of errors is used as
+  part of the authoring conformance criteria below.

+
+  
  1. If root is in memory, then the algorithm fails; abort these
+   steps.
    2. 
+
+   
  2. Collect all the elements in the item root; let results be the
+   resulting list of elements, and errors be the
+   resulting count of errors.
    3. 
+
+   
  3. Remove any elements from results that do
+   not have an itemprop attribute
+   specified.
    4. 
+
+   
  4. Let new memory be a new list consisting
+   of the old list memory with the addition of
+   root.
    5. 
+
+   
  5. For each element in results that has an
+   itemscope attribute specified,
+   crawl the properties of the element, with new memory as the memory. If this fails, then remove
+   the element from results and increment errors. (If it succeeds, the return value is
+   discarded.)
    6. 
+
+   
  6. Sort results in tree
+   order.
    7. 
+
+   
  7. Return results and errors.
    8. 
+
+  
To collect all the elements in the item root, the user agent must run these steps. They
+  return a list of elements and a count of errors.

+
+  
  1. Let results and pending be empty lists of elements.
    2. 
+
+   
  2. Let errors be zero.
    3. 
+
+   
  3. Add all the children elements of root to
+   pending.
    4. 
+
+   
  4. If root has an itemref attribute, split the value of that itemref attribute on spaces. For
+   each resulting token ID, if there is an element
+   in the home subtree of root with
+   the ID ID, then
+   add the first such element to pending.
    5. 
+
+   
  5. Loop: Remove an element from pending and let current be that
+   element.
    6. 
+
+   
  6. If current is already in results, increment errors.
    7. 
+
+   
  7. If current is not already in results and current does not
+   have an itemscope attribute,
+   then: add all the child elements of current to
+   pending.
    8. 
+
+   
  8. If current is not already in results, then: add current to
+   results.
    9. 
+
+   
  9. End of loop: If pending is not
+   empty, return to the step labeled loop.
    10. 
+
+   
  10. Return results and errors.
    11. 
+
+  
An item is a top-level microdata item if
+  its element does not have an itemprop attribute.

+
+  
An item is a used microdata item if it is a top-level microdata item,
+  or if it has an itemprop
+  attribute and would be found
+  to be the property of an item that is itself a used microdata item.

+
+  
A document must not contain any items that are not used microdata
+  items.

+
+  
A document must not contain any elements that have an itemprop attribute that would not be
+  found to be a property of any of the items in that document were their properties all to be
+  determined.

+
+  
A document must not contain any items for which crawling the properties of the element, with an
+  empty list as the value of memory, either fails
+  or returns an error count other than zero.

+
+  
The algorithms in this section are especially
+  inefficient, in the interests of keeping them easy to
+  understand. Implementors are strongly encouraged to refactor and
+  optimize them in their user agents.

+
+  

+
+   
In this example, a single license statement is applied to two
+   works, using itemref from the
+   items representing the works:

+
+   
<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Photo gallery</title>
+ </head>
+ <body>
+  <h1>My photos</h1>
+  <figure itemscope itemtype="http://n.whatwg.org/work" itemref="licenses">
+   <img itemprop="work" src="images/house.jpeg" alt="A white house, boarded up, sits in a forest.">
+   <figcaption itemprop="title">The house I found.</figcaption>
+  </figure>
+  <figure itemscope itemtype="http://n.whatwg.org/work" itemref="licenses">
+   <img itemprop="work" src="images/mailbox.jpeg" alt="Outside the house is a mailbox. It has a leaflet inside.">
+   <figcaption itemprop="title">The mailbox.</figcaption>
+  </figure>
+  <footer>
+   <p id="licenses">All images licensed under the <a itemprop="license"
+   href="http://www.opensource.org/licenses/mit-license.php">MIT
+   license</a>.</p>
+  </footer>
+ </body>
+</html>

+
+   
The above results in two items with the type "http://n.whatwg.org/work", one with:

+
+   
work
+    
images/house.jpeg
+    
title
+    
The house I found.
+    
license
+    
http://www.opensource.org/licenses/mit-license.php
+   
...and one with:

+
+   
work
+    
images/mailbox.jpeg
+    
title
+    
The mailbox.
+    
license
+    
http://www.opensource.org/licenses/mit-license.php
+   

+
+
+
+  
5.3 Microdata DOM API

+
+
+  
document . getItems( [ types ] )

+
+   

+
+    
Returns a NodeList of the elements in the Document that create items, that are not part of other items, and that are of one of the types given in the argument, if any are listed.

+
+    
The types argument is interpreted as a space-separated list of types.

+
+   

+
+   
element . properties

+
+   

+
+    
If the element has an itemscope attribute, returns an
+    HTMLPropertiesCollection object with all the element's
+    properties. Otherwise, an empty
+    HTMLPropertiesCollection object.

+
+   

+
+   
element . itemValue [ = value ]

+
+   

+
+    
Returns the element's value.

+
+    
Can be set, to change the element's value. Setting the value when the element has
+    no itemprop attribute or when
+    the element's value is an item
+    throws an INVALID_ACCESS_ERR exception.

+
+   

+
+  

+
+  
The document.getItems(typeNames) method takes an optional
+  string that contains an unordered set of unique
+  space-separated tokens representing types. When called, the
+  method must return a live NodeList object
+  containing all the elements in the document, in tree
+  order, that are each top-level microdata items
+  with a type equal to one of the types
+  specified in that argument, having obtained the types by splitting the string on
+  spaces. If there are no tokens specified in the argument, or
+  if the argument is missing, then the method must return a
+  NodeList containing all the top-level microdata
+  items in the document.
+  When the method is invoked on a Document object again
+  with the same argument, the user agent may return the same object as
+  the object returned by the earlier call. In other cases, a new
+  NodeList object must be returned.

+
+  
The itemScope IDL
+  attribute on HTML elements must reflect
+  the itemscope content attribute.
+  The itemType IDL
+  attribute on HTML elements must reflect
+  the itemtype content attribute,
+  as if it was a regular string attribute, not a URL
+  string attribute.  The itemId IDL attribute on
+  HTML elements must reflect the itemid content attribute. The itemProp IDL attribute on
+  HTML elements must reflect the itemprop content attribute. The itemRef IDL attribute on
+  HTML elements must reflect the itemref content attribute.

+
+  
The properties IDL
+  attribute on HTML elements must return an
+  HTMLPropertiesCollection rooted at the
+  Document node, whose filter matches only elements that
+  have property names and are the properties of the item created by the element
+  on which the attribute was invoked, while that element is an item, and matches nothing the rest of
+  the time.

+
+  
The itemValue IDL
+  attribute's behavior depends on the element, as follows:

+
+  
If the element has no itemprop attribute

+
+   
The attribute must return null on getting and must throw an
+   INVALID_ACCESS_ERR exception on setting.

+
+
+   
If the element has an itemscope attribute

+
+   
The attribute must return the element itself on getting and
+   must throw an INVALID_ACCESS_ERR exception on
+   setting.

+
+
+   
If the element is a meta element

+
+   
The attribute must act as it would if it was reflecting the element's content content
+   attribute.

+
+
+   
If the element is an audio, embed,
+   iframe, img, source, or
+   video element

+
+   
The attribute must act as it would if it was reflecting the element's src content attribute.

+
+
+   
If the element is an a, area, or
+   link element

+
+   
The attribute must act as it would if it was reflecting the element's href content attribute.

+
+
+   
If the element is an object element

+
+   
The attribute must act as it would if it was reflecting the element's data content attribute.

+
+
+   
If the element is a time element with a datetime attribute

+
+   
The attribute must act as it would if it was reflecting the element's datetime content
+   attribute.

+
+
+   
Otherwise

+
+   
The attribute must act the same as the element's
+   textContent attribute.

+
+  
When the itemValue IDL
+  attribute is reflecting a content
+  attribute or acting like the element's textContent
+  attribute, the user agent must, on setting, convert the new value to
+  the IDL DOMString value before using it
+  according to the mappings described above.

+
+  

+
+  

+
+   
In this example, a script checks to see if a particular element
+   element is declaring a particular property, and
+   if it is, it increments a counter:

+
+   
if (element.itemProp.contains('color'))
+  count += 1;

+
+  

+
+  

+
+   
This script iterates over each of the values of an element's
+   itemref attribute, calling a
+   function for each referenced element:

+
+   
for (var index = 0; index < element.itemRef.length; index += 1)
+  process(document.getElementById(element.itemRef[index]));

+
+  

+
+
+
+
+  
5.4 Microdata vocabularies

+
+
+
+  
5.4.1 vCard

+
+
+
+  
An item with the item type http://microformats.org/profile/hcard
+  represents a person's or organization's contact information.

+
+  
This vocabulary supports global identifiers for items.

+
+  
The following are the type's defined property names. They are based on the
+  vocabulary defined in the vCard specification and its extensions,
+  where more information on how to interpret the values can be
+  found. [RFC2426] [RFC4770]

+
+  
fn

+
+   

+
+    
Gives the formatted text corresponding to the name of the
+    person or organization.

+
+    
The value must be
+    text.

+
+    
Exactly one property with the name fn must be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
n

+
+   

+
+    
Gives the structured name of the person or organization.

+
+    
The value must be
+    an item with zero or more of
+    each of the family-name, given-name, additional-name, honorific-prefix, and
+    honorific-suffix
+    properties.

+
+    
Exactly one property with the name n must be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
family-name (inside n)

+
+   

+
+    
Gives the family name of the person, or the full name of the
+    organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name family-name may be present
+    within the item that forms the
+    value of the n property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
given-name (inside n)

+
+   

+
+    
Gives the given-name of the person.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name given-name may be present
+    within the item that forms the
+    value of the n property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
additional-name (inside n)

+
+   

+
+    
Gives the any additional names of the person.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name additional-name may be
+    present within the item that
+    forms the value of the
+    n property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
honorific-prefix (inside n)

+
+   

+
+    
Gives the honorific prefix of the person.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name honorific-prefix may be
+    present within the item that
+    forms the value of the
+    n property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
honorific-suffix (inside n)

+
+   

+
+    
Gives the honorific suffix of the person.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name honorific-suffix may be
+    present within the item that
+    forms the value of the
+    n property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
nickname

+
+   

+
+    
Gives the nickname of the person or organization.

+
+    
+    
The nickname is the descriptive name given instead
+    of or in addition to the one belonging to a person, place, or
+    thing. It can also be used to specify a familiar form of a proper
+    name specified by the fn or n properties.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name nickname may be present within
+    each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
photo

+
+   

+
+    
Gives a photograph of the person or organization.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name photo may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
bday

+
+   

+
+    
Gives the birth date of the person or organization.

+
+    
The value must be a
+    valid date string.

+
+    
A single property with the name bday may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
adr

+
+   

+
+    
Gives the delivery address of the person or organization.

+
+    
The value must be
+    an item with zero or more type, post-office-box, extended-address, and
+    street-address
+    properties, and optionally a locality property, optionally
+    a region property,
+    optionally a postal-code property, and
+    optionally a country-name
+    property.

+
+    
If no type properties
+    are present within an item that
+    forms the value of an
+    adr property of an item with the type http://microformats.org/profile/hcard, then the address type
+    strings intl,
+    postal, parcel, and work are implied.

+
+    
Any number of properties with the name adr may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
type (inside adr)

+
+   

+
+    
Gives the type of delivery address.

+
+    
The value must be
+    text that, when compared in a case-sensitive manner,
+    is equal to one of the address type strings.

+
+    
Within each item with the
+    type http://microformats.org/profile/hcard, there must be no more
+    than one adr property item with a type property whose value is
+    pref.

+
+    
Any number of properties with the name type may be present within the
+    item that forms the value of an adr property of an item with the type http://microformats.org/profile/hcard, but within each such adr property item there must only be one type property per distinct
+    value.

+
+   

+
+   
post-office-box (inside adr)

+
+   

+
+    
Gives the post office box component of the delivery address of
+    the person or organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name post-office-box may be
+    present within the item that
+    forms the value of an
+    adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
extended-address (inside adr)

+
+   

+
+    
Gives an additional component of the delivery address of the
+    person or organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name extended-address may
+    be present within the item that
+    forms the value of an
+    adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
street-address (inside adr)

+
+   

+
+    
Gives the street address component of the delivery address of
+    the person or organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name street-address may be
+    present within the item that
+    forms the value of an
+    adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
locality (inside adr)

+
+   

+
+    
Gives the locality component (e.g. city) of the delivery
+    address of the person or organization.

+
+    
The value must be
+    text.

+
+    
A single property with the name locality may be present
+    within the item that forms the
+    value of an adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
region (inside adr)

+
+   

+
+    
Gives the region component (e.g. state or province) of the
+    delivery address of the person or organization.

+
+    
The value must be
+    text.

+
+    
A single property with the name region may be present within
+    the item that forms the value of an adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
postal-code (inside adr)

+
+   

+
+    
Gives the postal code component of the delivery address of the
+    person or organization.

+
+    
The value must be
+    text.

+
+    
A single property with the name postal-code may be present
+    within the item that forms the
+    value of an adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
country-name (inside adr)

+
+   

+
+    
Gives the country name component of the delivery address of the
+    person or organization.

+
+    
The value must be
+    text.

+
+    
A single property with the name country-name may be
+    present within the item that
+    forms the value of an
+    adr property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
label

+
+   

+
+    
Gives the formatted text corresponding to the delivery address
+    of the person or organization.

+
+    
The value must be
+    either text or an item with zero
+    or more type properties
+    and exactly one value
+    property.

+
+    
If no type properties
+    are present within an item that
+    forms the value of a
+    label property of an item with the type http://microformats.org/profile/hcard, or if the value of such a label property is text, then the
+    address type strings intl, postal, parcel, and work are implied.

+
+    
Any number of properties with the name label may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
type (inside label)

+
+   

+
+    
Gives the type of delivery address.

+
+    
The value must be
+    text that, when compared in a case-sensitive manner,
+    is equal to one of the address type strings.

+
+    
Within each item with the
+    type http://microformats.org/profile/hcard, there must be no more
+    than one label property item with a type property whose value is
+    pref.

+
+    
Any number of properties with the name type may be present within the
+    item that forms the value of a label property of an item with the type http://microformats.org/profile/hcard, but within each such label property item there must only be one type property per distinct
+    value.

+
+   

+
+   
value (inside label)

+
+   

+
+    
Gives the actual formatted text corresponding to the delivery
+    address of the person or organization.

+
+    
The value must be
+    text.

+
+    
Exactly one property with the name value must be present within
+    the item that forms the value of a label property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
tel

+
+   

+
+    
Gives the telephone number of the person or organization.

+
+    
The value must be
+    either text that can be interpreted as a telephone number as
+    defined in the CCITT specifications E.163 and X.121, or an item with zero or more type properties and exactly one
+    value property. [E163] [X121]

+
+    
If no type properties
+    are present within an item that
+    forms the value of a
+    tel property of an item with the type http://microformats.org/profile/hcard, or if the value of such a tel property is text, then the telephone type string voice is implied.

+
+    
Any number of properties with the name tel may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
type (inside tel)

+
+   

+
+    
Gives the type of telephone number.

+
+    
The value must be
+    text that, when compared in a case-sensitive manner,
+    is equal to one of the telephone type strings.

+
+    
Within each item with the
+    type http://microformats.org/profile/hcard, there must be no more
+    than one tel property item with a type property whose value is
+    pref.

+
+    
Any number of properties with the name type may be present within the
+    item that forms the value of a tel property of an item with the type http://microformats.org/profile/hcard, but within each such tel property item there must only be one type property per distinct
+    value.

+
+   

+
+   
value (inside tel)

+
+   

+
+    
Gives the actual telephone number of the person or
+    organization.

+
+    
The value must be
+    text that can be interpreted as a telephone number as defined in
+    the CCITT specifications E.163 and X.121. [E163] [X121]

+
+    
Exactly one property with the name value must be present within the
+    item that forms the value of a tel property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
email

+
+   

+
+    
Gives the e-mail address of the person or organization.

+
+    
The value must be
+    either text or an item with zero
+    or more type properties
+    and exactly one value
+    property.

+
+    
If no type properties
+    are present within an item that
+    forms the value of an
+    email property of an item with the type http://microformats.org/profile/hcard, or if the value of such an email property is text, then the
+    e-mail type string internet is
+    implied.

+
+    
Any number of properties with the name email may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
type (inside email)

+
+   

+
+    
Gives the type of e-mail address.

+
+    
The value must be
+    text that, when compared in a case-sensitive manner,
+    is equal to one of the e-mail type strings.

+
+    
Within each item with the
+    type http://microformats.org/profile/hcard, there must be no more
+    than one email property item with a type property whose value is
+    pref.

+
+    
Any number of properties with the name type may be present within the
+    item that forms the value of an email property of an item with the type http://microformats.org/profile/hcard, but within each such email property item there must only be one type property per distinct
+    value.

+
+   

+
+   
value (inside email)

+
+   

+
+    
Gives the actual e-mail address of the person or
+    organization.

+
+    
The value must be
+    text.

+
+    
Exactly one property with the name value must be present within
+    the item that forms the value of an email property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
mailer

+
+   

+
+    
Gives the name of the e-mail software used by the person or
+    organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name mailer may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
tz

+
+   

+
+    
Gives the time zone of the person or organization.

+
+    
The value must be
+    text and must match the following syntax:

+
+    
  1. Either a U+002B PLUS SIGN character (+) or a U+002D
+     HYPHEN-MINUS character (-).
    2. 
+
+     
  2. A valid non-negative integer that is exactly two
+     digits long and that represents a number in the range
+     00..23.
    3. 
+
+     
  3. A U+003A COLON character (:).
    4. 
+
+     
  4. A valid non-negative integer that is exactly two
+     digits long and that represents a number in the range
+     00..59.
    5. 
+
+    
Any number of properties with the name tz may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
geo

+
+   

+
+    
Gives the geographical position of the person or
+    organization.

+
+    
The value must be
+    text and must match the following syntax:

+
+    
  1. Optionally, either a U+002B PLUS SIGN character (+) or a
+     U+002D HYPHEN-MINUS character (-).
    2. 
+
+     
  2. One or more digits in the range U+0030 DIGIT ZERO (0) to
+     U+0039 DIGIT NINE (9).
    3. 
+
+     
  3. Optionally*, a U+002E FULL STOP character (.) followed by one
+     or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+     NINE (9).
    4. 
+
+     
  4. A U+003B SEMICOLON character (;).
    5. 
+
+     
  5. Optionally, either a U+002B PLUS SIGN character (+) or a
+     U+002D HYPHEN-MINUS character (-).
    6. 
+
+     
  6. One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
+     DIGIT NINE (9).
    7. 
+
+     
  7. Optionally*, a U+002E FULL STOP character (.) followed by one
+     or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+     NINE (9).
    8. 
+
+    
The optional components marked with an asterisk (*) should be
+    included, and should have six digits each.

+
+    
+    
The value specifies latitude and longitude, in
+    that order (i.e., "LAT LON" ordering), in decimal degrees. The
+    longitude represents the location east and west of the prime
+    meridian as a positive or negative real number, respectively.  The
+    latitude represents the location north and south of the equator as
+    a positive or negative real number, respectively.

+
+    
Any number of properties with the name geo may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
title

+
+   

+
+    
Gives the job title, functional position or function of the
+    person or organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name title may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
role

+
+   

+
+    
Gives the role, occupation, or business category of the person
+    or organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name role may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   

+
+   

+
+    
Gives the logo of the person or organization.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name logo may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
agent

+
+   

+
+    
Gives the contact information of another person who will act on
+    behalf of the person or organization.

+
+    
The value must be
+    either an item with the type
+    http://microformats.org/profile/hcard, or an absolute
+    URL, or text.

+
+    
Any number of properties with the name agent may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
org

+
+   

+
+    
Gives the name and units of the organization.

+
+    
The value must be
+    either text or an item with one
+    organization-name
+    property and zero or more organization-unit
+    properties.

+
+    
Any number of properties with the name org may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
organization-name (inside org)

+
+   

+
+    
Gives the name of the organization.

+
+    
The value must be
+    text.

+
+    
Exactly one property with the name organization-name
+    must be present within the item
+    that forms the value
+    of an org property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
organization-unit (inside org)

+
+   

+
+    
Gives the name of the organization unit.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name organization-unit
+    may be present within the item
+    that forms the value
+    of the org property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
categories

+
+   

+
+    
Gives the name of a category or tag that the person or
+    organization could be classified as.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name categories may be present
+    within each item with the type
+    http://microformats.org/profile/hcard.

+
+   

+
+
+   
note

+
+   

+
+    
Gives supplemental information or a comment about the person or
+    organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name note may be present
+    within each item with the type
+    http://microformats.org/profile/hcard.

+
+   

+
+
+   
+
+
+   
rev

+
+   

+
+    
Gives the revision date and time of the contact
+    information.

+
+    
The value must be
+    text that is a valid global date and time string.

+
+    
+    
The value distinguishes the current revision of
+    the information for other renditions of the information.

+
+    
Any number of properties with the name rev may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
sort-string

+
+   

+
+    
Gives the string to be used for sorting the person or
+    organization.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name sort-string may be present
+    within each item with the type
+    http://microformats.org/profile/hcard.

+
+   

+
+
+   
sound

+
+   

+
+    
Gives a sound file relating to the person or organization.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name sound may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
+
+
+   
url

+
+   

+
+    
Gives a URL relating to the person or
+    organization.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name url may be present within each item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+   
+
+
+   
class

+
+   

+
+    
Gives the access classification of the information regarding
+    the person or organization.

+
+    
The value must be
+    text with one of the following values:

+
+    
  • public
    • 
+     
  • private
    • 
+     
  • confidential
    • 
+    
This is merely advisory and cannot be
+    considered a confidentiality measure.

+
+    
Any number of properties with the name class may be present
+    within each item with the type
+    http://microformats.org/profile/hcard.

+
+   

+
+
+   
+
+
+   
+
+   
impp

+
+   

+
+    
Gives a URL for instant messaging and presence
+    protocol communications with the person or organization.

+
+    
The value must be
+    either an absolute URL or an item with zero or more type properties and exactly one
+    value property.

+
+    
If no type properties
+    are present within an item that
+    forms the value of an
+    impp property of an item with the type http://microformats.org/profile/hcard, or if the value of such an impp property is an absolute
+    URL, then no IMPP type strings are
+    implied.

+
+    
Any number of properties with the name impp may be present within each
+    item with the type http://microformats.org/profile/hcard.

+
+   

+
+   
type (inside impp)

+
+   

+
+    
Gives the intended use of the IMPP URL.

+
+    
The value must be
+    text that, when compared in a case-sensitive manner,
+    is equal to one of the IMPP type strings.

+
+    
Within each item with the
+    type http://microformats.org/profile/hcard, there must be no more
+    than one impp property item with a type property whose value is
+    pref.

+
+    
Any number of properties with the name type may be present within the
+    item that forms the value of an impp property of an item with the type http://microformats.org/profile/hcard, but within each such impp property item there must only be one type property per distinct
+    value.

+
+   

+
+   
value (inside impp)

+
+   

+
+    
Gives the actual URL for instant messaging and
+    presence protocol communications with the person or
+    organization.

+
+    
The value must be
+    an absolute URL.

+
+    
Exactly one property with the name value must be present within
+    the item that forms the value of an impp property of an item with the type http://microformats.org/profile/hcard.

+
+   

+
+
+  
The address type strings are:

+
+  
dom

+   

+    
Indicates a domestic delivery address.

+   

+
+   
intl

+   

+    
Indicates an international delivery address.

+   

+
+   
postal

+   

+    
Indicates a postal delivery address.

+   

+
+   
parcel

+   

+    
Indicates a parcel delivery address.

+   

+
+   
home

+   

+    
Indicates a residential delivery address.

+   

+
+   
work

+   

+    
Indicates a delivery address for a place of work.

+   

+
+   
pref

+   

+
+    
Indicates the preferred delivery address when multiple
+    addresses are specified.

+
+   

+
+  
The telephone type strings are:

+
+  
home

+   

+    
Indicates a residential number.

+   

+
+   
msg

+   

+    
Indicates a telephone number with voice messaging support.

+   

+
+   
work

+   

+    
Indicates a telephone number for a place of work.

+   

+
+   
voice

+   

+    
Indicates a voice telephone number.

+   

+
+   
fax

+   

+    
Indicates a facsimile telephone number.

+   

+
+   
cell

+   

+    
Indicates a cellular telephone number.

+   

+
+   
video

+   

+    
Indicates a video conferencing telephone number.

+   

+
+   
pager

+   

+    
Indicates a paging device telephone number.

+   

+
+   
bbs

+   

+    
Indicates a bulletin board system telephone number.

+   

+
+   
modem

+   

+    
Indicates a MODEM-connected telephone number.

+   

+
+   
car

+   

+    
Indicates a car-phone telephone number.

+   

+
+   
isdn

+   

+    
Indicates an ISDN service telephone number.

+   

+
+   
pcs

+   

+    
Indicates a personal communication services telephone number.

+   

+
+   
pref

+   

+
+    
Indicates the preferred telephone number when multiple
+    telephone numbers are specified.

+
+   

+
+  
The e-mail type strings are:

+
+  
internet

+   

+    
Indicates an Internet e-mail address.

+   

+
+   
x400

+   

+    
Indicates a X.400 addressing type.

+   

+
+   
pref

+   

+
+    
Indicates the preferred e-mail address when multiple e-mail
+    addresses are specified.

+
+   

+
+  
The IMPP type strings are:

+
+  
personal

+   
business

+   

+    
Indicates the type of communication for which this IMPP
+    URL is appropriate.

+   

+
+   
home

+   
work

+   
mobile

+   

+    
Indicates the location of a device associated with this IMPP
+    URL.

+   

+
+   
pref

+   

+    
Indicates the preferred address when multiple IMPP
+    URLs are specified.

+   

+
+  
5.4.1.1 Conversion to vCard

+
+  
Given a list of nodes nodes in a
+  Document, a user agent must run the following algorithm
+  to extract any vCard data
+  represented by those nodes (only the first vCard is
+  returned):

+
+  
  1. If none of the nodes in nodes are items with the item type
+   http://microformats.org/profile/hcard, then
+   there is no vCard. Abort the algorithm, returning nothing.
    2. 
+
+   
  2. Let node be the first node in nodes that is an item with the item type
+   http://microformats.org/profile/hcard.
    3. 
+
+   
  3. Let output be an empty string.
    4. 
+
+   
  4. Add a vCard line with the type "BEGIN" and the value "VCARD"
+   to output.
    5. 
+
+   
  5. Add a vCard line with the type "PROFILE" and the value "VCARD" to output.
    6. 
+
+   
  6. Add a vCard line with the type "VERSION" and the value "3.0"
+   to output.
    7. 
+
+   
  7. Add a vCard line with the type "SOURCE" and the result of escaping the vCard
+   text string that is the document's current
+   address as the value to output.
    8. 
+
+   
  8. If the title element is not null,
+   add a vCard line with the type "NAME" and with the result of escaping the
+   vCard text string obtained from the textContent
+   of the title element as the value to output.
    9. 
+
+   
  9. If node has a global
+   identifier, add a vCard line with the type
+   "UID" and with the result of escaping
+   the vCard text string of that global identifier
+   as the value to output.
    10. 
+
+   
  10. 
+
+    
    For each element element that is a property of the item
+    node: for each name name
+    in element's property names, run
+    the following substeps:
    
+
+    
    1. Let parameters be an empty set of
+     name-value pairs.
      2. 
+
+     
    2. 
+
+      
      Run the appropriate set of substeps from the following
+      list. The steps will set a variable value,
+      which is used in the next step.
      
+
+      
      If the property's value is an item subitem
+       and name is n
      
+
+       
      
+
+        
      1. Let value be the empty
+         string.
        2. 
+
+         
      2. Append to value the result of
+         collecting the first vCard subproperty named
+         family-name in
+         subitem.
        
+
+         
      3. Append a U+003B SEMICOLON character (;) to value.
        4. 
+
+         
      4. Append to value the result of
+         collecting the first vCard subproperty named
+         given-name in subitem.
        
+
+         
      5. Append a U+003B SEMICOLON character (;) to value.
        6. 
+
+         
      6. Append to value the result of
+         collecting the first vCard subproperty named
+         additional-name in
+         subitem.
        
+
+         
      7. Append a U+003B SEMICOLON character (;) to value.
        8. 
+
+         
      8. Append to value the result of
+         collecting the first vCard subproperty named
+         honorific-prefix
+         in subitem.
        
+
+         
      9. Append a U+003B SEMICOLON character (;) to value.
        10. 
+
+         
      10. Append to value the result of
+         collecting the first vCard subproperty named
+         honorific-suffix
+         in subitem.
        
+
+        
      
+
+       
      If the property's value is an item subitem
+       and name is adr
      
+
+       
      
+
+        
      1. Let value be the empty
+         string.
        2. 
+
+         
      2. Append to value the result of
+         collecting vCard subproperties named post-office-box
+         in subitem.
        
+
+         
      3. Append a U+003B SEMICOLON character (;) to value.
        4. 
+
+         
      4. Append to value the result of
+         collecting vCard subproperties named extended-address
+         in subitem.
        
+
+         
      5. Append a U+003B SEMICOLON character (;) to value.
        6. 
+
+         
      6. Append to value the result of
+         collecting vCard subproperties named street-address in
+         subitem.
        
+
+         
      7. Append a U+003B SEMICOLON character (;) to value.
        8. 
+
+         
      8. Append to value the result of
+         collecting the first vCard subproperty named
+         locality in subitem.
        
+
+         
      9. Append a U+003B SEMICOLON character (;) to value.
        10. 
+
+         
      10. Append to value the result of
+         collecting the first vCard subproperty named
+         region in subitem.
        
+
+         
      11. Append a U+003B SEMICOLON character (;) to value.
        12. 
+
+         
      12. Append to value the result of
+         collecting the first vCard subproperty named
+         postal-code in
+         subitem.
        
+
+         
      13. Append a U+003B SEMICOLON character (;) to value.
        14. 
+
+         
      14. Append to value the result of
+         collecting the first vCard subproperty named
+         country-name
+         in subitem.
        
+
+         
      15. If there is a property named type in subitem, and the first such property has a
+         value that is not
+         an item and whose value
+         consists only of alphanumeric ASCII characters,
+         then add a parameter named "TYPE" whose
+         value is the value of that property
+         to parameters.
        16. 
+
+        
      
+
+       
      If the property's value is an item subitem
+       and name is org
      
+
+       
      
+
+        
      1. Let value be the empty
+         string.
        2. 
+
+         
      2. Append to value the result of
+         collecting the first vCard subproperty named
+         organization-name
+         in subitem.
        
+
+         
      3. 
+
+          
        For each property named organization-unit
+          in subitem, run the following steps:
        
+
+          
        1. If the value of the property
+           is an item, then skip
+           this property.
          2. 
+
+           
        2. Append a U+003B SEMICOLON character (;) to value.
          3. 
+
+           
        3. Append the result of escaping the vCard text
+           string given by the value of the property
+           to value.
          4. 
+
+          
        4. 
+
+        
      
+
+       
      If the property's value is an item subitem
+       with the item type http://microformats.org/profile/hcard
+       and name is agent
      
+
+       
      
+
+        
      1. Let value be the result of
+         escaping the vCard text string obtained from
+         extracting a vCard from the element that
+         represents subitem.
        2. 
+
+         
      2. Add a parameter named "VALUE"
+         whose value is "VCARD" to parameters.
        3. 
+
+        
      
+
+       
      If the property's value is an item and name
+       is none of the above
      
+
+       
      
+
+        
      1. Let value be the result of
+         collecting the first vCard subproperty named
+         value in subitem.
        
+
+         
      2. If there is a property named type in subitem, and the
+         first such property has a value that is not an
+         item and whose value
+         consists only of alphanumeric ASCII characters,
+         then add a parameter named "TYPE" whose
+         value is the value of that property
+         to parameters.
        3. 
+
+        
      
+
+       
      Otherwise (the property's value is not an item)
      
+
+       
      
+
+        
      1. Let value be the property's value.
        2. 
+
+         
      2. If element is one of the URL
+         property elements, add a parameter with the name "VALUE" and the value "URI" to parameters.
        3. 
+
+         
      3. Otherwise, if element is a
+         time element and the value is
+         a valid date string, add a parameter with the name
+         "VALUE" and the value "DATE" to parameters.
        4. 
+
+         
      4. Otherwise, if element is a
+         time element and the value is
+         a valid global date and time string, add a
+         parameter with the name "VALUE" and the
+         value "DATE-TIME" to parameters.
        5. 
+
+         
      5. Prefix every U+005C REVERSE SOLIDUS character (\) in
+         value with another U+005C REVERSE SOLIDUS
+         character (\).
        6. 
+
+         
      6. Prefix every U+002C COMMA character (,) in value with a U+005C REVERSE SOLIDUS character
+         (\).
        7. 
+
+         
      7. Unless name is geo, prefix every U+003B SEMICOLON
+         character (;) in value with a U+005C
+         REVERSE SOLIDUS character (\).
        8. 
+
+         
      8. Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
+         character pair (CRLF) in value with a
+         U+005C REVERSE SOLIDUS character (\) followed by a U+006E
+         LATIN SMALL LETTER N character (n).
        9. 
+
+         
      9. Replace every remaining U+000D CARRIAGE RETURN (CR) or
+         U+000A LINE FEED (LF) character in value
+         with a U+005C REVERSE SOLIDUS character (\) followed by a
+         U+006E LATIN SMALL LETTER N character (n).
        10. 
+
+        
      
+
+      
      3. 
+
+     
    3. 
+
+      
      Add a vCard line with the type name, the parameters parameters, and the value value to output.
      
+
+     
      4. 
+
+    
    11. 
+
+   
  11. Add a vCard line with the type "END" and the value "VCARD"
+   to output.
    12. 
+
+  
When the above algorithm says that the user agent is to add
+  a vCard line consisting of a type type,
+  optionally some parameters, and a value value to
+  a string output, it must run the following
+  steps:

+
+  
  1. Let line be an empty string.
+
+   
  2. Append type, converted to
+   ASCII uppercase, to line.
    3. 
+
+   
  3. 
+
+    
    If there are any parameters, then for each parameter, in the
+    order that they were added, run these substeps:
    
+
+    
    1. Append a U+003B SEMICOLON character (;) to line.
      2. 
+
+     
    2. Append the parameter's name to line.
      3. 
+
+     
    3. Append a U+003D EQUALS SIGN character (=) to line.
      4. 
+
+     
    4. Append the parameter's value to line.
      5. 
+
+    
    4. 
+
+   
  4. Append a U+003A COLON character (:) to line.
    5. 
+
+   
  5. Append value to line.
    6. 
+
+   
  6. Let maximum length be 75.
    7. 
+
+   
  7. 
+
+    
    If and while line is longer than maximum length Unicode code points long, run the
+    following substeps:
    
+
+    
    1. Append the first maximum length
+     Unicode code points of line to output.
      2. 
+
+     
    2. Remove the first maximum length
+     Unicode code points from line.
      3. 
+
+     
    3. Append a U+000D CARRIAGE RETURN character (CR) to output.
      4. 
+
+     
    4. Append a U+000A LINE FEED character (LF) to output.
      5. 
+
+     
    5. Append a U+0020 SPACE character to output.
      6. 
+
+     
    6. Let maximum length be 74.
      7. 
+
+    
    8. 
+
+   
  8. Append (what remains of) line to output.
    9. 
+
+   
  9. Append a U+000D CARRIAGE RETURN character (CR) to output.
    10. 
+
+   
  10. Append a U+000A LINE FEED character (LF) to output.
    11. 
+
+  
When the steps above require the user agent to obtain the result
+  of collecting vCard subproperties named subname in subitem, the user
+  agent must run the following steps:

+
+  
  1. Let value be the empty string.
    2. 
+
+   
  2. 
+
+    
    For each property named subname in the item
+    subitem, run the following substeps:
    
+
+    
    1. If the value
+     of the property is itself an item, then skip this
+     property.
      2. 
+
+     
    2. If this is not the first property named subname in subitem (ignoring
+     any that were skipped by the previous step), then append a U+002C
+     COMMA character (,) to value.
      3. 
+
+     
    3. Append the result of escaping the vCard text
+     string given by the value of the property to
+     value.
      4. 
+
+    
    3. 
+
+   
  3. Return value.
    4. 
+
+  
When the steps above require the user agent to obtain the result
+  of collecting the first vCard subproperty named subname in subitem, the user
+  agent must run the following steps:

+
+  
  1. If there are no properties named subname
+   in subitem, then abort these substeps,
+   returning the empty string.
    2. 
+
+   
  2. If the value of
+   the first property named subname in subitem is an item, then abort these substeps,
+   returning the empty string.
    3. 
+
+   
  3. Return the result of escaping the vCard text
+   string given by the value of the first property
+   named subname in subitem.
    4. 
+
+  
When the above algorithms say the user agent is to escape the vCard text
+  string value, the user agent must use the
+  following steps:

+
+  
  1. Prefix every U+005C REVERSE SOLIDUS character (\) in value with another U+005C REVERSE SOLIDUS character
+   (\).
    2. 
+
+   
  2. Prefix every U+002C COMMA character (,) in value with a U+005C REVERSE SOLIDUS character
+   (\).
    3. 
+
+   
  3. Prefix every U+003B SEMICOLON character (;) in value with a U+005C REVERSE SOLIDUS character
+   (\).
    4. 
+
+   
  4. Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
+   character pair (CRLF) in value with a U+005C
+   REVERSE SOLIDUS character (\) followed by a U+006E LATIN SMALL
+   LETTER N character (n).
    5. 
+
+   
  5. Replace every remaining U+000D CARRIAGE RETURN (CR) or
+   U+000A LINE FEED (LF) character in value with a
+   U+005C REVERSE SOLIDUS character (\) followed by a U+006E LATIN
+   SMALL LETTER N character (n).
    6. 
+
+   
  6. Return the mutated value.
    7. 
+
+  
This algorithm can generate invalid vCard output, if
+  the input does not conform to the rules described for the http://microformats.org/profile/hcard
+  item type and defined property names.
 
+
+
+
+  
5.4.1.2 Examples

+
+  
This section is non-normative.

+
+  

+
+   
Here is a long example vCard for a fictional character called
+   "Jack Bauer":

+
+   
<section id="jack" itemscope itemtype="http://microformats.org/profile/hcard">
+ <h1 itemprop="fn">Jack Bauer</h1>
+ <div itemprop="n">
+  <meta itemprop="given-name" content="Jack">
+  <meta itemprop="family-name" content="Bauer">
+ </div>
+ <img itemprop="photo" alt="" src="jack-bauer.jpg">
+ <p itemprop="org" itemscope>
+  <span itemprop="organization-name">Counter-Terrorist Unit</span>
+  (<span itemprop="organization-unit">Los Angeles Division</span>)
+ </p>
+ <p>
+  <span itemprop="adr" itemscope>
+   <span itemprop="street-address">10201 W. Pico Blvd.</span><br>
+   <span itemprop="locality">Los Angeles</span>,
+   <span itemprop="region">CA</span>
+   <span itemprop="postal-code">90064</span><br>
+   <span itemprop="country-name">United States</span><br>
+  </span>
+  <span itemprop="geo">34.052339;-118.410623</span>
+ </p>
+ <h2>Assorted Contact Methods</h2>
+ <ul>
+  <li itemprop="tel" itemscope>
+   <span itemprop="value">+1 (310) 597 3781</span> <span itemprop="type">work</span>
+   <meta itemprop="type" content="pref">
+  </li>
+  <li><a itemprop="url" href="http://en.wikipedia.org/wiki/Jack_Bauer">I'm on Wikipedia</a>
+  so you can leave a message on my user talk page.</li>
+  <li><a itemprop="url" href="http://www.jackbauerfacts.com/">Jack Bauer Facts</a></li>
+  <li itemprop="email"><a href="mailto:j.bauer@la.ctu.gov.invalid">j.bauer@la.ctu.gov.invalid</a></li>
+  <li itemprop="tel" itemscope>
+   <span itemprop="value">+1 (310) 555 3781</span> <span>
+   <meta itemprop="type" content="cell">mobile phone</span>
+  </li>
+ </ul>
+ <p itemprop="note">If I'm out in the field, you may be better off contacting <span
+ itemprop="agent" itemscope itemtype="http://microformats.org/profile/hcard"><a
+ itemprop="email" href="mailto:c.obrian@la.ctu.gov.invalid"><span
+ itemprop="fn"><span itemprop="n" itemscope><span
+ itemprop="given-name">Chloe</span> <span
+ itemprop="family=name">O'Brian</span></span></span></a></span>
+ if it's about work, or ask <span itemprop="agent">Tony Almeida</span>
+ if you're interested in the CTU five-a-side football team we're trying to get going.</p>
+ <ins datetime="2008-07-20T21:00:00+01:00">
+  <span itemprop="rev" itemscope>
+   <meta itemprop="type" content="date-time">
+   <meta itemprop="value" content="2008-07-20T21:00:00+01:00">
+  </span>
+  <p itemprop="tel" itemscope><strong>Update!</strong>
+  My new <span itemprop="type">home</span> phone number is
+  <span itemprop="value">01632 960 123</span>.</p>
+ </ins>
+</section>

+
+   
The odd line wrapping is needed because newlines are meaningful
+   in microdata: newlines would be preserved in a conversion to, for
+   example, the vCard format.

+
+  

+
+  

+
+   
This example shows a site's contact details (using the
+   address element) containing an address with two street
+   components:

+
+   
<address itemscope itemtype="http://microformats.org/profile/hcard">
+ <strong itemprop="fn"><span itemprop="n"><span itemprop="given-name">Alfred</span>
+ <span itemprop="family-name">Person</span></span></strong> <br>
+ <span itemprop="adr" itemscope>
+  <span itemprop="street-address">1600 Amphitheatre Parkway</span> <br>
+  <span itemprop="street-address">Building 43, Second Floor</span> <br>
+  <span itemprop="locality">Mountain View</span>,
+   <span itemprop="region">CA</span> <span itemprop="postal-code">94043</span>
+ </span>
+</address>

+
+  

+
+  

+
+   
The vCard vocabulary can be used to just mark up people's
+   names:

+
+   
<span itemscope itemtype="http://microformats.org/profile/hcard"
+><span itemprop=fn><span itemprop="n"><span itemprop="given-name"
+>George</span> <span itemprop="family-name">Washington</span></span
+></span></span>

+
+   
This creates a single item with a two name-value pairs, one with
+   the name "fn" and the value "George Washington", and the other with
+   the name "n" and a second item as its value, the second item having
+   the two name-value pairs "given-name" and "family-name" with the
+   values "George" and "Washington" respectively. This is defined to
+   map to the following vCard:

+
+   
BEGIN:VCARD
+PROFILE:VCARD
+VERSION:3.0
+SOURCE:document's address
+FN:George Washington
+N:Washington;George;;;
+END:VCARD

+
+  

+
+
+
+  
5.4.2 vEvent

+
+
+
+  
An item with the item type http://microformats.org/profile/hcalendar#vevent
+  represents an event.

+
+  
This vocabulary supports global identifiers for items.

+
+  
The following are the type's defined property names. They are based on the
+  vocabulary defined in the iCalendar specification, where more
+  information on how to interpret the values can be found. [RFC2445]

+
+  
Only the parts of the iCalendar vocabulary relating
+  to events are used here; this vocabulary cannot express a complete
+  iCalendar instance.

+
+  
attach

+
+   

+
+    
Gives the address of an associated document for the event.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name attach may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
categories

+
+   

+
+    
Gives the name of a category or tag that the event could be
+    classified as.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name categories may be present
+    within each item with the type
+    http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
class

+
+   

+
+    
Gives the access classification of the information regarding
+    the event.

+
+    
The value must be
+    text with one of the following values:

+
+    
  • public
    • 
+     
  • private
    • 
+     
  • confidential
    • 
+    
This is merely advisory and cannot be
+    considered a confidentiality measure.

+
+    
A single property with the name class may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
comment

+
+   

+
+    
Gives a comment regarding the event.

+
+    
The value must be
+    text.

+
+    
Any number of properties with the name comment may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
description

+
+   

+
+    
Gives a detailed description of the event.

+
+    
The value must be
+    text.

+
+    
A single property with the name description may be present
+    within each item with the type
+    http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
geo

+
+   

+
+    
Gives the geographical position of the event.

+
+    
The value must be
+    text and must match the following syntax:

+
+    
  1. Optionally, either a U+002B PLUS SIGN character (+) or a
+     U+002D HYPHEN-MINUS character (-).
    2. 
+
+     
  2. One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
+     DIGIT NINE (9).
    3. 
+
+     
  3. Optionally*, a U+002E FULL STOP character (.) followed by one
+     or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+     NINE (9).
    4. 
+
+     
  4. A U+003B SEMICOLON character (;).
    5. 
+
+     
  5. Optionally, either a U+002B PLUS SIGN character (+) or a
+     U+002D HYPHEN-MINUS character (-).
    6. 
+
+     
  6. One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
+     DIGIT NINE (9).
    7. 
+
+     
  7. Optionally*, a U+002E FULL STOP character (.) followed by one
+     or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+     NINE (9).
    8. 
+
+    
The optional components marked with an asterisk (*) should be
+    included, and should have six digits each.
 
+
+    
+    
The value specifies latitude and longitude, in
+    that order (i.e., "LAT LON" ordering), in decimal degrees. The
+    longitude represents the location east and west of the prime
+    meridian as a positive or negative real number, respectively.  The
+    latitude represents the location north and south of the equator as
+    a positive or negative real number, respectively.

+
+    
A single property with the name geo may be present within each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
location

+
+   

+
+    
Gives the location of the event.

+
+    
The value must be
+    text.
 
+
+    
A single property with the name location may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+   
resources

+
+   

+
+    
Gives a resource that will be needed for the event.

+
+    
The value must be
+    text.
 
+
+    
Any number of properties with the name resources may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
status

+
+   

+
+    
Gives the confirmation status of the event.

+
+    
The value must be
+    text with one of the following values:

+
+    
  • tentative
    • 
+     
  • confirmed
    • 
+     
  • cancelled
    •  
+    
A single property with the name status may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
summary

+
+   

+
+    
Gives a short summary of the event.

+
+    
The value must be
+    text.

+
+    
User agents should replace U+000A LINE FEED (LF) characters in
+    the value by U+0020
+    SPACE characters when using the value.

+
+    
A single property with the name summary may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
dtend

+
+   

+
+    
Gives the date and time by which the event ends.

+
+    
If the property with the name dtend is present within an item with the type http://microformats.org/profile/hcalendar#vevent
+    that has a property with the name dtstart whose value is a
+    valid date string, then the value of the property with
+    the name dtend must be text
+    that is a valid date string also. Otherwise, the
+    value of the property
+    must be text that is a valid global date and time
+    string.

+
+    
In either case, the value be later in time than
+    the value of the dtstart
+    property of the same item.

+
+    
The time given by the dtend property is not
+    inclusive. For day-long events, therefore, the dtend property's value will be the day
+    after the end of the event.

+
+    
A single property with the name dtend may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent,
+    so long as that http://microformats.org/profile/hcalendar#vevent
+    does not have a property with the name duration.

+
+   

+
+
+   
dtstart

+
+   

+
+    
Gives the date and time at which the event starts.

+
+    
The value must be
+    text that is either a valid date string or a
+    valid global date and time string.

+
+    
Exactly one property with the name dtstart must be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
duration

+
+   

+
+    
Gives the duration of the event.

+
+    
The value must be
+    text that is a valid vevent duration string.

+
+    
The duration represented is the sum of all the durations
+    represented by integers in the value.

+
+    
A single property with the name duration may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent,
+    so long as that http://microformats.org/profile/hcalendar#vevent
+    does not have a property with the name dtend.

+
+   

+
+
+   
transp

+
+   

+
+    
Gives whether the event is to be considered as consuming time
+    on a calendar, for the purpose of free-busy time searches.

+
+    
The value must be
+    text with one of the following values:

+
+    
  • opaque
    • 
+     
  • transparent
    • 
+    
A single property with the name transp may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+   
contact

+
+   

+
+    
Gives the contact information for the event.

+
+    
The value must be
+    text.
 
+
+    
Any number of properties with the name contact may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+   
+
+
+   
+
+
+   
url

+
+   

+
+    
Gives a URL for the event.

+
+    
The value must be
+    an absolute URL.

+
+    
A single property with the name url may be present within each
+    item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+   
exdate

+
+   

+
+    
Gives a date and time at which the event does not occur despite
+    the recurrence rules.

+
+    
The value must be
+    text that is either a valid date string or a
+    valid global date and time string.

+
+    
Any number of properties with the name exdate may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
exrule

+
+   

+
+    
Gives a rule for finding dates and times at which the event
+    does not occur despite the recurrence rules.

+
+    
The value must be
+    text that matches the RECUR value type defined in the iCalendar
+    specification. [RFC2445]

+
+    
Any number of properties with the name exrule may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
rdate

+
+   

+
+    
Gives a date and time at which the event recurs.

+
+    
The value must be
+    text that is one of the following:
+
+    
Any number of properties with the name rdate may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
rrule

+
+   

+
+    
Gives a rule for finding dates and times at which the event
+    occurs.

+
+    
The value must be
+    text that matches the RECUR value type defined in the iCalendar
+    specification. [RFC2445]

+
+    
Any number of properties with the name rrule may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
created

+
+   

+
+    
Gives the date and time at which the event information was first
+    created in a calendaring system.

+
+    
The value must be
+    text that is a valid global date and time string.

+
+    
A single property with the name created may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+   
last-modified

+
+   

+
+    
Gives the date and time at which the event information was last
+    modified in a calendaring system.

+
+    
The value must be
+    text that is a valid global date and time string.

+
+    
A single property with the name last-modified may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
sequence

+
+   

+
+    
Gives a revision number for the event information.

+
+    
The value must be
+    text that is a valid non-negative integer.

+
+    
A single property with the name sequence may be present within
+    each item with the type http://microformats.org/profile/hcalendar#vevent.

+
+   

+
+
+   
+
+
+  
A string is a valid vevent duration string if it
+  matches the following pattern:

+
+  
  1. A U+0050 LATIN CAPITAL LETTER P character (P).
    2. 
+
+   
  2. One of the following:
+
+    
    •  A valid non-negative integer followed by a
+     U+0057 LATIN CAPITAL LETTER W character (W). The integer
+     represents a duration of that number of weeks. 
      • 
+
+     
    •  At least one, and possible both in this order, of the
+     following:
+
+      
      1.  A valid non-negative integer followed by a
+       U+0044 LATIN CAPITAL LETTER D character (D). The integer
+       represents a duration of that number of days. 
        2. 
+
+       
      2.  A U+0054 LATIN CAPITAL LETTER T character (T) followed by
+       any one of the following, or the first and second of the
+       following in that order, or the second and third of the
+       following in that order, or all three of the following in this
+       order:
+
+        
        1.  A valid non-negative integer followed by a
+         U+0048 LATIN CAPITAL LETTER H character (H). The integer
+         represents a duration of that number of hours. 
          2. 
+
+         
        2.  A valid non-negative integer followed by a
+         U+004D LATIN CAPITAL LETTER M character (M). The integer
+         represents a duration of that number of minutes. 
          3. 
+
+         
        3.  A valid non-negative integer followed by a
+         U+0053 LATIN CAPITAL LETTER S character (S). The integer
+         represents a duration of that number of seconds. 
          4. 
+
+        
      • 
+
+    
    3. 
+
+  
5.4.2.1 Conversion to iCalendar

+
+  
Given a list of nodes nodes in a
+  Document, a user agent must run the following algorithm
+  to extract any vEvent data
+  represented by those nodes:

+
+  
  1. If none of the nodes in nodes are items with the type http://microformats.org/profile/hcalendar#vevent,
+   then there is no vEvent data. Abort the algorithm, returning
+   nothing.
    2. 
+
+   
  2. Let output be an empty string.
    3. 
+
+   
  3. Add an iCalendar line with the type "BEGIN" and the value "VCALENDAR" to output.
    4. 
+
+   
  4. Add an iCalendar line with the type "PRODID" and the value equal to a
+   user-agent-specific string representing the user agent to output.
    5. 
+
+   
  5. Add an iCalendar line with the type "VERSION" and the value "2.0"
+   to output.
    6. 
+
+   
  6. 
+
+    
    For each node node in nodes that is an item with the type http://microformats.org/profile/hcalendar#vevent,
+    run the following steps:
    
+
+    
    1. Add an iCalendar line with the type "BEGIN" and the value "VEVENT" to output.
      2. 
+
+     
    2. Add an iCalendar line with the type "DTSTAMP" and a value consisting of an iCalendar
+     DATE-TIME string representing the current date and time, with the
+     annotation "VALUE=DATE-TIME", to output.  [RFC2445]
      3. 
+
+     
    3. If the item has a
+     global identifier, add an iCalendar
+     line with the type "UID" and that
+     global identifier as the value to output.
      4. 
+
+     
    4. 
+
+      
      For each element element that is a property of the item
+      node: for each name name
+      in element's property names,
+      run the appropriate set of substeps from the following list:
      
+
+      
      If the property's value is an item
      
+
+       
      
+
+        
      Skip the property.
      
+
+       
      
+
+
+       
      If element is a time
+       element
      
+
+       
      
+
+        
      Let value be the result of stripping
+        all U+002D HYPHEN-MINUS (-) and U+003A COLON (:) characters
+        from the property's value.
      
+
+        
      If the property's value is a valid
+        date string then add an iCalendar line
+        with the type name and the value value to output, with the
+        annotation "VALUE=DATE".
      
+
+        
      Otherwise, if the property's value is a valid
+        global date and time string then add an iCalendar
+        line with the type name and the
+        value value to output,
+        with the annotation "VALUE=DATE-TIME".
      
+
+        
      Otherwise skip the property.
      
+
+       
      
+
+
+       
      Otherwise
      
+
+       
      
+
+        
      Add an iCalendar line with the type name and the property's value to output.
      
+
+       
      
+
+      
      5. 
+
+     
    5. Add an iCalendar line with the type "END" and the value "VEVENT"
+     to output.
      6. 
+
+    
    7. 
+
+   
  7. Add an iCalendar line with the type "END" and the value "VCALENDAR" to output.
    8. 
+
+  
When the above algorithm says that the user agent is to add
+  an iCalendar line consisting of a type type, a value value, and
+  optionally an annotation, to a string output, it
+  must run the following steps:

+
+  
  1. Let line be an empty string.
    2. 
+
+   
  2. Append type, converted to
+   ASCII uppercase, to line.
    3. 
+
+   
  3. 
+
+    
    If there is an annotation:
    
+
+    
    1. Append a U+003B SEMICOLON character (;) to line.
      2. 
+
+     
    2. Append the annotation to line.
      3. 
+
+    
    4. 
+
+   
  4. Append a U+003A COLON character (:) to line.
    5. 
+
+   
  5. Prefix every U+005C REVERSE SOLIDUS character (\) in
+   value with another U+005C REVERSE SOLIDUS
+   character (\).
    6. 
+
+   
  6. Prefix every U+002C COMMA character (,) in value with a U+005C REVERSE SOLIDUS character
+   (\).
    7. 
+
+   
  7. Prefix every U+003B SEMICOLON character (;) in value with a U+005C REVERSE SOLIDUS character
+   (\).
    8. 
+
+   
  8. Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
+   character pair (CRLF) in value with a U+005C
+   REVERSE SOLIDUS character (\) followed by a U+006E LATIN SMALL
+   LETTER N character (n).
    9. 
+
+   
  9. Replace every remaining U+000D CARRIAGE RETURN (CR) or
+   U+000A LINE FEED (LF) character in value with a
+   U+005C REVERSE SOLIDUS character (\) followed by a U+006E LATIN
+   SMALL LETTER N character (n).
    10. 
+
+   
  10. Append value to line.
    11. 
+
+   
  11. Let maximum length be 75.
    12. 
+
+   
  12. 
+
+    
    If and while line is longer than maximum length Unicode code points long, run the
+    following substeps:
    
+
+    
    1. Append the first maximum length
+     Unicode code points of line to output.
      2. 
+
+     
    2. Remove the first maximum length
+     Unicode code points from line.
      3. 
+
+     
    3. Append a U+000D CARRIAGE RETURN character (CR) to output.
      4. 
+
+     
    4. Append a U+000A LINE FEED character (LF) to output.
      5. 
+
+     
    5. Append a U+0020 SPACE character to output.
      6. 
+
+     
    6. Let maximum length be 74.
      7. 
+
+    
    13. 
+
+   
  13. Append (what remains of) line to output.
    14. 
+
+   
  14. Append a U+000D CARRIAGE RETURN character (CR) to output.
    15. 
+
+   
  15. Append a U+000A LINE FEED character (LF) to output.
    16. 
+
+  
This algorithm can generate invalid iCalendar
+  output, if the input does not conform to the rules described for the
+  http://microformats.org/profile/hcalendar#vevent
+  item type and defined property names.
 
+
+
+
+  
5.4.2.2 Examples

+
+  
This section is non-normative.

+
+
+
+  

+
+   
Here is an example of a page that uses the vEvent vocabulary to
+   mark up an event:

+
+   
<body itemscope itemtype="http://microformats.org/profile/hcalendar#vevent">
+ ...
+ <h1 itemprop="summary">Bluesday Tuesday: Money Road</h1>
+ ...
+ <time itemprop="dtstart" datetime="2009-05-05T19:00:00Z">May 5th @ 7pm</time>
+ (until <time itemprop="dtend" datetime="2009-05-05T21:00:00Z">9pm</time>)
+ ...
+ <a href="http://livebrum.co.uk/2009/05/05/bluesday-tuesday-money-road"
+    rel="bookmark" itemprop="url">Link to this page</a>
+ ...
+ <p>Location: <span itemprop="location">The RoadHouse</span></p>
+ ...
+ <p><input type=button value="Add to Calendar"
+           onclick="location = getCalendar(this)"></p>
+ ...
+ <meta itemprop="description" content="via livebrum.co.uk">
+</body>

+
+   
The "getCalendar()" method could look like
+   this:

+
+   
function getCalendar(node) {
+  // This function assumes the content is valid.
+  // It is not a compliant implementation of the algorithm for extracting vEvent data.
+  while (node && (!node.itemScope || !node.itemType == 'http://microformats.org/profile/hcalendar#vevent'))
+    node = node.parentNode;
+  if (!node) {
+    alert('No event data found.');
+    return;
+  }
+  var stamp = new Date();
+  var stampString = '' + stamp.getUTCFullYear() + (stamp.getUTCMonth() + 1) + stamp.getUTCDate() + 'T' +
+                         stamp.getUTCHours() + stamp.getUTCMinutes() + stamp.getUTCSeconds() + 'Z';
+  var calendar = 'BEGIN:VCALENDAR\r\nPRODID:HTML\r\nVERSION:2.0\r\nBEGIN:VEVENT\r\nDTSTAMP:' + stampString + '\r\n';
+  if (node.itemId)
+    calendar += 'UID:' + node.itemId + '\r\n';
+  for (var propIndex = 0; propIndex < node.properties.length; propIndex += 1) {
+    var prop = node.properties[propIndex];
+    var value = prop.itemValue;
+    var parameters = '';
+    if (prop.localName == 'time') {
+      value = value.replace(/[:-]/g, '');
+      if (value.match(/T/))
+        parameters = ';VALUE=DATE';
+      else
+        parameters = ';VALUE=DATE-TIME';
+    } else {
+      value = value.replace(/\\/g, '\\n');
+      value = value.replace(/;/g, '\\;');
+      value = value.replace(/,/g, '\\,');
+      value = value.replace(/\n/g, '\\n');
+    }
+    for (var nameIndex = 0; nameIndex < prop.itemProp.length; nameIndex += 1) {
+      var name = prop.itemProp[nameIndex];
+      if (!name.match(/:/) && !name.match(/\./))
+        calendar += name.toUpperCase() + parameters + ':' + value + '\r\n';
+    }
+  }
+  calendar += 'END:VEVENT\r\nEND:VCALENDAR\r\n';
+  return 'data:text/calendar;component=vevent,' + encodeURI(calendar);
+}

+
+   
The same page could offer some markup, such as the following,
+   for copy-and-pasting into blogs:

+
+   
<div itemscope itemtype="http://microformats.org/profile/hcalendar#vevent">
+ <p>I'm going to
+ <strong itemprop="summary">Bluesday Tuesday: Money Road</strong>,
+ <time itemprop="dtstart" datetime="2009-05-05T19:00:00Z">May 5th at 7pm</time>
+ to <time itemprop="dtend" content="2009-05-05T21:00:00Z">9pm</time>,
+ at <span itemprop="location">The RoadHouse</span>!</p>
+ <p><a href="http://livebrum.co.uk/2009/05/05/bluesday-tuesday-money-road"
+       itemprop="url">See this event on livebrum.co.uk</a>.</p>
+ <meta itemprop="description" content="via livebrum.co.uk">
+</div>

+
+  

+
+
+
+  
5.4.3 Licensing works

+
+
+
+  
An item with the item type http://n.whatwg.org/work
+  represents a work (e.g. an article, an image, a video, a song,
+  etc). This type is primarily intended to allow authors to include
+  licensing information for works.

+
+  
The following are the type's defined property names.

+
+  
work

+
+   

+
+    
Identifies the work being described.

+
+    
The value must be
+    an absolute URL.

+
+    
Exactly one property with the name work must be present within each item with the type http://n.whatwg.org/work.

+
+   

+
+
+   
title

+
+   

+
+    
Gives the name of the work.

+
+    
A single property with the name title may be present within each
+    item with the type http://n.whatwg.org/work.

+
+   

+
+
+   
author

+
+   

+
+    
Gives the name or contact information of one of the authors or
+    creators of the work.

+
+    
The value must be
+    either an item with the type
+    http://microformats.org/profile/hcard, or
+    text.

+
+    
Any number of properties with the name author may be present within each
+    item with the type http://n.whatwg.org/work.

+
+   

+
+
+   
license

+
+   

+
+    
Identifies one of the licenses under which the work is
+    available.

+
+    
The value must be
+    an absolute URL.

+
+    
Any number of properties with the name license may be present within each
+    item with the type http://n.whatwg.org/work.

+
+   

+
+  
5.4.3.1 Conversion to RDF

+
+  
For the purposes of RDF processors, the triples obtained from the
+  following Turtle must be applied:

+
+  
<http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Awork>
+  <http://www.w3.org/2002/07/owl#equivalentProperty>
+  <http://www.w3.org/2002/07/owl#sameAs> .
+<http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Atitle>
+  <http://www.w3.org/2002/07/owl#equivalentProperty>
+  <http://purl.org/dc/terms/title> .
+<http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Aauthor>
+  <http://www.w3.org/2002/07/owl#equivalentProperty>
+  <http://creativecommons.org/ns#attributionName> .
+<http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Alicense>
+  <http://www.w3.org/2002/07/owl#equivalentProperty>
+  <http://www.w3.org/1999/xhtml/vocab#license> .

+
+  
The subjects of the statements above are the
+  predicates that result from converting
+  to RDF an HTML page containing microdata with an item whose
+  type is "http://n.whatwg.org/work".

+
+
+
+  
5.4.3.2 Examples

+
+  
This section is non-normative.

+
+  

+
+   
This example shows an embedded image entitled My
+   Pond, licensed under the Creative Commons Attribution-Share
+   Alike 3.0 United States License and the MIT license
+   simultaneously.

+
+   
<figure itemscope itemtype="http://n.whatwg.org/work">
+ <img itemprop="work" src="mypond.jpeg">
+ <figcaption>
+  <p><cite itemprop="title">My Pond</cite></p>
+  <p><small>Licensed under the <a itemprop="license"
+  href="http://creativecommons.org/licenses/by-sa/3.0/us/">Creative
+  Commons Attribution-Share Alike 3.0 United States License</a>
+  and the <a itemprop="license"
+  href="http://www.opensource.org/licenses/mit-license.php">MIT
+  license</a>.</small>
+ </figcaption>
+</figure>

+
+  

+
+
+
+
+
+
+
+
+
+  

+
+  
5.5 Converting HTML to other formats

+
+
+
+
+  
5.5.1 JSON

+
+  
Given a list of nodes nodes in a
+  Document, a user agent must run the following algorithm
+  to extract the microdata from those
+  nodes into a JSON form:

+
+  
  1. Let result be an empty object.
    2. 
+
+   
  2. Let items be an empty array.
    3. 
+
+   
  3. For each node in nodes, check if the element is a top-level microdata item,
+   and if it is then get the object for that element and
+   add it to items.
    4. 
+
+   
  4. Add an entry to result called "items" whose value is the array items.
    5. 
+
+   
  5. Return the result of serializing result
+   to JSON.
    6. 
+
+  
When the user agent is to get the object for an item
+  item, it must run the following substeps:

+
+  
  1. Let result be an empty object.
    2. 
+
+   
  2. If the item has an item
+   type, add an entry to result called
+   "type" whose value is the item
+   type of item.
    3. 
+
+   
  3. If the item has an global
+   identifier, add an entry to result
+   called "id" whose value is the global
+   identifier of item.
    4. 
+
+   
  4. Let properties be an empty
+   object.
    5. 
+
+   
  5. 
+
+    
    For each element element that has one or
+    more property names and is one of the properties of the item item, in the order those elements are given by the
+    algorithm that returns the properties of an item, run
+    the following substeps:
    
+
+    
    1. Let value be the property value of element.
      2. 
+
+     
    2. If value is an item, then get the
+     object for value, and then replace
+     value with the object returned from those
+     steps.
      3. 
+
+     
    3. 
+
+      
      For each name name in element's property names, run the
+      following substeps:
      
+
+      
      1. If there is no entry named name in
+       properties, then add an entry named name to properties whose
+       value is an empty array.
        2. 
+
+       
      2. Append value to the entry named name in properties.
        3. 
+
+      
      4. 
+
+    
    6. 
+
+   
  6. Add an entry to result called "properties" whose value is the object properties.
    7. 
+
+   
  7. Return result.
    8. 
+
+  
5.5.2 RDF

+
+  
To convert a Document to
+  RDF, a user agent must run the following algorithm:

+
+  
  1. 
+
+    
    If the title element is not null,
+    then generate the following triple:
    
+
+    
    subject   
     the document's current address
+     
    predicate 
     http://purl.org/dc/terms/title
+     
    object    
     the concatenation of the data of all the child text nodes of the title element, in tree order, as a plain literal, with the language information set from the language of the title element, if it is not unknown.
+
+    
    2. 
+
+   
  2. 
+
+    
    For each a, area, and
+    link element in the Document, run these
+    substeps:
    
+
+    
    1. If the element does not have a rel
+     attribute, then skip this element.
      2. 
+
+     
    2. If the element does not have an href
+     attribute, then skip this element.
      3. 
+
+     
    3. If resolving the
+     element's href attribute relative to the
+     element is not successful, then skip this element.
      4. 
+
+     
    4. Otherwise, split
+     the value of the element's rel attribute on
+     spaces, obtaining list of tokens.
      5. 
+
+     
    5. Convert each token in list of tokens
+     that does not contain a U+003A COLON characters (:) to ASCII
+     lowercase.
      6. 
+
+     
    6. If list of tokens contains more than
+     one instance of the token up, then
+     remove all such tokens.
      7. 
+
+     
    7. Coalesce duplicate tokens in list of
+     tokens.
      8. 
+
+     
    8. If list of tokens contains both the
+     tokens alternate and stylesheet, then remove them both
+     and replace them with the single (uppercase) token ALTERNATE-STYLESHEET.
      9. 
+
+     
    9. 
+
+      
      For each token token in list of tokens that contains no U+003A COLON
+      characters (:), generate the following triple:
      
+
+      
      subject   
       the document's current address
+       
      predicate 
       the concatenation of the string "http://www.w3.org/1999/xhtml/vocab#" and token, with any characters in token that are not valid in the <ifragment> production of the IRI syntax being %-escaped [RFC3987]
+       
      object    
       the absolute URL that results from resolving the value of the element's href attribute relative to the element
+      
      For each token token in list of tokens that is an absolute
+      URL, generate the following triple:
      
+
+      
      subject   
       the document's current address
+       
      predicate 
       token
+       
      object    
       the absolute URL that results from resolving the value of the element's href attribute relative to the element
+      
      10. 
+
+    
    3. 
+
+   
  3. 
+
+    
    For each meta element in the Document
+    that has a name attribute and
+    a content attribute, if the
+    value of the name attribute
+    contains no U+003A COLON characters (:), generate the following
+    triple:
    
+
+    
    subject   
     the document's current address
+     
    predicate 
     the concatenation of the string "http://www.w3.org/1999/xhtml/vocab#" and the value of the element's name attribute, converted to ASCII lowercase, with any characters in the value that are not valid in the <ifragment> production of the IRI syntax being %-escaped [RFC3987]
+     
    object    
     the value of the element's content attribute, as a plain literal, with the language information set from the language of the element, if it is not unknown
+    
    For each meta element in the Document
+    that has a name attribute and
+    a content attribute, if the
+    value of the name attribute is
+    an absolute URL, generate the following triple:
    
+
+    
    subject   
     the document's current address
+     
    predicate 
     the value of the element's name attribute
+     
    object    
     the value of the element's content attribute, as a plain literal, with the language information set from the language of the element, if it is not unknown
+    
    4. 
+
+   
  4. 
+
+    
    For each blockquote and q element in
+    the Document that has a cite
+    attribute that resolves
+    successfully relative to the element, generate the following
+    triple:
    
+
+    
    subject   
     the document's current address
+     
    predicate 
     http://purl.org/dc/terms/source
+     
    object    
     the absolute URL that results from resolving the value of the element's cite attribute relative to the element
+    
    5. 
+
+   
  5. 
+
+    
    Let memory be a mapping of items to
+    subjects, initially empty.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    For each element that is also a top-level microdata item, run the
+    following steps:
    
+
+    
    1. 
+
+      
      Generate the
+      triples for the item. Pass a reference to memory as the item/subject list. Let result be the subject returned.
      
+
+     
      2. 
+
+     
    2. 
+
+      
      Generate the following triple:
      
+
+      
      subject   
       the document's current address
+       
      predicate 
       http://www.w3.org/1999/xhtml/microdata#item
+       
      object    
       result
+      
      3. 
+
+    
    7. 
+
+  
When the user agent is to generate the triples for an
+  item item, given a reference to an
+  item/subject list memory, and optionally given a
+  fallback type fallback type and property name
+  fallback name, it must follow the following
+  steps:

+
+  
  1. If there is an entry for item in memory, then let subject be the
+   subject of that entry. Otherwise, if item has a
+   global identifier and that global
+   identifier is an absolute URL, let subject be that global
+   identifier. Otherwise, let subject be a
+   new blank node.
    2. 
+
+   
  2. Add a mapping from item to subject in memory, if there
+   isn't one already.
    3. 
+
+   
  3. If item has an item type
+   and that item type is an absolute URL,
+   let type be that item
+   type. Otherwise, let type be the empty
+   string.
    4. 
+
+   
+
+   
  4. 
+
+    
    If type is not the empty string, run the
+    following steps:
    
+
+    
    1. Generate the following triple:
      
+
+      
      subject   
       subject
+       
      predicate 
       http://www.w3.org/1999/02/22-rdf-syntax-ns#type
+       
      object    
       type
+      
      2. 
+
+     
    2. If type does not contain a U+0023
+     NUMBER SIGN character (#), then append a U+0023 NUMBER SIGN
+     character (#) to type.
      3. 
+
+     
    3. If type does not have a U+003A COLON
+     character (:) after its U+0023 NUMBER SIGN character (#), append
+     a U+003A COLON character (:) to type.
      4. 
+
+    
    5. 
+
+   
  5. 
+
+    
    If type is the empty string, but fallback type is not, run the following
+    substeps:
    
+
+    
    1. Let type have the value of fallback type.
      2. 
+
+     
    2. If type does not contain a U+0023
+     NUMBER SIGN character (#), then append a U+0023 NUMBER SIGN
+     character (#) to type.
      3. 
+
+     
+
+     
    3. If type does not have a U+003A COLON
+     character (:) after its U+0023 NUMBER SIGN character (#), append
+     a U+003A COLON character (:) to type.
      4. 
+
+     
    4. If the last character of type is not a
+     U+003A COLON character (:), append a U+0025 PERCENT SIGN
+     character (%), a U+0032 DIGIT TWO character (2), and a U+0030
+     DIGIT ZERO character (0) to type.
      5. 
+
+     
    5. Append the value of fallback name to
+     type, with any characters in fallback name that are not valid in the
+     <ifragment> production of the IRI syntax being
+     %-escaped. [RFC3987]
      6. 
+
+    
    6. 
+
+   
  6. 
+
+    
    For each element element that has one or
+    more property names and is one of the properties of the item item, in the order those elements are given by the
+    algorithm that returns the properties of an item, run
+    the following substep:
    
+
+    
    1. 
+
+      
      For each name name in element's property names, run the
+      following substeps:
      
+
+      
      1. If type is the empty string and name is not an absolute URL, then
+       abort these substeps.
        2. 
+
+       
      2. Let value be the property value of element.
        3. 
+
+       
      3. If value is an item, then generate the triples for value. Pass a reference to memory as the item/subject list, and pass type as the fallback type and name as the fallback property name. Replace value by the subject returned from those
+       steps.
        4. 
+
+       
+
+       
      4. Otherwise, if element is not one of
+       the URL property elements, let value be a plain literal, with the language
+       information set from the language of the element, if
+       it is not unknown.
        5. 
+
+       
      5. 
+
+        
        If name is an absolute
+         URL
        
+
+         
        
+
+          
        Let predicate be name.
        
+
+         
        
+
+         
        If name contains no U+003A COLON
+         characters (:)
        
+
+         
        
+
+          
        1. Let s be type.
          2. 
+
+           
        2. If the last character of s is
+           not a U+003A COLON character (:), append a U+0025 PERCENT
+           SIGN character (%), a U+0032 DIGIT TWO character (2), and a
+           U+0030 DIGIT ZERO character (0) to s.
          3. 
+
+           
        3. Append the value of name to s, with any characters in name that are not valid in the
+           <ifragment> production of the IRI syntax being
+           %-escaped. [RFC3987]
          4. 
+
+           
        4. 
+
+            
          Let predicate be the concatenation
+            of the string "http://www.w3.org/1999/xhtml/microdata#"
+            and s, with any characters in s that are not valid in the <ifragment>
+            production of the IRI syntax being %-escaped, but without
+            double-escaping existing %-escapes. [RFC3987]
           
+
+            
          For example if the string s is "http://example.com/a#:q%20r", the
+            resulting predicate would be "http://www.w3.org/1999/xhtml/microdata#http://example.com/a%23:q%20r".
          
+
+           
          5. 
+
+          
        
+
+        
        6. 
+
+       
      6. 
+
+        
        Generate the following triple:
        
+
+        
        subject   
         subject
+         
        predicate 
         predicate
+         
        object    
         value
+        
        7. 
+
+      
      2. 
+
+    
    7. 
+
+   
  7. Return subject.
    8. 
+
+  
5.5.2.1 Examples

+
+  
This section is non-normative.

+
+  

+
+   
Here is an example of some HTML using Microdata to express RDF
+   statements:

+
+   
<dl itemscope
+    itemtype="http://purl.org/vocab/frbr/core#Work"
+    itemid="http://purl.oreilly.com/works/45U8QJGZSQKDH8N">
+ <dt>Title</dt>
+ <dd><cite itemprop="http://purl.org/dc/terms/title">Just a Geek</cite></dd>
+ <dt>By</dt>
+ <dd><span itemprop="http://purl.org/dc/terms/creator">Wil Wheaton</span></dd>
+ <dt>Format</dt>
+ <dd itemprop="http://purl.org/vocab/frbr/core#realization"
+     itemscope
+     itemtype="http://purl.org/vocab/frbr/core#Expression"
+     itemid="http://purl.oreilly.com/products/9780596007683.BOOK">
+  <link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/BOOK">
+  Print
+ </dd>
+ <dd itemprop="http://purl.org/vocab/frbr/core#realization"
+     itemscope
+     itemtype="http://purl.org/vocab/frbr/core#Expression"
+     itemid="http://purl.oreilly.com/products/9780596802189.EBOOK">
+  <link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/EBOOK">
+  Ebook
+ </dd>
+</dl>

+
+   
This is equivalent to the following Turtle:

+
+  
@prefix dc: <http://purl.org/dc/terms/> .
+ @prefix frbr: <http://purl.org/vocab/frbr/core#> .
+
+<http://purl.oreilly.com/works/45U8QJGZSQKDH8N> a frbr:Work ;
+     dc:creator "Wil Wheaton"@en ;
+     dc:title "Just a Geek"@en ;
+     frbr:realization <http://purl.oreilly.com/products/9780596007683.BOOK>,
+         <http://purl.oreilly.com/products/9780596802189.EBOOK> .
+
+<http://purl.oreilly.com/products/9780596007683.BOOK> a frbr:Expression ;
+     dc:type <http://purl.oreilly.com/product-types/BOOK> .
+
+<http://purl.oreilly.com/products/9780596802189.EBOOK> a frbr:Expression ;
+     dc:type <http://purl.oreilly.com/product-types/EBOOK> .

+
+  

+
+  

+
+   
The following snippet of HTML has microdata for two people with
+   the same address:

+
+   
<p>
+ Both
+ <span itemscope itemtype="http://microformats.org/profile/hcard" itemref="home"><span itemprop="fn"
+ ><span itemprop="n" itemscope><span itemprop="given-name">Princeton</span></span></span></span>
+ and
+ <span itemscope itemtype="http://microformats.org/profile/hcard" itemref="home"><span itemprop="fn"
+ ><span itemprop="n" itemscope><span itemprop="given-name">Trekkie</span></span></span></span>
+ live at
+ <span id="home" itemprop="adr" itemscope><span itemprop="street-address">Avenue Q</span>.</span>
+</p>

+
+   
It generates these triples expressed in Turtle (including a
+   triple that in this case is expressed twice, though that is not
+   meaningful in RDF):

+
+   
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix dct: <http://purl.org/dc/terms/> .
+@prefix hcard: <http://www.w3.org/1999/xhtml/microdata#http://microformats.org/profile/hcard%23:> .
+
+<> <http://www.w3.org/1999/xhtml/microdata#item> _:n0 ;
+   <http://www.w3.org/1999/xhtml/microdata#item> _:n1 .
+_:n0  rdf:type <http://microformats.org/profile/hcard> ;
+      hcard:fn "Princeton" ;
+      hcard:n _:n0a
+      hcard:adr _:n2 .
+_:n0a hcard:n%20given-name "Princeton" .
+_:n1  rdf:type <http://microformats.org/profile/hcard> ;
+      hcard:fn "Trekkie" ;
+      hcard:n _:n1a
+      hcard:adr _:n2 .
+_:n1a hcard:n%20given-name "Trekkie" .
+_:n2  hcard:adr%20street-address "Avenue Q" ;
+      hcard:adr%20street-address "Avenue Q" .

+
+  

+
+
+
+  

+
+
+
+  
5.5.3 Atom

+
+  
Given a Document source, a user
+  agent may run the following algorithm to extract an Atom feed. This is not the only algorithm
+  that can be used for this purpose; for instance, a user agent might
+  instead use the hAtom algorithm. [HATOM]

+
+  
  1. If the Document source does
+   not contain any article elements, then return nothing
+   and abort these steps. This algorithm can only be used with
+   documents that contain distinct articles.
    
+
+   
  2. Let R be an empty XML Document object whose address is user-agent
+   defined.
    3. 
+
+   
  3. Append a feed element in the
+   Atom namespace to R.
    4. 
+
+   
  4. 
+
+    
    For each meta element with a name attribute and a content attribute and whose name attribute's value is author, run the following substeps:
    
+
+    
    1. Append an author element in the
+     Atom namespace to the root element of R.
      2. 
+
+     
    2. Append a name element in the
+     Atom namespace to the element created in the
+     previous step.
      
+
+     
    3. Append a text node whose data is the value of the
+     meta element's content attribute to the element
+     created in the previous step.
      4. 
+
+    
    5. 
+
+   
  5. 
+
+    
    If there is a link element whose rel attribute's value includes the
+    keyword icon, and that element also
+    has an href attribute whose
+    value successfully resolves
+    relative to the link element, then append an icon element in the Atom namespace to
+    the root element of R whose contents is a text
+    node with its data set to the absolute URL resulting
+    from resolving the value of the
+    href attribute.
    
+
+    
+
+   
    6. 
+
+   
  6. 
+
+    
    Append an id element in the Atom
+    namespace to the root element of R
+    whose contents is a text node with its data set to the
+    document's current address.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Optionally: Let x be a link element in the Atom
+    namespace. Add a rel attribute whose
+    value is the string "self" to x. Append a text node with its data set to the
+    (user-agent-defined) address of R to x. Append x to the root element
+    of R.
    
+
+    
    This step would be skipped when the document R has no convenient address. The presence of the rel="self" link is a "should"-level requirement in
+    the Atom specification.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    Let x be a link
+    element in the Atom namespace. Add a rel attribute whose value is the string "alternate" to x. If the
+    document being converted is an HTML
+    document, add a type attribute whose
+    value is the string "text/html" to x. Otherwise, the document being converted is an
+    XML document; add a type attribute whose value is the string
+    "application/xhtml+xml" to x. Append a text node with its data set to
+    the document's current address to x. Append x to the root element
+    of R.
    
+
+   
    9. 
+
+   
  9. Let subheading text be the empty
+   string.
    10. 
+
+   
  10. Let heading be the first element of
+   heading content whose nearest ancestor of
+   sectioning content is the body
+   element, if any, or null if there is none.
    11. 
+
+   
  11. 
+
+    
    Take the appropriate action from the following list, as
+    determined by the type of the heading
+    element:
    
+
+    
    If heading is null
    
+
+     
    
+
+      
    Let heading text be the
+      textContent of the title
+      element, if there is one, or the empty string
+      otherwise.
    
+
+     
    
+
+     
    If heading is a hgroup element
    
+
+     
    
+
+      
    If heading contains no child
+      h1–h6 elements, let heading text be the empty string.
    
+
+      
    Otherwise, let headings list be a list of
+      all the h1–h6 element children
+      of heading, sorted first by descending
+      rank and then in tree order (so
+      h1s first, then h2s, etc, with each
+      group in the order they appear in the document). Then, let heading text be the textContent of
+      the first entry in headings list, and if
+      there are multiple entries, let subheading
+      text be the textContent of the second entry
+      in headings list.
    
+
+     
    
+
+     
    If heading is an h1–h6 element
    
+
+     
    
+
+      
    Let heading text be the
+      textContent of heading.
    
+
+     
    
+
+    
    12. 
+
+   
  12. 
+
+    
    Append a title element in the Atom
+    namespace to the root element of R
+    whose contents is a text node with its data set to heading text.
    
+
+   
    13. 
+
+   
  13. 
+
+    
    If subheading text is not the empty string,
+    append a subtitle element in the Atom
+    namespace to the root element of R
+    whose contents is a text node with its data set to subheading text.
    
+
+   
    14. 
+
+   
  14. Let global update date have no
+   value.
    15. 
+
+   
  15. 
+
+    
    For each article element article that does not have an ancestor
+    article element, run the following steps:
    
+
+    
    1. Let E be an entry element in the Atom namespace,
+     and append E to the root element of R.
      2. 
+
+     
    2. Let heading be the first element of
+     heading content whose nearest ancestor of
+     sectioning content is article,
+     if any, or null if there is none.
      3. 
+
+     
    3. 
+
+      
      Take the appropriate action from the following list, as
+      determined by the type of the heading
+      element:
      
+
+      
      If heading is null
      
+
+       
      
+
+        
      Let heading text be the empty
+        string.
      
+
+       
      
+
+       
      If heading is a hgroup element
      
+
+       
      
+
+        
      If heading contains no child
+        h1–h6 elements, let heading text be the empty string.
      
+
+        
      Otherwise, let headings list be a list
+        of all the h1–h6 element
+        children of heading, sorted first by
+        descending rank and then in tree
+        order (so h1s first, then
+        h2s, etc, with each group in the order they
+        appear in the document). Then, let heading
+        text be the textContent of the first entry
+        in headings list.
      
+
+       
      
+
+       
      If heading is an h1–h6 element
      
+
+       
      
+
+        
      Let heading text be the
+        textContent of heading.
      
+
+       
      
+
+      
      4. 
+
+     
    4. 
+
+      
      Append a title element in the
+      Atom namespace to E whose
+      contents is a text node with its data set to heading text.
      
+
+     
      5. 
+
+     
+
+     
    5. 
+
+      
      Clone article and its descendants into an
+      environment that has scripting
+      disabled, has no plugins, and
+      fails any attempt to fetch any
+      resources. Let cloned article be the
+      resulting clone article element.
      
+
+     
      6. 
+
+     
    6. 
+
+      
      Remove from the subtree rooted at cloned
+      article any article elements other than the
+      cloned article itself, any
+      header, footer, or nav
+      elements whose nearest ancestor of sectioning
+      content is the cloned article, and
+      the first element of heading content whose nearest
+      ancestor of sectioning content is the cloned article, if any.
      
+
+     
      7. 
+
+     
    7. 
+
+      
      If cloned article contains any
+      ins or del elements with datetime attributes whose
+      values parse
+      as global date and time strings without errors, then let
+      update date be the value of the datetime attribute that parses
+      to the newest global date and
+      time.
      
+
+      
      Otherwise, let update date have no
+      value.
      
+
+      
      This value is used below; it is calculated here
+      because in certain cases the next step mutates the cloned article.
      
+
+     
      8. 
+
+     
    8. 
+
+      
      If the document being converted is an HTML document, then: Let x
+      be a content element in the Atom
+      namespace. Add a type attribute
+      whose value is the string "html" to x. Append a text node with its data set to the
+      result of running the HTML fragment serialization
+      algorithm on cloned article to x. Append x to E.
      
+
+      
      Otherwise, the document being converted is an XML document: Let x be a content element in
+      the Atom namespace. Add a type attribute whose value is the string "xml" to x. Append a
+      div element to x. Move all the
+      child nodes of the cloned article node to
+      that div element, preserving their relative
+      order. Append x to E.
      
+
+     
      9. 
+
+     
    9. 
+
+      
      Establish the value of id and has-alternate from the first of the following to
+      apply:
      
+
+      
      If the article node has a descendant
+       a or area element with an href attribute that
+       successfully resolves
+       relative to that descendant and a rel attribute whose value
+       includes the bookmark
+       keyword
      
+
+       
      Let id be the absolute URL
+       resulting from resolving the
+       value of the href
+       attribute of the first such a or area
+       element, relative to the element. Let has-alternate be true.
      
+
+       
      If the article node has an id attribute
      
+
+       
      Let id be the document's current
+       address, with the fragment identifier (if any) removed,
+       and with a new fragment identifier specified, consisting of the
+       value of the article element's id attribute. Let has-alternate be false.
      
+
+       
      Otherwise
      
+
+       
      Let id be a user-agent-defined
+       undereferenceable yet globally unique valid absolute URL. The same
+       absolute URL should be generated for each run of
+       this algorithm when given the same input. Let has-alternate be false.
      
+
+      
      10. 
+
+     
    10. 
+
+      
      Append an id element in the Atom
+      namespace to E whose contents is a
+      text node with its data set to id.
      
+
+     
      11. 
+
+     
    11. 
+
+      
      If has-alternate is true: Let x be a link element in the
+      Atom namespace. Add a rel
+      attribute whose value is the string "alternate" to x. Append a
+      text node with its data set to id to x. Append x to E.
      
+
+     
      12. 
+
+     
    12. 
+
+      
      If article has a time
+      element descendant that has a pubdate attribute and whose
+      nearest ancestor article element is article, and the first such element's date is not unknown, then run
+      the following substeps, with e being the
+      first such element:
      
+
+      
      1. Let datetime be a global date and time whose date
+       component is the date of
+       e.
        2. 
+
+       
      2. If e's time and time-zone offset are not
+       unknown, then let datetime's time and
+       time-zone offset components be the time and time-zone offset of e. Otherwise, let them be midnight and no offset
+       respectively ("00:00Z").
        3. 
+
+       
      3. Let publication date be the
+       best representation of the global date and time
+       string datetime.
        4. 
+
+      
      Otherwise, let publication date have no
+      value.
      
+
+     
      13. 
+
+     
    13. 
+
+      
      If update date has no value but publication date does, then let update date have the value of publication date.
      
+
+      
      Otherwise, if publication date has no
+      value but update date does, then let publication date have the value of update date.
      
+
+     
      14. 
+
+     
    14. 
+
+      
      If update date has a value, and global update date has no value or is less recent
+      than update date, then let global update date have the value of update date.
      
+
+     
      15. 
+
+     
    15. 
+
+      
      If publication date and update date both still have no value, then let
+      them both value a value that is a valid global date and
+      time string representing the global date and time of the
+      moment that this algorithm was invoked.
      
+
+     
      16. 
+
+     
    16. 
+
+      
      Append an published element in the
+      Atom namespace to E whose
+      contents is a text node with its data set to publication date.
      
+
+     
      17. 
+
+     
    17. 
+
+      
      Append an updated element in the
+      Atom namespace to E whose
+      contents is a text node with its data set to update date.
      
+
+     
      18. 
+
+    
    16. 
+
+   
  16. 
+
+    
    If global update date has no value, then
+    let it have a value that is a valid global date and time
+    string representing the global date and time of the date
+    and time of the Document's source file's last
+    modification, if it is known, or else of the moment that this
+    algorithm was invoked.
    
+
+   
    17. 
+
+   
  17. 
+
+    
    Insert an updated element in the
+    Atom namespace into the root element of R before the first entry in
+    the Atom namespace whose contents is a text node with
+    its data set to global update date.
    
+
+   
    18. 
+
+   
  18. Return the Atom document R.
    19. 
+
+  
The above algorithm does not guarantee that the
+  output will be a conforming Atom feed. In particular, if
+  insufficient information is provided in the document (e.g. if the
+  document does not have any <meta name="author"
+  content="..."> elements), then the output will not be
+  conforming.

+
+  
The Atom namespace is: http://www.w3.org/2005/Atom

+
+
+
+  

+
+
+
+
+
+  
6 Loading Web pages

+
+  

+
+  
This section describes features that apply most directly to Web
+  browsers. Having said that, except where specified otherwise, the
+  requirements defined in this section do apply to all user
+  agents, whether they are Web browsers or not.

+
+  

+
+
+
+  
6.1 Browsing contexts

+
+  
A browsing context is an environment in which
+  Document objects are presented to the user.

+
+  
A tab or window in a Web browser typically contains
+  a browsing context, as does an iframe or frames in a
+  frameset.

+
+  
Each browsing context has a corresponding
+  WindowProxy object.

+
+  
A browsing context has a session
+  history, which lists the Document objects that
+  that browsing context has presented, is presenting, or
+  will present. At any time, one Document in each
+  browsing context is designated the active
+  document.

+
+  
Each Document is associated with a
+  Window object. A browsing context's
+  WindowProxy object forwards everything to the
+  browsing context's active document's
+  Window object.

+
+  
In general, there is a 1-to-1 mapping from the
+  Window object to the Document object. In
+  one particular case, a Window can be reused for the
+  presentation of a second Document in the same
+  browsing context, such that the mapping is then
+  2-to-1. This occurs when a browsing context is navigated from the initial
+  about:blank Document to another, with
+  replacement enabled.

+
+  
A Document does not necessarily have a
+  browsing context associated with it. In particular,
+  data mining tools are likely to never instantiate browsing
+  contexts.

+
+  
A browsing context can have a creator browsing
+  context, the browsing context that was
+  responsible for its creation. If a browsing context has
+  a parent browsing context, then that is its
+  creator browsing context. Otherwise, if the
+  browsing context has an opener browsing
+  context, then that is its creator browsing
+  context. Otherwise, the browsing context has no
+  creator browsing context.

+
+  
If a browsing context A has a
+  creator browsing context, then the
+  Document that was the active document of
+  that creator browsing context at the time A was created is the creator
+  Document.

+
+  

+
+  
When a browsing context is first created, it must be
+  created with a single Document in its session history,
+  whose address is
+  about:blank, which is marked as being an HTML document, and whose character encoding is
+  UTF-8. The Document must have a single child
+  html node, which itself has a single child
+  body node.

+
+  
If the browsing context is created
+  specifically to be immediately navigated, then that initial
+  navigation will have replacement enabled.

+
+  
The origin of the
+  about:blank Document is set when the
+  Document is created. If the new browsing
+  context has a creator browsing context, then the
+  origin of the about:blank
+  Document is the origin of the
+  creator Document. Otherwise, the
+  origin of the about:blank
+  Document is a globally unique identifier assigned when
+  the new browsing context is created.

+
+  

+
+
+  
6.1.1 Nested browsing contexts

+
+  
Certain elements (for example, iframe elements) can
+  instantiate further browsing
+  contexts. These are called nested browsing contexts. If a browsing context P has an element E in one of its
+  Documents D that nests another
+  browsing context C inside it, then P is said to be the parent browsing
+  context of C, C is
+  said to be a child browsing context of P, C is said to be nested through D, and E is said to be the
+  browsing context container of C.

+
+  
A browsing context A is said to be an
+  ancestor of a browsing context B if there exists
+  a browsing context A' that is a child
+  browsing context of A and that is itself
+  an ancestor of B, or if there is a browsing
+  context P that is a child browsing
+  context of A and that is the parent
+  browsing context of B.

+
+  
The browsing context with no parent browsing context
+  is the top-level browsing context of all the browsing
+  contexts nested within
+  it (either directly or indirectly through other nested browsing
+  contexts).

+
+  
The transitive closure of parent browsing contexts for a nested browsing
+  context gives the list of ancestor browsing contexts.

+
+  
The list of the descendant browsing contexts of a
+  Document d is the list returned by
+  the following algorithm:

+
+  
  1. Let list be an empty list.
    2. 
+
+   
  2. For each child browsing context of d that is nested through an element that is in the Document d, in the tree order of the elements of
+   the elements nesting those browsing
+   contexts, append to the list list the
+   list of the descendant browsing contexts of the
+   active document of that child browsing
+   context.
    3. 
+
+   
  3. Return the constructed list.
    4. 
+
+  
A Document is said to be fully active
+  when it is the active document of its browsing
+  context, and either its browsing context is a top-level
+  browsing context, or the Document through which that
+  browsing context is nested is itself fully active.

+
+  
Because they are nested through an element, child browsing contexts are always tied to
+  a specific Document in their parent browsing
+  context. User agents must not allow the user to interact with
+  child browsing contexts
+  of elements that are in Documents that are not
+  themselves fully active.

+
+  
A nested browsing context can have a seamless
+  browsing context flag set, if it is embedded through an
+  iframe element with a seamless attribute.

+
+
+  
+
+  
window . top

+
+   

+
+    
Returns the WindowProxy for the top-level browsing context.

+
+   

+
+   
window . parent

+
+   

+
+    
Returns the WindowProxy for the parent browsing context.

+
+   

+
+   
window . frameElement

+
+   

+
+    
Returns the Element for the browsing context container.

+
+    
Returns null if there isn't one.

+
+    
Throws a SECURITY_ERR exception in cross-origin situations.

+
+   

+
+  

+
+  
The top IDL attribute on
+  the Window object of a Document in a
+  browsing context b must return the
+  WindowProxy object of its top-level browsing
+  context (which would be its own WindowProxy
+  object if it was a top-level browsing context
+  itself).

+
+  
The parent IDL
+  attribute on the Window object of a
+  Document in a browsing context b must return the WindowProxy object of
+  the parent browsing context, if there is one (i.e. if
+  b is a child browsing context), or
+  the WindowProxy object of the browsing
+  context b itself, otherwise (i.e. if it
+  is a top-level browsing context).

+
+  
The frameElement
+  IDL attribute on the Window object of a
+  Document d, on getting, must run
+  the following algorithm:

+
+  
  1. If d is not a Document in a
+   child browsing context, return null and abort these
+   steps.
    2. 
+
+   
  2. If the parent browsing context's active
+   document does not have the same effective script origin as the
+   entry script, then throw a SECURITY_ERR
+   exception.
    3. 
+
+   
  3. Otherwise, return the browsing context
+   container for b.
    4. 
+
+  

+
+
+
+  
6.1.2 Auxiliary browsing contexts

+
+  
It is possible to create new browsing contexts that are related
+  to a top-level browsing context without being nested
+  through an element. Such browsing contexts are called auxiliary browsing
+  contexts. Auxiliary browsing contexts are always top-level browsing
+  contexts.

+
+  
An auxiliary browsing context has an opener
+  browsing context, which is the browsing context
+  from which the auxiliary browsing context was created,
+  and it has a furthest ancestor browsing context, which is
+  the top-level browsing context of the opener
+  browsing context when the auxiliary browsing
+  context was created.

+
+
+  
+
+  
The opener IDL
+  attribute on the Window object must return the
+  WindowProxy object of the browsing context
+  from which the current browsing context was created
+  (its opener browsing context), if there is one and it
+  is still available.

+
+
+
+
+  
6.1.3 Secondary browsing contexts

+
+  
User agents may support secondary browsing contexts, which are browsing contexts that form part of
+  the user agent's interface, apart from the main content area.

+
+
+  

+
+  
6.1.4 Security

+
+  
A browsing context A is allowed to navigate a second
+  browsing context B if one of the
+  following conditions is true:

+
+  
An element has a browsing context scope origin if its
+  Document's browsing context is a
+  top-level browsing context or if all of its
+  Document's ancestor browsing contexts all have active documents whose
+  origin are the same origin as the
+  element's Document's origin. If an element
+  has a browsing context scope origin, then its value is
+  the origin of the element's Document.

+
+  

+
+
+  

+
+  
6.1.5 Groupings of browsing contexts

+
+  
Each browsing context is defined as having a list of
+  zero or more directly reachable browsing contexts. These
+  are:

+
+  
The transitive closure of all the browsing contexts that are directly reachable
+  browsing contexts forms a unit of related browsing
+  contexts.

+
+  
Each unit of related browsing contexts is then
+  further divided into the smallest number of groups such that every
+  member of each group has an effective script origin
+  that, through appropriate manipulation of the document.domain attribute, could
+  be made to be the same as other members of the group, but could not
+  be made the same as members of any other group. Each such group is a
+  unit of related similar-origin browsing contexts.

+
+  
Each unit of related similar-origin browsing
+  contexts can have a entry script which is used to
+  obtain, amongst other things, the script's base URL to
+  resolve relative URLs used in scripts running in that unit
+  of related similar-origin browsing contexts. Initially, there
+  is no entry script.

+
+  
There is at most one event loop per
+  unit of related similar-origin browsing contexts.

+
+  

+
+
+
+  
6.1.6 Browsing context names

+
+  
Browsing contexts can have a browsing context name. By
+  default, a browsing context has no name (its name is not set).

+
+  
A valid browsing context name is any string with at
+  least one character that does not start with a U+005F LOW LINE
+  character. (Names starting with an underscore are reserved for
+  special keywords.)

+
+  
A valid browsing context name or keyword is any string
+  that is either a valid browsing context name or that is
+  an ASCII case-insensitive match for one of: _blank, _self, _parent, or _top.

+
+  

+
+  
The rules for choosing a browsing context given a browsing
+  context name are as follows. The rules assume that they are
+  being applied in the context of a browsing context.

+
+  
  1. If the given browsing context name is the empty string or
+   _self, then the chosen browsing context must
+   be the current one.
    2. 
+
+   
  2. If the given browsing context name is _parent, then the chosen browsing context must be
+   the parent browsing context of the current
+   one, unless there isn't one, in which case the chosen browsing
+   context must be the current browsing context.
    3. 
+
+   
  3. If the given browsing context name is _top, then the chosen browsing context must be the
+   most top-level browsing context of the current
+   one.
    4. 
+
+   
  4. 
+
+    
    If the given browsing context name is not _blank and there exists a browsing context whose
+    name is the same as the
+    given browsing context name, and the current browsing context is
+    allowed to navigate that browsing context, and the
+    user agent determines that the two browsing contexts are related
+    enough that it is ok if they reach each other, then that browsing
+    context must be the chosen one. If there are multiple matching
+    browsing contexts, the user agent should select one in some
+    arbitrary consistent manner, such as the most recently opened,
+    most recently focused, or more closely related.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Otherwise, a new browsing context is being requested, and what
+    happens depends on the user agent's configuration and/or
+    abilities:
    
+
+    
    If the current browsing context had
+     the sandboxed navigation browsing context flag set
+     when its active document was created.
    
+
+     
    The user agent may offer to create a new top-level
+     browsing context or reuse an existing top-level
+     browsing context. If the user picks one of those options,
+     then the designated browsing context must be the chosen one (the
+     browsing context's name isn't set to the given browsing context
+     name). Otherwise (if the user agent doesn't offer the option to
+     the user, or if the user declines to allow a browsing context to
+     be used) there must not be a chosen browsing context.
    
+
+
+     
    If the user agent has been configured such that
+     in this instance it will create a new browsing context, and the
+     browsing context is being requested as part of following a hyperlink whose
+     link types include the noreferrer keyword
    
+
+     
    A new top-level browsing context must be
+     created. If the given browsing context name is not _blank, then the new top-level browsing context's
+     name must be the given browsing context name (otherwise, it has
+     no name). The chosen browsing context must be this new browsing
+     context.
    
+
+     
    If it is immediately navigated, then the navigation will be
+     done with replacement enabled.
    
+
+
+     
    If the user agent has been configured such that in this
+     instance it will create a new browsing context, and the noreferrer keyword doesn't
+     apply
    
+
+     
    A new auxiliary browsing context must be
+     created, with the opener browsing context being the
+     current one. If the given browsing context name is not _blank, then the new auxiliary browsing context's
+     name must be the given browsing context name (otherwise, it has
+     no name). The chosen browsing context must be this new browsing
+     context.
    
+
+     
    If it is immediately navigated,
+     then the navigation will be done with replacement
+     enabled.
    
+
+
+     
    If the user agent has been configured such that in this
+     instance it will reuse the current browsing context
    
+
+     
    The chosen browsing context is the current browsing
+     context.
    
+
+
+     
    If the user agent has been configured such that in this
+     instance it will not find a browsing context
    
+
+     
    There must not be a chosen browsing context.
    
+
+    
    User agent implementors are encouraged to provide a way for
+    users to configure the user agent to always reuse the current
+    browsing context.
    
+
+   
    6. 
+
+  

+
+
+
+
+  
6.2 The Window object

+
+  
[OverrideBuiltins, ReplaceableNamedProperties] 
+interface Window {
+  // the current browsing context
+  readonly attribute WindowProxy window;
+  readonly attribute WindowProxy self;
+  readonly attribute Document document;
+           attribute DOMString name;
+  [PutForwards=href] readonly attribute Location location;
+  readonly attribute History history;
+  readonly attribute UndoManager undoManager;
+  Selection getSelection();
+  [Replaceable] readonly attribute BarProp locationbar;
+  [Replaceable] readonly attribute BarProp menubar;
+  [Replaceable] readonly attribute BarProp personalbar;
+  [Replaceable] readonly attribute BarProp scrollbars;
+  [Replaceable] readonly attribute BarProp statusbar;
+  [Replaceable] readonly attribute BarProp toolbar;
+  void close();
+  void stop();
+  void focus();
+  void blur();
+
+  // other browsing contexts
+  [Replaceable] readonly attribute WindowProxy frames;
+  [Replaceable] readonly attribute unsigned long length;
+  readonly attribute WindowProxy top;
+  [Replaceable] readonly attribute WindowProxy opener;
+  readonly attribute WindowProxy parent;
+  readonly attribute Element frameElement;
+  WindowProxy open(in optional DOMString url, in optional DOMString target, in optional DOMString features, in optional DOMString replace);
+  getter WindowProxy (in unsigned long index);
+  getter any (in DOMString name);
+
+  // the user agent
+  readonly attribute Navigator navigator; 
+  readonly attribute ApplicationCache applicationCache;
+
+  // user prompts
+  void alert(in DOMString message);
+  boolean confirm(in DOMString message);
+  DOMString prompt(in DOMString message, in optional DOMString default);
+  void print();
+  any showModalDialog(in DOMString url, in optional any argument);
+
+  // cross-document messaging
+  void postMessage(in any message, in DOMString targetOrigin, in optional MessagePortArray ports);
+
+  // event handler IDL attributes
+           attribute Function onabort;
+           attribute Function onafterprint;
+           attribute Function onbeforeprint;
+           attribute Function onbeforeunload;
+           attribute Function onblur;
+           attribute Function oncanplay;
+           attribute Function oncanplaythrough;
+           attribute Function onchange;
+           attribute Function onclick;
+           attribute Function oncontextmenu;
+           attribute Function ondblclick;
+           attribute Function ondrag;
+           attribute Function ondragend;
+           attribute Function ondragenter;
+           attribute Function ondragleave;
+           attribute Function ondragover;
+           attribute Function ondragstart;
+           attribute Function ondrop;
+           attribute Function ondurationchange;
+           attribute Function onemptied;
+           attribute Function onended;
+           attribute Function onerror;
+           attribute Function onfocus;
+           attribute Function onformchange;
+           attribute Function onforminput;
+           attribute Function onhashchange;
+           attribute Function oninput;
+           attribute Function oninvalid;
+           attribute Function onkeydown;
+           attribute Function onkeypress;
+           attribute Function onkeyup;
+           attribute Function onload;
+           attribute Function onloadeddata;
+           attribute Function onloadedmetadata;
+           attribute Function onloadstart;
+           attribute Function onmessage;
+           attribute Function onmousedown;
+           attribute Function onmousemove;
+           attribute Function onmouseout;
+           attribute Function onmouseover;
+           attribute Function onmouseup;
+           attribute Function onmousewheel;
+           attribute Function onoffline;
+           attribute Function ononline;
+           attribute Function onpause;
+           attribute Function onplay;
+           attribute Function onplaying;
+           attribute Function onpagehide;
+           attribute Function onpageshow;
+           attribute Function onpopstate;
+           attribute Function onprogress;
+           attribute Function onratechange;
+           attribute Function onreadystatechange;
+           attribute Function onredo;
+           attribute Function onresize;
+           attribute Function onscroll;
+           attribute Function onseeked;
+           attribute Function onseeking;
+           attribute Function onselect;
+           attribute Function onshow;
+           attribute Function onstalled;
+           attribute Function onstorage;
+           attribute Function onsubmit;
+           attribute Function onsuspend;
+           attribute Function ontimeupdate;
+           attribute Function onundo;
+           attribute Function onunload;
+           attribute Function onvolumechange;
+           attribute Function onwaiting;
+};
+Window implements EventTarget;

+
+
+
+  
window . window

+   
window . frames

+   
window . self

+
+   

+
+    
These attributes all return window.

+
+   

+
+
+   
window . document

+
+   

+
+    
Returns the active document.

+
+   

+
+
+   
document . defaultView

+
+   

+
+    
Returns the Window object of the active document.

+
+   

+
+  

+
+  
The window, frames, and self IDL attributes must all
+  return the Window object's browsing
+  context's WindowProxy object.

+
+  
The document IDL
+  attribute must return the Document object of the
+  Window object's Document's browsing
+  context's active document.

+
+  
The defaultView IDL
+  attribute of the HTMLDocument interface must return the
+  Document's browsing context's
+  WindowProxy object.

+
+  

+
+
+  

+
+  
6.2.1 Security

+
+  
User agents must raise a
+  SECURITY_ERR exception whenever any of the members of a
+  Window object are accessed by scripts whose
+  effective script origin is not the same as the
+  Window object's Document's effective
+  script origin, with the following exceptions:

+
+  
When a script whose effective script origin is not
+  the same as the Window object's Document's
+  effective script origin attempts to access that
+  Window object's methods or attributes, the user agent
+  must act as if any changes to the Window object's
+  properties, getters, setters, etc, were not present.

+
+  
For members that return objects (including function objects),
+  each distinct effective script origin that is not the
+  same as the Window object's Document's
+  effective script origin must be provided with a
+  separate set of objects. These objects must have the prototype chain
+  appropriate for the script for which the objects are created (not
+  those that would be appropriate for scripts whose script's
+  global object is the Window object in
+  question).

+
+  

+
+   
For instance, if two frames containing Documents
+   from different origins access the same
+   Window object's postMessage() method, they
+   will get distinct objects that are not equal.

+
+  

+
+  

+
+
+
+  
6.2.2 APIs for creating and navigating browsing contexts by name

+
+  
window = window . open( [ url [, target [, features [, replace ] ] ] ] )

+
+   

+
+    
Opens a window to show url (defaults to
+    about:blank), and returns it. The target argument gives the name of the new
+    window. If a window exists with that name already, it is
+    reused. The replace attribute, if true, means
+    that whatever page is currently open in that window will be
+    removed from the window's session history. The features argument is ignored.

+
+   

+
+   
window . name [ = value ]

+
+   

+
+    
Returns the name of the window.

+
+    
Can be set, to change the name.

+
+   

+
+   
window . close()

+
+   

+
+    
Closes the window.

+
+   

+
+   
window . stop()

+
+   

+
+    
Cancels the document load.

+
+   

+
+  

+
+  
The open() method on
+  Window objects provides a mechanism for navigating an existing browsing
+  context or opening and navigating an auxiliary browsing
+  context.

+
+  
The method has four arguments, though they are all optional.

+
+  
The first argument, url, must be a
+  valid non-empty URL for a page to load in the browsing
+  context. If no arguments are provided, or if the first argument is
+  the empty string, then the url argument defaults
+  to "about:blank". The argument must be resolved to an absolute
+  URL (or an error), relative to the entry
+  script's base URL,
+  when the method is invoked.

+
+  
The second argument, target, specifies the
+  name of the browsing
+  context that is to be navigated. It must be a valid browsing
+  context name or keyword. If fewer than two arguments are
+  provided, then the name argument defaults to the
+  value "_blank".

+
+  
The third argument, features, has no effect
+  and is supported for historical reasons only.

+
+  
The fourth argument, replace, specifies
+  whether or not the new page will replace the page currently loaded in the browsing
+  context, when target identifies an existing
+  browsing context (as opposed to leaving the current page in the
+  browsing context's session history). When three or
+  fewer arguments are provided, replace defaults
+  to false.

+
+  
When the method is invoked, the user agent must first select a
+  browsing context to navigate by applying the
+  rules for choosing a browsing context given a browsing context
+  name using the target argument as the
+  name and the browsing context of the script as the
+  context in which the algorithm is executed, unless the user has
+  indicated a preference, in which case the browsing context to
+  navigate may instead be the one indicated by the user.

+
+  
For example, suppose there is a user agent that
+  supports control-clicking a link to open it in a new tab. If a user
+  clicks in that user agent on an element whose onclick handler uses the window.open() API to open a page in an
+  iframe, but, while doing so, holds the control key down, the user
+  agent could override the selection of the target browsing context to
+  instead target a new tab.

+
+  
Then, the user agent must navigate the selected
+  browsing context to the absolute URL (or
+  error) obtained from resolving
+  url earlier. If the replace
+  is true, then replacement must be
+  enabled; otherwise, it must not be enabled unless the
+  browsing context was just created as part of
+  the rules for choosing a browsing context given a browsing
+  context name. The navigation must be done with the browsing context of the
+  entry script as the source browsing
+  context.

+
+  
The method must return the WindowProxy object of the
+  browsing context that was navigated, or null if no
+  browsing context was navigated.

+
+  
The name attribute of
+  the Window object must, on getting, return the current
+  name of the browsing context, and, on setting, set the
+  name of the browsing context to the new value.

+
+  
The name gets reset when
+  the browsing context is navigated to another domain.

+
+  
The close()
+  method on Window objects should, if the corresponding
+  browsing context A is an
+  auxiliary browsing context that was created by a script
+  (as opposed to by an action of the user), and if the browsing context of the
+  script that invokes the method
+  is allowed to navigate the browsing
+  context A, close the browsing
+  context A (and may discard it too).

+
+  
The stop() method
+  on Window objects should, if there is an existing
+  attempt to navigate the browsing context
+  and that attempt is not currently running the unload a
+  document algorithm, cancel that navigation and any associated instances of
+  the fetch algorithm. Otherwise, it must
+  do nothing.

+
+  

+
+
+  
6.2.3 Accessing other browsing contexts

+
+  
window . length

+
+   

+
+    
Returns the number of child browsing contexts.

+
+   

+
+   
window[index]

+
+   

+
+    
Returns the indicated child browsing context.

+
+   

+
+  

+
+  
The length IDL
+  attribute on the Window interface must return the
+  number of child browsing
+  contexts that are nested through elements that are in the Document that is the
+  active document of that Window object, if
+  that Window's browsing context shares the
+  same event loop as the script's browsing
+  context of the entry script accessing the IDL
+  attribute; otherwise, it must return zero.

+
+  
+
+  
The indices of the supported indexed properties on
+  the Window object at any instant are the numbers in the
+  range 0 .. n-1, where n is the number returned by the length IDL attribute. If n is zero then there are no supported indexed
+  properties.

+
+  
When a Window object is indexed to retrieve an indexed
+  property index, the value returned must be
+  the WindowProxy object of the indexth child browsing context of the
+  Document that is nested through an element that is
+  in the Document,
+  sorted in the tree order of the elements nesting those
+  browsing contexts.

+
+  
These properties are the dynamic nested browsing context
+  properties.

+
+  

+
+
+
+  
6.2.4 Named access on the Window object

+
+  
window[name]

+
+   

+
+    
Returns the indicated element or collection of elements.

+
+   

+
+  

+
+  
The Window interface supports named properties. The names of the
+  supported named properties at any moment consist of:

+
+  
When the Window
+  object is indexed for property retrieval using a name name, then the user agent must return the value
+  obtained using the following steps:

+
+  
  1. 
+
+    
    Let elements be the list of named elements with the
+    name name in the active document.
+
+    
    There will be at least one such element, by
+    definition.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If elements contains an iframe
+    element, then return the WindowProxy object of the
+    nested browsing context represented by the first such
+    iframe element in tree order, and abort
+    these steps.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Otherwise, if elements has only one
+    element, return that element and abort these steps.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Otherwise return an HTMLCollection rooted at the
+    Document node, whose filter matches only named elements with
+    the name name.
     
+
+   
    5. 
+
+  
Named elements
+  with the name name, for the purposes of the
+  above algorithm, are those that are either:

+
+  

+
+
+  

+
+  
6.2.5 Garbage collection and browsing contexts

+
+  
A browsing context has a strong reference to each of
+  its Documents and its WindowProxy object,
+  and the user agent itself has a strong reference to its top-level browsing
+  contexts.

+
+  
A Document has a strong reference to its
+  Window object.

+
+  
A Window object has a strong reference to its
+  Document object through its document attribute.  Thus, references
+  from other scripts to either of those objects will keep both
+  alive. Similarly, both Document and Window
+  objects have implied strong
+  references to the WindowProxy object.

+
+  
Each script has a strong
+  reference to its browsing
+  context and its document.

+
+  
When a browsing context is to discard a
+  Document, the user agent must run the following
+  steps:

+
+  
  1. Set the Document's salvageable state to
+   false.
    2. 
+
+   
  2. Run any unloading document cleanup steps for
+   the Document that are defined by this specification or
+   any other relevant specifications.
    3. 
+
+   
  3. Remove any tasks
+   associated with the Document in any task
+   source, without running those tasks.
    4. 
+
+   
  4. Discard
+   all the child browsing
+   contexts of the Document.
    5. 
+
+   
  5. Lose the strong reference from the Document's
+   browsing context to the
+   Document.
    6. 
+
+  
Whenever a Document object is discarded, it is also removed from
+  the list of the worker's Documents of each
+  worker whose list contains that Document.

+
+  
When a browsing context is
+  discarded, the strong reference from the user agent itself to
+  the browsing context must be severed, and all the
+  Document objects for all the entries in the
+  browsing context's session history must be discarded as well.

+
+  
User agents may discard top-level browsing contexts at any time (typically,
+  in response to user requests, e.g. when a user closes a window
+  containing one or more top-level browsing contexts). Other browsing contexts must be discarded
+  once their WindowProxy object is eligible for garbage
+  collection.

+
+  

+
+
+
+  
6.2.6 Browser interface elements

+
+  
To allow Web pages to integrate with Web browsers, certain Web
+  browser interface elements are exposed in a limited way to scripts
+  in Web pages.

+
+  
Each interface element is represented by a BarProp
+  object:

+
+  
interface BarProp {
+           attribute boolean visible;
+};

+
+  
window . locationbar . visible

+   

+    
Returns true if the location bar is visible; otherwise, returns false.

+   

+
+   
window . menubar . visible

+   

+    
Returns true if the menu bar is visible; otherwise, returns false.

+   

+
+   
window . personalbar . visible

+   
+   

+    
Returns true if the personal bar is visible; otherwise, returns false.

+   

+
+   
window . scrollbars . visible

+   

+    
Returns true if the scroll bars are visible; otherwise, returns false.

+   

+
+   
window . statusbar . visible

+   

+    
Returns true if the status bar is visible; otherwise, returns false.

+   

+
+   
window . toolbar . visible

+   

+    
Returns true if the toolbar is visible; otherwise, returns false.

+   

+
+  

+
+  
The visible attribute, on
+  getting, must return either true or a value determined by the user
+  agent to most accurately represent the visibility state of the user
+  interface element that the object represents, as described below. On
+  setting, the new value must be discarded.

+
+  
The following BarProp objects exist for each
+  Document object in a browsing
+  context. Some of the user interface elements represented by
+  these objects might have no equivalent in some user agents; for
+  those user agents, except when otherwise specified, the object must
+  act as if it was present and visible (i.e. its visible attribute must return
+  true).

+
+  
The location bar BarProp object

+
+   
Represents the user interface element that contains a control
+   that displays the URL of the active
+   document, or some similar interface concept.

+
+   
The menu bar BarProp object

+
+   
Represents the user interface element that contains a list of
+   commands in menu form, or some similar interface concept.

+
+   
The personal bar BarProp object

+
+   
Represents the user interface element that contains links to
+   the user's favorite pages, or some similar interface concept.

+
+   
The scrollbar BarProp object

+
+   
Represents the user interface element that contains a scrolling
+   mechanism, or some similar interface concept.

+
+   
The status bar BarProp object

+
+   
Represents a user interface element found immediately below or
+   after the document, as appropriate for the user's media. If the
+   user agent has no such user interface element, then the object may
+   act as if the corresponding user interface element was absent
+   (i.e. its visible
+   attribute may return false).

+
+   
The toolbar BarProp object

+
+   
Represents the user interface element found immediately above
+   or before the document, as appropriate for the user's media. If the
+   user agent has no such user interface element, then the object may
+   act as if the corresponding user interface element was absent
+   (i.e. its visible
+   attribute may return false).

+
+  
The locationbar
+  attribute must return the location bar BarProp
+  object.

+
+  
The menubar
+  attribute must return the menu bar BarProp
+  object.

+
+  
The personalbar
+  attribute must return the personal bar BarProp
+  object.

+
+  
The scrollbars
+  attribute must return the scrollbar BarProp
+  object.

+
+  
The statusbar attribute
+  must return the status bar BarProp
+  object.

+
+  
The toolbar
+  attribute must return the toolbar BarProp
+  object.

+
+
+
+  

+
+
+  

+
+  
6.2.7 The WindowProxy object

+
+
+  
As mentioned earlier, each browsing context has a
+  WindowProxy object. This object is unusual
+  in that all operations that would be performed on it must be
+  performed on the Window object of the browsing
+  context's active document instead. It is thus
+  indistinguishable from that Window object in every way
+  until the browsing context is navigated.

+
+  
There is no WindowProxy interface object.

+
+  
The WindowProxy object allows scripts
+  to act as if each browsing context had a single
+  Window object, while still keeping separate
+  Window objects for each Document.

+
+  

+
+   
In the following example, the variable x is
+   set to the WindowProxy object returned by the window accessor on the global object. All
+   of the expressions following the assignment return true, because in
+   every respect, the WindowProxy object acts like the
+   underlying Window object.

+
+   
var x = window;
+x instanceof Window; // true
+x === this; // true

+
+  

+
+  

+
+
+
+  
6.3 Origin

+  
+
+  
The origin of a resource and the effective script
+  origin of a resource are both either opaque identifiers or
+  tuples consisting of a scheme component, a host component, a port
+  component, and optionally extra data.

+
+  
The extra data could include the certificate of the
+  site when using encrypted connections, to ensure that if the site's
+  secure certificate changes, the origin is considered to change as
+  well.

+
+
+  

+
+  
These characteristics are defined as follows:

+
+  
For URLs

+
+   

+
+    
The origin and effective script
+    origin of the URL is whatever is returned by
+    the following algorithm:

+
+    
  1. Let url be the URL for
+     which the origin is being determined.
    2. 
+
+     
  2. Parse url.
    3. 
+
+     
  3. If url identifies a resource that is
+     its own trust domain (e.g. it identifies an e-mail on an IMAP
+     server or a post on an NNTP server) then return a globally unique
+     identifier specific to the resource identified by url, so that if this algorithm is invoked again
+     for URLs that identify the same resource,
+     the same identifier will be returned.
    4. 
+
+     
  4. If url does not use a server-based
+     naming authority, or if parsing url failed,
+     or if url is not an absolute
+     URL, then return a new globally unique
+     identifier.
    5. 
+
+     
  5. Let scheme be the <scheme> component of url, converted to ASCII lowercase.
    6. 
+
+     
  6. If the UA doesn't support the protocol given by scheme, then return a new globally unique
+     identifier.
    7. 
+
+     
  7. If scheme is "file", then the user agent may return a
+     UA-specific value.
    8. 
+
+     
  8. Let host be the <host> component of url.
    9. 
+
+     
  9. 
+
+      
    Apply the IDNA ToASCII algorithm to host,
+      with both the AllowUnassigned and UseSTD3ASCIIRules flags
+      set. Let host be the result of the ToASCII
+      algorithm.
    
+
+      
    If ToASCII fails to convert one of the components of the
+      string, e.g. because it is too long or because it contains
+      invalid characters, then return a new globally unique
+      identifier. [RFC3490]
    
+
+     
    10. 
+
+     
  10. Let host be the result of converting
+     host to
+     ASCII lowercase.
    11. 
+
+     
  11. If there is no <port>
+     component, then let port be the default port
+     for the protocol given by scheme. Otherwise,
+     let port be the <port> component of url.
    12. 
+
+     
  12. Return the tuple (scheme, host, port).
    13. 
+
+    
In addition, if the URL is in fact associated with
+    a Document object that was created by parsing the
+    resource obtained from fetching URL, and this was
+    done over a secure connection, then the server's secure
+    certificate may be added to the origin as additional data.

+
+   

+
+   
For scripts

+
+   

+
+    
The origin and effective script
+    origin of a script are determined from another resource,
+    called the owner:

+
+    
If a script is in a script element

+
+     
The owner is the Document to which the
+     script element belongs.

+
+
+     
If a script is in an event handler content attribute

+
+     
The owner is the Document to which the
+     attribute node belongs.

+
+
+     
If a script is a function or other code reference created by
+     another script

+
+     
The owner is the script that created it.

+
+
+     
If a script is a javascript: URL that was returned as the
+     location of an HTTP redirect (or equivalent in
+     other protocols)

+
+     
The owner is the URL that redirected to the
+     javascript: URL.

+
+
+     
If a script is a javascript: URL in an attribute

+
+     
The owner is the Document of the element on
+     which the attribute is found.

+
+
+     
If a script is a javascript: URL in a style sheet

+
+     
The owner is the URL of the style sheet.

+
+
+     
If a script is a javascript: URL to which a browsing
+     context is being navigated,
+     the URL having been provided by the user (e.g. by using a
+     bookmarklet)

+
+     
The owner is the Document of the browsing
+     context's active document.

+
+
+     
If a script is a javascript: URL to which a browsing
+     context is being navigated,
+     the URL having been declared in markup

+
+     
The owner is the Document of the element
+     (e.g. an a or area element) that
+     declared the URL.

+
+
+     
If a script is a javascript: URL to which a browsing
+     context is being navigated,
+     the URL having been provided by script

+
+     
The owner is the script that provided the URL.

+
+    
The origin of the script is then equal to the
+    origin of the owner, and the effective script
+    origin of the script is equal to the effective script
+    origin of the owner.

+
+   

+
+   
For Document objects and images

+
+   

+
+    
If a Document is in a
+     browsing context whose sandboxed origin
+     browsing context flag was set when the
+     Document was created

+
+     
If a Document was generated from a resource
+     labeled as text/html-sandboxed

+
+     
The origin is a globally unique identifier
+     assigned when the Document is created.

+
+
+     
If a Document or image was returned by the
+     XMLHttpRequest API

+
+     
The origin is equal to the XMLHttpRequest
+     origin of the XMLHttpRequest object. [XHR]

+
+
+     
If a Document or image was generated from a
+     javascript:
+     URL

+
+     
The origin is equal to the origin
+     of the script of that javascript: URL.

+
+
+     
If a Document or image was served over the
+     network and has an address that uses a URL scheme with a
+     server-based naming authority

+
+     
The origin is the origin of the
+     address of the
+     Document or the URL of the image, as
+     appropriate.

+
+
+     
If a Document or image was generated from a
+     data: URL that was returned as the location
+     of an HTTP redirect (or equivalent in
+     other protocols)

+
+     
The origin is the origin of the
+     URL that redirected to the data: URL.

+
+
+     
If a Document or image was generated from a
+     data: URL found in another
+     Document or in a script

+
+     
The origin is the origin of the
+     Document or script that initiated the navigation to that URL.

+
+
+     
If a Document has the address
+     "about:blank"

+
+     
The origin of the Document is the origin it was
+     assigned when its browsing context was created.

+
+
+     
If a Document is an iframe srcdoc document

+
+     
The origin of the Document is the
+     origin of the Document's browsing
+     context's browsing context container's
+     Document.

+
+
+     
If a Document or image was obtained in some
+     other manner (e.g. a data: URL typed in by
+     the user, a Document created using the createDocument()
+     API, etc)

+
+     
The origin is a globally unique identifier
+     assigned when the Document or image is created.

+
+    
When a Document is created, its effective
+    script origin is initialized to the origin of
+    the Document. However, the document.domain attribute can
+    be used to change it.

+
+   

+
+   
For audio and video elements

+
+   

+
+    
If value of the media element's currentSrc attribute is the
+    empty string, the origin is the same as the
+    origin of the element's Document's
+    origin.

+
+    
Otherwise, the origin is equal to the
+    origin of the absolute URL given by the
+    media element's currentSrc attribute.

+
+   

+
+  
The Unicode serialization of an origin is the string
+  obtained by applying the following algorithm to the given
+  origin:

+
+  
  1. If the origin in question is not a
+   scheme/host/port tuple, then return the literal string "null" and abort these steps.
    2. 
+
+   
  2. Otherwise, let result be the scheme part
+   of the origin tuple.
    3. 
+
+   
  3. Append the string "://" to result.
    4. 
+
+   
  4. Apply the IDNA ToUnicode algorithm to each component of the
+   host part of the origin tuple, and append the results
+   — each component, in the same order, separated by U+002E FULL
+   STOP characters (.) — to result. [RFC3490]
    5. 
+
+   
  5. If the port part of the origin tuple gives a port
+   that is different from the default port for the protocol given by
+   the scheme part of the origin tuple, then append a
+   U+003A COLON character (:) and the given port, in base ten, to
+   result.
    6. 
+
+   
  6. Return result.
    7. 
+
+  
The ASCII serialization of an origin is the string
+  obtained by applying the following algorithm to the given
+  origin:

+
+  
  1. If the origin in question is not a
+   scheme/host/port tuple, then return the literal string "null" and abort these steps.
    2. 
+
+   
  2. Otherwise, let result be the scheme part
+   of the origin tuple.
    3. 
+
+   
  3. Append the string "://" to result.
    4. 
+
+   
  4. 
+
+    
    Apply the IDNA ToASCII algorithm the host part of the
+    origin tuple, with both the AllowUnassigned and
+    UseSTD3ASCIIRules flags set, and append the results result.
    
+
+    
    If ToASCII fails to convert one of the components of the
+    string, e.g. because it is too long or because it contains invalid
+    characters, then return the empty string and abort these steps. [RFC3490]
    
+
+   
    5. 
+
+   
  5. If the port part of the origin tuple gives a port
+   that is different from the default port for the protocol given by
+   the scheme part of the origin tuple, then append a
+   U+003A COLON character (:) and the given port, in base ten, to
+   result.
    6. 
+
+   
  6. Return result.
    7. 
+
+  
Two origins are said to be the
+  same origin if the following algorithm returns true:

+
+  
  1. Let A be the first origin
+   being compared, and B be the second
+   origin being compared.
    2. 
+
+   
  2. If A and B are both
+   opaque identifiers, and their value is equal, then return
+   true.
    3. 
+
+   
  3. Otherwise, if either A or B or both are opaque identifiers, return
+   false.
    4. 
+
+   
  4. If A and B have
+   scheme components that are not identical, return false.
    5. 
+
+   
  5. If A and B have host
+   components that are not identical, return false.
    6. 
+
+   
  6. If A and B have port
+   components that are not identical, return false.
    7. 
+
+   
  7. If either A or B
+   have additional data, but that data is not identical for both,
+   return false.
    8. 
+
+   
  8. Return true.
    9. 
+
+  

+
+
+  
6.3.1 Relaxing the same-origin restriction

+
+  
document . domain [ = domain ]

+
+   

+
+    
Returns the current domain used for security checks.

+
+    
Can be set to a value that removes subdomains, to change the
+    effective script origin to allow pages on other
+    subdomains of the same domain (if they do the same thing) to
+    access each other.

+
+   

+
+  

+
+  
The domain
+  attribute on Document objects must be initialized to
+  the document's domain, if it has one, and the empty
+  string otherwise. If the value is an IPv6 address, then the square
+  brackets from the host portion of the <host> component must be omitted from
+  the attribute's value.

+
+  
On getting, the attribute must return its current
+  value, unless the document was created by
+  XMLHttpRequest, in which case it must throw an
+  INVALID_ACCESS_ERR exception.

+
+  
On setting, the user agent must run the following algorithm:

+
+  
  1. 
+
+    
    If the document was created by XMLHttpRequest,
+    throw an INVALID_ACCESS_ERR exception and abort these
+    steps.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If the new value is an IP address, let new
+    value be the new value. Otherwise, apply the IDNA ToASCII
+    algorithm to the new value, with both the AllowUnassigned and
+    UseSTD3ASCIIRules flags set, and let new value
+    be the result of the ToASCII algorithm.
    
+
+    
    If ToASCII fails to convert one of the components of the
+    string, e.g. because it is too long or because it contains invalid
+    characters, then throw a SECURITY_ERR exception and abort
+    these steps. [RFC3490]
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If new value is not exactly equal to the
+    current value of the document.domain attribute, then
+    run these substeps:
    
+
+    
    1. 
+
+      
      If the current value is an IP address, throw a
+      SECURITY_ERR exception and abort these steps.
      
+
+     
      2. 
+
+     
    2. 
+
+      
      If new value, prefixed by a U+002E FULL
+      STOP (.), does not exactly match the end of the current value,
+      throw a SECURITY_ERR exception and abort these
+      steps.
      
+
+     
      3. 
+
+     
    3. 
+
+      
      If new value matches a suffix in the
+      Public Suffix List, or, if new value,
+      prefixed by a U+002E FULL STOP (.), matches the end of a
+      suffix in the Public Suffix List, then throw a
+      SECURITY_ERR exception and abort these steps. [PSL]
      
+
+      
      Suffixes must be compared after applying the IDNA ToASCII
+      algorithm to them, with both the AllowUnassigned and
+      UseSTD3ASCIIRules flags set, in an ASCII
+      case-insensitive manner. [RFC3490]
      
+
+     
      4. 
+
+    
    4. 
+
+   
  4. Release the storage mutex.
    5. 
+
+   
  5. 
+
+    
    Set the attribute's value to new value.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Set the host part of the effective script origin
+    tuple of the Document to new
+    value.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Set the port part of the effective script origin
+    tuple of the Document to "manual override" (a value
+    that, for the purposes of comparing
+    origins, is identical to "manual override" but not
+    identical to any other value).
    
+
+   
    8. 
+
+  
The domain of a
+  Document is the host part of the document's
+  origin, if that is a scheme/host/port tuple. If it
+  isn't, then the document does not have a domain.

+
+  

+
+  
The domain
+  attribute is used to enable pages on different hosts of a domain to
+  access each others' DOMs.

+
+  
Do not use the document.domain attribute when
+  using shared hosting. If an untrusted third party is able to host an
+  HTTP server at the same IP address but on a different port, then the
+  same-origin protection that normally protects two different sites on
+  the same host will fail, as the ports are ignored when comparing
+  origins after the document.domain attribute has
+  been used.

+
+
+
+  
6.4 Session history and navigation

+
+  
6.4.1 The session history of browsing contexts

+
+  
The sequence of Documents in a browsing
+  context is its session history.

+
+  
History objects provide a representation of the
+  pages in the session history of browsing contexts. Each browsing
+  context, including nested browsing contexts, has a distinct session
+  history.

+
+  
Each Document object in a browsing
+  context's session history is associated with a
+  unique instance of the History object, although they
+  all must model the same underlying session history.

+
+  

+
+  
The history attribute
+  of the Window interface must return the object
+  implementing the History interface for that
+  Window object's Document.

+
+  

+
+  
History objects represent their browsing
+  context's session history as a flat list of session history entries. Each
+  session history entry consists of either a
+  URL or a state object, or both, and may in addition have a title, a
+  Document object, form data, a scroll position, and
+  other information associated with it.

+
+  

+
+  
This does not imply that the user interface need be
+  linear. See the notes below.

+
+  

+
+  
Titles associated with session history entries need not have any relation
+  with the current title of the
+  Document. The title of a session history
+  entry is intended to explain the state of the document at
+  that point, so that the user can navigate the document's
+  history.

+
+  
URLs without associated state
+  objects are added to the session history as the user (or
+  script) navigates from page to page.

+
+  
A state object is an object representing a user
+  interface state.

+
+  
Pages can add state objects between their entry in the
+  session history and the next ("forward") entry. These are then returned to the script when the user
+  (or script) goes back in the history, thus enabling authors to use
+  the "navigation" metaphor even in one-page applications.

+
+  

+
+   
State objects are intended to
+   be used for two main purposes: first, storing a preparsed
+   description of the state in the URL so that in the
+   simple case an author doesn't have to do the parsing (though one
+   would still need the parsing for handling URLs passed around by users, so it's only a minor
+   optimization), and second, so that the author can store state that
+   one wouldn't store in the URL because it only applies to the current
+   Document instance and it would have to be reconstructed
+   if a new Document were opened.

+
+   
An example of the latter would be something like keeping track of
+   the precise coordinate from which a popup div was made
+   to animate, so that if the user goes back, it can be made to animate
+   to the same location. Or alternatively, it could be used to keep a
+   pointer into a cache of data that would be fetched from the server
+   based on the information in the URL, so that when going
+   back and forward, the information doesn't have to be fetched
+   again.

+
+  

+
+  
At any point, one of the entries in the session history is the
+  current entry. This is the entry representing the
+  active document of the browsing
+  context. The current entry is usually an entry
+  for the location of the
+  Document. However, it can also be one of the entries
+  for state objects added to the
+  history by that document.

+
+  
Entries that consist of state
+  objects share the same Document as the entry for
+  the page that was active when they were added.

+
+  
Contiguous entries that differ just by fragment identifier also
+  share the same Document.

+
+  
All entries that share the same
+  Document (and that are therefore merely different
+  states of one particular document) are contiguous by definition.

+
+  

+
+  
User agents may discard
+  the Document objects of entries other than the
+  current entry that are not referenced from any script,
+  reloading the pages afresh when the user or script navigates back to
+  such pages. This specification does not specify when user agents
+  should discard Document objects and when they should
+  cache them.

+
+  
Entries that have had their Document objects
+  discarded must, for the purposes of the algorithms given below, act
+  as if they had not. When the user or script navigates back or
+  forwards to a page which has no in-memory DOM objects, any other
+  entries that shared the same Document object with it
+  must share the new object as well.

+
+  

+
+
+  
6.4.2 The History interface

+
+  
interface History {
+  readonly attribute long length;
+  void go(in optional long delta);
+  void back();
+  void forward();
+  void pushState(in any data, in DOMString title, in optional DOMString url);
+  void replaceState(in any data, in DOMString title, in optional DOMString url);
+};

+
+  
window . history . length

+
+   

+
+    
Returns the number of entries in the joint session history.

+
+   

+
+   
window . history . go( [ delta ] )

+
+   

+
+    
Goes back or forward the specified number of steps in the joint session history.

+
+    
A zero delta will reload the current page.

+
+    
If the delta is out of range, does nothing.

+
+   

+
+   
window . history . back()

+
+   

+
+    
Goes back one step in the joint session history.

+
+    
If there is no previous page, does nothing.

+
+   

+
+   
window . history . forward()

+
+   

+
+    
Goes forward one step in the joint session history.

+
+    
If there is no next page, does nothing.

+
+   

+
+   
window . history . pushState(data, title [, url ] )

+
+   

+
+    
Pushes the given data onto the session history, with the given title, and, if provided, the given URL.

+
+   

+
+   
window . history . replaceState(data, title [, url ] )

+
+   

+
+    
Updates the current entry in the session histor to have the given data, title, and, if provided, URL.

+
+   

+
+  
The joint session history of a History
+  object is the union of all the session
+  histories of all browsing
+  contexts of all the fully active
+  Document objects that share the History
+  object's top-level browsing context, with all the
+  entries that are current entries
+  in their respective session
+  histories removed except for the current entry of the
+  joint session history.

+
+  
The current entry of the joint session history is the
+  entry that most recently became a current entry in its
+  session history.

+
+  
Entries in the joint session history are ordered
+  chronologically by the time they were added to their respective
+  session histories. (Since all
+  these browsing contexts by
+  definition share an event loop, there is always a
+  well-defined sequential order in which their session histories had their entries added.) Each
+  entry has an index; the earliest entry has index 0, and the
+  subsequent entries are numbered with consecutively increasing
+  integers (1, 2, 3, etc).

+
+  

+
+  
The length
+  attribute of the History interface must return the
+  number of entries in the joint session history.

+
+  
The actual entries are not accessible from script.

+
+  
When the go(delta) method is invoked, if the
+  argument to the method was omitted or has the value zero, the user
+  agent must act as if the location.reload() method was
+  called instead. Otherwise, the user agent must traverse the
+  history by a delta whose value is the value of the method's
+  argument.

+
+  
When the back()
+  method is invoked, the user agent must traverse the history by
+  a delta −1.

+
+  
When the forward()method is
+  invoked, the user agent must traverse the history by a
+  delta +1.

+
+  
To traverse the history by a delta delta, the user agent must queue a task
+  to run the following steps. The task source for the
+  queued task is the history traversal task source.

+
+  
  1. Let delta be the argument to the
+   method.
    2. 
+
+   
  2. If the index of the current entry of the joint session
+   history plus delta is less than zero or
+   greater than or equal to the number of items in the joint
+   session history, then the user agent must do nothing.
    
+
+   
  3. Let specified entry be the entry in the
+   joint session history whose index is the sum of delta and the index of the current entry of
+   the joint session history.
    4. 
+
+   
  4. Let specified browsing context be the
+   browsing context of the specified
+   entry.
    5. 
+
+   
+
+   
  5. Traverse the history of the specified browsing context to the specified entry.
    
+
+  
When the user navigates through a browsing context,
+  e.g. using a browser's back and forward buttons, the user agent must
+  traverse the history by a delta equivalent to the
+  action specified by the user.

+
+  
The pushState(data, title, url) method adds a state object entry to
+  the history.

+
+  
The replaceState(data, title, url) method updates the state object,
+  title, and optionally the URL of the current
+  entry in the history.

+
+  
When either of these methods is invoked, the user agent must run
+  the following steps:

+
+  
  1. Let clone data be a structured
+   clone of the specified data. If this
+   throws an exception, then rethrow that exception and abort these
+   steps.
    2. 
+
+   
  2. 
+
+    
    If a third argument is specified, run these substeps:
    
+
+    
    1. Resolve the value of the
+     third argument, relative to the entry script's base URL.
      2. 
+
+     
    2. If that fails, raise a SECURITY_ERR exception
+     and abort these steps.
      3. 
+
+     
    3. Compare the resulting absolute URL to the
+     document's address. If any part of these two URLs differ other than the <path>, <query>, and <fragment> components, then
+     raise a SECURITY_ERR exception and abort these
+     steps.
      4. 
+
+     
    4. If the origin of the resulting absolute
+     URL is not the same as the origin of the
+     entry script's document, and either the <path> or <query> components of the two
+     URLs compared in the previous step
+     differ, raise a SECURITY_ERR exception and abort
+     these steps. (This prevents sandboxed content from spoofing other
+     pages on the same origin.)
      5. 
+
+    
    For the purposes of the comparisons in the above substeps, the
+    <path> and <query> components can only be the
+    same if the URLs are both hierarchical URLs.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If the method invoked was the pushState() method:
    
+
+    
    1. 
+
+      
      Remove all the entries in the browsing context's
+      session history after the current
+      entry. If the current entry is the last
+      entry in the session history, then no entries are
+      removed.
      
+
+      
      This doesn't
+      necessarily have to affect the user agent's user
+      interface.
      
+
+     
      2. 
+
+     
    2. Remove any tasks queued
+     by the history traversal task source.
      3. 
+
+     
    3. Add a state object entry to the session history, after the
+     current entry, with cloned data as
+     the state object, the given title as the title,
+     and, if the third argument is present, the absolute
+     URL that was found earlier in this algorithm as the
+     URL of the entry.
      4. 
+
+     
    4. Update the current entry to be the this newly
+     added entry.
      5. 
+
+    
    Otherwise, if the method invoked was the replaceState() method:
    
+
+    
    1. Update the current entry in the session
+     history so that cloned data is the entry's
+     new state object, the given title is the new
+     title, and, if the third argument is present, the absolute
+     URL that was found earlier in this algorithm is the
+     entry's new URL.
      2. 
+
+    
    4. 
+
+   
  4. 
+
+    
    If the third argument is present, set the document's
+    current address to the absolute URL that was
+    found earlier in this algorithm.
    
+
+    
    Since this is neither a navigation of the browsing
+    context nor a history
+    traversal, it does not cause a hashchange event to be fired.
    
+
+   
    5. 
+
+  
The title is purely
+  advisory. User agents might use the title in the user interface.

+
+  
User agents may limit the number of state objects added to the
+  session history per page. If a page hits the UA-defined limit, user
+  agents must remove the entry immediately after the first entry for
+  that Document object in the session history after
+  having added the new entry. (Thus the state history acts as a FIFO
+  buffer for eviction, but as a LIFO buffer for navigation.)

+
+  

+
+  

+
+   
Consider a game where the user can navigate along a line, such
+   that the user is always at some coordinate, and such that the user
+   can bookmark the page corresponding to a particular coordinate, to
+   return to it later.

+
+   
A static page implementing the x=5 position in such a game could
+   look like the following:

+
+   
<!DOCTYPE HTML>
+<!-- this is http://example.com/line?x=5 -->
+<title>Line Game - 5</title>
+<p>You are at coordinate 5 on the line.</p>
+<p>
+ <a href="?x=6">Advance to 6</a> or
+ <a href="?x=4">retreat to 4</a>?
+</p>

+
+   
The problem with such a system is that each time the user
+   clicks, the whole page has to be reloaded. Here instead is another
+   way of doing it, using script:

+
+   
<!DOCTYPE HTML>
+<!-- this starts off as http://example.com/line?x=5 -->
+<title>Line Game - 5</title>
+<p>You are at coordinate <span id="coord">5</span> on the line.</p>
+<p>
+ <a href="?x=6" onclick="go(1)">Advance to 6</a> or
+ <a href="?x=4" onclick="go(-1)">retreat to 4</a>?
+</p>
+<script>
+ var currentPage = 5; // prefilled by server
+ function go(d) {
+   history.pushState(currentPage, 'Line Game - ' + currentPage, '?x=' + currentPage);
+   setupPage(currentPage + d);
+ }
+ onpopstate = function(event) {
+   setupPage(event.state);
+ }
+ function setupPage(page) {
+   currentPage = page;
+   document.title = 'Line Game - ' + currentPage;
+   document.getElementById('coord').textContent = currentPage;
+   document.links[0].href = '?x=' + (currentPage+1);
+   document.links[0].textContent = 'Advance to ' + (currentPage+1);
+   document.links[1].href = '?x=' + (currentPage-1);
+   document.links[1].textContent = 'retreat to ' + (currentPage-1);
+ }
+</script>

+
+   
In systems without script, this still works like the previous
+   example. However, users that do have script support can
+   now navigate much faster, since there is no network access for the
+   same experience. Furthermore, contrary to the experience the user
+   would have with just a naïve script-based approach,
+   bookmarking and navigating the session history still work.

+
+   
In the example above, the data argument to
+   the pushState() method
+   is the same information as would be sent to the server, but in a
+   more convenient form, so that the script doesn't have to parse the
+   URL each time the user navigates.

+
+  

+
+  

+
+   
Applications might not use the same title for a session
+   history entry as the value of the document's
+   title element at that time. For example, here is a
+   simple page that shows a block in the title element.
+   Clearly, when navigating backwards to a previous state the user
+   does not go back in time, and therefore it would be inappropriate
+   to put the time in the session history title.

+
+   
<!DOCTYPE HTML>
+<TITLE>Line</TITLE>
+<SCRIPT>
+ setInterval(function () { document.title = 'Line - ' + new Date(); }, 1000);
+ var i = 1;
+ function inc() {
+   set(i+1);
+   history.pushState(i, 'Line - ' + i);
+ }
+ function set(newI) {
+   i = newI;
+   document.forms.F.I.value = newI;
+ }
+</SCRIPT>
+<BODY ONPOPSTATE="recover(event.state)">
+<FORM NAME=F>
+State: <OUTPUT NAME=I>1</OUTPUT> <INPUT VALUE="Increment" TYPE=BUTTON ONCLICK="inc()">
+</FORM>

+
+  

+
+
+
+  
6.4.3 The Location interface

+
+  
Each Document object in a browsing
+  context's session history is associated with a unique
+  instance of a Location object.

+
+  
document . location [ = value ]

+   
window . location [ = value ]

+
+   

+
+    
Returns a Location object with the current page's location.

+
+    
Can be set, to navigate to another page.

+
+   

+
+  

+
+  
The location attribute
+  of the HTMLDocument interface must return the
+  Location object for that Document object,
+  if it is in a browsing context, and null otherwise.

+
+  
The location
+  attribute of the Window interface must return the
+  Location object for that Window object's
+  Document.

+
+  

+
+  
Location objects provide a representation of their document's current
+  address, and allow the current entry of the
+  browsing context's session history to be changed, by
+  adding or replacing entries in the history object.

+
+  
interface Location {
+  stringifier attribute DOMString href;
+  void assign(in DOMString url);
+  void replace(in DOMString url);
+  void reload();
+
+  // URL decomposition IDL attributes 
+           attribute DOMString protocol;
+           attribute DOMString host;
+           attribute DOMString hostname;
+           attribute DOMString port;
+           attribute DOMString pathname;
+           attribute DOMString search;
+           attribute DOMString hash;
+
+  // resolving relative URLs
+  DOMString resolveURL(in DOMString url);
+};

+
+  
location . href [ = value ]

+
+   

+
+    
Returns the current page's location.

+
+    
Can be set, to navigate to another page.

+
+   

+
+   
location . assign(url)

+
+   

+
+    
Navigates to the given page.

+
+   

+
+   
location . replace(url)

+
+   

+
+    
Removes the current page from the session history and navigates to the given page.

+
+   

+
+   
location . reload()

+
+   

+
+    
Reloads the current page.

+
+   

+
+   
url = location . resolveURL(url)

+
+   

+
+    
Resolves the given relative URL to an absolute URL.

+
+   

+
+  

+
+  
The href
+  attribute must return the current address of the associated
+  Document object, as an absolute URL.

+
+  
On setting,  the user agent
+  must act as if the assign()
+  method had been called with the new value as its argument.

+
+  
+
+  
When the assign(url) method is invoked, the UA must
+  resolve the argument, relative to
+  the entry script's base
+  URL, and if that is successful, must navigate
+  the browsing context to the specified url. If the browsing context's
+  session history contains only one
+  Document, and that was the about:blank
+  Document created when the browsing context
+  was created, then the navigation must be done with
+  replacement enabled.
 
+
+  
When the replace(url) method is invoked, the UA must
+  resolve the argument, relative to
+  the entry script's base
+  URL, and if that is successful, navigate the
+  browsing context to the specified url with replacement enabled.

+
+  
Navigation for the assign() and replace() methods must be done
+  with the browsing
+  context of the script that invoked the method as the
+  source browsing context.

+
+  
If the resolving step of the
+  assign() and replace() methods is not
+  successful, then the user agent must instead throw a
+  SYNTAX_ERR exception.

+
+  
When the reload() method is
+  invoked, the user agent must run the appropriate steps from the
+  following list:

+
+  
If the currently executing task is the dispatch of a resize event in response to the user
+   resizing the browsing context

+
+   
Repaint the browsing context and abort these
+   steps.
 
+
+   
Otherwise

+
+   
Navigate the browsing context to
+   the document's current address with
+   replacement enabled. The source browsing
+   context must be the browsing context being
+   navigated.
 
+
+   
+
+  
When a user requests that the current page be reloaded through a
+  user interface element, the user agent should navigate
+  the browsing context to the same resource as
+  Document, with replacement enabled. In the
+  case of non-idempotent methods (e.g. HTTP POST), the user agent
+  should prompt the user to confirm the operation first, since
+  otherwise transactions (e.g. purchases or database modifications)
+  could be repeated. User agents may allow the user to explicitly
+  override any caches when reloading.

+
+  

+
+  
The Location interface also has the complement of
+  URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the rules given for URL decomposition IDL
+  attributes, with the input
+  being the current
+  address of the associated Document object, as an
+  absolute URL (same as the href attribute), and the common setter action being the
+  same as setting the href
+  attribute to the new output value.

+
+  

+
+  
The resolveURL(url) method must resolve its url argument, relative
+  to the entry script's base URL, and if that succeeds, return the resulting
+  absolute URL. If it fails, it must throw a
+  SYNTAX_ERR exception instead.

+
+  

+
+
+  

+
+  
6.4.3.1 Security

+
+  
User agents must raise a
+  SECURITY_ERR exception whenever any of the members of a
+  Location object are accessed by scripts whose
+  effective script origin is not the same as the Location object's associated
+  Document's effective script origin, with
+  the following exceptions:

+
+  

+
+
+  

+
+  
6.4.4 Implementation notes for session history

+  
+
+  
This section is non-normative.

+
+  
The History interface is not meant to place
+  restrictions on how implementations represent the session history to
+  the user.

+
+  
For example, session history could be implemented in a tree-like
+  manner, with each page having multiple "forward" pages. This
+  specification doesn't define how the linear list of pages in the
+  history object are derived from the
+  actual session history as seen from the user's perspective.

+
+  
Similarly, a page containing two iframes has a history object distinct from the
+  iframes' history
+  objects, despite the fact that typical Web browsers present the user
+  with just one "Back" button, with a session history that interleaves
+  the navigation of the two inner frames and the outer page.

+
+  
Security: It is suggested that to avoid letting
+  a page "hijack" the history navigation facilities of a UA by abusing
+  pushState(), the UA
+  provide the user with a way to jump back to the previous page
+  (rather than just going back to the previous state). For example,
+  the back button could have a drop down showing just the pages in the
+  session history, and not showing any of the states. Similarly, an
+  aural browser could have two "back" commands, one that goes back to
+  the previous state, and one that jumps straight back to the previous
+  page.

+
+  
In addition, a user agent could ignore calls to pushState() that are invoked on
+  a timer, or from event listeners that are not triggered in response
+  to a clear user action, or that are invoked in rapid succession.

+
+  

+
+
+  
6.5 Browsing the Web

+
+  

+
+  
+
+  
Certain actions cause the browsing context to
+  navigate to a new resource. Navigation always involves
+  source browsing context, which is the browsing context
+  which was responsible for starting the navigation.

+
+  
For example, following a hyperlink, form submission, and the window.open() and location.assign() methods can all
+  cause a browsing context to navigate.

+
+  
A user agent may provide various ways for the user to explicitly
+  cause a browsing context to navigate, in addition to those defined
+  in this specification.

+
+  
+  
When a browsing context is navigated
+  to a new resource, the user agent must run the following steps:

+
+  
  1. Release the storage mutex.
    2. 
+
+   
+
+   
+
+   
  2. If there is a preexisting attempt to navigate the
+   browsing context, and the source browsing
+   context is the same as the browsing context
+   being navigated, and that attempt is currently
+   running the unload a document algorithm, and the
+   origin of the URL of the resource being
+   loaded in that navigation is not the same origin as
+   the origin of the URL of the resource
+   being loaded in this navigation, then abort these steps
+   without affecting the preexisting attempt to navigate the
+   browsing context.
    3. 
+   
+
+   
  3. If there is a preexisting attempt to navigate the
+   browsing context, and either that attempt has not yet
+   matured (i.e. it has
+   not passed the point of making its Document the
+   active document), or that navigation's resource is not
+   to be fetched using HTTP GET or equivalent, or its
+   resource's absolute URL differs from this attempt's by
+   more than the presence, absence, or value of the <fragment> component, then cancel
+   that preexisting attempt to navigate the browsing
+   context.
    4. 
+
+   
+
+   
  4. Cancel any preexisting attempt to navigate the
+   browsing context.
    5. 
+
+   
  5. If the new resource is to be handled using a mechanism that
+   does not affect the browsing context, e.g. ignoring the navigation
+   request altogether because the specified scheme is not one of the
+   supported protocols, then abort these steps and proceed with that
+   mechanism instead.
    6. 
+
+   
  6. Prompt to
+   unload the Document object. If the user
+   refused to allow the document to be unloaded, then
+   these steps must be aborted.
    7. 
+
+   
  7. 
+
+    
    If the new resource is to be handled by displaying some sort of
+    inline content, e.g. an error message because the specified scheme
+    is not one of the supported protocols, or an inline prompt to
+    allow the user to select a registered
+    handler for the given scheme, then display the inline content and
+    abort these steps.
    
+
+    
    In the case of a registered handler being used,
+    the algorithm will be reinvoked with a new URL to handle the
+    request.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    If the new resource is to be fetched using HTTP GET or equivalent, then
+    check if there are any relevant application caches that are identified by a
+    URL with the same origin as the URL in question, and
+    that have this URL as one of their entries, excluding entries
+    marked as foreign. If so, then the
+    user agent must then get the resource from the most appropriate application
+    cache of those that match.
    
+
+    
    For example, imagine an HTML page with an
+    associated application cache displaying an image and a form, where
+    the image is also used by several other application caches. If the
+    user right-clicks on the image and chooses "View Image", then the
+    user agent could decide to show the image from any of those
+    caches, but it is likely that the most useful cache for the user
+    would be the one that was used for the aforementioned HTML
+    page. On the other hand, if the user submits the form, and the
+    form does a POST submission, then the user agent will not use an
+    application cache at all; the submission will be made to the
+    network.
    
+
+    
    Otherwise, unless it has already been obtained, fetch the new
+    resource, with the manual redirect flag set.
    
+
+    
    If the resource is being fetched using a method other than one
+    equivalent to
+    HTTP's GET, or, if the
+    navigation algorithm was invoked as
+    a result of the form submission
+    algorithm, then the fetching
+    algorithm must be invoked from the origin of
+    the active document of the source browsing
+    context, if any.
     
+
+    
    If the browsing context being navigated is a
+    child browsing context for an iframe or
+    object element, then the fetching
+    algorithm must be invoked from the iframe or
+    object element's browsing context scope
+    origin, if it has one.
     
+
+   
    9. 
+
+   
  9. 
+
+    
    At this point, unless this step has already been reached once
+    before in the execution of this instance of the algorithm, the
+    user agents must return to whatever algorithm invoked the
+    navigation steps and must continue these steps asynchronously.
    
+
+   
    10. 
+
+   
  10. 
+
+    
    If fetching the resource results in a redirect, and either the
+    URL of the target of the redirect has the same
+    origin as the original resource, or the resource is being
+    obtained using the POST method or a safe method (in HTTP terms),
+    return to the step labeled
+    "fragment identifiers" with the new resource.
    
+
+    
    Otherwise, if fetching the resource results in a redirect but
+    the URL of the target of the redirect does not have
+    the same origin as the original resource and the
+    resource is being obtained using a method that is neither the POST
+    method nor a safe method (in HTTP terms), then abort these
+    steps. The user agent may indicate to the user that the navigation
+    has been aborted for security reasons.
    
+
+   
    11. 
+
+   
  11. Wait for one or more bytes to be available or for the user
+   agent to establish that the resource in question is empty. During
+   this time, the user agent may allow the user to cancel this
+   navigation attempt or start other navigation attempts.
    12. 
+
+   
  12. 
+
+    
    If the resource was not fetched from an application
+    cache, and was to be fetched using HTTP GET or equivalent, and its
+    URL matches the
+    fallback namespace of one or more relevant application caches, and the
+    user didn't cancel the navigation attempt during the previous
+    step, and the navigation attempt failed (e.g. the server returned
+    a 4xx or 5xx status code or equivalent, or
+    there was a DNS error), then:
     
+
+    
    Let candidate be the fallback resource
+    specified for the fallback namespace in
+    question. If multiple application caches match, the user agent
+    must use the fallback of the most appropriate application
+    cache of those that match.
    
+
+    
    If candidate is not marked as foreign, then the user
+    agent must discard the failed load and instead continue along
+    these steps using candidate as the
+    resource. The document's address, if appropriate,
+    will still be the originally requested URL, not the fallback URL,
+    but the user agent may indicate to the user that the original page
+    load failed, that the page used was a fallback resource, and what
+    the URL of the fallback resource actually is.
    
+
+   
    13. 
+
+   
  13. If the document's out-of-band metadata (e.g. HTTP headers),
+   not counting any type information
+   (such as the Content-Type HTTP header), requires some sort of
+   processing that will not affect the browsing context, then perform
+   that processing and abort these steps.
    
+
+   
    
+    
    Such processing might be triggered by, amongst other things, the
+    following:
    
+    
    • HTTP status codes (e.g. 204 No Content or 205 Reset Content)
      • 
+     
    • HTTP Content-Disposition headers
      • 
+     
    • Network errors
      • 
+    
    
+
+    
+
+    
    HTTP 401 responses that do not include a challenge recognized
+    by the user agent must be processed as if they had no challenge,
+    e.g. rendering the entity body as if the response had been 200
+    OK.
    
+
+    
    User agents may show the entity body of an HTTP 401 response
+    even when the response do include a recognized challenge, with the
+    option to login being included in a non-modal fashion, to enable
+    the information provided by the server to be used by the user
+    before authenticating. Similarly, user agents should allow the
+    user to authenticate (in a non-modal fashion) against
+    authentication challenges included in other responses such as HTTP
+    200 OK responses, effectively allowing resources to present HTTP
+    login forms without requiring their use.
    
+
+   
    14. 
+
+   
  14. Let type be the sniffed type of the resource.
    15. 
+
+   
  15. If the user agent has been configured to process resources
+   of the given type using some mechanism other
+   than rendering the content in a browsing context, then
+   skip this step. Otherwise, if the type is one
+   of the following types, jump to the appropriate entry in the
+   following list, and process the resource as described there:
    
+
+    
    "text/html"
    
+     
    "text/html-sandboxed"
    
+     
    Follow the steps given in the HTML document section, and abort
+     these steps.
    
+
+     
+     
    Any type ending in "+xml"
     
+     
    "application/xml"
    
+     
    "text/xml"
    
+     
    Follow the steps given in the XML
+     document section. If that section determines that the
+     content is not to be displayed as a generic XML
+     document, then proceed to the next step in this overall set of
+     steps. Otherwise, abort these steps.
    
+
+     
    "text/plain"
    
+     
    Follow the steps given in the plain text file section, and abort
+     these steps.
    
+
+     
    A supported image type
    
+     
    Follow the steps given in the image section, and abort these
+     steps.
    
+
+     
    A type that will use an external application to render the
+     content in the browsing context
    
+     
    Follow the steps given in the plugin section, and abort these
+     steps.
    
+
+    
    Setting the document's
+    address: If there is no override URL, then any
+    Document created by these steps must have its address set to the
+    URL that was originally to be fetched, ignoring any other data that was
+    used to obtain the resource (e.g. the entity body in the case of a
+    POST submission is not part of the document's
+    address, nor is the URL of the fallback resource in the
+    case of the original load having failed and that URL having been
+    found to match a fallback
+    namespace). However, if there is an override
+    URL, then any Document created by these steps
+    must have its address
+    set to that URL instead.
    
+
+    
    An override URL
+    is set when dereferencing a
+    javascript: URL.
    
+
+    
    Creating a new
+    Document object: When a Document
+    is created as part of the above steps, a new Window
+    object must be created and associated with the
+    Document, with one exception: if the browsing
+    context's only entry in its session history is
+    the about:blank Document that was added
+    when the browsing context was created, and navigation
+    is occurring with replacement enabled, and that
+    Document has the same origin as the new
+    Document, then the Window object of that
+    Document must be used instead, and the document attribute of the
+    Window object must be changed to point to the new
+    Document instead.
    
+
+   
    16. 
+
+   
+
+   
  16. Otherwise, the document's type is such
+   that the resource will not affect the browsing context,
+   e.g. because the resource is to be handed to an external
+   application. Process the resource appropriately.
    
+
+  
Some of the sections below, to which the above algorithm defers
+  in certain cases, require the user agent to update the session
+  history with the new page. When a user agent is required to do
+  this, it must queue a task to run the following
+  steps:

+
+  
  1. Unload the
+   Document object of the current entry,
+   with the recycle parameter set to
+   false.
    2. 
+
+   
  2. 
+
+    
    If the navigation was initiated for entry update of
+     an entry
    
+
+     
    
+
+      
    1. Replace the Document of the entry being
+       updated, and any other entries that referenced the same
+       document as that entry, with the new
+       Document.
      2. 
+
+       
    2. Traverse the history to the new
+       entry.
      3. 
+
+      
    This can only happen if the entry being updated
+      is no the current entry, and can never happen with
+      replacement enabled. (It happens when the user
+      tried to traverse to a session history entry that no longer had
+      a Document object.)
    
+
+     
    
+
+
+     
    Otherwise
    
+
+     
    
+
+      
    1. 
+
+        
      Remove all the entries in the browsing
+        context's session history after the
+        current entry. If the current entry
+        is the last entry in the session history, then no entries are
+        removed.
      
+
+        
      This doesn't
+        necessarily have to affect the user agent's user
+        interface.
      
+
+       
      2. 
+
+       
    2. Remove any tasks
+       queued by the history traversal task
+       source.
      3.  
+
+       
    3. Append a new entry at the end of the History
+       object representing the new resource and its
+       Document object and related state.
      4. 
+
+       
    4. Traverse the history to the new entry. If
+       the navigation was initiated with replacement
+       enabled, then the traversal must itself be initiated
+       with replacement enabled.
      
+
+       
      5. 
+
+      
    
+
+    
    3. 
+
+   
  3. The navigation algorithm has
+   now matured.
    4. 
+
+   
  4. Fragment identifier loop: Spin the event
+   loop for a user-agent-defined amount of time, as desired by
+   the user agent implementor. (This is intended to allow the user
+   agent to optimize the user experience in the face of performance
+   concerns.)
    5. 
+
+   
  5. If the Document object has no parser, or its
+   parser has stopped parsing, or
+   the user agent has reason to believe the user is no longer
+   interested in scrolling to the fragment identifier, then abort
+   these steps.
    6. 
+
+   
  6. Scroll to the fragment identifier given in
+   the document's current address. If this fails to find
+   an indicated part
+   of the document, then return to the fragment identifier
+   loop step.
    7. 
+
+  
The task source for this task is the networking task
+  source.

+
+
+  
6.5.2 Page load processing model for HTML files

+
+  
When an HTML document is to be loaded in a browsing
+  context, the user agent must queue a task to
+  create a Document object, mark it as being
+  an HTML document, create an
+  HTML parser, and associate it with the document. Each
+  task that the networking
+  task source places on the task queue while the
+  fetching algorithm runs must then fill
+  the parser's input stream with the fetched bytes and
+  cause the HTML parser to perform the appropriate
+  processing of the input stream.

+
+  
The input stream converts bytes into
+  characters for use in the tokenizer. This process relies, in part,
+  on character encoding information found in the real Content-Type metadata of the resource;
+  the "sniffed type" is not used for this purpose.

+
+  
+
+  
When no more bytes are available, the user agent must queue
+  a task for the parser to process the implied EOF character,
+  which eventually causes a load event
+  to be fired.

+
+  
After creating the Document object, but before any
+  script execution, certainly before the parser stops, the user agent must update the session
+  history with the new page.

+
+  
Application
+  cache selection happens in the
+  HTML parser.

+
+  
The task source for the two tasks mentioned in this
+  section must be the networking task source.

+
+
+
+  
6.5.3 Page load processing model for XML files

+
+  
When faced with displaying an XML file inline, user agents must
+  first create a Document object, following
+  the requirements of the XML and Namespaces in XML recommendations,
+  RFC 3023, DOM3 Core, and other relevant specifications. [XML] [XMLNS] [RFC3023] [DOMCORE]

+
+  
The actual HTTP headers and other metadata, not the headers as
+  mutated or implied by the algorithms given in this specification,
+  are the ones that must be used when determining the character
+  encoding according to the rules given in the above
+  specifications. Once the character encoding is established, the
+  document's character encoding must be set to that
+  character encoding.

+
+  
If the root element, as parsed according to the XML
+  specifications cited above, is found to be an html
+  element with an attribute manifest whose value is not the
+  empty string, then, as soon as the element is inserted into the document, the user
+  agent must resolve the value of
+  that attribute relative to that element, and if that is successful,
+  must run the application cache
+  selection algorithm with the resulting absolute
+  URL with any <fragment> component removed as
+  the manifest URL, and passing in the newly-created
+  Document. Otherwise, if the attribute is absent, its
+  value is the empty string, or resolving its value fails, then as
+  soon as the root element is inserted into the document, the user agent must run
+  the application cache selection
+  algorithm with no manifest, and passing in the
+  Document.

+
+  
Because the processing of the manifest attribute happens
+  only once the root element is parsed, any URLs referenced by
+  processing instructions before the root element (such as <?xml-stylesheet?> and <?xbl?> PIs) will be fetched from the network and
+  cannot be cached.

+
+  
User agents may examine the namespace of the root
+  Element node of this Document object to
+  perform namespace-based dispatch to alternative processing tools,
+  e.g. determining that the content is actually a syndication feed and
+  passing it to a feed handler. If such processing is to take place,
+  abort the steps in this section, and jump to the next step (labeled
+  "non-document content") in the navigate steps
+  above.

+
+  
Otherwise, then, with the newly created Document,
+  the user agents must update the session history with the new
+  page. User agents may do this before the complete document
+  has been parsed (thus achieving incremental rendering), and
+  must do this before any scripts are to be executed.

+
+  
Error messages from the parse process (e.g. XML namespace
+  well-formedness errors) may be reported inline by mutating the
+  Document.

+
+
+  
6.5.4 Page load processing model for text files

+
+  
When a plain text document is to be loaded in a browsing
+  context, the user agent should queue a task to
+  create a Document object, mark it as being
+  an HTML document, create an
+  HTML parser, associate it with the document, act as if
+  the tokenizer had emitted a start tag token with the tag name "pre"
+  followed by a single U+000A LINE FEED (LF) character, and switch the HTML parser's tokenizer
+  to the PLAINTEXT state.  Each task that the networking task
+  source places on the task queue while the fetching algorithm runs must then fill the
+  parser's input stream with the fetched bytes and cause
+  the HTML parser to perform the appropriate processing
+  of the input stream.

+
+  
The rules for how to convert the bytes of the plain text document
+  into actual characters are defined in RFC 2046, RFC 2646, and
+  subsequent versions thereof. [RFC2046] [RFC2646]

+
+  
The document's character encoding must be set to the
+  character encoding used to decode the document.

+
+  
Upon creation of the Document object, the user agent
+  must run the application cache
+  selection algorithm with no manifest, and passing in the
+  newly-created Document.

+
+  
+
+  
When no more bytes are available, the user agent must queue
+  a task for the parser to process the implied EOF character,
+  which eventually causes a load event
+  to be fired.

+
+  
After creating the Document object, but potentially
+  before the page has finished parsing, the user agent must
+  update the session history with the new page.

+
+  
User agents may add content to the head element of
+  the Document, e.g. linking to a style sheet or an XBL
+  binding, providing script, giving the document a title,
+  etc.

+
+  
The task source for the two tasks mentioned in this
+  section must be the networking task source.

+
+
+  
6.5.5 Page load processing model for images

+
+  
When an image resource is to be loaded in a browsing
+  context, the user agent should create a
+  Document object, mark it as being an HTML document, append an
+  html element to the Document, append a
+  head element and a body element to the
+  html element, append an img to the
+  body element, and set the src attribute of the img
+  element to the address of the image.

+
+  
+
+  
Then, the user agent must act as if it had stopped parsing.

+
+  
Upon creation of the Document object, the user agent
+  must run the application cache
+  selection algorithm with no manifest, and passing in the
+  newly-created Document.

+
+  
After creating the Document object, but potentially
+  before the page has finished fully loading, the user agent must
+  update the session history with the new page.

+
+  
User agents may add content to the head element of
+  the Document, or attributes to the img
+  element, e.g. to link to a style sheet or an XBL binding, to provide
+  a script, to give the document a title, etc.

+
+
+  
6.5.6 Page load processing model for content that uses plugins

+
+  
When a resource that requires an external resource to be rendered
+  is to be loaded in a browsing context, the user agent
+  should create a Document object, mark it
+  as being an HTML document,
+  append an html element to the Document,
+  append a head element and a body element
+  to the html element, append an embed to
+  the body element, and set the src attribute of the
+  embed element to the address of the resource.

+
+  
+
+  
Then, the user agent must act as if it had stopped parsing.

+
+  
Upon creation of the Document object, the user agent
+  must run the application cache
+  selection algorithm with no manifest, and passing in the
+  newly-created Document.

+
+  
After creating the Document object, but potentially
+  before the page has finished fully loading, the user agent must
+  update the session history with the new page.

+
+  
User agents may add content to the head element of
+  the Document, or attributes to the embed
+  element, e.g. to link to a style sheet or an XBL binding, or to give
+  the document a title.

+
+  
If the sandboxed
+  plugins browsing context flag was set on the browsing
+  context when the Document was created, the
+  synthesized embed element will fail to render the content.

+
+
+  
6.5.7 Page load processing model for inline content that doesn't have a DOM

+
+  
When the user agent is to display a user agent page inline in a
+  browsing context, the user agent should create a
+  Document object, mark it as being an HTML document, and then either
+  associate that Document with a custom rendering that is
+  not rendered using the normal Document rendering rules,
+  or mutate that Document until it represents the content
+  the user agent wants to render.

+
+  
+
+  
Once the page has been set up, the user agent must act as if it
+  had stopped parsing.

+
+  
Upon creation of the Document object, the user agent
+  must run the application cache
+  selection algorithm with no manifest, passing in the
+  newly-created Document.

+
+  
After creating the Document object, but potentially
+  before the page has been completely set up, the user agent must
+  update the session history with the new page.

+
+
+
+  
6.5.8 Navigating to a fragment identifier

+
+  
When a user agent is supposed to navigate to a fragment
+  identifier, then the user agent must queue a task to
+  run the following steps:

+
+  
  1. 
+
+    
    Remove all the entries in the browsing context's
+    session history after the current
+    entry. If the current entry is the last entry
+    in the session history, then no entries are removed.
    
+
+    
    This doesn't necessarily
+    have to affect the user agent's user interface.
    
+
+   
    2. 
+
+   
  2. Remove any tasks queued by
+   the history traversal task source.
    3. 
+
+   
  3. Append a new entry at the end of the History
+   object representing the new resource and its Document
+   object and related state. Its URL must be set to the
+   address to which the user agent was navigating. The title must be left
+   unset.
    4. 
+
+   
  4. Traverse the history to the new entry. This
+   will scroll to the fragment identifier given in what
+   is now the document's current address.
    5. 
+
+  
If the scrolling fails because the relevant ID has
+  not yet been parsed, then the original navigation algorithm will take care of the
+  scrolling instead, as the last few steps of its update the
+  session history with the new page algorithm.

+
+  
When the user agent is required to scroll to the fragment
+  identifier, it must change the scrolling position of the
+  document, or perform some other action, such that the
+  indicated part of the document is brought to the user's
+  attention. If there is no indicated part, then the user agent must
+  not scroll anywhere.

+
+  
The indicated part of the document is the one that the
+  fragment identifier, if any, identifies. The semantics of the
+  fragment identifier in terms of mapping it to a specific DOM Node is
+  defined by the specification that defines the MIME type
+  used by the Document (for example, the processing of
+  fragment identifiers for XML MIME
+  types is the responsibility of RFC3023). [RFC3023]

+
+  
For HTML documents (and HTML MIME
+  types), the following processing model must be followed to
+  determine what the indicated part of the document
+  is.

+
+  
  1. Parse the URL,
+   and let fragid be the <fragment> component of the
+   URL.
    2. 
+
+   
  2. If fragid is the empty string, then
+   the indicated part of the document is the top of the
+   document; stop the algorithm here.
    3. 
+
+   
  3. Let decoded fragid be the result of
+   expanding any sequences of percent-encoded octets in fragid that are valid UTF-8 sequences into Unicode
+   characters as defined by UTF-8. If any percent-encoded octets in
+   that string are not valid UTF-8 sequences, then skip this step and
+   the next one.
    
+
+   
  4. If this step was not skipped and there is an element in the
+   DOM that has an ID exactly equal to decoded
+   fragid, then the first such element in tree order is
+   the indicated part of the document; stop the algorithm
+   here.
    5. 
+
+   
  5. If there is an a element in the DOM that has a
+   name attribute whose value is
+   exactly equal to fragid (not decoded fragid), then the first such element in tree
+   order is the indicated part of the document; stop the
+   algorithm here.
    6. 
+
+   
  6. If fragid is an ASCII
+   case-insensitive match for the string top, then the indicated part of the
+   document is the top of the document; stop the algorithm
+   here.
    7. 
+
+   
  7. Otherwise, there is no indicated part of the document.
    8. 
+
+  
For the purposes of the interaction of HTML with Selectors' :target pseudo-class, the
+  target element is the indicated part of the
+  document, if that is an element; otherwise there is no
+  target element. [SELECTORS]

+
+  

+
+
+
+  
6.5.9 History traversal
 
+
+  

+
+  
When a user agent is required to traverse the history
+  to a specified entry, optionally with replacement
+  enabled, the user agent must act as follows:

+
+  
  1. If there is no longer a Document object for the
+   entry in question, the user agent must navigate the
+   browsing context to the location for that entry to perform an
+   entry update of that entry, and abort these steps. The
+   "navigate" algorithm reinvokes this "traverse"
+   algorithm to complete the traversal, at which point there
+   is a Document object and so this step gets
+   skipped. The navigation must be done using the same source
+   browsing context as was used the first time this entry was
+   created. (This can never happen with replacement
+   enabled.)
    2. 
+
+   
  2. If the current entry's title was not set by the
+   pushState() or replaceState() methods,
+   then set its title to the value returned by the document.title IDL
+   attribute.
    3. 
+
+   
  3. 
+
+    
    If appropriate, update the current entry in the
+    browsing context's Document object's
+    History object to reflect any state that the user
+    agent wishes to persist. The entry is then said to be an
+    entry with persisted user state.
    
+
+    
    For example, some user agents might want to
+    persist the scroll position, or the values of form controls.
    
+
+   
    4. 
+
+   
  4. If the specified entry has a different
+   Document object than the current entry
+   then the user agent must run the following substeps:
    
+
+    
    1. If the browsing context is a top-level browsing
+     context, but not an auxiliary browsing
+     context, and the origin of the
+     Document of the specified entry is not the
+     same as the origin
+     of the Document of the current entry,
+     then the following sub-sub-steps must be run:
+
+      
      1. The current browsing context name must be
+       stored with all the entries in the history that are associated
+       with Document objects with the same
+       origin as the active document and
+       that are contiguous with the current entry.
        2. 
+
+       
      2. The browsing context's browsing
+       context name must be unset.
        3. 
+
+      
      2. 
+
+     
    2. The user agent must make the
+     specified entry's Document object the
+     active document of the browsing
+     context.
      3. 
+
+     
    3. If the specified entry has a browsing
+     context name stored with it, then the following
+     sub-sub-steps must be run:
+
+      
      1. The browsing context's browsing context name
+       must be set to the name stored with the specified entry.
        2. 
+
+       
      2. Any browsing context name stored with the
+       entries in the history that are associated with
+       Document objects with the same origin
+       as the new active document, and that are
+       contiguous with the specified entry, must be cleared.
        3. 
+
+      
      4. 
+
+     
    4. If the specified entry's
+     Document has any input elements whose
+     resulting autocompletion state is off, invoke the reset algorithm of each
+     of those elements.
      5. 
+
+     
    5. If the current document readiness of the
+     specified entry's Document is "complete",
+     queue a task to fire a pageshow event at the
+     Window object of that Document, but
+     with its target set to the
+     Document object (and the currentTarget set to the
+     Window object), using the
+     PageTransitionEvent interface, with the persisted
+     attribute set to true. This event must not bubble, must not be
+     cancelable, and has no default action.
      6. 
+
+    
    5. 
+
+   
  5. Set the document's current address to the URL
+   of the specified entry.
    6. 
+
+   
  6. If the specified entry has a URL that differs from
+   the current entry's only by its fragment identifier,
+   and the two share the same Document object, then let
+   hash changed be true, and let old
+   URL be the URL of the current entry and new URL be the URL of the specified
+   entry. Otherwise, let hash changed be
+   false.
    7. 
+
+   
  7. If the traversal was initiated with replacement
+   enabled, remove the entry immediately before the
+   specified entry in the session history.
    
+
+   
  8. If the specified entry is not an entry with
+   persisted user state, but its URL has a fragment identifier,
+   scroll to the fragment identifier.
    9. 
+
+   
  9. If the entry is an entry with persisted user
+   state, the user agent may update aspects of the document and
+   its rendering, for instance the scroll position or values of form
+   fields, that it had previously recorded.
    10. 
+
+   
  10. 
+
+    
    If the specified entry is a state object or the first
+    entry for a Document, the user agent must run the
+    following substeps:
    
+
+    
    1. If the entry is a state object entry, let state be a structured clone of that
+     state object. Otherwise, let state be
+     null.
      2. 
+
+     
    2. 
+
+      
      Run the appropriate steps according to the conditions
+      described:
      
+
+      
      If the current document readiness is set to the
+       string "complete"
      
+
+       
      Queue a task to fire a popstate event at the
+       Window object of the Document, using
+       the PopStateEvent interface, with the state attribute set to
+       the value of state. This event must bubble
+       but not be cancelable and has no default action.
      
+
+       
      Otherwise
      
+
+       
      Let the Document's pending state
+       object be state. (If there was already
+       a pending state object, the previous one is
+       discarded.)
      
+
+       
      The event will then be fired just after the load event.
      
+
+      
      3. 
+
+    
    11. 
+
+   
  11. If hash changed is true, then
+   queue a task to fire a hashchange event at the
+   browsing context's Window object, using
+   the HashChangeEvent interface, with the oldURL attribute set to
+   old URL and the newURL attribute set to
+   new URL. This event must bubble but not be
+   cancelable and has no default action.
    12. 
+
+   
  12. The current entry is now the specified
+   entry.
    13. 
+
+  
The pending state object must be initially null.

+
+  
The task source for the tasks mentioned above is the
+  DOM manipulation task source.

+
+
+  
6.5.9.1 Event definitions

+
+  

+
+  
The popstate event
+  is fired when navigating to a session history entry
+  that represents a state object.

+
+  
interface PopStateEvent : Event {
+  readonly attribute any state;
+  void initPopStateEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any stateArg);
+};

+
+  
event . state

+
+   

+
+    
Returns a copy of the information that was provided to pushState() or replaceState().

+
+   

+
+  

+
+  
The initPopStateEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces. [DOMEVENTS]

+
+  
The state
+  attribute represents the context information for the event, or null,
+  if the state represented is the initial state of the
+  Document.

+
+  

+
+  
The hashchange
+  event is fired when navigating to a session history
+  entry whose URL differs from that of the
+  previous one only in the fragment identifier.

+
+  
interface HashChangeEvent : Event {
+  readonly attribute any oldURL;
+  readonly attribute any newURL;
+  void initHashChangeEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString oldURLArg, in DOMString newURLArg);
+};

+
+  
event . oldURL

+
+   

+
+    
Returns the URL of the session history
+    entry that was previously current.

+
+   

+
+
+   
event . newURL

+
+   

+
+    
Returns the URL of the session history
+    entry that is now current.

+
+   

+
+  

+
+  
The initHashChangeEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces. [DOMEVENTS]

+
+  
The oldURL
+  attribute represents context information for the event, specifically
+  the URL of the session history entry that was traversed
+  from.

+
+  
The newURL
+  attribute represents context information for the event, specifically
+  the URL of the session history entry that was traversed
+  to.

+
+  

+
+  
The pageshow event
+  is fired when traversing to a session history
+  entry.

+
+  
The pagehide
+  event is fired when traversing from a session history
+  entry.

+
+  
interface PageTransitionEvent : Event {
+  readonly attribute any persisted;
+  void initPageTransitionEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any persistedArg);
+};

+
+  
event . persisted

+
+   

+
+    
Returns false if the page is newly being loaded (and the load event will fire). Otherwise, returns true.

+
+   

+
+  

+
+  
The initPageTransitionEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces. [DOMEVENTS]

+
+  
The persisted
+  attribute represents the context information for the event.

+
+  

+
+
+
+  
6.5.10 Unloading documents

+
+  

+
+  
A Document has a salvageable state, which
+  is initially true.

+
+  
When a user agent is to prompt to unload a document,
+  it must run the following steps.

+
+  
  1. Let event be a new
+   BeforeUnloadEvent event object with the name beforeunload, which does not
+   bubble but is cancelable.
    2. 
+
+   
  2. Dispatch: Dispatch event at the
+   Document's Window object.
    3. 
+
+   
  3. Release the storage mutex.
    4. 
+
+   
  4. If any event listeners were triggered by the earlier
+   dispatch step, then set the Document's salvageable state to
+   false.
    5. 
+
+   
  5. 
+
+    
    If the returnValue
+    attribute of the event object is not the empty
+    string, or if the event was canceled, then the user agent should
+    ask the user to confirm that they wish to unload the document.
    
+
+    
    The prompt shown by the user agent may include the string of
+    the returnValue
+    attribute, or some leading subset thereof. (A user agent may want
+    to truncate the string to 1024 characters for display, for
+    instance.)
    
+
+    
    The user agent must pause while waiting for the
+    user's response.
    
+
+    
    If the user did not confirm the page navigation, then the user
+    agent refused to allow the document to be unloaded.
    
+
+   
    6. 
+
+   
  6. If this algorithm was invoked by another instance of the
+   "prompt to unload a document" algorithm (i.e. through the steps
+   below that invoke this algorithm for all descendant browsing
+   contexts), then abort these steps here.
    7. 
+
+   
  7. Let descendants be the list of the
+   descendant browsing contexts of the
+   Document.
    8. 
+
+   
  8. 
+
+    
    If descendants is not an empty list, then
+    for each browsing context b in
+    descendants run the following substeps:
    
+
+    
    1. Prompt to
+     unload the active document of the
+     browsing context b. If the user
+     refused to allow the document to be unloaded, then
+     the user implicitly also refused to allow this document
+     to be unloaded; abort these steps.
      
+
+     
    2. If salvageable state of
+     the active document of the browsing
+     context b is false, then set the salvageable state of
+     this document to false also.
      3. 
+
+    
    9. 
+
+  
When a user agent is to unload a document, it must run
+  the following steps. These steps are passed an argument, recycle, which is either true or false, indicating
+  whether the Document object is going to be
+  re-used. (This is set by the document.open() method.)

+
+  
  1. Fire a pagehide event at
+   the Window object of the Document, but
+   with its target set to the
+   Document object (and the currentTarget set to the
+   Window object), using the
+   PageTransitionEvent interface, with the persisted
+   attribute set to true. This event must not bubble, must not be
+   cancelable, and has no default action.
    2. 
+
+   
  2. Unload event: Fire a simple event named
+   unload at the
+   Document's Window object.
    3. 
+
+   
  3. Release the storage mutex.
    4. 
+
+   
  4. If any event listeners were triggered by the earlier
+   unload event step, then set the Document
+   object's salvageable state to
+   false.
    5. 
+
+   
  5. Run any unloading document cleanup steps for
+   Document that are defined by this specification or any
+   other relevant specifications.
    6. 
+
+   
  6. If this algorithm was invoked by another instance of the
+   "unload a document" algorithm (i.e. through the steps below that
+   invoke this algorithm for all descendant browsing contexts), then
+   abort these steps here.
    7. 
+
+   
  7. Let descendants be the list of the
+   descendant browsing contexts of the
+   Document.
    8. 
+
+   
  8. 
+
+    
    If descendants is not an empty list, then
+    for each browsing context b in
+    descendants run the following substeps:
    
+
+    
    1. Unload the
+     active document of the browsing context
+     b with the recycle
+     parameter set to false.
      2. 
+
+     
    2. If salvageable state of
+     the active document of the browsing
+     context b is false, then set the salvageable state of
+     this document to false also.
      3. 
+
+    
    9. 
+
+   
  9. If salvageable and recycle are both false, then the
+   Document's browsing context must discard the
+   Document.
    10. 
+
+  
This specification defines the following unloading document
+  cleanup steps. Other specifications can define more.

+
+  
  1. If there are any outstanding transactions that have
+   callbacks that involve scripts
+   whose global object is
+   the Document's Window object, roll them
+   back (without invoking any of the callbacks) and set the
+   Document's salvageable state to
+   false. [WEBSQL] 
    2. 
+
+   
  2. Close the WebSocket connection of any
+   WebSocket objects that were created by the WebSocket() constructor visible on the
+   Document's Window object. If this
+   affected any WebSocket objects, the set
+   Document's salvageable state to
+   false.
+   
+   [WEBSOCKET]
+   
+   
    3. 
+
+   
  3. If the Document's salvageable state is
+   false, empty the Document's Window's
+   list of active timeouts and its list of active
+   intervals.
    4. 
+
+  
6.5.10.1 Event definition

+
+  

+
+  
interface BeforeUnloadEvent : Event {
+           attribute DOMString returnValue;
+};

+
+  
event . returnValue [ = value ]

+
+   

+
+    
Returns the current return value of the event (the message to show the user).

+
+    
Can be set, to update the message.

+
+   

+
+  
There are no BeforeUnloadEvent-specific
+  initialization methods.

+
+  

+
+  
The returnValue
+  attribute represents the message to show the user. When the event is
+  created, the attribute must be set to the empty string. On getting,
+  it must return the last value it was set to. On setting, the
+  attribute must be set to the new value.

+
+  

+
+
+  

+
+  
6.5.11 Aborting a document load

+
+  
If the user cancels any instance of the fetching algorithm in the context of a
+  Document in a browsing context, then, if
+  that Document is an active document, the
+  user agent must queue a task to fire a simple
+  event named abort at that
+  Document's Window object.

+
+  
+
+  

+
+
+  
6.6 Offline Web applications

+
+  
+
+  
6.6.1 Introduction

+
+  
This section is non-normative.

+
+  
In order to enable users to continue interacting with Web
+  applications and documents even when their network connection is
+  unavailable — for instance, because they are traveling outside
+  of their ISP's coverage area — authors can provide a manifest
+  which lists the files that are needed for the Web application to
+  work offline and which causes the user's browser to keep a copy of
+  the files for use offline.

+
+  
To illustrate this, consider a simple clock applet consisting of
+  an HTML page "clock.html", a CSS style sheet
+  "clock.css", and a JavaScript script "clock.js".

+
+  
Before adding the manifest, these three files might look like
+  this:

+
+  
<!-- clock.html -->
+<!DOCTYPE HTML>
+<html>
+ <head>
+  <title>Clock</title>
+  <script src="clock.js"></script>
+  <link rel="stylesheet" href="clock.css">
+ </head>
+ <body>
+  <p>The time is: <output id="clock"></output></p>
+ </body>
+</html>

+  
/* clock.css */
+output { font: 2em sans-serif; }

+  
/* clock.js */
+setTimeout(function () {
+    document.getElementById('clock').value = new Date();
+}, 1000);

+
+  
If the user tries to open the "clock.html"
+  page while offline, though, the user agent (unless it happens to
+  have it still in the local cache) will fail with an error.

+
+  
The author can instead provide a manifest of the three files:

+
+  
CACHE MANIFEST
+clock.html
+clock.css
+clock.js

+
+  
With a small change to the HTML file, the manifest (served as
+  text/cache-manifest) is linked to the application:

+
+  
<!-- clock.html -->
+<!DOCTYPE HTML>
+<html manifest="clock.manifest">
+ <head>
+  <title>Clock</title>
+  <script src="clock.js"></script>
+  <link rel="stylesheet" href="clock.css">
+ </head>
+ <body>
+  <p>The time is: <output id="clock"></output></p>
+ </body>
+</html>

+
+  
Now, if the user goes to the page, the browser will cache the
+  files and make them available even when the user is offline.

+
+  
Authors are encouraged to include the main page in
+  the manifest also, but in practice the page that referenced the
+  manifest is automatically cached even if it isn't explicitly
+  mentioned.

+
+  
HTTP cache headers and restrictions on caching pages
+  served over TLS (encrypted, using https:) are
+  overridden by manifests. Thus, pages will not expire from an
+  application cache before the user agent has updated it, and even
+  applications served over TLS can be made to work offline.

+
+
+
+  
6.6.1.1 Event summary

+
+  
This section is non-normative.

+
+  
When the user visits a page that declares a manifest, the browser
+  will try to update the cache. It does this by fetching a copy of the
+  manifest and, if the manifest has changed since the user agent last
+  saw it, redownloading all the resources it mentions and caching them
+  anew.

+
+  
As this is going on, a number of events get fired on the
+  ApplicationCache object to keep the script updated as
+  to the state of the cache update, so that the user can be notified
+  appropriately. The events are as follows:

+
+  
 Event name
+      Interface
+      Dispatched when...
+      Next events
+   
 checking
+      Event
+      The user agent is checking for an update, or attempting to download the manifest for the first time. This is always the first event in the sequence.
+      noupdate, downloading, obsolete, error
+    
 noupdate
+      Event
+      The manifest hadn't changed.
+      Last event in sequence.
+    
 downloading
+      Event
+      The user agent has found an update and is fetching it, or is downloading the resources listed by the manifest for the first time.
+      progress, error, cached, updateready
+    
 progress
+      ProgressEvent
+      The user agent is downloading resources listed by the manifest.
+      progress, error, cached, updateready
+    
 cached
+      Event
+      The resources listed in the manifest have been downloaded, and the application is now cached.
+      Last event in sequence.
+    
 updateready
+      Event
+      The resources listed in the manifest have been newly redownloaded, and the script can use swapCache() to switch to the new cache.
+      Last event in sequence.
+    
 obsolete
+      Event
+      The manifest was found to have become a 404 or 410 page, so the application cache is being deleted.
+      Last event in sequence.
+    
 error
+      Event
+      The manifest was a 404 or 410 page, so the attempt to cache the application has been aborted.
+      Last event in sequence.
+    
 The manifest hadn't changed, but the page referencing the manifest failed to download properly.
+    
 A fatal error occurred while fetching the resources listed in the manifest.
+    
 The manifest changed while the update was being run.
+      The user agent will try fetching the files again momentarily.
+  

+
+  
6.6.2 Application caches

+
+  
An application cache is a set of cached resources
+  consisting of:

+
+  
  • 
+
+    
    One or more resources (including their out-of-band metadata,
+    such as HTTP headers, if any), identified by URLs, each falling
+    into one (or more) of the following categories:
    
+
+    
    Master entries
+
+     
    Documents that were added to the cache because a
+     browsing context was navigated to that document and the
+     document indicated that this was its cache, using the manifest attribute.
+
+
+     
    The manifest
+
+     
    The resource corresponding to the URL that was given in a
+     master entry's html element's manifest attribute. The
+     manifest is fetched and processed during the application
+     cache download process. All the master entries have
+     the same origin as the manifest.
+
+
+     
    Explicit entries
+
+     
    Resources that were listed in the cache's manifest in an explicit
+     section. Explicit entries can also be marked as foreign, which means that
+     they have a manifest
+     attribute but that it doesn't point at this cache's manifest.
+
+
+     
    Fallback entries
+
+     
    Resources that were listed in the cache's manifest in a fallback
+     section.
+
+
+    
    A URL in the list can be flagged with multiple
+    different types, and thus an entry can end up being categorized as
+    multiple entries. For example, an entry can be a manifest entry
+    and an explicit entry at the same time, if the manifest is listed
+    within the manifest.
    
+
+   
    • 
+
+   
  • Zero or more fallback
+   namespaces: URLs, used as prefix match
+   patterns, each of which is mapped to a fallback entry. Each
+   namespace URL has the same origin as the manifest.
    • 
+
+   
  • Zero or more URLs that form the online whitelist
+   namespaces.
+
+   
  • An online whitelist
+   wildcard flag, which is either open or blocking.
    • 
+
+  
Each application cache has a completeness flag, which is
+  either complete or incomplete.

+
+  
An application cache group is a group of application caches, identified by
+  the absolute URL of a resource manifest which is used to
+  populate the caches in the group.

+
+  
An application cache is newer than another if it was
+  created after the other (in other words, application caches in an application cache
+  group have a chronological order).

+
+  
Only the newest application cache in an
+  application cache group can have its completeness flag set to
+  incomplete; the others are always all complete.

+
+  
Each application cache group has an update status, which is one of
+  the following: idle, checking, downloading.

+
+  
A relevant application cache is an application
+  cache that is the newest in its group to be
+  complete.

+
+  
Each application cache group has a list of pending master
+  entries. Each entry in this list consists of a resource and a
+  corresponding Document object. It is used during the
+  application cache download process to ensure that new
+  master entries are cached even if the application cache
+  download process was already running for their
+  application cache group when they were loaded.

+
+  
An application cache group can be marked as obsolete, meaning that it
+  must be ignored when looking at what application cache groups exist.

+
+  
A cache host is a Document or a
+  SharedWorkerGlobalScope object. A cache
+  host can be associated with an application
+  cache.
+  
+  [WEBWORKERS]
+  
+  

+
+  
A Document initially is not associated with an
+  application cache, but can become associated with one
+  early during the page load process, when steps in the parser and in the navigation sections cause cache selection to occur.

+
+  
A SharedWorkerGlobalScope can be associated with an
+  application cache when it is created.
+  
+  [WEBWORKERS]
+  
+  

+
+  
Each cache host has an associated
+  ApplicationCache object.

+
+  
Multiple application
+  caches in different application cache groups can contain the same
+  resource, e.g. if the manifests all reference that resource. If the
+  user agent is to select an
+  application cache from a list of relevant application caches that contain a
+  resource, the user agent must use the application cache that the
+  user most likely wants to see the resource from, taking into account
+  the following:

+
+  
  • which application cache was most recently updated,
+
+   
  • which application cache was being used to display the
+   resource from which the user decided to look at the new resource,
+   and
+
+   
  • which application cache the user prefers.
+
+  
A URL matches a
+  fallback namespace if there exists a relevant
+  application cache whose manifest's URL has the
+  same origin as the URL in question, and that has a
+  fallback namespace
+  that is a prefix match for the URL being examined. If
+  multiple fallback namespaces match the same URL, the longest one is
+  the one that matches. A URL looking for a fallback namespace can
+  match more than one application cache at a time, but only matches
+  one namespace in each cache.

+
+  

+
+   
If a manifest http://example.com/app1/manifest declares that
+   http://example.com/resources/images is a
+   fallback namespace, and the user navigates to HTTP://EXAMPLE.COM:80/resources/images/cat.png,
+   then the user agent will decide that the application cache
+   identified by http://example.com/app1/manifest contains a
+   namespace with a match for that URL.

+
+   
+
+  

+
+  

+
+
+
+  
6.6.3 The cache manifest syntax

+
+
+  
6.6.3.1 A sample manifest

+
+  
This section is non-normative.

+
+  
This example manifest requires two images and a style sheet to be
+  cached and whitelists a CGI script.

+
+  
CACHE MANIFEST
+# the above line is required
+
+# this is a comment
+# there can be as many of these anywhere in the file
+# they are all ignored
+  # comments can have spaces before them
+  # but must be alone on the line
+
+# blank lines are ignored too
+
+# these are files that need to be cached they can either be listed
+# first, or a "CACHE:" header could be put before them, as is done
+# lower down.
+images/sound-icon.png
+images/background.png
+# note that each file has to be put on its own line
+
+# here is a file for the online whitelist -- it isn't cached, and
+# references to this file will bypass the cache, always hitting the
+# network (or trying to, if the user is offline).
+NETWORK:
+comm.cgi
+
+# here is another set of files to cache, this time just the CSS file.
+CACHE:
+style/default.css

+
+  
It could equally well be written as follows:

+
+  
CACHE MANIFEST
+NETWORK:
+comm.cgi
+CACHE:
+style/default.css
+images/sound-icon.png
+images/background.png

+
+  
The following manifest defines a catch-all error page that is
+  displayed for any page on the site while the user is offline. It
+  also specifies that the online whitelist
+  wildcard flag is open, meaning that accesses
+  to resources on other sites will not be blocked. (Resources on the
+  same site are already not blocked because of the catch-all fallback
+  namespace.)

+
+  
So long as all pages on the site reference this manifest, they
+  will get cached locally as they are fetched, so that subsequent hits
+  to the same page will load the page immediately from the
+  cache. Until the manifest is changed, those pages will not be
+  fetched from the server again. When the manifest changes, then all
+  the files will be redownloaded.

+
+  
Subresources, such as style sheets, images, etc, would only be
+  cached using the regular HTTP caching semantics, however.

+
+  
CACHE MANIFEST
+FALLBACK:
+/ /offline.html
+NETWORK:
+*

+
+
+  
6.6.3.2 Writing cache manifests

+
+  
Manifests must be served using the
+  text/cache-manifest MIME type. All
+  resources served using the text/cache-manifest
+  MIME type must follow the syntax of application cache
+  manifests, as described in this section.

+
+  
An application cache manifest is a text file, whose text is
+  encoded using UTF-8. Data in application cache manifests is
+  line-based. Newlines must be represented by U+000A LINE FEED (LF)
+  characters, U+000D CARRIAGE RETURN (CR) characters, or U+000D
+  CARRIAGE RETURN (CR) U+000A LINE FEED (LF) pairs.

+
+  
This is a willful violation of two
+  aspects of RFC 2046, which requires all text/*
+  types to support an open-ended set of character encodings and only
+  allows CRLF line breaks. These requirements, however, are outdated;
+  UTF-8 is now widely used, such that supporting other encodings is no
+  longer necessary, and use of CR, LF, and CRLF line breaks is
+  commonly supported and indeed sometimes CRLF is not
+  supported by text editors. [RFC2046]

+  
+
+  
The first line of an application cache manifest must consist of
+  the string "CACHE", a single U+0020 SPACE character, the string
+  "MANIFEST", and either a U+0020 SPACE character, a U+0009 CHARACTER
+  TABULATION (tab) character, a U+000A LINE FEED (LF) character, or a
+  U+000D CARRIAGE RETURN (CR) character. The first line may optionally
+  be preceded by a U+FEFF BYTE ORDER MARK (BOM) character. If any
+  other text is found on the first line, it is ignored.

+
+  
Subsequent lines, if any, must all be one of the following:

+
+  
A blank line
+   

+    
Blank lines must consist of zero or more U+0020 SPACE and
+    U+0009 CHARACTER TABULATION (tab) characters only.

+
+   
A comment
+   

+    
Comment lines must consist of zero or more U+0020 SPACE and
+    U+0009 CHARACTER TABULATION (tab) characters, followed by a single
+    U+0023 NUMBER SIGN character (#), followed by zero or more
+    characters other than U+000A LINE FEED (LF) and U+000D CARRIAGE
+    RETURN (CR) characters.

+
+    
Comments must be on a line on their own. If they
+    were to be included on a line with a URL, the "#" would be
+    mistaken for part of a fragment identifier.

+
+   
A section header
+   

+    
Section headers change the current section. There are three
+    possible section headers:
+
+    
CACHE:
+     
Switches to the explicit section.
+
+     
FALLBACK:
+     
Switches to the fallback section.
+
+     
NETWORK:
+     
Switches to the online whitelist section.
+
+    
Section header lines must consist of zero or more U+0020 SPACE
+    and U+0009 CHARACTER TABULATION (tab) characters, followed by one
+    of the names above (including the U+003A COLON character (:))
+    followed by zero or more U+0020 SPACE and U+0009 CHARACTER
+    TABULATION (tab) characters.

+
+    
Ironically, by default, the current section is the
+    explicit section.

+
+   
Data for the current section
+   

+    
The format that data lines must take depends on the current
+    section.

+
+    
When the current section is the explicit
+    section, data lines must consist of zero or more U+0020
+    SPACE and U+0009 CHARACTER TABULATION (tab) characters, a
+    valid URL identifying a resource other than the
+    manifest itself, and then zero or more U+0020 SPACE and U+0009
+    CHARACTER TABULATION (tab) characters.

+
+    
When the current section is the fallback
+    section, data lines must consist of zero or more U+0020
+    SPACE and U+0009 CHARACTER TABULATION (tab) characters, a
+    valid URL identifying a resource other than the
+    manifest itself, one or more U+0020 SPACE and U+0009 CHARACTER
+    TABULATION (tab) characters, another valid URL
+    identifying a resource other than the manifest itself, and then
+    zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab)
+    characters.

+
+    
When the current section is the online whitelist
+    section, data lines must consist of zero or more U+0020
+    SPACE and U+0009 CHARACTER TABULATION (tab) characters, either a
+    single U+002A ASTERISK character (*)  or a valid
+    URL identifying a resource other than the manifest itself,
+    and then zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION
+    (tab) characters.

+
+
+
+  
Manifests may contain sections more than once. Sections may be
+  empty.

+
+  
If the manifest's <scheme>
+  is https: or another scheme intended for
+  encrypted data transfer, then all URLs in explicit sections
+  must have the same origin as the manifest itself.

+
+  
URLs that are to be fallback pages associated with fallback namespaces, and
+  those namespaces themselves, must be given in fallback sections,
+  with the namespace being the first URL of the data line, and the
+  corresponding fallback page being the second URL. All the other
+  pages to be cached must be listed in explicit
+  sections.

+
+  
Fallback
+  namespaces and fallback entries must have
+  the same origin as the manifest itself.

+
+  
A fallback
+  namespace must not be listed more than once.

+
+  
Namespaces that the user agent is to put into the online whitelist
+  must all be specified in online whitelist
+  sections. (This is needed for any URL that the page is
+  intending to use to communicate back to the server.) To specify that
+  all URLs are automatically whitelisted in this way, a U+002A
+  ASTERISK character character (*) may be specified as one of the
+  URLs. 

+
+  
Authors should not include namespaces in the online whitelist for
+  which another namespace in the online whitelist is
+  a prefix match.

+
+  
Relative URLs must be given relative to the manifest's own
+  URL. All URLs in the manifest must have the same <scheme> as the manifest itself
+  (either explicitly or implicitly, through the use of relative
+  URLs).

+
+  
URLs in manifests must not have fragment identifiers (i.e. the
+  U+0023 NUMBER SIGN character isn't allowed in URLs in
+  manifests).

+
+  
Fallback
+  namespaces and namespaces in the online whitelist are
+  matched by prefix match.

+
+
+  

+
+  
6.6.3.3 Parsing cache manifests

+
+  
When a user agent is to parse a manifest, it means
+  that the user agent must run the following steps:

+
+  
  1. The user agent must decode the byte stream corresponding with
+   the manifest to be parsed, treating it as UTF-8. Bytes or sequences
+   of bytes that are not valid UTF-8 sequences must be interpreted as
+   a U+FFFD REPLACEMENT CHARACTER. 
    2. 
+
+   
  2. Let base URL be the absolute
+   URL representing the manifest.
    3. 
+
+   
  3. Let explicit URLs be an initially empty
+   list of absolute URLs for explicit entries.
    4. 
+
+   
  4. Let fallback URLs be an initially empty
+   mapping of fallback
+   namespaces to absolute
+   URLs for fallback
+   entries.
    5. 
+
+   
  5. Let online whitelist namespaces be an
+   initially empty list of absolute
+   URLs for an online
+   whitelist.
    6. 
+
+   
  6. Let online whitelist wildcard flag be blocking. 
    7. 
+
+   
  7. Let input be the decoded text of the
+   manifest's byte stream.
    8. 
+
+   
  8. Let position be a pointer into input, initially pointing at the first
+   character.
    9. 
+
+   
  9. If position is pointing at a U+FEFF BYTE
+   ORDER MARK (BOM) character, then advance position to the next character.
    10. 
+
+   
  10. If the characters starting from position
+   are "CACHE", followed by a U+0020 SPACE character, followed by
+   "MANIFEST", then advance position to the next
+   character after those. Otherwise, this isn't a cache manifest;
+   abort this algorithm with a failure while checking for the magic
+   signature.
    11. 
+
+   
  11. If the character at position is neither
+   a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab)
+   character, U+000A LINE FEED (LF) character, nor a U+000D CARRIAGE
+   RETURN (CR) character, then this isn't a cache manifest; abort this
+   algorithm with a failure while checking for the magic
+   signature.
    12. 
+
+   
  12. This is a cache manifest. The algorithm cannot fail beyond
+   this point (though bogus lines can get ignored).
    13. 
+
+   
  13. Collect a sequence of characters that are
+   not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)
+   characters, and ignore those characters. (Extra text on the first
+   line, after the signature, is ignored.)
    14. 
+
+   
  14. Let mode be "explicit".
    15. 
+
+   
  15. Start of line: If position is
+   past the end of input, then jump to the last
+   step. Otherwise, collect a sequence of characters that
+   are U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), U+0020
+   SPACE, or U+0009 CHARACTER TABULATION (tab) characters.
    16. 
+   
+
+   
  16. Now, collect a sequence of characters that are
+   not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)
+   characters, and let the result be line.
    17. 
+
+   
  17. Drop any trailing U+0020 SPACE and U+0009 CHARACTER
+   TABULATION (tab) characters at the end of line.
    18. 
+
+   
  18. If line is the empty string, then jump
+   back to the step labeled "start of line".
    19. 
+
+   
  19. If the first character in line is a
+   U+0023 NUMBER SIGN character (#), then jump back to the step
+   labeled "start of line".
    20. 
+
+   
  20. If line equals "CACHE:" (the word
+   "CACHE" followed by a U+003A COLON character (:)), then set mode to "explicit" and jump back to the step
+   labeled "start of line".
    21. 
+
+   
  21. If line equals "FALLBACK:" (the word
+   "FALLBACK" followed by a U+003A COLON character (:)), then set mode to "fallback" and jump back to the step
+   labeled "start of line".
    22. 
+
+   
  22. If line equals "NETWORK:" (the word
+   "NETWORK" followed by a U+003A COLON character (:)), then set mode to "online whitelist" and jump back to the step
+   labeled "start of line".
    23. 
+
+   
  23. If line ends with a U+003A COLON
+   character (:), then set mode to "unknown" and
+   jump back to the step labeled "start of line".
    24. 
+
+   
  24. This is either a data line or it is syntactically
+   incorrect.
    25. 
+
+   
  25. Let position be a pointer into line, initially pointing at the start of the
+   string.
    26. 
+
+   
  26. Let tokens be a list of strings,
+   initially empty.
    27. 
+
+   
  27. 
+
+    
    While position doesn't point past the end
+    of line:
    
+
+    
    1. Let current token be an empty
+     string.
      2. 
+
+     
    2. While position doesn't point past the
+     end of line and the character at position is neither a U+0020 SPACE nor a U+0009
+     CHARACTER TABULATION (tab) character, add the character at position to current token and
+     advance position to the next character in
+     input.
      3. 
+
+     
    3. Add current token to the tokens list.
      4. 
+
+     
    4. While position doesn't point past the
+     end of line and the character at position is either a U+0020 SPACE or a U+0009
+     CHARACTER TABULATION (tab) character, advance position to the next character in input.
      5. 
+
+    
    28. 
+
+   
  28. 
+
+    
    Process tokens as follows:
    
+
+    
    If mode is "explicit"
    
+
+     
    
+
+      
    Resolve the first item in
+      tokens, relative to base
+      URL; ignore the rest.
    
+
+      
    If this fails, then jump back to the step labeled "start of
+      line".
    
+
+      
    If the resulting absolute URL has a different
+      <scheme> component than
+      the manifest's URL (compared in an ASCII
+      case-insensitive manner), then jump back to the step
+      labeled "start of line". If the manifest's <scheme> is https: or another scheme intended for encrypted
+      data transfer, and the resulting absolute URL does
+      not have the same origin as the manifest's URL,
+      then jump back to the step labeled "start of line".
    
+
+      
    Drop the <fragment>
+      component of the resulting absolute URL, if it has
+      one.
    
+
+      
    Add the resulting absolute URL to the explicit URLs.
    
+
+     
    
+
+     
    If mode is "fallback"
    
+
+     
    
+
+      
    Let part one be the first token in tokens, and let part two be
+      the second token in tokens.
    
+
+      
    Resolve part
+      one and part two, relative to base URL.
    
+
+      
    If either fails, then jump back to the step labeled "start of
+      line".
    
+
+      
    If the absolute URL corresponding to either part one or part two does not
+      have the same origin as the manifest's URL, then
+      jump back to the step labeled "start of line".
     
+
+      
    Drop any the <fragment> components of the
+      resulting absolute URLs.
    
+
+      
    If the absolute URL corresponding to part one is already in the fallback
+      URLs mapping as a fallback namespace,
+      then jump back to the step labeled "start of line".
    
+
+      
    Otherwise, add the absolute URL corresponding to
+      part one to the fallback
+      URLs mapping as a fallback namespace,
+      mapped to the absolute URL corresponding to part two as the fallback entry.
    
+
+     
    
+
+     
    If mode is "online whitelist"
    
+
+     
    
+
+      
    If the first item in tokens is a U+002A
+      ASTERISK character (*), then set online whitelist
+      wildcard flag to open and jump back to the
+      step labeled "start of line".
    
+
+      
    Otherwise, resolve the
+      first item in tokens, relative to base URL; ignore the rest.
    
+
+      
    If this fails, then jump back to the step labeled "start of
+      line".
    
+
+      
    If the resulting absolute URL has a different
+      <scheme> component than
+      the manifest's URL (compared in an ASCII
+      case-insensitive manner), then jump back to the step
+      labeled "start of line".
    
+
+      
    Drop the <fragment>
+      component of the resulting absolute URL, if it has
+      one.
    
+
+      
    Add the resulting absolute URL to the online whitelist namespaces.
    
+
+     
    
+
+     
    If mode is "unknown"
    
+
+     
    
+
+      
    Do nothing. The line is ignored.
    
+
+     
    
+
+    
    29. 
+
+   
  29. Jump back to the step labeled "start of line". (That step
+   jumps to the next, and last, step when the end of the file is
+   reached.)
    30. 
+
+   
  30. Return the explicit URLs list, the fallback URLs mapping, the online
+   whitelist namespaces, and the online whitelist
+   wildcard flag.
    31. 
+
+  

+
+   
If a resource is listed in the explicit section
+   or as a fallback
+   entry in the fallback section,
+   the resource will always be taken from the cache, regardless of any
+   other matching entries in the fallback namespaces or
+   online whitelist
+   namespaces.

+
+   
When a fallback
+   namespace and an online whitelist
+   namespace overlap, the online whitelist
+   namespace has priority.

+
+   
The online whitelist
+   wildcard flag is applied last, only for URLs that match
+   neither the online
+   whitelist namespace nor the fallback namespace and
+   that are not listed in the explicit
+   section.

+
+  

+
+
+  
6.6.4 Downloading or updating an application cache

+
+  
When the user agent is required (by other parts of this
+  specification) to start the application cache download
+  process for an absolute URL purported to identify
+  a manifest, or for an
+  application cache group, potentially given a particular
+  cache host, and potentially given a master resource, the user
+  agent must run the steps below. These steps are always run
+  asynchronously, in parallel with the event loop tasks.

+
+  
Some of these steps have requirements that only apply if the user
+  agent shows caching progress. Support for this is
+  optional. Caching progress UI could consist of a progress bar or
+  message panel in the user agent's interface, or an overlay, or
+  something else. Certain events fired during the application
+  cache download process allow the script to override the display
+  of such an interface. The goal of this is to allow Web applications
+  to provide more seamless update mechanisms, hiding from the user the
+  mechanics of the application cache mechanism. User agents may
+  display user interfaces independent of this, but are encouraged to
+  not show prominent update progress notifications for applications
+  that cancel the relevant events.

+
+  
These events are delayed until after the load event has fired.

+
+  
The application cache download process steps are as
+  follows:
+
+  
  1. Optionally, wait until the permission to start the
+   application cache download process has been obtained
+   from the user and until the user agent is confident that the
+   network is available. This could include doing nothing until the
+   user explicitly opts-in to caching the site, or could involve
+   prompting the user for permission. The algorithm might never get
+   past this point. (This step is particularly intended to be used by
+   user agents running on severely space-constrained devices or in
+   highly privacy-sensitive environments).
    2. 
+
+   
  2. 
+
+    
    Atomically, so as to avoid race conditions, perform the
+    following substeps:
    
+
+    
    1. 
+
+      
      Pick the appropriate substeps:
      
+
+      
      If these steps were invoked with an absolute
+       URL purported to identify a manifest
      
+
+       
      
+
+        
      Let manifest URL be that absolute
+        URL.
      
+
+        
      If there is no application cache group
+        identified by manifest URL, then create a
+        new application cache group identified by manifest URL. Initially, it has no application caches. One will
+        be created later in this algorithm.
      
+
+       
      
+
+
+       
      If these steps were invoked with an application cache
+       group
      
+
+       
      
+
+        
      Let manifest URL be the absolute
+        URL of the manifest used to
+        identify the application cache group to be
+        updated.
      
+
+       
      
+
+      
      2. 
+
+     
    2. Let cache group be the
+     application cache group identified by manifest URL.
      3. 
+
+     
    3. If these steps were invoked with a master resource, then add
+     the resource, along with the resource's Document, to
+     cache group's list of pending master
+     entries.
      4. 
+
+     
    4. If these steps were invoked with a cache
+     host, and the status of cache group is checking or
+     downloading, then queue a post-load task to
+     fire a simple event named checking that is
+     cancelable at the ApplicationCache singleton of that
+     cache host. The default action of this event must
+     be, if the user agent shows caching progress, the
+     display of some sort of user interface indicating to the user
+     that the user agent is checking to see if it can download the
+     application.
      5. 
+
+     
    5. If these steps were invoked with a cache
+     host, and the status of cache group is downloading, then also
+     queue a post-load task to fire a simple
+     event named downloading that is
+     cancelable at the ApplicationCache singleton of that
+     cache host. The default action of this event must
+     be, if the user agent shows caching progress, the
+     display of some sort of user interface indicating to the user the
+     application is being downloaded.
      6. 
+
+     
    6. If the status
+     of the cache group is either checking
+     or downloading, then abort this instance of the
+     application cache download process, as an update is
+     already in progress.
      7. 
+
+     
    7. Set the status of cache group to checking.
      
+
+     
    8. For each cache host associated with an
+     application cache in cache
+     group, queue a post-load task to fire a
+     simple event that is cancelable named checking at the
+     ApplicationCache singleton of the cache
+     host. The default action of these events must be, if the
+     user agent shows caching progress, the display of
+     some sort of user interface indicating to the user that the user
+     agent is checking for the availability of updates.
      9. 
+
+    
    The remainder of the steps run asynchronously.
    
+
+    
    If cache group already has an
+    application cache in it, then this is an upgrade attempt. Otherwise,
+    this is a cache
+    attempt.
    
+
+   
    3. 
+
+   
  3. If this is a cache
+   attempt, then this algorithm was invoked with a cache
+   host; queue a post-load task to fire a
+   simple event named checking that is cancelable
+   at the ApplicationCache singleton of that cache
+   host. The default action of this event must be, if the user
+   agent shows caching progress, the display of some sort
+   of user interface indicating to the user that the user agent is
+   checking for the availability of updates.
    4. 
+
+   
  4. 
+
+    
    Fetching the manifest: Fetch the resource
+    from manifest URL, and let manifest be that resource.
     
+
+    
    If the resource is labeled with the MIME type
+    text/cache-manifest, parse manifest according to the rules for parsing manifests, obtaining a list of
+    explicit entries,
+    fallback entries
+    and the fallback
+    namespaces that map to them, entries for the online whitelist,
+    and a value for the online whitelist
+    wildcard flag.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If fetching the manifest fails due to a 404 or 410
+    response or
+    equivalent, then run these substeps:
    
+
+    
    1. Mark cache group as obsolete. This cache group no longer exists for any purpose other
+     than the processing of Document objects already
+     associated with an application cache in the cache group.
      2. 
+
+     
    2. Let task list be an empty list of
+     tasks.
      
+
+     
    3. For each cache host associated with an
+     application cache in cache
+     group, create a task to
+     fire a simple event named obsolete that is
+     cancelable at the ApplicationCache singleton of the
+     cache host, and add it to task
+     list. The default action of these events must be, if the
+     user agent shows caching progress, the display of
+     some sort of user interface indicating to the user that the
+     application is no longer available for offline use.
      4. 
+
+     
    4. For each entry in cache group's list of pending master
+     entries, create a task
+     to fire a simple event that is cancelable named
+     error (not obsolete!) at the
+     ApplicationCache singleton of the cache
+     host the Document for this entry, if there
+     still is one, and add it to task list. The
+     default action of this event must be, if the user agent
+     shows caching progress, the display of some sort of
+     user interface indicating to the user that the user agent failed
+     to save the application for offline use.
      5. 
+
+     
    5. If cache group has an
+     application cache whose completeness flag is
+     incomplete, then discard that application
+     cache.
      
+
+     
    6. If appropriate, remove any user interface indicating that
+     an update for this cache is in progress.
      7. 
+
+     
    7. Let the status of cache group be idle.
      8. 
+
+     
    8. For each task in task list, queue that task as a post-load task.
      9. 
+
+     
    9. Abort the application cache download
+     process.
      10. 
+
+    
    6. 
+
+   
  6. 
+
+    
    Otherwise, if fetching the manifest fails in some other
+    way (e.g. the server returns another 4xx or 5xx response or equivalent, or
+    there is a DNS error, or the connection times out, or the user
+    cancels the download, or the parser for manifests fails when
+    checking the magic signature), or if the server returned a
+    redirect, or if the resource is labeled with a MIME
+    type other than text/cache-manifest, then run
+    the cache failure steps.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    If this is an upgrade
+    attempt and the newly downloaded manifest is byte-for-byte identical to the manifest
+    found in the newest
+    application cache in cache group,
+    or the server reported it as "304 Not Modified" or equivalent, then
+    run these substeps:
    
+
+    
    1. Let cache be the newest application
+     cache in cache group.
      2. 
+
+     
    2. Let task list be an empty list of
+     tasks.
      
+
+     
    3. 
+
+      
      For each entry in cache group's list of pending master
+      entries, wait for the resource for this entry to have
+      either completely downloaded or failed.
      
+
+      
      If the download failed (e.g. the connection times out, or the
+      user cancels the download), then create a task to fire a simple
+      event that is cancelable named error at the
+      ApplicationCache singleton of the cache
+      host the Document for this entry, if there
+      still is one, and add it to task list. The
+      default action of this event must be, if the user agent
+      shows caching progress, the display of some sort of
+      user interface indicating to the user that the user agent failed
+      to save the application for offline use.
      
+
+      
      Otherwise, associate the Document for this entry
+      with cache; store the resource for this
+      entry in cache, if it isn't already there,
+      and categorize its entry as a master entry. If the
+      resource's URL has a <fragment> component, it must
+      be removed from the entry in cache
+      (application caches never include fragment identifiers).
      
+
+      
      HTTP caching rules, such as Cache-Control: no-store, are ignored for the
+      purposes of the application cache download
+      process.
      
+
+     
      4. 
+
+     
    4. For each cache host associated with an
+     application cache in cache
+     group, create a task to
+     fire a simple event that is cancelable named noupdate at the
+     ApplicationCache singleton of the cache
+     host, and add it to task list. The
+     default action of these events must be, if the user agent
+     shows caching progress, the display of some sort of
+     user interface indicating to the user that the application is up
+     to date.
      5. 
+
+     
    5. Empty cache group's list of pending master
+     entries.
      6. 
+
+     
    6. If appropriate, remove any user interface indicating that
+     an update for this cache is in progress.
      7. 
+
+     
    7. Let the status of cache group be idle.
      8. 
+
+     
    8. For each task in task list, queue that task as a post-load task.
      9. 
+
+     
    9. Abort the application cache download
+     process.
      10. 
+
+    
    8. 
+
+   
  8. Let new cache be a newly created
+   application cache in cache
+   group. Set its completeness flag to
+   incomplete.
    9. 
+
+   
  9. For each entry in cache group's list of pending master
+   entries, associate the Document for this entry
+   with new cache.
    10. 
+
+   
  10. Set the status
+   of cache group to downloading.
    11. 
+
+   
  11. For each cache host associated with an
+   application cache in cache group,
+   queue a post-load task to fire a simple
+   event that is cancelable named downloading at the
+   ApplicationCache singleton of the cache
+   host. The default action of these events must be, if the
+   user agent shows caching progress, the display of some
+   sort of user interface indicating to the user that a new version is
+   being downloaded.
    12. 
+
+   
  12. Let file list be an empty list of
+   URLs with flags.
    13. 
+
+   
  13. Add all the URLs in the list of explicit entries obtained
+   by parsing manifest to file
+   list, each flagged with "explicit entry".
    14. 
+
+   
  14. Add all the URLs in the list of fallback entries obtained
+   by parsing manifest to file
+   list, each flagged with "fallback entry".
    15. 
+
+   
  15. If this is an upgrade
+   attempt, then add all the URLs of master entries in the newest application
+   cache in cache group whose completeness flag is
+   complete to file list, each flagged with
+   "master entry".
    16. 
+
+   
  16. If any URL is in file list more than
+   once, then merge the entries into one entry for that URL, that
+   entry having all the flags that the original entries had.
    17. 
+
+   
  17. 
+
+    
    For each URL in file list, run the
+    following steps. These steps may be run in parallel for two or
+    more of the URLs at a time.
    
+
+    
    1. 
+
+      
      If the resource URL being processed was flagged as neither an
+      "explicit entry" nor or a "fallback entry", then the user agent
+      may skip this URL.
      
+
+      
      This is intended to allow user agents to expire
+      resources not listed in the manifest from the cache. Generally,
+      implementors are urged to use an approach that expires
+      lesser-used resources first.
      
+
+     
      2. 
+
+     
    2. For each cache host associated with an
+     application cache in cache
+     group, queue a post-load task to fire an event
+     with the name progress, which does not
+     bubble, which is cancelable, and which uses the
+     ProgressEvent interface, at the
+     ApplicationCache singleton of the cache
+     host. The lengthComputable
+     attribute must be set to true, the total attribute must be
+     set to the number of files in file list, and
+     the loaded
+     attribute must be set to the number of number of files in file list that have been either downloaded or
+     skipped so far. The default action of these events must be, if
+     the user agent shows caching progress, the display
+     of some sort of user interface indicating to the user that a file
+     is being downloaded in preparation for updating the
+     application. [PROGRESS]
      3. 
+
+     
    3. 
+
+      
      Fetch the resource, from the origin
+      of the URL manifest URL. If
+      this is an upgrade
+      attempt, then use the newest application
+      cache in cache group as an HTTP
+      cache, and honor HTTP caching semantics (such as expiration,
+      ETags, and so forth) with respect to that cache. User agents may
+      also have other caches in place that are also honored.
       
+
+      
      If the resource in question is already being
+      downloaded for other reasons then the existing download process
+      can sometimes be used for the purposes of this step, as defined
+      by the fetching algorithm.
      
+
+      
      An example of a resource that might already
+      be being downloaded is a large image on a Web page that is being
+      seen for the first time. The image would get downloaded to
+      satisfy the img element on the page, as well as
+      being listed in the cache manifest. According to the rules for
+      fetching that image only need be
+      downloaded once, and it can be used both for the cache and for
+      the rendered Web page.
      
+
+     
      4. 
+
+     
    4. 
+
+      
      If the previous step fails (e.g. the server returns a 4xx or
+      5xx response or
+      equivalent, or there is a DNS error, or the connection
+      times out, or the user cancels the download), or if the server
+      returned a redirect, then run the first appropriate step from
+      the following list:
      
+
+      
      If the URL being processed was flagged as an "explicit
+       entry" or a "fallback entry"
      
+
+       
      
+
+        
      Run the cache failure steps.
      
+
+        
      Redirects are fatal because they are either
+        indicative of a network problem (e.g. a captive portal); or
+        would allow resources to be added to the cache under URLs that
+        differ from any URL that the networking model will allow
+        access to, leaving orphan entries; or would allow resources to
+        be stored under URLs different than their true URLs. All of
+        these situations are bad.
      
+
+       
      
+
+       
      If the error was a 404 or 410 HTTP response or equivalent
      
+
+       
      
+
+        
      Skip this resource. It is dropped from the cache.
      
+
+       
      
+
+       
      Otherwise
      
+
+       
      
+
+        
      Copy the resource and its metadata from the newest application
+        cache in cache group whose completeness flag
+        is complete, and act as if that was the fetched
+        resource, ignoring the resource obtained from the network.
      
+
+       
      
+
+      
      User agents may warn the user of these errors as an aid to
+      development.
      
+
+      
      These rules make errors for resources listed in
+      the manifest fatal, while making it possible for other resources
+      to be removed from caches when they are removed from the server,
+      without errors, and making non-manifest resources survive
+      server-side errors.
      
+
+     
      5. 
+
+     
    5. Otherwise, the fetching succeeded. Store the resource in
+     the new cache.
      6. 
+
+     
    6. If the URL being processed was flagged as an "explicit
+     entry" in file list, then categorize the
+     entry as an explicit
+     entry.
      7. 
+
+     
    7. If the URL being processed was flagged as a "fallback
+     entry" in file list, then categorize the
+     entry as a fallback
+     entry.
      8. 
+
+     
    8. If the URL being processed was flagged as an "master
+     entry" in file list, then categorize the
+     entry as a master
+     entry.
      9. 
+
+     
    9. As an optimization, if the resource is an HTML or XML file
+     whose root element is an html element with a manifest attribute whose value
+     doesn't match the manifest URL of the application cache being
+     processed, then the user agent should mark the entry as being
+     foreign.
      
+
+    
    18. 
+
+   
  18. For each cache host associated with an
+   application cache in cache group,
+   queue a post-load task to fire an event with the name
+   progress, which does
+   not bubble, which is cancelable, and which uses the
+   ProgressEvent interface, at the
+   ApplicationCache singleton of the cache
+   host. The lengthComputable
+   attribute must be set to true, the total and the loaded attributes must be
+   set to the number of number of files in file
+   list. The default action of these events must be, if the user
+   agent shows caching progress, the display of some sort
+   of user interface indicating to the user that all the files have
+   been downloaded. [PROGRESS]
    19. 
+
+   
  19. Store the list of fallback namespaces,
+   and the URLs of the fallback entries that they
+   map to, in new cache.
    20. 
+
+   
  20. Store the URLs that form the new online whitelist in
+   new cache.
    21. 
+
+   
  21. Store the value of the new online whitelist
+   wildcard flag in new cache.
    22. 
+
+   
  22. 
+
+    
    For each entry in cache group's list of pending master
+    entries, wait for the resource for this entry to have
+    either completely downloaded or failed.
    
+
+    
    If the download failed (e.g. the connection times out, or the
+    user cancels the download), then run these substeps:
    
+
+    
    1. Unassociate the Document for this entry from
+     new cache.
      2. 
+
+     
    2. Queue a post-load task to fire a simple
+     event that is cancelable named error at the
+     ApplicationCache singleton of the
+     Document for this entry, if there still is one. The
+     default action of this event must be, if the user agent
+     shows caching progress, the display of some sort of
+     user interface indicating to the user that the user agent failed
+     to save the application for offline use.
      
+
+     
    3. 
+
+      
      If this is a cache
+      attempt and this entry is the last entry in cache group's list of pending master
+      entries, then run these further substeps:
      
+
+      
      1. Discard cache group and its only
+       application cache, new
+       cache.
        
+
+       
      2. If appropriate, remove any user interface indicating
+       that an update for this cache is in progress.
        3. 
+
+       
      3. Abort the application cache download
+       process.
        4. 
+
+      
      4. 
+
+     
    4. Otherwise, remove this entry from cache
+     group's list
+     of pending master entries.
      5. 
+
+    
    Otherwise, store the resource for this entry in new cache, if it isn't already there, and
+    categorize its entry as a master entry.
    
+
+   
    23. 
+
+   
  23. 
+
+    
    Fetch the resource from manifest
+    URL again, and let second manifest be
+    that resource.
     
+
+   
    24. 
+
+   
  24. 
+
+    
    If the previous step failed for any reason, or if the fetching
+    attempt involved a redirect, or if second
+    manifest and manifest are not
+    byte-for-byte identical, then schedule a rerun of the entire
+    algorithm with the same parameters after a short delay, and run
+    the cache failure steps.
    
+
+   
    25. 
+
+   
  25. 
+
+    
    Otherwise, store manifest in new cache, if it's not there already, and
+    categorize its entry as the manifest.
    
+
+   
    26. 
+
+   
  26. Set the completeness flag of
+   new cache to complete.
    27. 
+
+   
  27. Let task list be an empty list of tasks.
    
+
+   
  28. 
+
+    
    If this is a cache
+    attempt, then for each cache host associated
+    with an application cache in cache
+    group, create a task to
+    fire a simple event that is cancelable named cached at the
+    ApplicationCache singleton of the cache
+    host, and add it to task list. The
+    default action of these events must be, if the user agent
+    shows caching progress, the display of some sort of
+    user interface indicating to the user that the application has
+    been cached and that they can now use it offline.
    
+
+    
    Otherwise, it is an upgrade attempt. For each
+    cache host associated with an application
+    cache in cache group, create a task to fire a simple
+    event that is cancelable named updateready at the
+    ApplicationCache singleton of the cache
+    host, and add it to task list. The
+    default action of these events must be, if the user agent
+    shows caching progress, the display of some sort of
+    user interface indicating to the user that a new version is
+    available and that they can activate it by reloading the page.
    
+
+   
    29. 
+
+   
  29. If appropriate, remove any user interface indicating that
+   an update for this cache is in progress.
    30. 
+
+   
  30. Set the update
+   status of cache group to
+   idle.
    31. 
+
+   
  31. For each task in task list, queue that task as a post-oad task.
    32. 
+
+  
The cache failure steps are as follows:

+
+  
  1. Let task list be an empty list of tasks.
    
+
+   
  2. 
+
+    
    For each entry in cache group's list of pending master
+    entries, run the following further substeps. These steps
+    may be run in parallel for two or more entries at a time.
    
+
+    
    1. Wait for the resource for this entry to have either
+     completely downloaded or failed.
      
+
+     
    2. Unassociate the Document for this entry from
+     its application cache, if it has one.
      3. 
+
+     
    3. Create a task to
+     fire a simple event that is cancelable named error at the
+     ApplicationCache singleton of the
+     Document for this entry, if there still is one, and
+     add it to task list. The default action of
+     these events must be, if the user agent shows caching
+     progress, the display of some sort of user interface
+     indicating to the user that the user agent failed to save the
+     application for offline use.
      
+
+    
    3. 
+
+   
  3. For each cache host still associated with an
+   application cache in cache group,
+   create a task to fire a
+   simple event that is cancelable named error at the
+   ApplicationCache singleton of the cache
+   host, and add it to task list. The
+   default action of these events must be, if the user agent
+   shows caching progress, the display of some sort of
+   user interface indicating to the user that the user agent failed to
+   save the application for offline use.
    4. 
+
+   
  4. Empty cache group's list of pending master
+   entries.
    5. 
+
+   
  5. If cache group has an application
+   cache whose completeness flag is
+   incomplete, then discard that application
+   cache.
    
+
+   
  6. If appropriate, remove any user interface indicating that an
+   update for this cache is in progress.
    7. 
+
+   
  7. Let the status
+   of cache group be idle.
    8. 
+
+   
  8. If this was a cache
+   attempt, discard cache group
+   altogether.
    
+
+   
  9. For each task in task list, queue that task as a post-load task.
    10. 
+
+   
  10. Abort the application cache download
+   process.
    11. 
+
+  
Attempts to fetch resources as part of the
+  application cache download process may be done with
+  cache-defeating semantics, to avoid problems with stale or
+  inconsistent intermediary caches.

+
+  
User agents may invoke the application cache download
+  process, in the background, for any application
+  cache, at any time (with no cache host). This
+  allows user agents to keep caches primed and to update caches even
+  before the user visits a site.

+
+  
Each Document has a list of pending application
+  cache download process tasks that is used to delay events
+  fired by the algorithm above until the document's load event has fired. When the
+  Document is created, the list must be empty.

+
+  
When the steps above say to queue a post-load task
+  task, where task is a task that dispatches an event on a
+  target ApplicationCache object target, the user agent must run the appropriate steps
+  from the following list:

+
+  
If target's Document has
+   completely loaded

+
+   
Queue the task task.

+
+   
Otherwise

+
+   
Add task to target's
+   Document's list of pending application cache
+   download process tasks.

+
+  
The task source for these tasks is the networking task
+  source.

+
+
+
+
+  
6.6.5 The application cache selection algorithm

+
+  
When the application cache
+  selection algorithm algorithm is invoked with a
+  Document document and optionally a
+  manifest URL manifest URL, the user
+  agent must run the first applicable set of steps from the following
+  list:

+
+  
If there is a manifest URL, and document was loaded from an application
+   cache, and the URL of the manifest of that cache's
+   application cache group is not the same as
+   manifest URL

+
+   

+
+    
Mark the entry for the resource from which document was taken in the application
+    cache from which it was loaded as foreign.

+
+    
Restart the current navigation from the top of the navigation algorithm, undoing any changes
+    that were made as part of the initial load (changes can be avoided
+    by ensuring that the step to update the session history with
+    the new page is only ever completed after this
+    application cache selection
+    algorithm is run, though this is not required).

+
+    
The navigation will not result in the same
+    resource being loaded, because "foreign" entries are never picked
+    during navigation.

+
+    
User agents may notify the user of the inconsistency between
+    the cache manifest and the document's own metadata, to aid in
+    application development.

+
+   

+
+
+   
If document was loaded from an
+   application cache

+
+   

+
+    
Associate document with the
+    application cache from which it was loaded. Invoke,
+    in the background, the application cache download
+    process for that application cache's
+    application cache group, with document as the cache host.

+
+   

+
+
+   
If document  was loaded using
+   HTTP GET or
+   equivalent, and, there is a manifest
+   URL, and manifest URL has the same
+   origin as document

+
+   

+
+    
Invoke, in the background, the application cache download
+    process for manifest URL, with document as the cache host and with
+    the resource from which document was parsed as
+    the master
+    resource.

+
+   

+
+
+   
Otherwise
 
+
+   

+
+    
The Document is not associated with any
+    application cache.

+
+    
If there was a manifest URL, the user agent
+    may report to the user that it was ignored, to aid in application
+    development.

+
+   

+
+  
6.6.6 Changes to the networking model

+
+  
When a cache host is associated with an
+  application cache whose completeness flag is
+  complete, any and all loads for resources related to that
+  cache host other than those for child browsing contexts must go through the
+  following steps instead of immediately invoking the mechanisms
+  appropriate to that resource's scheme:

+
+  
  1. If the resource is not to be fetched using the HTTP GET
+   mechanism or
+   equivalent, or if its URL has a different <scheme> component than the
+   application cache's manifest, then
+   fetch the resource normally and abort these
+   steps.
    2. 
+
+   
  2. If the resource's URL is a master entry, the manifest, an explicit entry, or
+   a fallback entry in
+   the application cache, then get the resource from the
+   cache (instead of fetching it), and abort these steps.
    3. 
+
+   
  3. If there is an entry in the application cache's
+   online
+   whitelist that has the same origin as the
+   resource's URL and that is a prefix match for the
+   resource's URL, then fetch the resource normally and
+   abort these steps.
    4. 
+
+   
  4. 
+
+    
    If the resource's URL has the same origin as the
+    manifest's URL, and there is a fallback namespace
+    f in the application cache that
+    is a prefix match for the resource's URL, then:
    
+
+    
    Fetch the resource normally. If this results in a
+    redirect to a resource with another origin
+    (indicative of a captive portal), or a 4xx or 5xx status code
+    or equivalent,
+    or if there were network errors (but not if the user canceled the
+    download), then instead get, from the cache, the resource of the
+    fallback entry
+    corresponding to the fallback namespace
+    f. Abort these steps.
    
+
+   
    5. 
+
+   
  5. If the application cache's online whitelist
+   wildcard flag is open, then
+   fetch the resource normally and abort these
+   steps.
    6. 
+
+   
  6. Fail the resource load as if there had been a generic
+   network error.
    7. 
+
+  
The above algorithm ensures that so long as the
+  online
+  whitelist wildcard flag is blocking,
+  resources that are not present in the manifest will always fail
+  to load (at least, after the application cache has been
+  primed the first time), making the testing of offline applications
+  simpler.

+
+  

+
+
+  
6.6.7 Expiring application caches

+
+  
As a general rule, user agents should not expire application
+  caches, except on request from the user, or after having been left
+  unused for an extended period of time.

+
+  
Application caches and cookies have similar implications with
+  respect to privacy (e.g. if the site can identify the user when
+  providing the cache, it can store data in the cache that can be used
+  for cookie resurrection). Implementors are therefore encouraged to
+  expose application caches in a manner related to HTTP cookies,
+  allowing caches to be expunged together with cookies and other
+  origin-specific data.

+
+  
For example, a user agent could have a "delete
+  site-specific data" feature that clears all cookies, application
+  caches, local storage, databases, etc, from an origin all at
+  once.

+
+
+
+  
6.6.8 Application cache API

+
+  
interface ApplicationCache {
+
+  // update status
+  const unsigned short UNCACHED = 0;
+  const unsigned short IDLE = 1;
+  const unsigned short CHECKING = 2;
+  const unsigned short DOWNLOADING = 3;
+  const unsigned short UPDATEREADY = 4;
+  const unsigned short OBSOLETE = 5;
+  readonly attribute unsigned short status;
+
+  // updates
+  void update();
+  void swapCache();
+
+  // events
+           attribute Function onchecking;
+           attribute Function onerror;
+           attribute Function onnoupdate;
+           attribute Function ondownloading;
+           attribute Function onprogress;
+           attribute Function onupdateready;
+           attribute Function oncached;
+           attribute Function onobsolete;
+};
+ApplicationCache implements EventTarget;

+
+  
cache = window . applicationCache

+   

+
+    
(In a window.) Returns the ApplicationCache object that applies to the active document of that Window.

+
+   

+
+   
cache = self . applicationCache

+   

+
+    
(In a shared worker.) Returns the ApplicationCache object that applies to the current shared worker.
+    
+    [WEBWORKERS]
+    
+    

+
+   

+
+   
cache . status

+   

+
+    
Returns the current status of the application cache, as given by the constants defined below.

+
+   

+
+   
cache . update()

+   

+
+    
Invokes the application cache download process.

+
+    
Throws an INVALID_STATE_ERR exception if there is no application cache to update.

+
+   

+
+   
cache . swapCache()

+   

+
+    
Switches to the most recent application cache, if there is a
+    newer one. If there isn't, throws an
+    INVALID_STATE_ERR exception.

+
+    
This does not cause previously-loaded resources to be reloaded;
+    for example, images do not suddenly get reloaded and style sheets
+    and scripts do not get reparsed or reevaluated. The only change is
+    that subsequent requests for cached resources will obtain the
+    newer copies.

+
+   

+
+  

+
+  
There is a one-to-one mapping from cache
+  hosts to ApplicationCache objects. The applicationCache
+  attribute on Window objects must return the
+  ApplicationCache object associated with the
+  Window object's active document. The applicationCache
+  attribute on SharedWorkerGlobalScope objects must
+  return the ApplicationCache object associated with the
+  worker.
+  
+  [WEBWORKERS]
+  
+  

+
+  
A Window or
+  SharedWorkerGlobalScope object has an associated
+  ApplicationCache object even if that cache
+  host has no actual application cache.

+
+  
The status
+  attribute, on getting, must return the current state of the
+  application cache that the
+  ApplicationCache object's cache host is
+  associated with, if any. This must be the appropriate value from the
+  following list:

+
+  

+
+  
UNCACHED
+   (numeric value 0)

+
+   
The ApplicationCache object's cache
+   host is not associated with an application
+   cache at this time.

+
+   
IDLE
+   (numeric value 1)

+
+   
The ApplicationCache object's cache
+   host is associated with an application cache
+   whose application cache group's update status is
+   idle, and that application cache is the newest cache in its
+   application cache group, and the application
+   cache group is not marked as obsolete.

+
+   
CHECKING
+   (numeric value 2)

+
+   
The ApplicationCache object's cache
+   host is associated with an application cache
+   whose application cache group's update status is
+   checking.

+
+   
DOWNLOADING
+   (numeric value 3)

+
+   
The ApplicationCache object's cache
+   host is associated with an application cache
+   whose application cache group's update status is
+   downloading.

+
+   
UPDATEREADY
+   (numeric value 4)

+
+   
The ApplicationCache object's cache
+   host is associated with an application cache
+   whose application cache group's update status is
+   idle, and whose application cache group is not
+   marked as obsolete,
+   but that application cache is not the newest cache in its
+   group.

+
+   
OBSOLETE
+   (numeric value 5)

+
+   
The ApplicationCache object's cache
+   host is associated with an application cache
+   whose application cache group is marked as obsolete.

+
+  

+
+  
If the update() method is
+  invoked, the user agent must invoke the application cache
+  download process, in the background, for the application
+  cache with which the ApplicationCache object's
+  cache host is associated, but without giving that
+  cache host to the algorithm. If there is no such
+  application cache, or if it is marked as obsolete, then the method
+  must raise an INVALID_STATE_ERR exception instead.

+
+  
If the swapCache() method
+  is invoked, the user agent must run the following steps:
+
+  
  1. Check that ApplicationCache object's
+   cache host is associated with an application
+   cache. If it is not, then raise an
+   INVALID_STATE_ERR exception and abort these
+   steps.
    2. 
+
+   
  2. Let cache be the application
+   cache with which the ApplicationCache object's
+   cache host is associated. (By definition, this is the
+   same as the one that was found in the previous step.)
    3. 
+
+   
  3. If cache's application cache
+   group is marked as obsolete, then unassociate
+   the ApplicationCache object's cache host
+   from cache and abort these steps. (Resources
+   will now load from the network instead of the cache.)
    4. 
+
+   
  4. Check that there is an application cache in the same
+   application cache group as cache
+   whose completeness
+   flag is complete and that is newer than cache. If there is not, then raise an
+   INVALID_STATE_ERR exception and abort these
+   steps.
    5. 
+
+   
  5. Let new cache be the newest application
+   cache in the same application cache group as
+   cache whose completeness flag is
+   complete.
    6. 
+
+   
  6. Unassociate the ApplicationCache object's
+   cache host from cache and instead
+   associate it with new cache.
    7. 
+
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported, as IDL attributes, by
+  all objects implementing the ApplicationCache
+  interface:

+
+  
Event handler Event handler event type
+   
onchecking  checking
+    
onerror  error
+    
onnoupdate  noupdate
+    
ondownloading  downloading
+    
onprogress  progress
+    
onupdateready  updateready
+    
oncached  cached
+    
onobsolete  obsolete
+  

+
+
+  
6.6.9 Browser state

+
+  
window . navigator . onLine

+
+   

+
+    
Returns false if the user agent is definitely offline
+    (disconnected from the network). Returns true if the user agent
+    might be online.

+
+   

+
+  

+
+  
The navigator.onLine
+  attribute must return false if the user agent will not contact the
+  network when the user follows links or when a script requests a
+  remote page (or knows that such an attempt would fail), and must
+  return true otherwise.

+
+  
When the value that would be returned by the navigator.onLine attribute of
+  the Window changes from true to false, the user agent
+  must queue a task to fire a simple event
+  named offline at the
+  Window object.

+
+  
On the other hand, when the value that would be returned by the
+  navigator.onLine attribute
+  of the Window changes from false to true, the user
+  agent must queue a task to fire a simple
+  event named online at the
+  Window object.

+
+  
The task source for these tasks is the networking task
+  source.

+
+  

+
+  
This attribute is inherently unreliable. A computer
+  can be connected to a network without having Internet access.

+
+
+
+  
7 Web application APIs

+
+  
7.1 Scripting

+
+  
7.1.1 Introduction

+
+  
Various mechanisms can cause author-provided executable code to
+  run in the context of a document. These mechanisms include, but are
+  probably not limited to:

+
+  

+
+  
7.1.2 Enabling and disabling scripting

+
+  
Scripting is enabled in a
+  browsing context when all of the
+  following conditions are true:

+
+  
Scripting is disabled in a
+  browsing context when any of the above conditions are
+  false (i.e. when scripting is not enabled).

+
+  
Scripting is enabled for a
+  node if the Document object of the node (the
+  node itself, if it is itself a Document object) has an
+  associated browsing context, and scripting is enabled in that
+  browsing context.

+
+  
Scripting is disabled for a
+  node if there is no such browsing context, or if scripting is disabled in that
+  browsing context.

+
+  

+
+
+  

+
+  
+  
7.1.3 Processing model

+
+  
7.1.3.1 Definitions

+
+  
A script has:

+
+  
A script execution environment

+
+   

+
+    
The characteristics of the script execution environment depend
+    on the language, and are not defined by this specification.

+
+    
In JavaScript, the script execution environment
+    consists of the interpreter, the stack of execution
+    contexts, the global code and function code and
+    the Function objects resulting, and so forth.

+
+   

+
+   
A list of code entry-points

+
+   

+
+    
Each code entry-point represents a block of executable code
+    that the script exposes to other scripts and to the user
+    agent.

+
+    
Each Function object in a JavaScript
+    script execution environment has a corresponding code
+    entry-point, for instance.

+
+    
The main program code of the script, if any, is the
+    initial code entry-point. Typically, the code
+    corresponding to this entry-point is executed immediately after
+    the script is parsed.

+
+    
In JavaScript, this corresponds to the
+    execution context of the global code.

+
+   

+
+   
A relationship with the script's global object

+
+   

+
+    
An object that provides the APIs that the code can use.

+
+    
This is typically a Window
+    object. In JavaScript, this corresponds to the global
+    object.

+
+    
When a script's global object is an
+    empty object, it can't do anything that interacts with the
+    environment.

+
+    
If the script's global object is a
+    Window object, then in JavaScript, the ThisBinding of
+    the global execution context for this script must be the
+    Window object's WindowProxy object,
+    rather than the global object. [ECMA262]

+
+    
This is a willful violation of the
+    JavaScript specification current at the time of writing
+    (ECMAScript edition 5, as defined in section 10.4.1.1 Initial
+    Global Execution Context, step 3). The JavaScript specification
+    requires that the this keyword in the global
+    scope return the global object, but this is not compatible with
+    the security design prevalent in implementations as specified
+    herein. [ECMA262]

+
+   

+
+   
A relationship with the script's browsing context

+
+   

+
+    
A browsing context that is assigned responsibility
+    for actions taken by the script.

+
+    
When a script creates and navigates a new top-level browsing
+    context, the opener
+    attribute of the new browsing context's
+    Window object will be set to the script's
+    browsing context's WindowProxy object.

+
+   

+
+   
A relationship with the script's document

+
+   

+
+    
A Document that is assigned responsibility for
+    actions taken by the script.

+
+    
When a script fetches a resource, the current address of the
+    script's document will be used to set the Referer (sic) header.

+
+   

+
+   
A URL character encoding

+
+   

+
+    
A character encoding, set when the script is created, used to
+    encode URLs. If the character
+    encoding is set from another source, e.g. a document's
+    character encoding, then the script's URL character
+    encoding must follow the source, so that if the source's
+    changes, so does the script's.

+
+   

+
+   
A base URL

+
+   

+
+    
A URL, set when the script is created, used to
+    resolve relative URLs. If the
+    base URL is set from another source, e.g. a document base
+    URL, then the script's base URL must follow
+    the source, so that if the source's changes, so does the
+    script's.

+
+   

+
+  

+
+
+  

+
+  
7.1.3.2 Calling scripts

+
+  
When a user agent is to jump to a code entry-point for
+  a script, for example to invoke
+  an event listener defined in that script, the user agent must run the
+  following steps:

+
+  
  1. If the script's global object is a
+   Window object whose Document object is
+   not fully active, then abort these steps without doing
+   anything. The callback is not fired.
    
+
+   
  2. Set the entry script to be the script being invoked.
    3. 
+
+   
  3. Make the script
+   execution environment for the script execute the code for the given
+   code entry-point.
    4. 
+
+   
  4. Set the entry script back to whatever it was
+   when this algorithm started.
    5. 
+
+  
This algorithm is not invoked by one script calling another.

+
+  

+
+
+  

+
+  
7.1.3.3 Creating scripts

+
+  
When the specification says that a script is to be created, given some script source, its scripting
+  language, a global object, a browsing context, a URL character
+  encoding, and a base URL, the user agent must run the following
+  steps:

+
+  
  1. If scripting is
+   disabled for browsing context passed to this
+   algorithm, then abort these steps, as if the script did nothing but
+   return void.
    
+
+   
  2. Set up a script execution environment as
+   appropriate for the scripting language.
    3. 
+
+   
  3. Parse/compile/initialize the source of the script using the
+   script execution environment, as appropriate for the
+   scripting language, and thus obtain the list of code
+   entry-points for the script. If the semantics of the
+   scripting language and the given source code are such that there is
+   executable code to be immediately run, then the initial code
+   entry-point is the entry-point for that code.
    4. 
+
+   
  4. Set up the script's global object, the
+   script's browsing context, the script's
+   document, the script's URL character encoding,
+   and the script's base URL from the settings passed to
+   this algorithm.
    5. 
+
+   
  5. Jump to the
+   script's initial code
+   entry-point.
    6. 
+
+  
When the user agent is to create an impotent script,
+  given some script source, its scripting language, and a browsing
+  context, the user agent must create a script, using the
+  given script source and scripting language, using a new empty object
+  as the global object, and using the given browsing context as the
+  browsing context. The URL character encoding and base URL for the
+  resulting script are not
+  important as no APIs are exposed to the script.

+
+  
When the specification says that a script is to be created from a node node, given some script source and its scripting
+  language, the user agent must create a script, using
+  the given script source and scripting language, and using the
+  script settings determined from the node node.

+
+  
The script settings determined from the node node are computed as follows:

+
+  
  1. Let document be the
+   Document of node (or node itself if it is a
+   Document).
    2. 
+
+   
  2. The browsing context is the browsing context of
+   document.
    
+
+   
  3. The global object is the Window object of
+   document.
    4. 
+
+   
  4. The URL character encoding is the character encoding of document. (This is a
+   reference, not a copy.)
    5. 
+
+   
  5. The base URL is the base
+   URL of document. (This is a reference, not a copy.)
    6. 
+
+  

+
+
+  

+
+  
7.1.3.4 Killing scripts

+
+  
User agents may impose resource limitations on scripts, for
+  example CPU quotas, memory limits, total execution time limits, or
+  bandwidth limitations. When a script exceeds a limit, the user agent
+  may either throw a QUOTA_EXCEEDED_ERR exception, abort
+  the script without an exception, prompt the user, or throttle script
+  execution.

+
+  

+
+   
For example, the following script never terminates. A user agent
+   could, after waiting for a few seconds, prompt the user to either
+   terminate the script or let it continue.

+
+   
<script>
+ while (true) { /* loop */ }
+</script>

+
+  

+
+  
User agents are encouraged to allow users to disable scripting
+  whenever the user is prompted either by a script (e.g. using the
+  window.alert() API) or because of a
+  script's actions (e.g. because it has exceeded a time limit).

+
+  
If scripting is disabled while a script is executing, the script
+  should be terminated immediately.

+
+  

+
+
+  

+
+  
7.1.4 Event loops

+
+  
7.1.4.1 Definitions

+
+  
To coordinate events, user interaction, scripts, rendering,
+  networking, and so forth, user agents must use event loops as described in this section.

+
+  
There must be at least one event loop per user
+  agent, and at most one event loop per unit of
+  related similar-origin browsing contexts.

+
+  
An event loop always has at least one browsing
+  context. If an event loop's browsing contexts all go away, then
+  the event loop goes away as well. A browsing
+  context always has an event loop coordinating
+  its activities.

+
+  
+  
Other specifications can define new kinds of event
+  loops that aren't associated with browsing contexts; in particular,
+  the Web Workers specification does so.

+  
+
+  
An event loop has one or more task queues. A task queue is an ordered
+  list of tasks, which can be:

+
+  
Events

+
+   

+
+    
Asynchronously dispatching an Event object at a
+    particular EventTarget object is a task.

+
+    
Not all events are dispatched using the task
+    queue, many are dispatched synchronously during other
+    tasks.

+
+   

+
+
+   
Parsing

+
+   
The HTML parser tokenizing a single byte, and
+   then processing any resulting tokens, is a task.

+
+
+   
Callbacks

+
+   
Calling a callback asynchronously is a task.

+
+
+   
Using a resource

+
+   
When an algorithm fetches a
+   resource, if the fetching occurs asynchronously then the processing
+   of the resource once some or all of the resource is available is a
+   task.

+
+
+   
Reacting to DOM manipulation

+
+   
Some elements have tasks that trigger in response to DOM
+   manipulation, e.g. when that element is inserted into the document.

+
+  
When a user agent is to queue a task, it must add the
+  given task to one of the task queues
+  of the relevant event loop. All the tasks from one
+  particular task source (e.g. the callbacks generated by
+  timers, the events dispatched for mouse movements, the tasks queued
+  for the parser) must always be added to the same task
+  queue, but tasks from different task sources may be placed in different task queues.

+
+  
For example, a user agent could have one
+  task queue for mouse and key events (the user
+  interaction task source), and another for everything
+  else. The user agent could then give keyboard and mouse events
+  preference over other tasks three quarters of the time, keeping the
+  interface responsive but not starving other task queues, and never
+  processing events from any one task source out of
+  order.

+
+  
Each task that is queued onto a task queue of
+  an event loop defined by this specification is
+  associated with a Document; if the task was queued in
+  the context of an element, then it is the element's
+  Document; if the task was queued in the context of a
+  browsing context, then it is the browsing
+  context's active document at the time the task
+  was queued; if the task was queued by or for a script then the document is the
+  script's document.

+
+  
A user agent is required to have one storage
+  mutex. This mutex is used to control access to shared state
+  like cookies. At any one point, the storage mutex is
+  either free, or owned by a particular event loop or
+  instance of the fetching algorithm.

+
+  
Whenever a script calls into
+  a plugin, and whenever a plugin calls into
+  a script, the user agent must
+  release the storage mutex.

+
+
+  
7.1.4.2 Processing model

+
+  
An event loop must continually run through the
+  following steps for as long as it exists:

+
+  
  1. Run the oldest task on one
+   of the event loop's task
+   queues, ignoring tasks whose associated
+   Documents are not fully active. The user
+   agent may pick any task queue.
    2. 
+
+   
  2. If the storage mutex is now owned by the
+   event loop, release it so that it is once again
+   free.
    
+
+   
  3. Remove that task from its task queue.
    4. 
+
+   
  4. If any asynchronously-running algorithms are awaiting a stable state, then
+   run their synchronous section and then resume running
+   their asynchronous algorithm.
    
+
+   
    A synchronous section never mutates
+   the DOM, runs any script, or has any other side-effects.
    
+
+   
    Steps in synchronous sections are marked with
+   ⌛.
    5. 
+
+   
  5. If necessary, update the rendering or user interface of any
+   Document or browsing context to reflect
+   the current state.
    6. 
+
+   
  6. Return to the first step of the event
+   loop.
    7. 
+
+  
When an algorithm says to spin the event loop until
+  a condition goal is met, the user agent must run
+  the following steps:

+
+  
  1. Let task source be the task
+   source of the currently running task.
    2. 
+
+   
  2. Stop the currently running task, allowing the event
+   loop to resume, but continue these steps
+   asynchronously.
    3. 
+
+   
  3. Wait until the condition goal is
+   met.
    4. 
+
+   
  4. Queue a task to continue running these steps,
+   using the task source task
+   source. Wait until this task runs before continuing these
+   steps.
    5. 
+
+   
  5. Return to the caller.
    6. 
+
+  
Some of the algorithms in this specification, for historical
+  reasons, require the user agent to pause while running a
+  task until some condition has been
+  met. While a user agent has a paused task, the corresponding event
+  loop must not run further tasks, and any script in the currently
+  running task must block. User
+  agents should remain responsive to user input while paused, however,
+  albeit in a reduced capacity since the event loop will
+  not be doing anything.

+
+  
When a user agent is to obtain the storage mutex as
+  part of running a task, it must
+  run through the following steps:

+
+  
  1. If the storage mutex is already owned by this
+   task's event loop,
+   then abort these steps.
    2. 
+
+   
  2. Otherwise, pause until the storage
+   mutex can be taken by the event loop.
    3. 
+
+   
  3. Take ownership of the storage mutex.
    4. 
+
+  

+
+
+  

+
+  
7.1.4.3 Generic task sources

+
+  
The following task sources are
+  used by a number of mostly unrelated features in this and other
+  specifications.

+
+  
The DOM manipulation task source

+
+   

+
+    
This task source is used for features that react
+    to DOM manipulations, such as things that happen asynchronously
+    when an element is inserted into the document.

+
+    
+
+   

+
+   
The user interaction task source

+
+   

+
+    
This task source is used for features that react
+    to user interaction, for example keyboard or mouse input.

+
+    
Asynchronous events sent in response to user input (e.g. click events) must be dispatched using
+    tasks queued with the user interaction task
+    source. [DOMEVENTS]

+
+   

+
+   
The networking task source

+
+   

+
+    
This task source is used for features that trigger
+    in response to network activity.

+
+    
+
+   

+
+   
The history traversal task source

+
+   

+
+    
This task source is used to queue calls to history.back() and similar
+    APIs.

+
+   

+
+  

+
+
+
+  

+
+  
+  
7.1.5 The javascript: protocol

+
+  
When a URL using the javascript: protocol is dereferenced, the user agent must run
+  the following steps:

+
+  
  1. Let the script source be the string obtained using the
+   content retrieval operation defined for javascript: URLs. [JSURL]
    2. 
+
+   
  2. 
+
+    
    Use the appropriate step from the following list:
    
+
+    
    If a browsing context is being navigated to a javascript:
+     URL, and the active document of that browsing
+     context has the same origin as the script given by
+     that URL
    
+
+     
    
+
+      
+
+      
    Let address be the address of the active
+      document of the browsing context being
+      navigated.
    
+
+      
    If address is about:blank,
+      and the browsing context being navigated has a
+      creator browsing context, then let address be the address of the creator
+      Document instead.
    
+
+      
    Create a
+      script from the Document node of the
+      active document, using the aforementioned script
+      source, and assuming the scripting language is JavaScript.
    
+
+      
    Let result be the return value of the
+      initial code entry-point of this script. If an exception was
+      raised, let result be void instead. (The
+      result will be void also if scripting is disabled.)
    
+
+      
    When it comes time to set the document's address
+      in the navigation algorithm, use
+      address as the override
+      URL.
    
+
+     
    
+
+     
    If the Document object of the element,
+     attribute, or style sheet from which the javascript:
+     URL was reached has an associated browsing
+     context
    
+
+     
    
+
+      
    Create an impotent script using the
+      aforementioned script source, with the scripting language set to
+      JavaScript, and with the Document's object's
+      browsing context as the browsing context.
    
+
+      
    Let result be the return value of the
+      initial code entry-point of this script. If an exception was
+      raised, let result be void instead. (The
+      result will be void also if scripting is disabled.)
    
+
+     
    
+
+     
    Otherwise
    
+
+     
    
+
+      
    Let result be void.
    
+
+     
    
+
+    
    3. 
+
+   
  3. 
+
+    
    If the result of executing the script is void (there is no
+    return value), then the URL must be treated in a manner equivalent
+    to an HTTP resource with an HTTP 204 No Content response.
    
+
+    
    Otherwise, the URL must be treated in a manner equivalent to an
+    HTTP resource with a 200 OK response whose Content-Type metadata is
+    text/html and whose response body is the return value
+    converted to a string value.
    
+
+    
    Certain contexts, in particular img
+    elements, ignore the Content-Type
+    metadata.
    
+
+   
    4. 
+
+  

+
+   
So for example a javascript: URL for a
+   src attribute of an
+   img element would be evaluated in the context of an
+   empty object as soon as the attribute is set; it would then be
+   sniffed to determine the image type and decoded as an image.

+
+   
A javascript: URL in an href attribute of an a
+   element would only be evaluated when the link was followed.

+
+   
The src attribute of an
+   iframe element would be evaluated in the context of
+   the iframe's own browsing context; once
+   evaluated, its return value (if it was not void) would replace that
+   browsing context's document, thus changing the
+   variables visible in that browsing context.

+
+  

+
+  

+
+
+
+  
7.1.6 Events

+
+  

+
+  
7.1.6.1 Event handlers

+
+  

+
+  
+
+  
Many objects can have event handlers specified. These
+  act as bubbling event listeners for the object on which they are
+  specified.

+
+  
An event handler can either
+  have the value null or be set to a Function
+  object. Initially, event handlers must be set to
+  null.

+
+  
Event handlers are exposed in one or two ways.

+
+  
The first way, common to all event handlers, is as an event handler IDL
+  attribute.

+
+  
The second way is as an event handler content attribute. Event handlers
+  on HTML elements and some of the event handlers on
+  Window objects are exposed in this way.

+
+  

+
+  
Event handler IDL attributes, on setting, must set the
+  corresponding event handler to their new value, and on
+  getting, must return whatever the current value of the corresponding
+  event handler is (possibly null).

+
+  
If an event handler
+  IDL attribute exposes an event
+  handler of an object that doesn't exist, it must always
+  return null on getting and must do nothing on setting.

+
+  
This can happen in particular for event handler IDL attribute on
+  body elements that do not have corresponding
+  Window objects.

+
+  
Certain event handler IDL attributes have additional
+  requirements, in particular the onmessage attribute of
+  MessagePort objects.

+
+  

+
+  
Event handler content attributes, when specified, must
+  contain valid JavaScript code matching the FunctionBody production. [ECMA262]

+
+  

+
+  
+  
When an event
+  handler content attribute is set, if the element is owned by
+  a Document that is in a browsing context,
+  and scripting is enabled for
+  that browsing context, the user agent must run the
+  following steps to create a script after setting the content
+  attribute to its new value:

+
+  
  1. Set up a script execution environment for
+   JavaScript.
    2. 
+
+   
  2. 
+
+    
    Using this script execution environment, create a function
+    object (as defined in ECMAScript edition 5 section 13.2 Creating
+    Function Objects), with:
    
+
+    
    Parameter list FormalParameterList
    
+
+     
    
+
+      
    If the attribute is the onerror attribute of the
+       Window object
    
+
+       
    Let the function have three arguments, named event, source, and fileno.
    
+
+       
    Otherwise
    
+
+       
    Let the function have a single argument called event.
    
+
+      
    
+
+     
    Function body FunctionBody
    
+
+     
    The event
+     handler content attribute's new value.
    
+
+     
    Lexical Environment Scope
    
+
+     
    
+
+      
    1. Let Scope be the result of
+       NewObjectEnvironment(the element's Document, the
+       global environment).
      2. 
+
+       
    2. If the element has a form owner, let Scope be the result of NewObjectEnvironment(the
+       element's form owner, Scope).
      3. 
+
+       
    3. Let Scope be the result of
+       NewObjectEnvironment(the element's object, Scope).
      4. 
+
+      
    NewObjectEnvironment() is defined in ECMAScript
+      edition 5 section 10.2.2.3 NewObjectEnvironment (O, E). [ECMA262]
    
+
+     
    
+
+     
    Boolean flag Strict
    
+
+     
    False.
    
+
+    
    Let this new function be the only entry in the script's
+    list of code entry-points.
    
+
+   
    3. 
+
+   
  3. If the previous steps failed to compile the script, then set
+   the corresponding event handler
+   to null and abort these steps.
    4. 
+
+   
  4. Set up the script's global object, the
+   script's browsing context, the script's
+   document, the script's URL character encoding,
+   and the script's base URL from the script
+   settings determined from the node on which the attribute is
+   being set.
    5. 
+
+   
  5. Set the corresponding event
+   handler to the aforementioned function.
    6. 
+
+  
When an event handler content attribute is removed, the user
+  agent must set the corresponding event
+  handler to null.

+  
+
+  

+
+  
When an event handler content attribute is set on an
+  element owned by a Document that is not in a
+  browsing context, the corresponding event handler is
+  not changed.

+
+  
+
+  

+
+  
All event handlers on an object, whether an element
+  or some other object, and whether set to null or to a
+  Function object, must be registered as event listeners
+  on the object when it is created, as if the addEventListener()
+  method on the object's EventTarget interface had been
+  invoked, with the event type (type
+  argument) equal to the type corresponding to the event handler (the
+  event handler event type), the listener set to be a
+  target and bubbling phase listener (useCapture argument set to
+  false), and the event listener itself (listener argument) set to do
+  nothing while the event handler's value is not a
+  Function object, and set to invoke the call() callback of the
+  Function object associated with the event handler
+  otherwise.

+
+  

+
+  
Event handlers therefore always fire before event listeners
+  attached using addEventListener().

+
+  

+
+  
The listener
+  argument is emphatically not the event handler itself.

+
+  
The interfaces implemented by the event object do
+  not influence whether an event
+  handler is triggered or not.

+
+  
When an event handler's
+  Function object is invoked, its call() callback must be invoked
+  with one argument, set to the Event object of the event
+  in question.

+
+  
The handler's return value must then be processed as follows:

+
+  
If the event type is mouseover

+
+   
If the return value is a boolean with the value true, then
+   the event must be canceled.

+
+   
If the event object is a BeforeUnloadEvent object

+
+   
If the return value is a string, and the event object's
+   returnValue
+   attribute's value is the empty string, then set the returnValue
+   attribute's value to the return value.

+
+   
Otherwise

+
+   
If the return value is a boolean with the value false, then
+   the event must be canceled.

+
+  

+
+  
+
+  
The Function interface represents a function in the
+  scripting language being used. It is represented in IDL as
+  follows:

+
+  
[Callback=FunctionOnly, NoInterfaceObject]
+interface Function {
+  any call(in any... arguments);
+};

+
+  
The call(...)
+  method is the object's callback.

+
+  
In JavaScript, any Function
+  object implements this interface.

+
+  
If the Function object is a JavaScript Function, then when it is invoked by the user agent,
+  the user agent must set the thisArg (as defined
+  by ECMAScript edition 5 section 10.4.3 Entering Function Code) to
+  the event handler's object. [ECMA262]

+
+  

+
+   
For example, the following document fragment:

+
+   
<body onload="alert(this)" onclick="alert(this)">

+
+   
...leads to an alert saying "[object Window]" when the document is loaded,
+   and an alert saying "[object HTMLBodyElement]" whenever the user
+   clicks something in the page.

+
+  

+
+  
The return value of the function is affects whether the event is
+  canceled or not: as described above, if
+  the return value is false, the event is canceled (except for mouseover events, where the return
+  value has to be true to cancel the event). With beforeunload events, the value is
+  instead used to determine the message to show the user.

+
+
+  

+
+  
7.1.6.2 Event handlers on elements, Document objects, and Window objects

+
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported by all HTML
+  elements, as both content attributes and IDL attributes, and
+  on Document and Window objects, as IDL
+  attributes.

+
+  
Event handler Event handler event type
+   
onabort  abort
+    
oncanplay  canplay
+    
oncanplaythrough  canplaythrough
+    
onchange  change 
+    
onclick  click 
+    
oncontextmenu  contextmenu 
+    
ondblclick  dblclick 
+    
ondrag  drag
+    
ondragend  dragend
+    
ondragenter  dragenter
+    
ondragleave  dragleave
+    
ondragover  dragover
+    
ondragstart  dragstart 
+    
ondrop  drop
+    
ondurationchange  durationchange
+    
onemptied  emptied
+    
onended  ended
+    
onformchange  formchange
+    
onforminput  forminput
+    
oninput  input
+    
oninvalid  invalid
+    
onkeydown  keydown 
+    
onkeypress  keypress 
+    
onkeyup  keyup 
+    
onloadeddata  loadeddata
+    
onloadedmetadata  loadedmetadata
+    
onloadstart  loadstart
+    
onmousedown  mousedown 
+    
onmousemove  mousemove 
+    
onmouseout  mouseout 
+    
onmouseover  mouseover 
+    
onmouseup  mouseup 
+    
onmousewheel  mousewheel 
+    
onpause  pause
+    
onplay  play
+    
onplaying  playing
+    
onprogress  progress
+    
onratechange  ratechange
+    
onreadystatechange  readystatechange
+    
onscroll  scroll  
+    
onseeked  seeked
+    
onseeking  seeking
+    
onselect  select  
+    
onshow  show
+    
onstalled  stalled
+    
onsubmit  submit 
+    
onsuspend  suspend
+    
ontimeupdate  timeupdate
+    
onvolumechange  volumechange
+    
onwaiting  waiting
+
+
+ 
+ 
+ 
+
+ 
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported by all HTML
+  elements other than body, as both content
+  attributes and IDL attributes, and on Document objects,
+  as IDL attributes:

+
+  
Event handler Event handler event type
+   
onblur  blur 
+    
onerror  error
+    
onfocus  focus 
+    
onload  load
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported by Window
+  objects, as IDL attributes on the Window object, and
+  with corresponding content attributes and IDL attributes exposed on
+  the body and frameset elements:

+
+  
Event handler Event handler event type
+   
onafterprint  afterprint
+    
onbeforeprint  beforeprint
+    
onbeforeunload  beforeunload
+    
onblur  blur
+    
onerror  error
+    
onfocus  focus
+    
onhashchange  hashchange 
+    
onload  load 
+    
onmessage  message 
+    
onoffline  offline 
+    
ononline  online 
+    
onpagehide  pagehide 
+    
onpageshow  pageshow 
+    
onpopstate  popstate 
+    
onredo  redo 
+    
onresize  resize  
+    
onstorage  storage 
+    
onundo  undo 
+    
onunload  unload 
+  
The onerror
+  handler is also used for reporting script errors.

+
+  

+
+
+  

+
+  
7.1.6.3 Event firing

+
+  
Certain operations and methods are defined as firing events on
+  elements. For example, the click()
+  method on the HTMLElement interface is defined as
+  firing a click event on the
+  element. [DOMEVENTS]

+
+  
Firing a click event means that a click event, which bubbles and is
+  cancelable, and which uses the MouseEvent interface,
+  must be dispatched at the given target. The event object must have
+  its screenX, screenY,
+  clientX, clientY, and
+  button attributes set to 0, its ctrlKey, shiftKey, altKey, and metaKey attributes
+  set according to the current state of the key input device, if any
+  (false for any keys that are not available), its detail attribute set to 1, and its relatedTarget attribute set to null. The getModifierState() method on the object must return
+  values appropriately describing the state of the key input device at
+  the time the event is created.

+
+  
Firing a simple event named e means that an event with the name e, which does not bubble (except where otherwise
+  stated) and is not cancelable (except where otherwise stated), and
+  which uses the Event interface, must be dispatched at
+  the given target.

+
+
+
+  
The default action of these event is to do nothing except where
+  otherwise stated.

+
+  

+
+
+  

+
+  
7.1.6.4 Events and the Window object

+
+  
When an event is dispatched at a DOM node in a
+  Document in a browsing context, if the
+  event is not a load event, the user
+  agent must also dispatch the event to the Window, as
+  follows:

+
+  
  1. In the capture phase, the event must propagate to the
+   Window object before propagating to any of the nodes,
+   as if the Window object was the parent of the
+   Document in the dispatch chain.
    2. 
+
+   
  2. In the bubble phase, the event must propagate up to the
+   Window object at the end of the phase, unless bubbling
+   has been prevented, again as if the Window object was
+   the parent of the Document in the dispatch chain.
    3. 
+
+  

+
+
+  

+
+  
7.1.6.5 Runtime script errors

+
+  
This section only applies to user agents that support
+  scripting in general and JavaScript in particular.

+
+  
Whenever an uncaught runtime script error occurs in one of the
+  scripts associated with a Document, the user agent must
+  report the error using the onerror event handler of the script's global
+  object. If the error is still not handled after this, then
+  the error may be reported to the user.

+
+  
When the user agent is required to report an error error using the
+  event handler onerror, it must run these steps, after which the
+  error is either handled or not handled:

+
+  
If the value of onerror is a
+   Function

+
+   

+
+    
The function must be invoked with three arguments. The three
+    arguments passed to the function are all DOMStrings;
+    the first must give the message that the UA is considering
+    reporting, the second must give the absolute URL of
+    the resource in which the error occurred, and the third must give
+    the line number in that resource on which the error occurred.

+
+    
If the function returns false, then the error is handled. Otherwise, the error is
+    not handled.

+
+    
Any uncaught exceptions thrown or errors caused by this
+    function may be reported to the user immediately after the error
+    that the function was called for; the report an error algorithm must not be used to handle
+    exceptions thrown or errors caused by this function.

+
+   

+
+   
Otherwise

+
+   

+
+    
The error is not handled.

+
+   

+
+  

+
+
+  
7.2 Timers

+
+  
The setTimeout()
+  and setInterval()
+  methods allow authors to schedule timer-based callbacks.

+
+
[Supplemental, NoInterfaceObject]
+interface WindowTimers {
+  long setTimeout(in any handler, in optional any timeout, in any... args);
+  void clearTimeout(in long handle);
+  long setInterval(in any handler, in optional any timeout, in any... args);
+  void clearInterval(in long handle);
+};
+Window implements WindowTimers;

+
+  
handle = window . setTimeout( handler [, timeout [, arguments ] ] )

+
+   

+
+    
Schedules a timeout to run handler after
+    timeout milliseconds. Any arguments are passed straight through to the handler.

+
+   

+
+   
handle = window . setTimeout( code [, timeout ] )

+
+   

+
+    
Schedules a timeout to compile and run code
+    after timeout milliseconds.

+
+   

+
+   
window . clearTimeout( handle )

+
+   

+
+    
Cancels the timeout set with setTimeout() identified by handle.

+
+   

+
+   
handle = window . setInterval( handler [, timeout [, arguments ] ] )

+
+   

+
+    
Schedules a timeout to run handler every
+    timeout milliseconds. Any arguments are passed straight through to the handler.

+
+   

+
+   
handle = window . setInterval( code [, timeout ] )

+
+   

+
+    
Schedules a timeout to compile and run code
+    every timeout milliseconds.

+
+   

+
+   
window . clearInterval( handle )

+
+   

+
+    
Cancels the timeout set with setInterval() identified by handle.

+
+   

+
+  
This API does not guarantee that timers will fire
+  exactly on schedule. Delays due to CPU load, other tasks, etc, are
+  to be expected.

+
+  

+
+  
The WindowTimers interface adds to the
+  Window interface and the WorkerUtils
+  interface (part of Web Workers).

+
+  
Each object that implements the WindowTimers
+  interface has a list of active timeouts and a list
+  of active intervals. Each entry in these lists is identified
+  by a number, which must be unique within its list for the lifetime
+  of the object that implements the WindowTimers
+  interface.

+
+  
The setTimeout()
+  method must run the following steps:
+
+  
  1. Let handle be a user-agent-defined integer
+   that is greater than zero that will identify the timeout to be set
+   by this call.
    2. 
+
+   
  2. Add an entry to the list of active timeouts for
+   handle.
    3. 
+
+   
  3. Get the timed task handle in
+   the list of active timeouts, and let task be the result.
    4. 
+
+   
  4. Get the timeout, and let timeout be the result.
    5. 
+
+   
  5. If the currently running task is a task that was created by the
+   setTimeout()
+   method, and timeout is less than 4, then
+   increase timeout to 4.
    6. 
+
+   
  6. Return handle, and then continue running
+   this algorithm asynchronously.
    7. 
+
+   
  7. 
+
+    
    If the method context is a Window
+    object, wait until the Document associated with the
+    method context has been fully active for
+    a further timeout milliseconds (not
+    necessarily consecutively).
    
+
+    
    Otherwise, if the method context is a
+    WorkerUtils object, wait until timeout milliseconds have passed with the worker
+    not suspended (not necessarily consecutively).
    
+
+    
    Otherwise, act as described in the specification that defines
+    that the WindowTimers interface is implemented by
+    some other object.
    
+
+   
    8. 
+
+   
  8. Wait until any invocations of this algorithm started before
+   this one whose timeout is equal to or less than
+   this one's have completed.
    9. 
+
+   
  9. Queue the task task.
    10. 
+
+  
The clearTimeout()
+  method must clear the entry identified as handle
+  from the list of active timeouts of the
+  WindowTimers object on which the method was invoked,
+  where handle is the argument passed to the
+  method.

+
+  
The setInterval()
+  method must run the following steps:
+
+  
  1. Let handle be a user-agent-defined integer
+   that is greater than zero that will identify the interval to be set
+   by this call.
    2. 
+
+   
  2. Add an entry to the list of active intervals for
+   handle.
    3. 
+
+   
  3. Get the timed task handle in
+   the list of active intervals, and let task be the result.
    4. 
+
+   
  4. Get the timeout, and let timeout be the result.
    5. 
+
+   
  5. If timeout is less than 10, then
+   increase timeout to 10.
    6.  
+
+   
  6. Return handle, and then continue running
+   this algorithm asynchronously.
    7. 
+
+   
+
+   
  7. 
+
+    
    Wait: If the method context is a
+    Window object, wait until the Document
+    associated with the method context has been fully
+    active for a further interval
+    milliseconds (not necessarily consecutively).
    
+
+    
    Otherwise, if the method context is a
+    WorkerUtils object, wait until interval milliseconds have passed with the worker
+    not suspended (not necessarily consecutively).
    
+
+    
    Otherwise, act as described in the specification that defines
+    that the WindowTimers interface is implemented by
+    some other object.
    
+
+   
    8. 
+
+   
  8. Queue the task task.
    9. 
+
+   
  9. Return to the step labeled wait.
    10. 
+
+  
The clearInterval()
+  method must clear the entry identified as handle
+  from the list of active intervals of the
+  WindowTimers object on which the method was invoked,
+  where handle is the argument passed to the
+  method.

+
+  
The method context, when referenced by the algorithms
+  in this section, is the object on which the method for which the
+  algorithm is running is implemented (a Window or
+  WorkerUtils object).

+
+  
When the above methods are invoked and try to get the timed
+  task handle in list list,
+  they must run the following steps:

+
+  
  1. 
+
+    
    If the first argument to the invoked method is an object that
+    has an internal [[Call]] method, then return a task that checks if the entry for handle in list has been cleared,
+    and if it has not, calls the aforementioned [[Call]] method with
+    as its arguments the third and subsequent arguments to the invoked
+    method (if any), and abort these steps.
    
+
+    
    Otherwise, continue with the remaining steps.
    
+
+   
    2. 
+
+   
  2. Apply the ToString() abstract operation to the first
+   argument to the method, and let script source
+   be the result. [ECMA262]
    3. 
+
+   
  3. Let script language be
+   JavaScript.
    4. 
+
+   
  4. 
+
+    
    If the method context is a Window
+    object, let global object be the method
+    context, let browsing context be the
+    browsing context with which global
+    object is associated, let character
+    encoding be the character encoding of the Document
+    associated with global object (this is a reference, not a copy), and let
+    base URL be the base URL of the Document associated with
+    global object (this is
+    a reference, not a copy).
    
+
+    
    Otherwise, if the method context is a
+    WorkerUtils object, let global
+    object, browsing context, document, character encoding,
+    and base URL be the script's global
+    object, script's browsing context,
+    script's document, script's URL character
+    encoding, and script's base URL (respectively)
+    of the script that the
+    run a worker algorithm created when it created the
+    method context.
    
+
+    
    Otherwise, act as described in the specification that defines
+    that the WindowTimers interface is implemented by
+    some other object.
    
+
+   
    5. 
+
+   
  5. Return a task that checks
+   if the entry for handle in list has been cleared, and if it has not, creates a script using script source as the script source, scripting language as the scripting language, global object as the global object, browsing context as the browsing context, document as the document, character
+   encoding as the URL character encoding, and base URL as the base URL.
    6. 
+
+  
When the above methods are to get the timeout, they
+  must run the following steps:

+
+  
  1. Let timeout be the second argument to
+   the method, or zero if the argument was omitted.
    2. 
+
+   
  2. Apply the ToString() abstract operation to timeout, and let timeout
+   be the result. [ECMA262]
    3. 
+
+   
  3. Apply the ToNumber() abstract operation to timeout, and let timeout be the
+   result. [ECMA262]
    4. 
+
+   
  4. If timeout is an Infinity value, a
+   Not-a-Number (NaN) value, or negative, let timeout be zero.
    5. 
+
+   
  5. Round timeout down to the nearest
+   integer, and let timeout be the
+   result.
    6. 
+
+   
  6. Return timeout.
    7. 
+
+  
The task source for these tasks is the timer task
+  source.

+
+  

+
+
+
+  
7.3 User prompts

+
+  
+
+  
7.3.1 Simple dialogs

+
+  
window . alert(message)

+   

+
+    
Displays a modal alert with the given message, and waits for the user to dismiss it.

+
+    
A call to the navigator.yieldForStorageUpdates()
+    method is implied when this method is invoked.

+
+   

+
+   
result = window . confirm(message)

+   

+
+    
Displays a modal OK/Cancel prompt with the given message, waits
+    for the user to dismiss it, and returns true if the user clicks OK
+    and false if the user clicks Cancel.

+
+    
A call to the navigator.yieldForStorageUpdates()
+    method is implied when this method is invoked.

+
+   

+
+   
result = window . prompt(message [, default] )

+   

+
+    
Displays a modal text field prompt with the given message,
+    waits for the user to dismiss it, and returns the value that the
+    user entered. If the user cancels the prompt, then returns null
+    instead. If the second argument is present, then the given value
+    is used as a default.

+
+    
A call to the navigator.yieldForStorageUpdates()
+    method is implied when this method is invoked.

+
+   

+
+  

+
+  
The alert(message) method, when invoked, must
+  release the storage mutex and show the given message to the user. The user agent may make the
+  method wait for the user to acknowledge the message before
+  returning; if so, the user agent must pause while the
+  method is waiting.

+
+  
The confirm(message) method, when invoked, must
+  release the storage mutex and show the given message to the user, and ask the user to respond with
+  a positive or negative response. The user agent must then
+  pause as the method waits for the user's response. If
+  the user responds positively, the method must return true, and if
+  the user responds negatively, the method must return false.

+
+  
The prompt(message, default)
+  method, when invoked, must release the storage mutex,
+  show the given message to the user, and ask the
+  user to either respond with a string value or abort. The user agent
+  must then pause as the method waits for the user's
+  response. The second argument is optional. If the second argument
+  (default) is present, then the response must be
+  defaulted to the value given by default. If the
+  user aborts, then the method must return null; otherwise, the method
+  must return the string that the user responded with.

+
+  

+
+
+  
7.3.2 Printing

+
+  
window . print()

+
+   

+
+    
Prompts the user to print the page.

+
+    
A call to the navigator.yieldForStorageUpdates()
+    method is implied when this method is invoked.

+
+   

+
+  

+
+  
The print() method,
+  when invoked, must run the printing steps.

+
+  
User agents should also run the printing steps
+  whenever the user asks for the opportunity to obtain a
+  physical form (e.g. printed copy), or the representation of a
+  physical form (e.g. PDF copy), of a document.

+
+  
The printing steps are as follows:

+
+  
  1. 
+
+    
    The user agent may display a message to the user and/or may
+    abort these steps.
    
+
+    
    For instance, a kiosk browser could silently
+    ignore any invocations of the print() method.
    
+
+    
    For instance, a browser on a mobile device
+    could detect that there are no printers in the vicinity and
+    display a message saying so before continuing to offer a "save to
+    PDF" option.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    The user agent must fire a simple event named
+    beforeprint at the
+    Window object of the Document that is
+    being printed, as well as any nested browsing contexts in it.
    
+
+    
    The beforeprint event can be used
+    to annotate the printed copy, for instance adding the time at
+    which the document was printed.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    The user agent must release the storage mutex.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    The user agent should offer the user the opportunity to
+    obtain a physical form (or the representation of a
+    physical form) of the document. The user agent may wait for the
+    user to either accept or decline before returning; if so, the user
+    agent must pause while the method is waiting. Even if
+    the user agent doesn't wait at this point, the user agent must use
+    the state of the relevant documents as they are at this point in
+    the algorithm if and when it eventually creates the alternate
+    form.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    The user agent must fire a simple event named
+    afterprint at the
+    Window object of the Document that is
+    being printed, as well as any nested browsing contexts in it.
    
+
+    
    The afterprint event can be used
+    to revert annotations added in the earlier event, as well as
+    showing post-printing UI. For instance, if a page is walking the
+    user through the steps of applying for a home loan, the script
+    could automatically advance to the next step after having printed
+    a form or other.
    
+
+   
    6. 
+
+  

+
+
+  
7.3.3 Dialogs implemented using separate documents

+
+  
result = window . showModalDialog(url [, argument] )

+
+   

+
+    
Prompts the user with the given page, waits for that page to
+    close, and returns the return value.

+
+    
A call to the navigator.yieldForStorageUpdates()
+    method is implied when this method is invoked.

+
+   

+
+  

+
+  
The showModalDialog(url, argument) method, when invoked, must
+  cause the user agent to run the following steps:

+
+  
  1. 
+
+    
    Resolve url relative to the entry script's
+    base URL.
    
+
+    
    If this fails, then throw a SYNTAX_ERR exception
+    and abort these steps.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Release the storage mutex.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If the user agent is configured such that this invocation of
+    showModalDialog() is
+    somehow disabled, then return the empty string and abort these
+    steps.
    
+
+    
    User agents are expected to disable this method in
+    certain cases to avoid user annoyance (e.g. as part of their popup
+    blocker feature). For instance, a user agent could require that a
+    site be white-listed before enabling this method, or the user
+    agent could be configured to only allow one modal dialog at a
+    time.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Let the list of background browsing
+    contexts be a list of all the browsing contexts that:
    
+
+    
    ...as well as any browsing contexts that are nested inside any
+    of the browsing contexts matching those conditions.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Disable the user interface for all the browsing contexts in
+    the list of background browsing contexts. This
+    should prevent the user from navigating those browsing contexts,
+    causing events to be sent to those browsing context, or editing
+    any content in those browsing contexts. However, it does not
+    prevent those browsing contexts from receiving events from sources
+    other than the user, from running scripts, from running
+    animations, and so forth.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Create a new auxiliary browsing context, with the
+    opener browsing context being the browsing context of
+    the Window object on which the showModalDialog() method was
+    called. The new auxiliary browsing context has no name.
    
+
+    
    This browsing context's
+    Documents' Window objects all implement
+    the WindowModal interface.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Let the dialog arguments of the new browsing
+    context be set to the value of argument, or
+    the 'undefined' value if the argument was omitted.
    
+
+   
    8. 
+
+   
  8. 
+
+    
    Let the dialog arguments' origin be the
+    origin of the script that called the showModalDialog() method.
    
+
+   
    9. 
+
+   
  9. 
+
+    
    Navigate the new browsing context to
+    the absolute URL that resulted from resolving url
+    earlier, with replacement enabled, and with the browsing context of the
+    script that invoked the method
+    as the source browsing context.
    
+
+   
    10. 
+
+   
  10. 
+
+    
    Spin the event loop until the new browsing
+    context is closed. (The user agent must allow the user to
+    indicate that the browsing context is to be
+    closed.)
    
+
+   
    11. 
+
+   
  11. 
+
+    
    Reenable the user interface for all the browsing contexts in
+    the list of background browsing contexts.
    
+
+   
    12. 
+
+   
  12. 
+
+    
    Return the auxiliary browsing context's
+    return value.
    
+
+   
    13. 
+
+  
The Window objects of Documents hosted
+  by browsing contexts created
+  by the above algorithm must all have the WindowModal
+  interface added to their Window interface:

+
+  

+
+  
[Supplemental, NoInterfaceObject] interface WindowModal {
+  readonly attribute any dialogArguments;
+           attribute DOMString returnValue;
+};

+
+  
window . dialogArguments

+
+   

+
+    
Returns the argument argument that was
+    passed to the showModalDialog() method.

+
+   

+
+   
window . returnValue [ = value ]

+
+   

+
+    
Returns the current return value for the window.

+
+    
Can be set, to change the value that will be returned by the
+    showModalDialog()
+    method.

+
+   

+
+  

+
+  
Such browsing contexts have associated dialog
+  arguments, which are stored along with the dialog
+  arguments' origin. These values are set by the showModalDialog() method in the
+  algorithm above, when the browsing context is created, based on the
+  arguments provided to the method.

+
+  
The dialogArguments
+  IDL attribute, on getting, must check whether its browsing context's
+  active document's origin is the same as the dialog arguments'
+  origin. If it is, then the browsing context's dialog
+  arguments must be returned unchanged. Otherwise, if the
+  dialog arguments are an object, then the empty string
+  must be returned, and if the dialog arguments are not
+  an object, then the stringification of the dialog
+  arguments must be returned.
+
+  
These browsing contexts also have an associated return
+  value. The return value of a browsing context
+  must be initialized to the empty string when the browsing context is
+  created.

+
+  
The returnValue
+  IDL attribute, on getting, must return the return value
+  of its browsing context, and on setting, must set the return
+  value to the given new value.

+
+  

+
+  
The window.close() method can be used to
+  close the browsing context.

+
+
+
+
+  
7.4 System state and capabilities

+
+  

+
+  
The navigator
+  attribute of the Window interface must return an
+  instance of the Navigator interface, which represents
+  the identity and state of the user agent (the client), and allows
+  Web pages to register themselves as potential protocol and content
+  handlers:

+
+  

+
+  
interface Navigator {
+  // objects implementing this interface also implement the interfaces given below
+};
+Navigator implements NavigatorID;
+Navigator implements NavigatorOnLine;
+Navigator implements NavigatorAbilities;
+
+[Supplemental, NoInterfaceObject]
+interface NavigatorID {
+  readonly attribute DOMString appName;
+  readonly attribute DOMString appVersion;
+  readonly attribute DOMString platform;
+  readonly attribute DOMString userAgent;
+};
+
+[Supplemental, NoInterfaceObject]
+interface NavigatorOnLine {
+  readonly attribute boolean onLine;
+};
+
+[Supplemental, NoInterfaceObject]
+interface NavigatorAbilities {
+  // content handler registration
+  void registerProtocolHandler(in DOMString scheme, in DOMString url, in DOMString title);
+  void registerContentHandler(in DOMString mimeType, in DOMString url, in DOMString title);
+  void yieldForStorageUpdates();
+};

+
+  

+
+  
These interfaces are defined separately so that other
+  specifications can re-use parts of the Navigator
+  interface.

+
+   
+
+   
+
+  

+
+
+  
7.4.1 Client identification

+
+  
In certain cases, despite the best efforts of the entire
+  industry, Web browsers have bugs and limitations that Web authors
+  are forced to work around.

+
+  
This section defines a collection of attributes that can be used
+  to determine, from script, the kind of user agent in use, in order
+  to work around these issues.

+
+  
Client detection should always be limited to detecting known
+  current versions; future versions and unknown versions should always
+  be assumed to be fully compliant.

+
+  
window . navigator . appName

+   

+    
Returns the name of the browser.

+   

+
+   
window . navigator . appVersion

+   

+    
Returns the version of the browser.

+   

+
+   
window . navigator . platform

+   

+    
Returns the name of the platform.

+   

+
+   
window . navigator . userAgent

+   

+    
Returns the complete User-Agent header.

+   

+
+  

+
+  
appName

+   
Must return either the string "Netscape" or the full name of the browser, e.g. "Mellblom Browsernator".

+
+   
appVersion

+   
Must return either the string "4.0" or a string representing the version of the browser in detail, e.g. "1.0 (VMS; en-US) Mellblomenator/9000".

+
+   
+
+   
+
+   
platform

+   
Must return either the empty string or a string representing the platform on which the browser is executing, e.g. "MacIntel", "Win32", "FreeBSD i386", "WebTV OS".

+
+   
+
+   
+
+   
+
+   
+
+   
userAgent

+   
Must return the string used for the value of the "User-Agent" header in HTTP requests, or the empty string if no such header is ever sent.

+
+   
+
+   
+
+  

+
+
+  
7.4.2 Custom scheme and content handlers

+
+  
The registerProtocolHandler()
+  method allows Web sites to register themselves as possible handlers
+  for particular schemes. For example, an online telephone messaging
+  service could register itself as a handler of the sms:
+  scheme ([RFC5724]), so that if the user
+  clicks on such a link, he is given the opportunity to use that Web
+  site. Analogously, the registerContentHandler()
+  method allows Web sites to register themselves as possible handlers
+  for content in a particular MIME type. For example, the
+  same online telephone messaging service could register itself as a
+  handler for text/directory files ([RFC2425]), so that if the user has no
+  native application capable of handling vCards ([RFC2426]), his Web browser can instead
+  suggest he use that site to view contact information stored on
+  vCards that he opens.

+
+  
window . navigator . registerProtocolHandler(scheme, url, title)

+   
window . navigator . registerContentHandler(mimeType, url, title)

+
+   

+
+    
Registers a handler for the given scheme or content type, at
+    the given URL, with the given title.

+
+    
The string "%s" in the URL is used as a
+    placeholder for where to put the URL of the content to be
+    handled.

+
+    
Throws a SECURITY_ERR exception if the user agent
+    blocks the registration (this might happen if trying to register
+    as a handler for "http", for instance).

+
+    
Throws a SYNTAX_ERR if the "%s" string is missing in the URL.

+
+   

+
+  

+
+  
User agents may, within the constraints described in this
+  section, do whatever they like when the methods are called. A UA
+  could, for instance, prompt the user and offer the user the
+  opportunity to add the site to a shortlist of handlers, or make the
+  handlers his default, or cancel the request. UAs could provide such
+  a UI through modal UI or through a non-modal transient notification
+  interface. UAs could also simply silently collect the information,
+  providing it only when relevant to the user.

+
+  
User agents should keep track of which sites have registered
+  handlers (even if the user has declined such registrations) so that
+  the user is not repeatedly prompted with the same request.

+
+  
The arguments to the methods have the following meanings and
+  corresponding implementation requirements:

+
+  
protocol (registerProtocolHandler() only)

+
+   

+
+    
A scheme, such as ftp or sms. The
+    scheme must be compared in an ASCII case-insensitive
+    manner by user agents for the purposes of comparing with the
+    scheme part of URLs that they consider against the list of
+    registered handlers.

+
+    
The scheme value, if it contains a colon
+    (as in "ftp:"), will never match anything, since
+    schemes don't contain colons.

+
+    
This feature is not intended to be used with
+    non-standard protocols.

+
+   

+
+   
mimeType (registerContentHandler() only)

+
+   

+
+    
A MIME type, such as
+    model/vnd.flatland.3dml or
+    application/vnd.google-earth.kml+xml. The MIME
+    type must be compared in an ASCII
+    case-insensitive manner by user agents for the purposes of
+    comparing with MIME types of documents that they consider against
+    the list of registered handlers.

+
+    
User agents must compare the given values only to the MIME
+    type/subtype parts of content types, not to the complete type
+    including parameters. Thus, if mimeType values
+    passed to this method include characters such as commas or
+    whitespace, or include MIME parameters, then the handler being
+    registered will never be used.

+
+    
The type is compared to the MIME type
+    used by the user agent after the sniffing algorithms have
+    been applied.

+
+   

+
+
+   
url

+
+   

+
+    
A string used to build the URL of the page that
+    will handle the requests.

+
+    
When the user agent uses this URL, it must replace the first
+    occurrence of the exact literal string "%s"
+    with an escaped version of the absolute URL of the
+    content in question (as defined below), then resolve the resulting URL, relative to the base URL of the entry
+    script at the time the registerContentHandler()
+    or registerProtocolHandler()
+    methods were invoked, and then navigate an
+    appropriate browsing context to the resulting URL
+    using the GET method (or
+    equivalent for non-HTTP URLs).

+
+    
To get the escaped version of the absolute URL of
+    the content in question, the user agent must replace every
+    character in that absolute URL that doesn't match the
+    <query> production defined in RFC 3986 by the
+    percent-encoded form of that character. [RFC3986]

+
+    

+
+     
If the user had visited a site at http://example.com/ that made the following
+     call:

+
+     
navigator.registerContentHandler('application/x-soup', 'soup?url=%s', 'SoupWeb™')

+
+     
...and then, much later, while visiting http://www.example.net/, clicked on a link such
+     as:

+
+     
<a href="chickenkïwi.soup">Download our Chicken Kïwi soup!</a>

+
+     
...then, assuming this chickenkïwi.soup file
+     was served with the MIME type
+     application/x-soup, the UA might navigate to the
+     following URL:

+
+     
http://example.com/soup?url=http://www.example.net/chickenk%C3%AFwi.soup

+
+     
This site could then fetch the chickenkïwi.soup
+     file and do whatever it is that it does with soup (synthesize it
+     and ship it to the user, or whatever).

+
+    

+
+   

+
+   
title

+
+   

+
+    
A descriptive title of the handler, which the UA might use to
+    remind the user what the site in question is.

+
+   

+
+  
User agents should raise SECURITY_ERR exceptions if
+  the methods are called with scheme or mimeType values that the UA deems to be
+  "privileged". For example, a site attempting to register a handler
+  for http URLs or text/html content in a
+  Web browser would likely cause an exception to be raised.

+
+  
User agents must raise a SYNTAX_ERR exception if the
+  url argument passed to one of these methods does
+  not contain the exact literal string "%s", or if resolving the url
+  argument with the first occurrence of the string "%s" removed, relative to the entry
+  script's base URL, is
+  not successful.

+
+  
User agents must not raise any other exceptions (other than
+  binding-specific exceptions, such as for an incorrect number of
+  arguments in an JavaScript implementation).

+
+  
This section does not define how the pages registered by these
+  methods are used, beyond the requirements on how to process the url value (see above). To some extent, the processing model for navigating across
+  documents defines some cases where these methods are
+  relevant, but in general UAs may use this information wherever they
+  would otherwise consider handing content to native plugins or helper
+  applications.

+
+  
UAs must not use registered content handlers to handle content
+  that was returned as part of a non-GET transaction (or rather, as
+  part of any non-idempotent transaction), as the remote site would
+  not be able to fetch the same data.

+
+  

+
+
+  

+
+  
7.4.2.1 Security and privacy

+
+  
These mechanisms can introduce a number of concerns, in
+  particular privacy concerns.

+
+  
Hijacking all Web usage. User agents should not
+  allow schemes that are key to its normal operation, such as
+  http or https, to be rerouted through
+  third-party sites. This would allow a user's activities to be
+  trivially tracked, and would allow user information, even in secure
+  connections, to be collected.

+
+  
Hijacking defaults. It is strongly recommended
+  that user agents do not automatically change any defaults, as this
+  could lead the user to send data to remote hosts that the user is
+  not expecting. New handlers registering themselves should never
+  automatically cause those sites to be used.

+
+  
Registration spamming. User agents should
+  consider the possibility that a site will attempt to register a
+  large number of handlers, possibly from multiple domains (e.g. by
+  redirecting through a series of pages each on a different domain,
+  and each registering a handler for video/mpeg —
+  analogous practices abusing other Web browser features have been
+  used by pornography Web sites for many years). User agents should
+  gracefully handle such hostile attempts, protecting the user.

+
+  
Misleading titles. User agents should not rely
+  wholly on the title argument to the methods when
+  presenting the registered handlers to the user, since sites could
+  easily lie. For example, a site hostile.example.net
+  could claim that it was registering the "Cuddly Bear Happy Content
+  Handler". User agents should therefore use the handler's domain in
+  any UI along with any title.

+
+  
Hostile handler metadata. User agents should
+  protect against typical attacks against strings embedded in their
+  interface, for example ensuring that markup or escape characters in
+  such strings are not executed, that null bytes are properly handled,
+  that over-long strings do not cause crashes or buffer overruns, and
+  so forth.

+
+  
Leaking Intranet URLs. The mechanism described
+  in this section can result in secret Intranet URLs being leaked, in
+  the following manner:

+
+  
  1. The user registers a third-party content handler as the default
+   handler for a content type.
    2. 
+
+   
  2. The user then browses his corporate Intranet site and accesses
+   a document that uses that content type.
    3. 
+
+   
  3. The user agent contacts the third party and hands the third
+   party the URL to the Intranet content.
    4. 
+
+  
No actual confidential file data is leaked in this manner, but
+  the URLs themselves could contain confidential information. For
+  example, the URL could be
+  http://www.corp.example.com/upcoming-aquisitions/the-sample-company.egf,
+  which might tell the third party that Example Corporation is
+  intending to merge with The Sample Company. Implementors might wish
+  to consider allowing administrators to disable this feature for
+  certain subdomains, content types, or schemes.

+
+  
Leaking secure URLs. User agents should not send
+  HTTPS URLs to third-party sites registered as content handlers, in
+  the same way that user agents do not send Referer (sic) HTTP headers from secure
+  sites to third-party sites.

+
+  
Leaking credentials. User agents must never send
+  username or password information in the URLs that are escaped and
+  included sent to the handler sites. User agents may even avoid
+  attempting to pass to Web-based handlers the URLs of resources
+  that are known to require authentication to access, as such sites
+  would be unable to access the resources in question without
+  prompting the user for credentials themselves (a practice that would
+  require the user to know whether to trust the third-party handler, a
+  decision many users are unable to make or even understand).

+
+  

+
+
+  

+
+  
7.4.2.2 Sample user interface

+
+  
This section is non-normative.

+
+  
A simple implementation of this feature for a desktop Web browser
+  might work as follows.

+
+  
The registerContentHandler()
+  method could display a modal dialog box:

+
+  
The modal dialog box could have the title 'Content Handler Registration', and could say 'This Web page: Kittens at work http://kittens.example.org/ ...would like permission to handle files of type: application/x-meowmeow using the following Web-based application: Kittens-at-work displayer http://kittens.example.org/?show=%s Do you trust the administrators of the "kittens.example.org" domain?' with two buttons, 'Trust kittens.example.org' and 'Cancel'.

+
+  
In this dialog box, "Kittens at work" is the title of the page
+  that invoked the method, "http://kittens.example.org/" is the URL of
+  that page, "application/x-meowmeow" is the string that was passed to
+  the registerContentHandler()
+  method as its first argument (mimeType),
+  "http://kittens.example.org/?show=%s" was the second argument (url), and "Kittens-at-work displayer" was the third
+  argument (title).

+
+  
If the user clicks the Cancel button, then nothing further
+  happens. If the user clicks the "Trust" button, then the handler is
+  remembered.

+
+  
When the user then attempts to fetch a URL that uses the
+  "application/x-meowmeow" MIME type, then it might
+  display a dialog as follows:

+
+  
The dialog box could have the title 'Unknown File Type' and could say 'You have attempted to access:' followed by a URL, followed by a prompt such as 'How would you like FerretBrowser to handle this resource?' with three radio buttons, one saying 'Contact the FerretBrowser plugin registry to see if there is an official way to handle this resource.', one saying 'Pass this URL to a local application' with an application selector, and one saying 'Pass this URL to the "Kittens-at-work displayer" application at "kittens.example.org"', with a checkbox labeld 'Always do this for resources using the "application/x-meowmeow" type in future.', and with two buttons, 'Ok' and 'Cancel'.

+
+  
In this dialog, the third option is the one that was primed by
+  the site registering itself earlier.

+
+  
If the user does select that option, then the browser, in
+  accordance with the requirements described in the previous two
+  sections, will redirect the user to
+  "http://kittens.example.org/?show=data%3Aapplication/x-meowmeow;base64,S2l0dGVucyBhcmUgdGhlIGN1dGVzdCE%253D".

+
+  
The registerProtocolHandler()
+  method would work equivalently, but for schemes instead of unknown
+  content types.

+
+  

+
+
+
+  
7.4.3 Manually releasing the storage mutex

+
+  
window . navigator . yieldForStorageUpdates()

+
+   

+
+    
If a script uses the document.cookie API, or the
+    localStorage API, the
+    browser will block other scripts from accessing cookies or storage
+    until the first script finishes.
+    
+    [WEBSTORAGE]
+    
+    

+
+    
Calling the navigator.yieldForStorageUpdates()
+    method tells the user agent to unblock any other scripts that may
+    be blocked, even though the script hasn't returned.

+
+    
Values of cookies and items in the Storage objects
+    of localStorage attributes
+    can change after calling this method, whence its name.
+    
+    [WEBSTORAGE]
+    
+    

+
+   

+
+  

+
+   
The yieldForStorageUpdates()
+   method, when invoked, must, if the storage mutex is
+   owned by the event loop of the task that resulted in the method being
+   called, release the storage mutex so that it is once
+   again free. Otherwise, it must do nothing.

+
+  

+
+
+
+
+  
8 User interaction

+
+
+  
8.1 The hidden attribute

+
+  
All HTML elements may have the hidden content attribute set. The hidden attribute is a boolean
+  attribute. When specified on an element, it indicates that
+  the element is not yet, or is no longer, relevant. User agents should not render elements that have the
+  hidden attribute
+  specified.

+
+  

+
+   
In the following skeletal example, the attribute is used to hide
+   the Web game's main screen until the user logs in:

+
+   
  <h1>The Example Game</h1>
+  <section id="login">
+   <h2>Login</h2>
+   <form>
+    ...
+    <!-- calls login() once the user's credentials have been checked -->
+   </form>
+   <script>
+    function login() {
+      // switch screens
+      document.getElementById('login').hidden = true;
+      document.getElementById('game').hidden = false;
+    }
+   </script>
+  </section>
+  <section id="game" hidden>
+   ...
+  </section>

+
+  

+
+  
The hidden attribute must not be
+  used to hide content that could legitimately be shown in another
+  presentation. For example, it is incorrect to use hidden to hide panels in a tabbed dialog,
+  because the tabbed interface is merely a kind of overflow
+  presentation — one could equally well just show all the form
+  controls in one big page with a scrollbar. It is similarly incorrect
+  to use this attribute to hide content just from one presentation
+  — if something is marked hidden, it is hidden from all
+  presentations, including, for instance, screen readers.

+
+  
+  
+
+  
Elements that are not hidden
+  should not link to or refer to elements that are hidden.

+
+  

+
+   
For example, it would be incorrect to use the href attribute to link to a
+   section marked with the hidden
+   attribute. If the content is not applicable or relevant, then there
+   is no reason to link to it.

+
+   
It would similarly be incorrect to use the ARIA aria-describedby attribute to
+   refer to descriptions that are themselves hidden. Hiding a section means that it
+   is not applicable or relevant to anyone at the current time, so
+   clearly it cannot be a valid description of content the user can
+   interact with.

+
+  

+
+  
Elements in a section hidden by the hidden attribute are still active,
+  e.g. scripts and form controls in such sections still execute
+  and submit respectively. Only their presentation to the user
+  changes.

+
+  

+
+  
The hidden IDL
+  attribute must reflect the content attribute of the
+  same name.

+
+  

+
+
+
+  
8.2 Activation

+
+  
+
+  
element . click()

+
+   

+
+    
Acts as if the element was clicked.

+
+   

+
+  

+
+  
Each element has a click in progress flag,
+  initially set to false.

+
+  
The click() method must
+  run these steps:

+
+  
  1. If the element's click in progress flag
+   is set to true, then abort these steps.
    2. 
+
+   
  2. Set the click in progress flag on the
+   element to true.
    3. 
+
+   
  3. If the element has a defined activation behavior,
+   run synthetic click activation steps on the
+   element. Otherwise, fire a click event at
+   the element.
    4. 
+
+   
  4. Set the click in progress flag on the
+   element to false.
    5. 
+
+  

+
+
+  
8.3 Scrolling elements into view
 
+
+  
element . scrollIntoView( [ top ] )

+
+   

+
+    
Scrolls the element into view. If the top
+    argument is true, then the element will be scrolled to the top of
+    the viewport, otherwise it'll be scrolled to the bottom. The
+    default is the top.

+
+   

+
+  

+
+  
The scrollIntoView([top]) method, when called, must cause
+  the element on which the method was called to have the attention of
+  the user called to it.

+
+  
In a speech browser, this could happen by having the
+  current playback position move to the start of the given
+  element.

+
+  
If the element in question cannot be brought to the user's
+  attention, e.g. because it is hidden, or is not being
+  rendered, then the user agent must do nothing instead.

+
+  
In visual user agents, if the argument is present and has the
+  value false, the user agent should scroll the element into view such
+  that both the bottom and the top of the element are in the viewport,
+  with the bottom of the element aligned with the bottom of the
+  viewport. If it isn't possible to show the entire element in that
+  way, or if the argument is omitted or is true, then the user agent
+  should instead align the top of the element with the top of the
+  viewport. If the entire scrollable part of the content is visible
+  all at once (e.g. if a page is shorter than the viewport), then the
+  user agent should not scroll anything. Visual user agents should
+  further scroll horizontally as necessary to bring the element to the
+  attention of the user.

+
+  
Non-visual user agents may ignore the argument, or may treat it
+  in some media-specific manner most useful to the user.

+
+  

+
+
+  
8.4 Focus

+
+  
+
+  
+
+  
+
+  
+
+  
+
+  

+
+  
When an element is focused, key events received by the
+  document must be targeted at that element. There may be no element
+  focused; when no element is focused, key events received by the
+  document must be targeted at the body element.

+
+  
User agents may track focus for each browsing
+  context or Document individually, or may support
+  only one focused element per top-level browsing context
+  — user agents should follow platform conventions in this
+  regard.

+
+  
Which elements within a top-level browsing context
+  currently have focus must be independent of whether or not the
+  top-level browsing context itself has the system
+  focus.

+
+  
When an element is focused, the element matches the
+  CSS :focus pseudo-class.

+
+  

+
+
+  
8.4.1 Sequential focus navigation

+
+  
The tabindex
+  content attribute specifies whether the element is focusable,
+  whether it can be reached using sequential focus navigation, and the
+  relative order of the element for the purposes of sequential focus
+  navigation. The name "tab index" comes from the common use of the
+  "tab" key to navigate through the focusable elements. The term
+  "tabbing" refers to moving forward through the focusable elements
+  that can be reached using sequential focus navigation.

+
+  
The tabindex attribute, if
+  specified, must have a value that is a valid
+  integer.

+
+  

+
+  
If the attribute is specified, it must be parsed using the
+  rules for parsing integers. The attribute's values have
+  the following meanings:

+
+  
If the attribute is omitted or parsing the value returns an
+   error

+
+   

+
+    
The user agent should follow platform conventions to determine if
+    the element is to be focusable and, if so, whether the element can
+    be reached using sequential focus navigation, and if so, what its
+    relative order should be.

+
+   

+
+   
If the value is a negative integer

+
+   

+
+    
The user agent must allow the element to be focused, but should
+    not allow the element to be reached using sequential focus
+    navigation.

+
+   

+
+   
If the value is a zero

+
+   

+
+    
The user agent must allow the element to be focused, should
+    allow the element to be reached using sequential focus navigation,
+    and should follow platform conventions to determine the element's
+    relative order.

+
+   

+
+   
If the value is greater than zero

+
+   

+
+    
The user agent must allow the element to be focused, should
+    allow the element to be reached using sequential focus navigation,
+    and should place the element in the sequential focus navigation
+    order so that it is:

+
+    
  • before any focusable element whose tabindex attribute has been
+     omitted or whose value, when parsed, returns an error,
    • 
+
+     
  • before any focusable element whose tabindex attribute has a value equal
+     to or less than zero,
    • 
+
+     
  • after any element whose tabindex attribute has a value
+     greater than zero but less than the value of the tabindex attribute on the
+     element,
    • 
+
+     
  • after any element whose tabindex attribute has a value equal
+     to the value of the tabindex
+     attribute on the element but that is earlier in the document in
+     tree order than the element,
    • 
+
+     
  • before any element whose tabindex attribute has a value equal
+     to the value of the tabindex
+     attribute on the element but that is later in the document in
+     tree order than the element, and
    • 
+
+     
  • before any element whose tabindex attribute has a value
+     greater than the value of the tabindex attribute on the
+     element.
    • 
+
+    

+
+  
An element is specially focusable if the tabindex attribute's definition above
+  defines the element to be focusable.

+
+  
An element that is specially focusable but does not
+  otherwise have an activation behavior defined has an
+  activation behavior that does nothing.

+
+  
This means that an element that is only focusable
+  because of its tabindex attribute
+  will fire a click event in response
+  to a non-mouse activation (e.g. hitting the "enter" key while the
+  element is focused).

+
+  
The tabIndex IDL
+  attribute must reflect the value of the tabindex content attribute. If the
+  attribute is not present, or parsing its value returns an error,
+  then the IDL attribute must return 0 for elements that are focusable
+  and −1 for elements that are not focusable.

+
+  

+
+
+
+  

+
+  
8.4.2 Focus management

+
+  
An element is focusable if the user agent's default
+  behavior allows it to be focusable or if the element is
+  specially focusable, but only if the element is either
+  being rendered or  is a
+  descendant of a canvas element that
+  represents embedded content.

+
+  
User agents should make the following elements
+  focusable, unless platform conventions dictate
+  otherwise:

+
+  
  • a elements that have an href attribute
    • 
+
+   
  • link elements that have an href attribute
    • 
+
+   
  • button elements that are not disabled
    • 
+
+   
  • input elements whose type attribute are not in the
+   Hidden state and that
+   are not disabled
    • 
+
+   
  • select elements that are not disabled
    • 
+
+   
  • textarea elements that are not disabled
    • 
+
+   
  • command elements that do not have a disabled attribute
    • 
+
+   
  • Elements with a draggable
+   attribute set, if that would enable the user agent to allow the
+   user to begin a drag operations for those elements without the use
+   of a pointing device
    • 
+
+  
In addition, each shape that is generated for an
+  area element should be focusable, unless
+  platform conventions dictate otherwise. (A single area
+  element can correspond to multiple shapes, since image maps can be
+  reused with multiple images on a page.)

+
+  
The focusing steps are as follows:

+
+  
  1. If focusing the element will remove the focus from another
+   element, then run the unfocusing steps for that
+   element.
    2. 
+
+   
  2. 
+
+    
    Make the element the currently focused element in its
+    top-level browsing context.
    
+
+    
    Some elements, most notably area, can correspond
+    to more than one distinct focusable area. If a particular area was
+    indicated when the element was focused, then that is the area that
+    must get focus; otherwise, e.g. when using the focus() method, the first such region in
+    tree order is the one that must be focused.
    
+
+   
    3. 
+
+   
  3. Fire a simple event named focus at the element.
    4. 
+
+  
User agents must synchronously run the focusing
+  steps for an element whenever the user moves the focus to a
+  focusable element.

+
+  
The unfocusing steps are as follows:

+
+  
  1. If the element is an input element, and the
+   change event applies to the
+   element, and the element does not have a defined activation
+   behavior, and the user has changed the element's value or its list of selected files
+   while the control was focused without committing that change, then
+   fire a simple event that bubbles named change at the element, then
+   broadcast formchange
+   events at the element's form owner.
    
+
+   
  2. Unfocus the element.
    3. 
+
+   
  3. Fire a simple event named blur at the element.
    4. 
+
+  
When an element that is focused stops being a
+  focusable element, or stops being focused without
+  another element being explicitly focused in its stead, the user
+  agent should synchronously run the focusing steps for
+  the body element, if there is one; if there is not,
+  then the user agent should synchronously run the unfocusing
+  steps for the affected element only.

+
+  
For example, this might happen because the
+  element is removed from its Document, or has a hidden attribute added. It would also
+  happen to an input element when the element gets disabled.

+
+  

+
+
+  
8.4.3 Document-level focus APIs

+
+  
document . activeElement

+
+   

+
+    
Returns the currently focused element.

+
+   

+
+   
document . hasFocus()

+
+   

+
+    
Returns true if the document has focus; otherwise, returns false.

+
+   

+
+   
window . focus()

+
+   

+
+    
Focuses the window. Use of this method is discouraged. Allow the user to control window focus instead.

+
+   

+
+   
window . blur()

+
+   

+
+    
Unfocuses the window. Use of this method is discouraged. Allow the user to control window focus instead.

+
+   

+
+  

+
+  
The activeElement
+  attribute on HTMLDocument objects must return the
+  element in the document that is focused. If no element in the
+  Document is focused, this must return the body
+  element.

+
+  
The hasFocus() method
+  on HTMLDocument objects must return true if the
+  document's browsing context is focused, and all its
+  ancestor browsing
+  contexts are also focused, and the top-level browsing
+  context has the system focus.

+
+  
The focus()
+  method on the Window object, when invoked, provides a
+  hint to the user agent that the script believes the user might be
+  interested in the contents of the browsing context of
+  the Window object on which the method was invoked.

+
+  
User agents are encouraged to have this focus() method trigger some kind of
+  notification.

+
+  
The blur() method
+  on the Window object, when invoked, provides a hint to
+  the user agent that the script believes the user probably is not
+  currently interested in the contents of the browsing
+  context of the Window object on which the method
+  was invoked, but that the contents might become interesting again in
+  the future.

+
+  
User agents are encouraged to ignore calls to this blur() method entirely.

+
+  
Historically the focus() and blur() methods actually affected the
+  system focus, but hostile sites widely abuse this behavior to the
+  user's detriment.

+
+  

+
+
+  
8.4.4 Element-level focus APIs

+
+  
element . focus()

+
+   

+
+    
Focuses the element.

+
+   

+
+   
element . blur()

+
+   

+
+    
Unfocuses the element. Use of this method is discouraged. Focus
+    another element instead.

+
+    
Do not use this method to hide the focus ring if you find the
+    focus ring unsightly. Instead, use a CSS rule to override the
+    'outline' property.

+
+    

+
+     
For example, to hide the outline from links, you could use:

+
+     
:link:focus, :visited:focus { outline: none; }

+
+    

+
+   

+
+  

+
+  
The focus() method,
+  when invoked, must run the following algorithm:

+
+  
  1. If the element is marked as locked for focus, then abort
+   these steps.
    2. 
+
+   
  2. If the element is not focusable, then abort these
+   steps.
    3. 
+
+   
  3. Mark the element as locked for focus.
    4. 
+
+   
  4. If the element is not already focused, run the focusing
+   steps for the element.
    5. 
+
+   
  5. Unmark the element as locked for focus.
    6. 
+
+  
The blur() method, when
+  invoked, should run the focusing steps for the
+  body element, if there is one; if there is not, then it
+  should run the unfocusing steps for the element on
+  which the method was called instead. User agents may selectively or
+  uniformly ignore calls to this method for usability reasons.

+
+  
For example, if the blur() method is unwisely being used to
+  remove the focus ring for aesthetics reasons, the page would become
+  unusable by keyboard users. Ignoring calls to this method would thus
+  allow keyboard users to interact with the page.

+
+  

+
+
+
+
+  
8.5 The accesskey attribute

+
+  
All HTML elements may have the accesskey content attribute set. The
+  accesskey attribute's value is
+  used by the user agent as a guide for creating a keyboard shortcut
+  that activates or focuses the element.

+
+  
If specified, the value must be an ordered set of unique
+  space-separated tokens, each of which must be exactly one
+  Unicode code point in length.

+
+  

+
+  
An element's assigned access key is a key combination
+  derived from the element's accesskey content attribute as
+  follows:

+
+  
  1. If the element has no accesskey attribute, then skip to the
+   fallback step below.
    2. 
+
+   
  2. Otherwise, the user agent must split the attribute's value on spaces, and let
+   keys be the resulting tokens.
    3. 
+
+   
  3. 
+
+    
    For each value in keys in turn, in the
+    order the tokens appeared in the attribute's value, run the
+    following substeps:
    
+
+    
    1. If the value is not a string exactly one Unicode code
+     point in length, then skip the remainder of these steps for this
+     value.
      2. 
+
+     
    2. If the value does not correspond to a key on the system's
+     keyboard, then skip the remainder of these steps for this
+     value.
      3. 
+
+     
    3. If the user agent can find a combination of modifier keys
+     that, with the key that corresponds to the value given in the
+     attribute, can be used as a shortcut key, then the user agent may
+     assign that combination of keys as the element's assigned
+     access key and abort these steps.
      4. 
+
+    
    4. 
+
+   
  4. Fallback: Optionally, the user agent may assign a key
+   combination of its choosing as the element's assigned access
+   key and then abort these steps.
    5. 
+
+   
  5. If this step is reached, the element has no assigned
+   access key.
    6. 
+
+  
Once a user agent has selected and assigned an access key for an
+  element, the user agent should not change the element's
+  assigned access key unless the accesskey content attribute is changed
+  or the element is moved to another Document.

+
+  
When the user presses the key combination corresponding to the
+  assigned access key for an element, if the element
+  defines a command, and the
+  command's Hidden
+  State facet is false (visible), and the command's Disabled State facet is
+  also false (enabled), then the user agent must trigger the Action of the command.

+
+  
User agents may expose elements that have an accesskey attribute in other ways as
+  well, e.g. in a menu displayed in response to a specific key
+  combination.

+
+  

+
+  

+
+  
The accessKey IDL
+  attribute must reflect the accesskey content attribute.

+
+  
The accessKeyLabel IDL
+  attribute must return a string that represents the element's
+  assigned access key, if any. If the element does not
+  have one, then the IDL attribute must return the empty string.

+
+  

+
+  

+
+   
In the following example, a variety of links are given with
+   access keys so that keyboard users familiar with the site can
+   more quickly navigate to the relevant pages:

+
+   
<nav>
+ <p>
+  <a title="Consortium Activities" accesskey="A" href="/Consortium/activities">Activities</a> |
+  <a title="Technical Reports and Recommendations" accesskey="T" href="/TR/">Technical Reports</a> |
+  <a title="Alphabetical Site Index" accesskey="S" href="/Consortium/siteindex">Site Index</a> |
+  <a title="About This Site" accesskey="B" href="/Consortium/">About Consortium</a> |
+  <a title="Contact Consortium" accesskey="C" href="/Consortium/contact">Contact</a>
+ </p>
+</nav>

+
+  

+
+  

+
+   
In the following example, the search field is given two possible
+   access keys, "s" and "0" (in that order). A user agent on a device
+   with a full keyboard might pick
+   Ctrl+Alt+S as the
+   shortcut key, while a user agent on a small device with just a
+   numeric keypad might pick just the plain unadorned key
+   0:

+
+   
<form action="/search">
+ <label>Search: <input type="search" name="q" accesskey="s 0"></label>
+ <input type="submit">
+</form>

+
+  

+
+  

+
+   
In the following example, a button has possible access keys
+   described. A script then tries to update the button's label to
+   advertise the key combination the user agent selected.

+
+   
<input type=submit accesskey="N @ 1" value="Compose">
+...
+<script>
+ function labelButton(button) {
+   if (button.accessKeyLabel)
+     button.value += ' (' + button.accessKeyLabel + ')';
+ }
+ var inputs = document.getElementsByTagName('input');
+ for (var i = 0; i < inputs.length; i += 1) {
+   if (inputs[i].type == "submit")
+     labelButton(inputs[i]);
+ }
+</script>

+
+   
On one user agent, the button's label might become
+   "Compose (⌘N)". On another, it might become
+   "Compose (Alt+⇧+1)". If the user agent doesn't
+   assign a key, it will be just "Compose". The exact
+   string depends on what the assigned access key is, and
+   on how the user agent represents that key combination.

+
+  

+
+
+
+  
8.6 The text selection APIs

+
+  
Every browsing context has a selection. The selection can be empty, and the
+  selection can have more than one range (a disjointed selection). The
+  user agent should allow the user to change the selection. User
+  agents are not required to let the user select more than one range,
+  and may collapse multiple ranges in the selection to a single range
+  when the user interacts with the selection. (But, of course, the
+  user agent may let the user create selections with multiple
+  ranges.)

+
+  
This one selection must be shared by all the content of the
+  browsing context (though not by nested browsing contexts), including any editing hosts in
+  the document. (Editing hosts that are not inside a document cannot
+  have a selection.)

+
+  

+
+  
If the selection is empty (collapsed, so that it has only one
+  segment and that segment's start and end points are the same) then
+  the selection's position should equal the caret position. When the
+  selection is not empty, this specification does not define the caret
+  position; user agents should follow platform conventions in deciding
+  whether the caret is at the start of the selection, the end of the
+  selection, or somewhere else.

+
+  
On some platforms (such as those using Wordstar editing
+  conventions), the caret position is totally independent of the start
+  and end of the selection, even when the selection is empty. On such
+  platforms, user agents may ignore the requirement that the cursor
+  position be linked to the position of the selection altogether.

+
+  

+
+  
Mostly for historical reasons, in addition to the browsing
+  context's selection, each
+  textarea and input element has an
+  independent selection. These are the text field selections.

+
+  

+
+  
User agents may selectively ignore attempts to use the API to
+  adjust the selection made after the user has modified the
+  selection. For example, if the user has just selected part of a
+  word, the user agent could ignore attempts to use the API call to
+  immediately unselect the selection altogether, but could allow
+  attempts to change the selection to select the entire word.

+
+  
User agents may also allow the user to create selections that are
+  not exposed to the API.

+
+  

+
+  
+  
The select element also has a selection, indicating
+  which items have been picked by the user. This is not discussed in
+  this section.

+
+  
This specification does not specify how selections
+  are presented to the user. 

+
+
+
+  
8.6.1 APIs for the browsing context selection

+
+  
window . getSelection()

+   
document . getSelection()

+
+   

+
+    
Returns the Selection object for the window, which
+    stringifies to the text of the current selection.

+
+   

+
+  

+
+  
The getSelection() method on
+  the Window interface must return the
+  Selection object representing the
+  selection of that Window object's
+  browsing context.
+
+  
For historical reasons, the getSelection()
+  method on the HTMLDocument interface must return the
+  same Selection object.

+
+  

+
+  
interface Selection {
+  readonly attribute Node anchorNode;
+  readonly attribute long anchorOffset;
+  readonly attribute Node focusNode;
+  readonly attribute long focusOffset;
+  readonly attribute boolean isCollapsed;
+  void collapse(in Node parentNode, in long offset);
+  void collapseToStart();
+  void collapseToEnd();
+  void selectAllChildren(in Node parentNode);
+  void deleteFromDocument();
+  readonly attribute long rangeCount;
+  Range getRangeAt(in long index);
+  void addRange(in Range range);
+  void removeRange(in Range range);
+  void removeAllRanges();
+  stringifier DOMString ();
+};

+
+
+  
The Selection interface represents a list of
+  Range objects. The first item in the list has index 0,
+  and the last item has index count-1, where count is the number of ranges in the list. [DOMRANGE]

+
+  
All of the members of the Selection interface are
+  defined in terms of operations on the Range objects
+  represented by this object. These operations can raise exceptions,
+  as defined for the Range interface; this can therefore
+  result in the members of the Selection interface
+  raising exceptions as well, in addition to any explicitly called out
+  below.

+
+  
selection . anchorNode

+
+   

+
+    
Returns the element that contains the start of the selection.

+
+    
Returns null if there's no selection.

+
+   

+
+   
selection . anchorOffset

+
+   

+
+    
Returns the offset of the start of the selection relative to the element that contains the start of the selection.

+
+    
Returns 0 if there's no selection.

+
+   

+
+   
selection . focusNode

+
+   

+
+    
Returns the element that contains the end of the selection.

+
+    
Returns null if there's no selection.

+
+   

+
+   
selection . focusOffset

+
+   

+
+    
Returns the offset of the end of the selection relative to the element that contains the end of the selection.

+
+    
Returns 0 if there's no selection.

+
+   

+
+   
collapsed = selection . isCollapsed()

+
+   

+
+    
Returns true if there's no selection or if the selection is empty. Otherwise, returns false.

+
+   

+
+   
selection . collapse(parentNode, offset)

+
+   

+
+    
Replaces the selection with an empty one at the given position.

+
+    
Throws a WRONG_DOCUMENT_ERR exception if the given node is in a different document.

+
+   

+
+   
selection . collapseToStart()

+
+   

+
+    
Replaces the selection with an empty one at the position of the start of the current selection.

+
+    
Throws an INVALID_STATE_ERR exception if there is no selection.

+
+   

+
+   
selection . collapseToEnd()

+
+   

+
+    
Replaces the selection with an empty one at the position of the end of the current selection.

+
+    
Throws an INVALID_STATE_ERR exception if there is no selection.

+
+   

+
+   
selection . selectAllChildren(parentNode)

+
+   

+
+    
Replaces the selection with one that contains all the contents of the given element.

+
+    
Throws a WRONG_DOCUMENT_ERR exception if the given node is in a different document.

+
+   

+
+   
selection . deleteFromDocument()

+
+   

+
+    
Deletes the selection.

+
+   

+
+   
selection . rangeCount

+
+   

+
+    
Returns the number of ranges in the selection.

+
+   

+
+   
selection . getRangeAt(index)

+
+   

+
+    
Returns the given range.

+
+    
Throws an INDEX_SIZE_ERR exception if the value is out of range.

+
+   

+
+   
selection . addRange(range)

+
+   

+
+    
Adds the given range to the selection.

+
+   

+
+   
selection . removeRange(range)

+
+   

+
+    
Removes the given range from the selection, if the range was one of the ones in the selection.

+
+   

+
+   
selection . removeAllRanges()

+
+   

+
+    
Removes all the ranges in the selection.

+
+   

+
+  

+
+  
The anchorNode
+  attribute must return the value returned by the startContainer attribute of the last
+  Range object in the list, or null if the list is
+  empty.

+
+  
The anchorOffset
+  attribute must return the value returned by the startOffset attribute of the last Range
+  object in the list, or 0 if the list is empty.

+
+  
The focusNode
+  attribute must return the value returned by the endContainer attribute of the last
+  Range object in the list, or null if the list is
+  empty.

+
+  
The focusOffset
+  attribute must return the value returned by the endOffset attribute of the last Range
+  object in the list, or 0 if the list is empty.

+
+  
The isCollapsed
+  attribute must return true if there are zero ranges, or if there is
+  exactly one range and its collapsed attribute
+  is itself true. Otherwise it must return false.

+
+  
The collapse(parentNode, offset)
+  method must raise a WRONG_DOCUMENT_ERR DOM exception if
+  parentNode's Document is not the
+  HTMLDocument object with which the
+  Selection object is associated. Otherwise it is, and
+  the method must remove all the ranges in the Selection
+  list, then create a new Range object, add it to the
+  list, and invoke its setStart() and setEnd() methods with the parentNode and offset values as
+  their arguments.

+
+  
The collapseToStart()
+  method must raise an INVALID_STATE_ERR DOM exception if
+  there are no ranges in the list. Otherwise, it must invoke the collapse() method with the
+  startContainer and startOffset values of the first Range
+  object in the list as the arguments.

+
+  
The collapseToEnd()
+  method must raise an INVALID_STATE_ERR DOM exception if
+  there are no ranges in the list. Otherwise, it must invoke the collapse() method with the
+  endContainer and endOffset values of the last Range
+  object in the list as the arguments.

+
+  
The selectAllChildren(parentNode)
+  method must invoke the collapse() method with the
+  parentNode value as the first argument and 0 as the
+  second argument, and must then invoke the selectNodeContents() method on the first (and only)
+  range in the list with the parentNode value as the
+  argument.

+
+  
The deleteFromDocument()
+  method must invoke the deleteContents() method
+  on each range in the list, if any, from first to last.

+
+  
The rangeCount
+  attribute must return the number of ranges in the list.

+
+  
The getRangeAt(index)
+  method must return the indexth range in the list. If
+  index is less than zero or greater or equal to the value
+  returned by the rangeCount attribute, then
+  the method must raise an INDEX_SIZE_ERR DOM
+  exception.

+
+  
The addRange(range)
+  method must add the given range Range object to the list
+  of selections, at the end (so the newly added range is the new last
+  range). Duplicates are not prevented; a range may be added more than
+  once in which case it appears in the list more than once, which (for
+  example) will cause stringification to return the
+  range's text twice.

+
+  
The removeRange(range)
+  method must remove the first occurrence of range in the
+  list of ranges, if it appears at all.

+
+  
The removeAllRanges()
+  method must remove all the ranges from the list of ranges, such that
+  the rangeCount
+  attribute returns 0 after the removeAllRanges()
+  method is invoked (and until a new range is added to the list,
+  either through this interface or via user interaction).

+
+  
Objects implementing this interface must stringify to a concatenation
+  of the results of invoking the toString()
+  method of the Range object on each of the ranges of the
+  selection, in the order they appear in the list (first to last).

+
+  

+
+  

+   
In the following document fragment, the emphasized parts
+   indicate the selection.

+   
<p>The cute girl likes the <cite>Oxford English Dictionary</cite>.</p>

+   
If a script invoked window.getSelection().toString(), the return value
+   would be "the Oxford English".

+  

+
+  
+
+
+  
8.6.2 APIs for the text field selections

+
+  
+
+  
The input and textarea elements define
+  the following members in their DOM interfaces for handling their
+  text selection:

+
+  
  void select();
+           attribute unsigned long selectionStart;
+           attribute unsigned long selectionEnd;
+  void setSelectionRange(in unsigned long start, in unsigned long end);

+  
+
+  
These methods and attributes expose and control the selection of
+  input and textarea text fields.

+
+  
element . select()

+
+   

+
+    
Selects everything in the text field.

+
+   

+
+   
element . selectionStart [ = value ]

+
+   

+
+    
Returns the offset to the start of the selection.

+
+    
Can be set, to change the start of the selection.

+
+   

+
+   
element . selectionEnd [ = value ]

+
+   

+
+    
Returns the offset to the end of the selection.

+
+    
Can be set, to change the end of the selection.

+
+   

+
+   
element . setSelectionRange(start, end)

+
+   

+
+    
Changes the selection to cover the given substring.

+
+   

+
+  

+
+  
When these methods and attributes are used with
+  input elements while they don't apply, they must raise
+  an INVALID_STATE_ERR exception. Otherwise, they must
+  act as described below.

+
+  
The select() method
+  must cause the contents of the text field to be fully selected.

+
+  
The selectionStart
+  attribute must, on getting, return the offset (in logical order) to
+  the character that immediately follows the start of the
+  selection. If there is no selection, then it must return the offset
+  (in logical order) to the character that immediately follows the
+  text entry cursor.

+
+  
On setting, it must act as if the setSelectionRange()
+  method had been called, with the new value as the first argument,
+  and the current value of the selectionEnd
+  attribute as the second argument, unless the current value of the
+  selectionEnd is
+  less than the new value, in which case the second argument must also
+  be the new value.

+
+  
The selectionEnd
+  attribute must, on getting, return the offset (in logical order) to
+  the character that immediately follows the end of the selection. If
+  there is no selection, then it must return the offset (in logical
+  order) to the character that immediately follows the text entry
+  cursor.

+
+  
On setting, it must act as if the setSelectionRange()
+  method had been called, with the current value of the selectionStart
+  attribute as the first argument, and new value as the second
+  argument.

+
+  
The setSelectionRange(start, end) method
+  must set the selection of the text field to the sequence of
+  characters starting with the character at the startth position (in logical order) and ending with
+  the character at the (end-1)th position. Arguments greater than the
+  length of the value in the text field must be treated as pointing at
+  the end of the text field. If end is less than
+  or equal to start then the start of the
+  selection and the end of the selection must both be placed
+  immediately before the character with offset end. In UAs where there is no concept of an empty
+  selection, this must set the cursor to be just before the character
+  with offset end.

+
+  

+
+  

+
+   
To obtain the currently selected text, the following JavaScript
+   suffices:

+
+   
var selectionText = control.value.substring(control.selectionStart, control.selectionEnd);

+
+   
...where control is the input
+   or textarea element.

+
+  

+
+  
Characters with no visible rendering, such as U+200D ZERO WIDTH
+  JOINER, still count as characters. Thus, for instance, the selection
+  can include just an invisible character, and the text insertion
+  cursor can be placed to one side or another of such a character.

+
+
+
+  
8.7 The contenteditable attribute

+
+  
The contenteditable
+  attribute is an enumerated attribute whose keywords are
+  the empty string, true, and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In
+  addition, there is a third state, the inherit state, which is
+  the missing value default (and the invalid value
+  default).

+
+  
The true state indicates that the element is editable. The
+  inherit state indicates that the element is editable if its
+  parent is. The false state indicates that the element is not
+  editable.

+
+  

+
+  
Specifically, if an HTML
+  element has a contenteditable attribute set to
+  the true state, or it has its contenteditable attribute set to
+  the inherit state and if its nearest ancestor HTML element with the contenteditable attribute set to
+  a state other than the inherit state has its attribute set to the
+  true state, or if it and its ancestors all have their contenteditable attribute set to
+  the inherit state but the Document has designMode enabled, then the
+  UA must treat the element as editable (as described
+  below).

+
+  
Otherwise, either the HTML
+  element has a contenteditable attribute set to
+  the false state, or its contenteditable attribute is set
+  to the inherit state and its nearest ancestor HTML element with the contenteditable attribute set to
+  a state other than the inherit state has its attribute set to the
+  false state, or all its ancestors have their contenteditable attribute set to
+  the inherit state and the Document itself has designMode disabled; either
+  way, the element is not editable.

+
+  

+
+  
element . contentEditable [ = value ]

+
+   

+
+    
Returns "true", "false", or "inherit", based
+    on the state of the contenteditable attribute.

+
+    
Can be set, to change that state.

+
+    
Throws a SYNTAX_ERR exception if the new value
+    isn't one of those strings.

+
+   

+
+   
element . isContentEditable

+
+   

+
+    
Returns true if the element is editable; otherwise, returns false.

+
+   

+
+  

+
+  
The contentEditable IDL
+  attribute, on getting, must return the string "true" if the content attribute is set to the true
+  state, false" if the content attribute is set
+  to the false state, and "inherit"
+  otherwise. On setting, if the new value is an ASCII
+  case-insensitive match for the string "inherit" then the content attribute must be removed,
+  if the new value is an ASCII case-insensitive match for
+  the string "true" then the content attribute
+  must be set to the string "true", if the new
+  value is an ASCII case-insensitive match for the string
+  "false" then the content attribute must be set
+  to the string "false", and otherwise the
+  attribute setter must raise a SYNTAX_ERR exception.

+
+  
The isContentEditable
+  IDL attribute, on getting, must return true if the element is
+  editable, and false otherwise.

+
+  
If an element is editable and its parent element is
+  not, or if an element is editable and it has no parent
+  element, then the element is an editing host. Editable
+  elements can be nested. User agents must make editing hosts
+  focusable (which typically means they enter the tab order). An editing host can contain
+  non-editable sections, these are handled as described below. An
+  editing host can contain non-editable sections that contain further
+  editing hosts.

+
+  
When an editing host has focus, it must have a caret
+  position that specifies where the current editing position
+  is. It may also have a selection.

+
+  
How the caret and selection are represented depends
+  entirely on the UA.

+
+  
+
+  

+
+
+  

+
+  
8.7.1 User editing actions

+
+  
There are several actions that the user agent should allow the
+  user to perform while the user is interacting with an editing
+  host. How exactly each action is triggered is not defined for every
+  action, but when it is not defined, suggested key bindings are
+  provided to guide implementors.

+
+  
Move the caret

+
+   
User agents must allow users to move the caret to any
+   position within an editing host, even into nested editable
+   elements. This could be triggered as the default action of keydown events with various key
+   identifiers and as the default action of mousedown events.

+
+
+   
Change the selection

+
+   
User agents must allow users to change the
+   selection within an editing host, even into nested editable
+   elements. User agents may prevent selections from being made in
+   ways that cross from editable elements into non-editable elements
+   (e.g. by making each non-editable descendant atomically selectable,
+   but not allowing text selection within them). This could be
+   triggered as the default action of keydown events with various key
+   identifiers and as the default action of mousedown events.

+
+
+   
Insert text

+
+   
This action must be triggered as the default action of a
+   textInput event, and may be
+   triggered by other commands as well. It must cause the user agent
+   to insert the specified text (given by the event object's data attribute in the case of the textInput event) at the caret.

+
+   
If the caret is positioned somewhere where phrasing
+   content is not allowed (e.g. inside an empty ol
+   element), then the user agent must not insert the text directly at
+   the caret position. In such cases the behavior is UA-dependent,
+   but user agents must not, in response to a request to insert text,
+   generate a DOM that is less conformant than the DOM prior to the
+   request.

+
+   
User agents should allow users to insert new paragraphs into
+   elements that contains only content other than paragraphs.

+
+   

+    
For example, given the markup:

+    
<section>
+ <dl>
+  <dt> Ben </dt>
+  <dd> Goat </dd>
+ </dl>
+</section>

+    
...the user agent should allow the user to insert
+    p elements before and after the dl
+    element, as children of the section element.

+   

+
+   

+
+
+   
Break block

+
+   
UAs should offer a way for the user to request that the
+   current paragraph be broken at the caret, e.g. as the default
+   action of a keydown event whose
+   identifier is the "Enter" key and that has no modifiers set.

+
+   
The exact behavior is UA-dependent, but user agents must not,
+   in response to a request to break a paragraph, generate a DOM that
+   is less conformant than the DOM prior to the request.

+
+
+   
Insert a line separator

+
+   
UAs should offer a way for the user to request an explicit
+   line break at the caret position without breaking the paragraph,
+   e.g. as the default action of a keydown event whose identifier is the
+   "Enter" key and that has a shift modifier set. Line separators are
+   typically found within a poem verse or an address. To insert a line
+   break, the user agent must insert a br element.

+
+   
If the caret is positioned somewhere where phrasing
+   content is not allowed (e.g. in an empty ol
+   element), then the user agent must not insert the br
+   element directly at the caret position. In such cases the behavior
+   is UA-dependent, but user agents must not, in response to a request
+   to insert a line separator, generate a DOM that is less conformant
+   than the DOM prior to the request.

+
+
+   
Delete

+
+   
UAs should offer a way for the user to delete text and
+   elements, including non-editable descendants, e.g. as the default
+   action of keydown events whose
+   identifiers are "U+0008" or "U+007F".

+
+   
Five edge cases in particular need to be considered carefully
+   when implementing this feature: backspacing at the start of an
+   element, backspacing when the caret is immediately after an
+   element, forward-deleting at the end of an element,
+   forward-deleting when the caret is immediately before an element,
+   and deleting a selection whose
+   start and end points do not share a common parent node.

+
+   
In any case, the exact behavior is UA-dependent, but user
+   agents must not, in response to a request to delete text or an
+   element, generate a DOM that is less conformant than the DOM prior
+   to the request.

+
+
+   
Insert, and wrap text in,
+   semantic elements

+
+   
UAs should offer the user the ability to mark text and
+   paragraphs with semantics that HTML can express.

+
+   
UAs should similarly offer a way for the user to insert empty
+   semantic elements to subsequently fill by entering text
+   manually.

+
+   
UAs should also offer a way to remove those semantics from
+   marked up text, and to remove empty semantic element that have been
+   inserted.

+
+   
In response to a request from a user to mark text up in italics,
+   user agents should use the i element to represent the
+   semantic. The em element should be used only if the
+   user agent is sure that the user means to indicate stress
+   emphasis.

+
+   
In response to a request from a user to mark text up in bold,
+   user agents should use the b element to represent the
+   semantic. The strong element should be used only if
+   the user agent is sure that the user means to indicate
+   importance.

+
+   
The exact behavior is UA-dependent, but user agents must not,
+   in response to a request to wrap semantics around some text or to
+   insert or remove a semantic element, generate a DOM that is less
+   conformant than the DOM prior to the request.

+
+
+   
Select and move non-editable elements nested inside editing hosts

+
+   
UAs should offer a way for the user to move images and other
+   non-editable parts around the content within an editing host. This
+   may be done using the drag and drop mechanism. User
+   agents must not, in response to a request to move non-editable
+   elements nested inside editing hosts, generate a DOM that is less
+   conformant than the DOM prior to the request.

+
+
+   
Edit form controls nested inside editing hosts

+
+   
When an editable form control is edited, the
+   changes must be reflected in both its current value and
+   its default value. For input elements this means
+   updating the defaultValue IDL attribute as
+   well as the value IDL
+   attribute; for select elements it means updating the
+   option elements' defaultSelected IDL
+   attribute as well as the selected IDL attribute; for
+   textarea elements this means updating the defaultValue IDL attribute
+   as well as the value IDL
+   attribute. (Updating the default* IDL
+   attributes causes content attributes to be updated as well.)

+
+  
User agents may perform several commands per user request; for
+  example if the user selects a block of text and hits
+  Enter, the UA might interpret that as a
+  request to delete the content of the selection followed
+  by a request to break the paragraph at that position.

+
+  
User agents may add DOM changes entries to the
+  undo transaction history of the editing
+  host's Document object each time an action is
+  triggered.

+
+  
All of the actions defined above, whether triggered by the user
+  or programmatically (e.g. by execCommand() commands),
+  must fire mutation events as appropriate.

+
+  

+
+
+
+  
8.7.2 Making entire documents editable

+
+  

+
+  
Documents have a designMode, which
+  can be either enabled or disabled.

+
+  

+
+  
document . designMode [ = value ]

+
+   

+
+    
Returns "on" if the document is editable,
+    and "off" if it isn't.

+
+    
Can be set, to change the document's current state.

+
+   

+
+  

+
+  
The designMode IDL
+  attribute on the Document object takes two values,
+  "on" and "off". When it
+  is set, the new value must be compared in an ASCII
+  case-insensitive manner to these two values. If it matches
+  the "on" value, then designMode must be enabled,
+  and if it matches the "off" value, then designMode must be
+  disabled. Other values must be ignored.

+
+  
When designMode is
+  enabled, the IDL attribute must return the value "on", and when it is disabled, it must return the
+  value "off".

+
+  
The last state set must persist until the document is destroyed
+  or the state is changed. Initially, documents must have their designMode disabled.

+
+  

+
+
+
+  
8.8 Spelling and grammar checking

+
+  

+
+  
User agents can support the checking of spelling and grammar of
+  editable text, either in form controls (such as the value of
+  textarea elements), or in elements in an editing
+  host (using contenteditable).

+
+  
For each element, user agents must establish a default behavior, either
+  through defaults or through preferences expressed by the user. There
+  are three possible default behaviors for each element:

+
+  
true-by-default
+
+   
The element will be checked for spelling and grammar if its
+   contents are editable.
+
+   
false-by-default
+
+   
The element will never be checked for spelling and grammar.
+
+   
inherit-by-default
+
+   
The element's default behavior is the same as its parent
+   element's. Elements that have no parent element cannot have this as
+   their default behavior.
+
+  

+
+  
The spellcheck
+  attribute is an enumerated attribute whose keywords are
+  the empty string, true and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In
+  addition, there is a third state, the default state, which is
+  the missing value default (and the invalid value
+  default).

+
+  
The true state indicates that the element is to have its
+  spelling and grammar checked. The default state indicates
+  that the element is to act according to a default behavior, possibly
+  based on the parent element's own spellcheck state. The false
+  state indicates that the element is not to be checked.

+
+  

+
+  

+
+  
element . spellcheck [ = value ]

+
+   

+
+    
Returns "true", "false", or "default", based
+    on the state of the spellcheck attribute.

+
+    
Can be set, to change that state.

+
+    
Throws a SYNTAX_ERR exception if the new value
+    isn't one of those strings.

+
+   

+
+  

+
+  
The spellcheck IDL
+  attribute, on getting, must return the string "true" if the content attribute is set to the true
+  state, false" if the content attribute is set
+  to the false state, and "default"
+  otherwise. On setting, if the new value is an ASCII
+  case-insensitive match for the string "default" then the content attribute must be removed,
+  if the new value is an ASCII case-insensitive match for
+  the string "true" then the content attribute
+  must be set to the string "true", if the new
+  value is an ASCII case-insensitive match for the string
+  "false" then the content attribute must be set
+  to the string "false", and otherwise the
+  attribute setter must raise a SYNTAX_ERR exception.

+
+  
The spellcheck
+  IDL attribute is not affected by user preferences that override the
+  spellcheck content attribute,
+  and therefore might not reflect the actual spellchecking state.

+
+  
On setting, if the new value is true, then the element's spellcheck content attribute must be
+  set to the literal string "true", otherwise it
+  must be set to the literal string "false".
+
+  
User agents must only consider the following pieces of text as
+  checkable for the purposes of this feature:

+
+  
For text that is part of a text node, the element
+  with which the text is associated is the element that is the
+  immediate parent of the first character of the word, sentence, or
+  other piece of text. For text in attributes, it is the attribute's
+  element. For the values of input and
+  textarea elements, it is the element itself.

+
+  
To determine if a word, sentence, or other piece of text in an
+  applicable element (as defined above) is to have spelling- and/or
+  grammar-checking enabled, the UA must use the following
+  algorithm:

+
+  
  1. If the user has disabled the checking for this text, then the
+   checking is disabled.
    2. 
+
+   
  2. Otherwise, if the user has forced the checking for this text to
+   always be enabled, then the checking is enabled.
    3. 
+
+   
+
+   
  3. Otherwise, if the element with which the text is associated has
+   a spellcheck content
+   attribute, then: if that attribute is in the true state,
+   then checking is enabled; otherwise, if that attribute is in the
+   false state, then checking is disabled.
    4. 
+
+   
+
+   
  4. Otherwise, if there is an ancestor element with a spellcheck content attribute that is
+   not in the default state, then: if the nearest such
+   ancestor's spellcheck content
+   attribute is in the true state, then checking is enabled;
+   otherwise, checking is disabled.
    5. 
+
+   
+
+   
  5. Otherwise, if the element's default behavior is true-by-default,
+   then checking is enabled.
    6. 
+
+   
  6. Otherwise, if the element's default behavior is false-by-default,
+   then checking is disabled.
    7. 
+
+   
+
+   
  7. Otherwise, if the element's parent element has its
+   checking enabled, then checking is enabled.
    8. 
+
+   
  8. Otherwise, checking is disabled.
    9. 
+
+  
If the checking is enabled for a word/sentence/text, the user
+  agent should indicate spelling and/or grammar errors in that
+  text. User agents should take into account the other semantics given
+  in the document when suggesting spelling and grammar
+  corrections. User agents may use the language of the element to
+  determine what spelling and grammar rules to use, or may use the
+  user's preferred language settings. UAs should use
+  input element attributes such as pattern to ensure that the
+  resulting value is valid, where possible.

+
+  
If checking is disabled, the user agent should not indicate
+  spelling or grammar errors for that text.

+
+  

+
+   
The element with ID "a" in the following example would be the
+   one used to determine if the word "Hello" is checked for spelling
+   errors. In this example, it would not be.

+
+   
<div contenteditable="true">
+ <span spellcheck="false" id="a">Hell</span><em>o!</em>
+</div>

+
+   
The element with ID "b" in the following example would have
+   checking enabled (the leading space character in the attribute's
+   value on the input element causes the attribute to be
+   ignored, so the ancestor's value is used instead, regardless of the
+   default).

+
+   
<p spellcheck="true">
+ <label>Name: <input spellcheck=" false" id="b"></label>
+</p>

+
+  

+
+  

+
+  
This specification does not define the user
+  interface for spelling and grammar checkers. A user agent could
+  offer on-demand checking, could perform continuous checking while
+  the checking is enabled, or could use other interfaces.

+
+
+  
8.9 Drag and drop

+
+
+
+  
This section defines an event-based drag-and-drop mechanism.

+
+  
This specification does not define exactly what a
+  drag-and-drop operation actually is.

+
+  
On a visual medium with a pointing device, a drag operation could
+  be the default action of a mousedown event that is followed by a
+  series of mousemove events, and
+  the drop could be triggered by the mouse being released.

+
+  
On media without a pointing device, the user would probably have
+  to explicitly indicate his intention to perform a drag-and-drop
+  operation, stating what he wishes to drag and what he wishes to
+  drop, respectively.

+
+  

+
+  
However it is implemented, drag-and-drop operations must have a
+  starting point (e.g. where the mouse was clicked, or the start of
+  the selection or element that was selected for the
+  drag), may have any number of intermediate steps (elements that the
+  mouse moves over during a drag, or elements that the user picks as
+  possible drop points as he cycles through possibilities), and must
+  either have an end point (the element above which the mouse button
+  was released, or the element that was finally selected), or be
+  canceled. The end point must be the last element selected as a
+  possible drop point before the drop occurs (so if the operation is
+  not canceled, there must be at least one element in the middle
+  step).

+
+  

+
+
+  
8.9.1 Introduction

+
+  
This section is non-normative.

+
+  
To make an element draggable is simple: give the element a draggable attribute, and set an event
+  listener for dragstart that
+  stores the data being dragged.

+
+  
The event handler typically needs to check that it's not a text
+  selection that is being dragged, and then needs to store data into
+  the DataTransfer object and set the allowed effects
+  (copy, move, link, or some combination).

+
+  
For example:

+
+  
<p>What fruits do you like?</p>
+<ol ondragstart="dragStartHandler(event)">
+ <li draggable data-value="fruit-apple">Apples</li>
+ <li draggable data-value="fruit-orange">Oranges</li>
+ <li draggable data-value="fruit-pear">Pears</li>
+</ol>
+<script>
+  var internalDNDType = 'text/x-example'; // set this to something specific to your site
+  function dragStartHandler(event) {
+    if (event.target instanceof HTMLLIElement) {
+      // use the element's data-value="" attribute as the value to be moving:
+      event.dataTransfer.setData(internalDNDType, event.target.dataset.value);
+      event.effectAllowed = 'move'; // only allow moves
+    } else {
+      event.preventDefault(); // don't allow selection to be dragged
+    }
+  }
+</script>

+
+  
To accept a drop, the drop target has to listen to at least three
+  events. First, the dragenter
+  event, which is used to determine whether or not the drop target is
+  to accept the drop. If the drop is to be accepted, then this event
+  has to be canceled. Second, the dragover event, which is used to
+  determine what feedback is to be shown to the user. If the event is
+  canceled, then the feedback (typically the cursor) is updated based
+  on the dropEffect
+  attribute's value, as set by the event handler; otherwise, the
+  default behavior (typically to do nothing) is used instead. Finally,
+  the drop event, which allows the
+  actual drop to be performed. This event also needs to be canceled,
+  so that the dropEffect attribute's
+  value can be used by the source (otherwise it's reset).

+
+  
For example:

+
+  
<p>Drop your favorite fruits below:</p>
+<ol class="dropzone"
+    ondragenter="dragEnterHandler(event)"
+    ondragover="dragOverHandler(event)"
+    ondrop="dropHandler(event)">
+</ol>
+<script>
+  var internalDNDType = 'text/x-example'; // set this to something specific to your site
+  function dragEnterHandler(event) {
+    // cancel the event if the drag contains data of our type
+    if (event.dataTransfer.types.contains(internalDNDType))
+      event.preventDefault();
+  }
+  function dragOverHandler(event) {
+    event.dataTransfer.dropEffect = 'move';
+    event.preventDefault();
+  }
+  function dropHandler(event) {
+    // drop the data
+    var li = document.createElement('li');
+    var data = event.dataTransfer.getData(internalDNDType);
+    if (data == 'fruit-apple') {
+      li.textContent = 'Apples';
+    } else if (data == 'fruit-orange') {
+      li.textContent = 'Oranges';
+    } else if (data == 'fruit-pear') {
+      li.textContent = 'Pears';
+    } else {
+      li.textContent = 'Unknown Fruit';
+    }
+    event.target.appendChild(li);
+  }
+</script>

+
+  
To remove the original element (the one that was dragged) from
+  the display, the dragend event
+  can be used.

+
+  
For our example here, that means updating the original markup to
+  handle that event:

+
+
+  
<p>What fruits do you like?</p>
+<ol ondragstart="dragStartHandler(event)" ondragend="dragEndHandler(event)">
+ ...as before...
+</ol>
+<script>
+  function dragStartHandler(event) {
+    // ...as before...
+  }
+  function dragEndHandler(event) {
+    // remove the dragged element
+    event.target.parentNode.removeChild(event.target);
+  }
+</script>

+
+
+
+
+  
8.9.2 The DragEvent and DataTransfer interfaces

+
+  
The drag-and-drop processing model involves several events. They
+  all use the DragEvent interface.

+
+  
interface DragEvent : MouseEvent {
+  readonly attribute DataTransfer dataTransfer;
+
+  void initDragEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dummyArg, in long detailArg, in long screenXArg, in long screenYArg, in long clientXArg, in long clientYArg, in boolean ctrlKeyArg, in boolean altKeyArg, in boolean shiftKeyArg, in boolean metaKeyArg, in unsigned short buttonArg, in EventTarget relatedTargetArg, in DataTransfer dataTransferArg);
+};

+
+  
event . dataTransfer

+
+   

+
+    
Returns the DataTransfer object for the event.

+
+   

+
+  

+
+  
The initDragEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces, except that the
+  dummyArg argument must be ignored. [DOMEVENTS]

+
+  
The dataTransfer
+  attribute of the DragEvent interface represents the
+  context information for the event.

+
+  

+
+  
interface DataTransfer {
+           attribute DOMString dropEffect;
+           attribute DOMString effectAllowed;
+
+  readonly attribute DOMStringList types;
+  void clearData(in optional DOMString format);
+  void setData(in DOMString format, in DOMString data);
+  DOMString getData(in DOMString format);
+  readonly attribute FileList files;
+
+  void setDragImage(in Element image, in long x, in long y);
+  void addElement(in Element element);
+};

+
+  
DataTransfer objects can hold pieces of data, each
+  associated with a unique format. Formats are generally given by
+  MIME types, with some values
+  special-cased for legacy reasons. However, the API does not enforce
+  this; non-MIME-type values can be added as well. All formats are
+  identified by strings that are converted to ASCII
+  lowercase by the API.

+
+  
dataTransfer . dropEffect [ = value ]

+
+   

+
+    
Returns the kind of operation that is currently selected. If
+    the kind of operation isn't one of those that is allowed by the
+    effectAllowed
+    attribute, then the operation will fail.

+
+    
Can be set, to change the selected operation.

+
+    
The possible values are none, copy, link, and move.

+
+   

+
+   
dataTransfer . effectAllowed [ = value ]

+
+   

+
+    
Returns the kinds of operations that are to be allowed.

+
+    
Can be set, to change the allowed operations.

+
+    
The possible values are none, copy, copyLink, copyMove, link, linkMove, move, all, and uninitialized,

+
+   

+
+   
dataTransfer . types

+
+   

+
+    
Returns a DOMStringList listing the formats that
+    were set in the dragstart
+    event. In addition, if any files are being dragged, then one of
+    the types will be the string "Files".

+
+   

+
+   
dataTransfer . clearData( [ format ] )

+
+   

+
+    
Removes the data of the specified formats. Removes all data if
+    the argument is omitted.

+
+   

+
+   
dataTransfer . setData(format, data)

+
+   

+
+    
Adds the specified data.

+
+   

+
+   
data = dataTransfer . getData(format)

+
+   

+
+    
Returns the specified data. If there is no such data, returns the empty string.

+
+   

+
+   
dataTransfer . files

+
+   

+
+    
Returns a FileList of the files being dragged, if any.

+
+   

+
+   
dataTransfer . setDragImage(element, x, y)

+
+   

+
+    
Uses the given element to update the drag feedback, replacing any previously specified feedback.

+
+   

+
+   
dataTransfer . addElement(element)

+
+   

+
+    
Adds the given element to the list of elements used to render the drag feedback.

+
+   

+
+  

+
+  
When a DataTransfer object is created, it must be
+  initialized as follows:

+
+  
  • The DataTransfer object must initially contain no
+   data, no elements, and have no associated image.
    • 
+
+   
  • The DataTransfer object's effectAllowed
+   attribute must be set to "uninitialized".
    • 
+
+   
  • The dropEffect
+   attribute must be set to "none".
    • 
+
+  
The dropEffect
+  attribute controls the drag-and-drop feedback that the user is given
+  during a drag-and-drop operation.

+
+  
The attribute must ignore any attempts to set it to a value other
+  than none, copy, link, and move. On getting,
+  the attribute must return the last of those four values that it was
+  set to.

+
+  
The effectAllowed
+  attribute is used in the drag-and-drop processing model to
+  initialize the dropEffect attribute
+  during the dragenter and dragover events.

+
+  
The attribute must ignore any attempts to set it to a value other
+  than none, copy, copyLink, copyMove, link, linkMove, move, all, and uninitialized. On getting, the attribute must return
+  the last of those values that it was set to.

+
+  
The types
+  attribute must return a live DOMStringList
+  that contains the list of formats that were added to the
+  DataTransfer object in the corresponding dragstart event. The same object must
+  be returned each time. If any files were included in the drag, then
+  the DOMStringList object must in addition include the
+  string "Files". (This value can be
+  distinguished from the other values because it is not
+  lowercase.)

+
+  
The clearData()
+  method, when called with no arguments, must clear the
+  DataTransfer object of all data (for all formats).

+
+  
The clearData() method does
+  not affect whether any files were included in the drag, so the types attribute's list might
+  still not be empty after calling clearData() (it would
+  still contain the "Files" string if any files
+  were included in the drag).

+
+  
When called with an argument, the clearData(format) method must clear the
+  DataTransfer object of any data associated with the
+  given format, converted to ASCII
+  lowercase. If format (after conversion to
+  lowercase) is the value "text", then it must
+  be treated as "text/plain". If the format (after conversion to lowercase) is "url", then it must be treated as "text/uri-list".

+
+  
The setData(format, data) method
+  must add data to the data stored in the
+  DataTransfer object, labeled as being of the type format, converted to ASCII
+  lowercase. This must replace any previous data that had been
+  set for that format. If format (after conversion
+  to lowercase) is the value "text", then it
+  must be treated as "text/plain". If the format (after conversion to lowercase) is "url", then it must be treated as "text/uri-list".

+
+  
The getData(format) method must return the data that
+  is associated with the type format
+  converted to ASCII lowercase, if any, and must return
+  the empty string otherwise. If format (after
+  conversion to lowercase) is the value "text",
+  then it must be treated as "text/plain". If
+  the format (after conversion to lowercase) is
+  "url", then the data associated with the
+  "text/uri-list" format must be parsed as
+  appropriate for text/uri-list data, and the
+  first URL from the list must be returned. If there is no data with
+  that format, or if there is but it has no URLs, then the method must
+  return the empty string. [RFC2483]

+
+  
The files
+  attribute must return the FileList object that contains
+  the files that are stored in the DataTransfer
+  object. There is one such object per DataTransfer
+  object.

+
+  
This version of the API does not expose the types of
+  the files during the drag.

+
+  
The setDragImage(element, x, y) method sets which element to use to generate the drag feedback. The
+  element argument can be any
+  Element; if it is an img element, then the
+  user agent should use the element's image (at its intrinsic size) to
+  generate the feedback, otherwise the user agent should base the
+  feedback on the given element (but the exact mechanism for doing so
+  is not specified).

+
+  
The addElement(element) method is an alternative way of
+  specifying how the user agent is to render the drag feedback. It adds an
+  element to the DataTransfer object.

+
+  
The difference between setDragImage() and
+  addElement() is
+  that the latter automatically generates the image based on the
+  current rendering of the elements added, whereas the former uses the
+  exact specified image.

+
+  

+
+
+  
8.9.3 Events fired during a drag-and-drop action

+
+  
The following events are involved in the drag-and-drop
+  model.

+
+  

+
+  
Whenever the processing model described below causes one of these
+  events to be fired, the event fired must use the
+  DragEvent interface defined above, must have the
+  bubbling and cancelable behaviors given in the table below, and must
+  have the context information set up as described after the table,
+  with the detail attribute
+  set to zero, the mouse and key attributes set according to the state
+  of the input devices as they would be for user interaction events,
+  and the relatedTarget attribute set to
+  null.

+
+  
If there is no relevant pointing device, the object must have its
+  screenX, screenY, clientX, clientY, and button attributes set to 0.

+
+  
+
+  

+
+  
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+     
+    
 Event Name  Target  Bubbles?  Cancelable?  dataTransfer  effectAllowed  dropEffect  Default Action 
dragstartSource node✓ Bubbles✓ CancelableContains source node unless a selection is being dragged, in which case it is empty; files returns any files included in the drag operationuninitializednoneInitiate the drag-and-drop operation
dragSource node✓ Bubbles✓ CancelableEmptySame as last eventnoneContinue the drag-and-drop operation
dragenterImmediate user selection or the body element✓ Bubbles✓ CancelableEmptySame as last eventBased on effectAllowed valueReject immediate user selection as potential target element
dragleavePrevious target element✓ Bubbles—EmptySame as last eventnoneNone
dragoverCurrent target element✓ Bubbles✓ CancelableEmptySame as last eventBased on effectAllowed valueReset the current drag operation to "none"
dropCurrent target element✓ Bubbles✓ CancelablegetData() returns data set in dragstart event; files returns any files included in the drag operationSame as last eventCurrent drag operationVaries
dragendSource node✓ Bubbles—EmptySame as last eventCurrent drag operationVaries
"Empty" in the table above means that the getData() and files attributes act as if
+  there is no data being dragged.

+
+  

+
+  
The dataTransfer
+  object's contents are empty (the getData() and files attributes act as if
+  there is no data being dragged) except for dragstart events and drop events, for which the contents are
+  set as described in the processing model, below.

+
+  
The effectAllowed
+  attribute must be set to "uninitialized" for
+  dragstart events, and to
+  whatever value the field had after the last drag-and-drop event was
+  fired for all other events (only counting events fired by the user
+  agent for the purposes of the drag-and-drop model described
+  below).

+
+  
The dropEffect attribute must
+  be set to "none" for dragstart, drag, and dragleave events (except when stated
+  otherwise in the algorithms given in the sections below), to the
+  value corresponding to the current drag operation for
+  drop and dragend events, and to a value based on
+  the effectAllowed
+  attribute's value and to the drag-and-drop source, as given by the
+  following table, for the remaining events (dragenter and dragover):

+
+  
+     
+    
+    
+   
+    
+   
+    
+   
+    
+   
+    
+   
+    
+   
+    
+   
+    
+   
effectAlloweddropEffect
nonenone
copy, copyLink, copyMove, allcopy
link, linkMovelink
movemove
uninitialized when what is being dragged is a selection from a text fieldmove
uninitialized when what is being dragged is a selectioncopy
uninitialized when what is being dragged is an a element with an href attributelink
Any other casecopy

+
+
+  

+
+  
8.9.4 Drag-and-drop processing model

+
+  
When the user attempts to begin a drag operation, the user agent
+  must first determine what is being dragged. If the drag operation
+  was invoked on a selection, then it is the selection that is being
+  dragged. Otherwise, it is the first element, going up the ancestor
+  chain, starting at the node that the user tried to drag, that has
+  the IDL attribute draggable set
+  to true. If there is no such element, then nothing is being dragged,
+  the drag-and-drop operation is never started, and the user agent
+  must not continue with this algorithm.

+
+  
img elements and a
+  elements with an href
+  attribute have their draggable
+  attribute set to true by default.

+
+  
If the user agent determines that something can be dragged, a
+  dragstart event must then be
+  fired at the source node.

+
+  
The source node depends on the kind of drag and how it
+  was initiated. If it is a selection that is being dragged, then the
+  source node is the text node that the user started the
+  drag on (typically the text node that the user originally
+  clicked). If the user did not specify a particular node, for example
+  if the user just told the user agent to begin a drag of "the
+  selection", then the source node is the first text node
+  containing a part of the selection. If it is not a selection that is
+  being dragged, then the source node is the element that
+  is being dragged.

+
+  
Multiple events are fired on the source node during
+  the course of the drag-and-drop operation.

+
+  
The list of dragged nodes also depends on the kind of
+  drag. If it is a selection that is being dragged, then the
+  list of dragged nodes contains, in tree
+  order, every node that is partially or completely included in
+  the selection (including all their ancestors). Otherwise, the
+  list of dragged nodes contains only the source
+  node.

+
+  
If it is a selection that is being dragged, the dataTransfer member of the
+  event must be created with no nodes. Otherwise, it must be created
+  containing just the source node. Script can use the
+  addElement() method
+  to add further elements to the list of what is being dragged. (This
+  list is only used for rendering the drag feedback.)

+
+  
The dataTransfer
+  member of the event also has data added to it, as follows:

+
+  
  • 
+
+    
    If it is a selection that is being dragged, then the user agent
+    must add the text of the selection to the dataTransfer member,
+    associated with the text/plain format.
    
+
+   
    • 
+
+   
  • 
+
+    
    If files are being dragged, then the user agent must add the
+    files to the dataTransfer member's
+    files attribute's
+    FileList object. (Dragging files can only happen from
+    outside a browsing context, for example from a file
+    system manager application, and thus the dragstart event is actually implied
+    in this case.)
    
+
+   
    • 
+
+
+
+   
  • 
+
+    
    The user agent must take the list of dragged nodes
+    and extract the microdata from those
+    nodes into a JSON form, and then must add the resulting
+    string to the dataTransfer member,
+    associated with the application/microdata+json format.
    
+
+   
    • 
+
+
+
+
+
+   
+
+   
  • 
+
+    
    The user agent must run the following steps:
    
+
+    
    1. Let urls be an empty list of absolute URLs.
      2. 
+
+     
    2. 
+
+      
      For each node in nodes:
      
+
+      
      If the node is an a element with an href
      
+
+       
      Add to urls the result of resolving the element's href content attribute relative to
+       the element.
      
+
+       
      If the node is an img element with an src
      
+
+       
      Add to urls the result of resolving the element's src content attribute relative to the
+       element.
      
+
+       
+
+      
      3. 
+
+     
    3. If urls is still empty, abort these
+     steps.
      4. 
+
+     
    4. Let url string be the result of
+     concatenating the strings in urls, in the
+     order they were added, separated by a U+000D CARRIAGE RETURN
+     U+000A LINE FEED character pair (CRLF).
      5. 
+
+     
    5. Add url string to the dataTransfer member,
+     associated with the text/uri-list
+     format.
      6. 
+
+    
    • 
+
+  
If the event is canceled, then the drag-and-drop operation must
+  not occur; the user agent must not continue with this algorithm.

+
+  
If it is not canceled, then the drag-and-drop operation must be
+  initiated.

+
+  
Since events with no event listeners registered are,
+  almost by definition, never canceled, drag-and-drop is always
+  available to the user if the author does not specifically prevent
+  it.

+
+  
The drag-and-drop feedback must be
+  generated from the first of the following sources that is
+  available:

+
+  
  1. The element specified in the last call to the setDragImage() method
+   of the dataTransfer
+   object of the dragstart event,
+   if the method was called. In visual media, if this is used, the
+   x and y arguments that were
+   passed to that method should be used as hints for where to put the
+   cursor relative to the resulting image. The values are expressed as
+   distances in CSS pixels from the left side and from the top side of
+   the image respectively. [CSS]
    2. 
+
+   
  2. The elements that were added to the dataTransfer object, both
+   before the event was fired, and during the handling of the event
+   using the addElement()
+   method, if any such elements were indeed added.
    3. 
+
+   
  3. The selection that the user is dragging.
    4. 
+
+  
The user agent must take a note of the data that was placed in
+  the dataTransfer
+  object. This data will be made available again when the drop event is fired.

+
+  
From this point until the end of the drag-and-drop operation,
+  device input events (e.g. mouse and keyboard events) must be
+  suppressed. In addition, the user agent must track all DOM changes
+  made during the drag-and-drop operation, and add them to its undo history as one atomic operation once the
+  drag-and-drop operation has ended.

+
+  
During the drag operation, the element directly indicated by the
+  user as the drop target is called the immediate user
+  selection. (Only elements can be selected by the user; other
+  nodes must not be made available as drop targets.)
+
+  However, the immediate user selection is not
+  necessarily the current target element, which is the
+  element currently selected for the drop part of the drag-and-drop
+  operation.
+
+  The immediate user selection changes as the user
+  selects different elements (either by pointing at them with a
+  pointing device, or by selecting them in some other way). The
+  current target element changes when the immediate
+  user selection changes, based on the results of event
+  listeners in the document, as described below.

+
+  
Both the current target element and the
+  immediate user selection can be null, which means no
+  target element is selected. They can also both be elements in other
+  (DOM-based) documents, or other (non-Web) programs altogether. (For
+  example, a user could drag text to a word-processor.) The
+  current target element is initially null.

+
+  
In addition, there is also a current drag operation,
+  which can take on the values "none", "copy", "link", and "move".
+  Initially, it has the value "none". It is updated by the user agent
+  as described in the steps below.

+
+  
User agents must, as soon as the drag operation is initiated and
+  every 350ms (±200ms) thereafter for as long as the drag
+  operation is ongoing, queue a task to perform the
+  following steps in sequence:

+
+  
  1. 
+
+    
    If the user agent is still performing the previous iteration of
+    the sequence (if any) when the next iteration becomes due, the
+    user agent must not execute the overdue iteration, effectively
+    "skipping missed frames" of the drag-and-drop operation.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    The user agent must fire a drag
+    event at the source node. If this event is canceled,
+    the user agent must set the current drag operation to
+    none (no drag operation).
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Next, if the drag event was not
+    canceled and the user has not ended the drag-and-drop operation,
+    the user agent must check the state of the drag-and-drop
+    operation, as follows:
    
+
+    
    1. 
+
+      
      First, if the user is indicating a different immediate
+      user selection than during the last iteration (or if this
+      is the first iteration), and if this immediate user
+      selection is not the same as the current target
+      element, then the current target element must
+      be updated, as follows:
      
+
+      
      If the new immediate user selection is null, or
+       is in a non-DOM document or application
      
+
+       
      The user agent must set the current target
+       element to the same value.
      
+
+       
      Otherwise
      
+
+       
      
+
+        
      The user agent must fire a dragenter event at the
+        immediate user selection.
      
+
+        
      If the event is canceled, then the current target
+        element must be set to the immediate user
+        selection.
      
+
+        
      Otherwise, the user agent must act as follows:
      
+
+        
      If the current target element is a text
+         field (e.g. textarea, or an input
+         element whose type
+         attribute is in the Text state) or an
+         editable element
      
+
+         
      The current target element must be set to
+         the immediate user selection anyway.
      
+
+         
      If the current target element is
+         the body element
      
+
+         
      The current target element is left
+         unchanged.
      
+
+         
      Otherwise
      
+
+         
      The user agent must fire a dragenter event at the
+         body element, and the current target
+         element must be set to the body element,
+         regardless of whether that event was canceled or not. (If
+         the body element is null, then the current
+         target element would be set to null too in this case,
+         it wouldn't be set to the Document
+         object.)
      
+
+        
      
+
+      
      2. 
+
+     
    2. 
+
+      
      If the previous step caused the current target
+      element to change, and if the previous target element was
+      not null or a part of a non-DOM document, the user agent must fire
+      a dragleave event at the
+      previous target element.
      
+
+     
      3. 
+
+     
    3. 
+
+      
      If the current target element is a DOM element,
+      the user agent must fire a dragover event at this current
+      target element.
      
+
+      
      If the dragover event is
+      not canceled, the user agent must act as follows:
      
+
+      
      If the current target element is a text field
+       (e.g. textarea, or an input element
+       whose type attribute is in
+       the Text state) or an
+       editable element
      
+
+       
      The user agent must set the current drag
+       operation to either "copy" or "move", as appropriate
+       given the platform conventions.
      
+
+       
      Otherwise
      
+
+       
      The user agent must reset the current drag
+       operation to "none".
      
+
+      
      Otherwise (if the dragover event is
+      canceled), the current drag operation must be set
+      based on the values the effectAllowed and
+      dropEffect
+      attributes of the dataTransfer object
+      had after the event was handled, as per the following table:
      
+
+      
+         
+         
+        
+        
+        
+       
+        
+        
+       
+        
+        
+       
+        
+       
      effectAlloweddropEffectDrag operation
      uninitialized, copy, copyLink, copyMove, or allcopy"copy"
      uninitialized, link, copyLink, linkMove, or alllink"link"
      uninitialized, move, copyMove, linkMove, or allmove"move"
      Any other case"none"
      Then, regardless of whether the dragover event was canceled or
+      not, the drag feedback (e.g. the mouse cursor) must be updated
+      to match the current drag operation, as
+      follows:
      
+
+      
+         
+        
+        
+       
+        
+       
+        
+       
+        
+       
      Drag operationFeedback
      "copy"Data will be copied if dropped here.
      "link"Data will be linked if dropped here.
      "move"Data will be moved if dropped here.
      "none"No operation allowed, dropping here will cancel the drag-and-drop operation.
      4. 
+
+     
    4. 
+
+      
      Otherwise, if the current target element is not a
+      DOM element, the user agent must use platform-specific mechanisms
+      to determine what drag operation is being performed (none, copy,
+      link, or move). This sets the current drag operation.
      
+
+     
      5. 
+
+    
    4. 
+
+   
  4. 
+
+    
    Otherwise, if the user ended the drag-and-drop operation (e.g.
+    by releasing the mouse button in a mouse-driven drag-and-drop
+    interface), or if the drag event
+    was canceled, then this will be the last iteration. The user agent
+    must execute the following steps, then stop looping.
    
+
+    
    1. 
+
+      
      If the current drag operation is none (no drag
+      operation), or, if the user ended the drag-and-drop operation by
+      canceling it (e.g. by hitting the Escape key), or if
+      the current target element is null, then the drag
+      operation failed. If the current target element is
+      a DOM element, the user agent must fire a dragleave event at it; otherwise,
+      if it is not null, it must use platform-specific conventions for
+      drag cancellation.
      
+
+     
      2. 
+
+     
    2. 
+
+      
      Otherwise, the drag operation was as success. If the
+      current target element is a DOM element, the user
+      agent must fire a drop event at
+      it; otherwise, it must use platform-specific conventions for
+      indicating a drop.
      
+
+      
      When the target is a DOM element, the dropEffect attribute
+      of the event's dataTransfer object
+      must be given the value representing the current drag
+      operation (copy, link, or move), and the
+      object must be set up so that the getData() method will
+      return the data that was added during the dragstart event, and the files attribute will
+      return a FileList object with any files that were
+      dragged.
      
+
+      
      If the event is canceled, the current drag
+      operation must be set to the value of the dropEffect attribute
+      of the event's dataTransfer object as
+      it stood after the event was handled.
      
+
+      
      Otherwise, the event is not canceled, and the user agent must
+      perform the event's default action, which depends on the exact
+      target as follows:
      
+
+      
      If the current target element is a text field
+       (e.g. textarea, or an input element
+       whose type attribute is in
+       the Text state) or an
+       editable element
      
+
+       
      The user agent must insert the data associated with the
+       text/plain format, if any, into the text field or
+       editable element in a manner consistent with
+       platform-specific conventions (e.g. inserting it at the current
+       mouse cursor position, or inserting it at the end of the
+       field).
      
+
+       
      Otherwise
      
+
+       
      Reset the current drag operation to
+       "none".
      
+
+      
      3. 
+
+     
    3. 
+
+      
      Finally, the user agent must fire a dragend event at the source
+      node, with the dropEffect attribute
+      of the event's dataTransfer object
+      being set to the value corresponding to the current drag
+      operation.
      
+
+      
      The current drag operation can
+      change during the processing of the drop event, if one was fired.
      
+
+      
      The event is not cancelable. After the event has been
+      handled, the user agent must act as follows:
      
+
+      
      If the current target element is a text field
+       (e.g. textarea, or an input element
+       whose type attribute is in
+       the Text state), and
+       a drop event was fired in the
+       previous step, and the current drag operation is
+       "move", and the source of the drag-and-drop operation is a
+       selection in the DOM
      
+
+       
      The user agent should delete the range representing the
+       dragged selection from the DOM.
      
+
+       
      If the current target element is a text field
+       (e.g. textarea, or an input element
+       whose type attribute is in
+       the Text state), and
+       a drop event was fired in the
+       previous step, and the current drag operation is
+       "move", and the source of the drag-and-drop operation is a
+       selection in a text field
      
+
+       
      The user agent should delete the dragged selection from the
+       relevant text field.
      
+
+       
      Otherwise
      
+
+       
      The event has no default action.
      
+
+      
      4. 
+
+    
    5. 
+
+  

+
+
+  

+
+  
8.9.4.1 When the drag-and-drop operation starts or ends in another
+  document

+
+  
The model described above is independent of which
+  Document object the nodes involved are from; the events
+  must be fired as described above and the rest of the processing
+  model must be followed as described above, irrespective of how many
+  documents are involved in the operation.

+
+  

+
+
+
+  

+
+  
8.9.4.2 When the drag-and-drop operation starts or ends in another
+  application

+
+  
If the drag is initiated in another application, the source
+  node is not a DOM node, and the user agent must use
+  platform-specific conventions instead when the requirements above
+  involve the source node. User agents in this situation must act as
+  if the dragged data had been added to the DataTransfer
+  object when the drag started, even though no dragstart event was actually fired;
+  user agents must similarly use platform-specific conventions when
+  deciding on what drag feedback to use.

+
+  
All the format strings must be converted to ASCII
+  lowercase. If the platform conventions do not use MIME types to label the dragged data, the
+  user agent must map the types to MIME types first.

+
+  
If a drag is started in a document but ends in another
+  application, then the user agent must instead replace the parts of
+  the processing model relating to handling the target
+  according to platform-specific conventions.

+
+  
In any case, scripts running in the context of the document must
+  not be able to distinguish the case of a drag-and-drop operation
+  being started or ended in another application from the case of a
+  drag-and-drop operation being started or ended in another document
+  from another domain.

+
+  

+
+
+  
8.9.5 The draggable attribute

+
+  
All HTML elements may have the draggable content attribute set. The
+  draggable attribute is an
+  enumerated attribute. It has three states. The first
+  state is true and it has the keyword true. The second state is false and it has
+  the keyword false. The third state is
+  auto; it has no keywords but it is the missing value
+  default.

+
+  
The true state means the element is draggable; the
+  false state means that it is not. The auto state
+  uses the default behavior of the user agent.

+
+  
element . draggable [ = value ]

+
+   

+
+    
Returns true if the element is draggable; otherwise, returns
+    false.

+
+    
Can be set, to override the default and set the draggable content attribute.

+
+   

+
+  

+
+  
The draggable IDL
+  attribute, whose value depends on the content attribute's in the way
+  described below, controls whether or not the element is
+  draggable. Generally, only text selections are draggable, but
+  elements whose draggable IDL
+  attribute is true become draggable as well.

+
+  
If an element's draggable
+  content attribute has the state true, the draggable IDL attribute must return
+  true.

+
+  
Otherwise, if the element's draggable content attribute has the
+  state false, the draggable IDL attribute must return
+  false.

+
+  
Otherwise, the element's draggable content attribute has the
+  state auto. If the element is an img element,
+  or, if the element is an a element with an href content attribute, the draggable IDL attribute must return
+  true.

+
+  
Otherwise, the draggable DOM
+  must return false.

+
+  
If the draggable IDL attribute
+  is set to the value false, the draggable content attribute must be
+  set to the literal value false. If the draggable IDL attribute is set to the
+  value true, the draggable
+  content attribute must be set to the literal value true.

+
+  

+
+
+
+
+
+  

+
+  
8.9.6 Security risks in the drag-and-drop model

+
+  
User agents must not make the data added to the
+  DataTransfer object during the dragstart event available to scripts
+  until the drop event, because
+  otherwise, if a user were to drag sensitive information from one
+  document to a second document, crossing a hostile third document in
+  the process, the hostile document could intercept the data.

+
+  
For the same reason, user agents must consider a drop to be
+  successful only if the user specifically ended the drag operation
+  — if any scripts end the drag operation, it must be considered
+  unsuccessful (canceled) and the drop
+  event must not be fired.

+
+  
User agents should take care to not start drag-and-drop
+  operations in response to script actions. For example, in a
+  mouse-and-window environment, if a script moves a window while the
+  user has his mouse button depressed, the UA would not consider that
+  to start a drag. This is important because otherwise UAs could cause
+  data to be dragged from sensitive sources and dropped into hostile
+  documents without the user's consent.

+
+  

+
+
+  
8.10 Undo history

+
+  

+
+  
8.10.1 Definitions

+
+  
The user agent must associate an undo transaction
+  history with each HTMLDocument object.

+
+  
The undo transaction history is a list of
+  entries. The entries are of two types: DOM changes and
+  undo objects.

+
+  
Each DOM changes entry in the undo transaction
+  history consists of batches of one or more of the
+  following:

+
+  
Undo object entries consist of objects representing
+  state that scripts running in the document are managing. For
+  example, a Web mail application could use an undo
+  object to keep track of the fact that a user has moved an
+  e-mail to a particular folder, so that the user can undo the
+  action and have the e-mail return to its former location.

+
+  
Broadly speaking, DOM changes entries are handled by
+  the UA in response to user edits of form controls and editing hosts on the page, and
+  undo object entries are handled by script in response
+  to higher-level user actions (such as interactions with server-side
+  state, or in the implementation of a drawing tool).

+
+  

+
+
+  
8.10.2 The UndoManager interface

+
+  
To manage undo object entries in the undo
+  transaction history, the UndoManager
+  interface can be used:

+
+  
interface UndoManager {
+  readonly attribute unsigned long length;
+  getter any item(in unsigned long index);
+  readonly attribute unsigned long position;
+  unsigned long add(in any data, in DOMString title);
+  void remove(in unsigned long index);
+  void clearUndo();
+  void clearRedo();
+};

+
+  
window . undoManager

+
+   

+
+    
Returns the UndoManager object.

+
+   

+
+   
undoManager . length

+   

+
+    
Returns the number of entries in the undo history.

+
+   

+
+   
data = undoManager . item(index)

+   
undoManager[index]

+   

+
+    
Returns the entry with index index in the undo history.

+
+    
Returns null if index is out of range.

+
+   

+
+   
undoManager . position

+   

+
+    
Returns the number of the current entry in the undo history. (Entries at and past this point are redo entries.)

+
+   

+
+   
undoManager . add(data, title)

+   

+
+    
Adds the specified entry to the undo history.

+
+   

+
+   
undoManager . remove(index)

+   

+
+    
Removes the specified entry to the undo history.

+
+    
Throws an INDEX_SIZE_ERR exception if the given index is out of range.

+
+   

+
+   
undoManager . clearUndo()

+   

+
+    
Removes all entries before the current position in the undo history.

+
+   

+
+   
undoManager . clearRedo()

+   

+
+    
Removes all entries at and after the current position in the undo history.

+
+   

+
+  

+
+  
The undoManager
+  attribute of the Window interface must return the
+  object implementing the UndoManager interface for that
+  Window object's associated
+  HTMLDocument object.

+
+  
UndoManager objects represent their document's
+  undo transaction history. Only undo object
+  entries are visible with this API, but this does not mean that
+  DOM changes entries are absent from the undo
+  transaction history.

+
+  
The length
+  attribute must return the number of undo object entries
+  in the undo transaction history. This is the length.

+
+  
The object's indices of the supported indexed
+  properties are the numbers in the range zero to length-1, unless the
+  length is zero, in which
+  case there are no supported indexed properties.

+
+  
The item(n) method must return the nth undo object entry in the undo
+  transaction history, if there is one, or null otherwise.

+
+  
The undo transaction history has a current position. This is the position between two
+  entries in the undo transaction history's list where
+  the previous entry represents what needs to happen if the user
+  invokes the "undo" command (the "undo" side, lower numbers), and the
+  next entry represents what needs to happen if the user invokes the
+  "redo" command (the "redo" side, higher numbers).

+
+  
The position
+  attribute must return the index of the undo object
+  entry nearest to the undo position, on the "redo"
+  side. If there are no undo object entries on the "redo"
+  side, then the attribute must return the same as the length attribute. If there are
+  no undo object entries on the "undo" side of the
+  undo position, the position attribute returns
+  zero.

+
+  
Since the undo transaction history
+  contains both undo object entries and DOM
+  changes entries, but the position attribute only
+  returns indices relative to undo object entries, it is
+  possible for several "undo" or "redo" actions to be performed
+  without the value of the position attribute
+  changing.

+
+  
The add(data,
+  title) method's behavior depends on the
+  current state. Normally, it must insert the data object
+  passed as an argument into the undo transaction history
+  immediately before the undo position, optionally
+  remembering the given title to use in the UI. If the
+  method is called during an undo
+  operation, however, the object must instead be added
+  immediately after the undo position.

+
+  
If the method is called and there is neither an undo operation in progress nor a redo operation in progress then any entries
+  in the undo transaction history after the undo
+  position must be removed (as if clearRedo() had been
+  called).

+
+  
The remove(index) method must remove the undo
+  object entry with the specified index. If
+  the index is less than zero or greater than or equal to length then the method must
+  raise an INDEX_SIZE_ERR exception. DOM
+  changes entries are unaffected by this method.

+
+  
The clearUndo()
+  method must remove all entries in the undo transaction
+  history before the undo position, be they
+  DOM changes entries or undo object
+  entries.

+
+  
The clearRedo()
+  method must remove all entries in the undo transaction
+  history after the undo position, be they
+  DOM changes entries or undo object
+  entries.

+
+  

+
+
+  

+
+  
8.10.3 Undo: moving back in the undo transaction history

+
+  
When the user invokes an undo operation, or when the execCommand() method is
+  called with the undo command, the
+  user agent must perform an undo operation.

+
+  
If the undo position is at the start of the
+  undo transaction history, then the user agent must do
+  nothing.

+
+  
If the entry immediately before the undo position is
+  a DOM changes entry, then the user agent must remove
+  that DOM changes entry, reverse the DOM changes that
+  were listed in that entry, and, if the changes were reversed with no
+  problems, add a new DOM changes entry (consisting of
+  the opposite of those DOM changes) to the undo transaction
+  history on the other side of the undo
+  position.

+
+  
If the DOM changes cannot be undone (e.g. because the DOM state
+  is no longer consistent with the changes represented in the entry),
+  then the user agent must simply remove the DOM changes
+  entry, without doing anything else.

+
+  
If the entry immediately before the undo position is
+  an undo object entry, then the user agent must first
+  remove that undo object entry from the undo
+  transaction history, and then must fire an undo event at the Window
+  object, using the undo object entry's associated undo
+  object as the event's data.

+
+  
Any calls to add() while
+  the event is being handled will be used to populate the redo
+  history, and will then be used if the user invokes the "redo"
+  command to undo his undo.

+
+
+  
8.10.4 Redo: moving forward in the undo transaction history

+
+  
When the user invokes a redo operation, or when the execCommand() method is
+  called with the redo command, the
+  user agent must perform a redo operation.

+
+  
This is mostly the opposite of an undo
+  operation, but the full definition is included here for
+  completeness.

+
+  
If the undo position is at the end of the undo
+  transaction history, then the user agent must do nothing.

+
+  
If the entry immediately after the undo position is
+  a DOM changes entry, then the user agent must remove
+  that DOM changes entry, reverse the DOM changes that
+  were listed in that entry, and, if the changes were reversed with no
+  problems, add a new DOM changes entry (consisting of
+  the opposite of those DOM changes) to the undo transaction
+  history on the other side of the undo
+  position.

+
+  
If the DOM changes cannot be redone (e.g. because the DOM state
+  is no longer consistent with the changes represented in the entry),
+  then the user agent must simply remove the DOM changes
+  entry, without doing anything else.

+
+  
If the entry immediately after the undo position is
+  an undo object entry, then the user agent must first
+  remove that undo object entry from the undo
+  transaction history, and then must fire a redo event at the Window
+  object, using the undo object entry's associated undo
+  object as the event's data.

+
+  

+
+
+  
8.10.5 The UndoManagerEvent interface and the undo and redo events

+
+  
interface UndoManagerEvent : Event {
+  readonly attribute any data;
+  void initUndoManagerEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dataArg);
+};

+
+  
event  . data

+
+   

+
+    
Returns the data that was passed to the add() method.

+
+   

+
+  

+
+  
The initUndoManagerEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces. [DOMEVENTS]

+
+  
The data
+  attribute represents the undo object for the event.

+
+  
The undo and redo events do not bubble,
+  cannot be canceled, and have no default action. When the user agent
+  fires one of these events it must use the
+  UndoManagerEvent interface, with the data field containing the
+  relevant undo object.

+
+  

+
+
+  

+
+  
8.10.6 Implementation notes

+
+  
How user agents present the above conceptual model to the user is
+  not defined. The undo interface could be a filtered view of the
+  undo transaction history, it could manipulate the
+  undo transaction history in ways not described above,
+  and so forth. For example, it is possible to design a UA that
+  appears to have separate undo
+  transaction histories for each form control; similarly, it is
+  possible to design systems where the user has access to more undo
+  information than is present in the official (as described above)
+  undo transaction history (such as providing a
+  tree-based approach to document state). Such UI models should be
+  based upon the single undo transaction history
+  described in this section, however, such that to a script there is
+  no detectable difference.

+
+  

+
+
+
+
+
+  
8.11 Editing APIs

+
+  
document . execCommand(commandId [, showUI [, value ] ] )

+
+   

+
+    
Runs the action specified by the first argument, as described
+    in the list below. The second and third arguments sometimes affect
+    the action. (If they don't they are ignored.)

+
+   

+
+   
document . queryCommandEnabled(commandId)

+
+   

+
+    
Returns whether the given command is enabled, as described in the list below.

+
+   

+
+   
document . queryCommandIndeterm(commandId)

+
+   

+
+    
Returns whether the given command is indeterminate, as described in the list below.

+
+   

+
+   
document . queryCommandState(commandId)

+
+   

+
+    
Returns the state of the command, as described in the list below.

+
+   

+
+   
document . queryCommandSupported(commandId)

+
+   

+
+    
Returns true if the command is supported; otherwise, returns false.

+
+   

+
+   
document . queryCommandValue(commandId)

+
+   

+
+    
Returns the value of the command, as described in the list below.

+
+   

+
+  

+
+  
The execCommand(commandId, showUI, value) method on the
+  HTMLDocument interface allows scripts to perform
+  actions on the current selection
+  or at the current caret position. Generally, these commands would be
+  used to implement editor UI, for example having a "delete" button on
+  a toolbar.

+
+  
There are three variants to this method, with one, two, and three
+  arguments respectively. The showUI and value parameters, even if specified, are ignored
+  except where otherwise stated.

+
+  
When execCommand()
+  is invoked, the user agent must follow the following steps:

+
+  
  1. If the given commandId maps to an entry in
+   the list below whose "Enabled When" entry has a condition that is
+   currently false, do nothing; abort these steps.
    2. 
+
+   
  2. Otherwise, execute the "Action" listed below for the given commandId.
    3. 
+
+  

+
+  
A document is ready for editing host commands if it
+  has a selection that is entirely within an editing
+  host, or if it has no selection but its caret is inside an
+  editing host.

+
+  

+
+  
The queryCommandEnabled(commandId) method, when invoked, must
+  return true if the condition listed below under "Enabled When" for
+  the given commandId is true, and false
+  otherwise.

+
+  
The queryCommandIndeterm(commandId) method, when invoked, must
+  return true if the condition listed below under "Indeterminate When"
+  for the given commandId is true, and false
+  otherwise.

+
+  
The queryCommandState(commandId) method, when invoked, must
+  return the value expressed below under "State" for the given commandId.

+
+  
The queryCommandSupported(commandId) method, when invoked, must
+  return true if the given commandId is in the
+  list below, and false otherwise.

+
+  
The queryCommandValue(commandId) method, when invoked, must
+  return the value expressed below under "Value" for the given commandId.

+
+  

+
+  
The possible values for commandId, and their
+  corresponding meanings, are as follows. These
+  values must be compared to the argument in an ASCII
+  case-insensitive manner.

+
+  
bold

+   
Summary: Toggles whether the selection is bold.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the b element (or, again,
+   unwrapped, or have that semantic inserted or removed, as defined by
+   the UA).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: True if the selection, or the caret, if
+   there is no selection, is, or is contained within, a
+   b element. False otherwise.

+   
Value: The string "true"
+   if the expression given for the "State" above is true, the string
+   "false" otherwise.

+
+   
createLink

+   
Summary: Toggles whether the selection is a
+   link or not. If the second argument is true, and a link is to be
+   added, the user agent will ask the user for the address. Otherwise,
+   the third argument will be used as the address.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the a element (or, again,
+   unwrapped, or have that semantic inserted or removed, as defined by
+   the UA). If the user agent creates an a element or
+   modifies an existing a element, then if the showUI argument is present and has the value false,
+   then the value of the value argument must be
+   used as the URL of the link. Otherwise, the user agent
+   should prompt the user for the URL of the link.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
delete

+   
Summary: Deletes the selection or the
+   character before the cursor.

+   
Action: The user agent must act as if the user
+   had performed a backspace
+   operation.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
formatBlock

+   
Summary: Wraps the selection in the element
+   given by the second argument. If the second argument doesn't
+   specify an element that is a formatBlock
+   candidate, does nothing.

+   

+    
Action: The user agent must run the following
+    steps:

+    
  1. If the value argument wasn't
+     specified, abort these steps without doing anything.
    2. 
+     
  2. If the value argument has a leading
+     U+003C LESS-THAN SIGN character (<) and a trailing U+003E
+     GREATER-THAN SIGN character (>), then remove the first and last
+     characters from value.
    3. 
+     
  3. 
+      
    If value is (now) an ASCII
+      case-insensitive match for the tag name of an element
+      defined by this specification that is defined to be a
+      formatBlock candidate, then,
+      for every position in the selection, take the nearest
+      formatBlock candidate
+      ancestor element of that position that contains only
+      phrasing content, and, if that element is
+      editable, is not an editing host, and
+      has a parent element whose content model allows that parent to
+      contain any flow content, replace it with an
+      element in the HTML namespace whose name is value, and move all the children that were in it
+      to the new element, and copy all the attributes that were on it
+      to the new element.
    
+      
    If there is no selection, then, where in the description
+      above refers to the selection, the user agent must act as if the
+      selection was an empty range (with just one position) at the
+      caret position.
    
+     
    4. 
+    

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
forwardDelete

+   
Summary: Deletes the selection or the
+   character after the cursor.

+   
Action: The user agent must act as if the user
+   had performed a forward delete
+   operation.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertImage

+   
Summary: Toggles whether the selection is an
+   image or not. If the second argument is true, and an image is to be
+   added, the user agent will ask the user for the address. Otherwise,
+   the third argument will be used as the address.

+   
Action: The user agent must act
+   as if the user had requested that the selection be wrapped in the
+   semantics of the img element (or, again,
+   unwrapped, or have that semantic inserted or removed, as defined by
+   the UA). If the user agent creates an img element or
+   modifies an existing img element, then if the showUI argument is present and has the value false,
+   then the value of the value argument must be
+   used as the URL of the image. Otherwise, the user
+   agent should prompt the user for the URL of the image.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertHTML

+   
Summary: Replaces the selection with the value
+   of the third argument parsed as HTML.

+   

+    
Action: The user agent must run the following
+    steps:

+    
  1. If the document is an XML
+     document, then throw an INVALID_ACCESS_ERR
+     exception and abort these steps.
    2. 
+     
  2. If the value argument wasn't
+     specified, abort these steps without doing anything.
    3. 
+     
  3. If there is a selection, act as if the user had requested
+     that the selection be
+     deleted.
    4. 
+     
  4. Invoke the HTML fragment parsing algorithm
+     with an arbitrary orphan body element owned by the
+     same Document as the context element and with
+     the value argument as input.
    5. 
+     
  5. Insert the nodes returned by the previous step into the
+     document at the location of the caret, firing any mutation events
+     as appropriate.
    6. 
+    

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertLineBreak

+   
Summary: Inserts a line break.

+   
Action: The user agent must act as if the user
+   had requested a line
+   separator.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertOrderedList

+   
Summary: Toggles whether the selection is an ordered list.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the ol element (or unwrapped, or, if
+   there is no selection, have that semantic inserted or removed
+   — the exact behavior is UA-defined).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertUnorderedList

+   
Summary: Toggles whether the selection is an unordered list.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the ul element (or unwrapped, or, if
+   there is no selection, have that semantic inserted or removed
+   — the exact behavior is UA-defined).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertParagraph

+   
Summary: Inserts a paragraph break.

+   
Action: The user agent must act as if the user
+   had performed a break
+   block editing action.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
insertText

+   
Summary: Inserts the text given in the third parameter.

+   
Action: The user agent must act as if the user
+   had inserted text
+   corresponding to the value parameter.

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
italic

+   
Summary: Toggles whether the selection is italic.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the i element (or, again,
+   unwrapped, or have that semantic inserted or removed, as defined by
+   the UA).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: True if the selection, or the caret, if
+   there is no selection, is, or is contained within, a
+   i element. False otherwise.

+   
Value: The string "true"
+   if the expression given for the "State" above is true, the string
+   "false" otherwise.

+
+   
redo

+   
Summary: Acts as if the user had requested a redo.

+   
Action: The user agent must move forward one step in its undo
+   transaction history, restoring the associated state. If the
+   undo position is at the end of the undo
+   transaction history, the user agent must do nothing. See the
+   undo history.

+   
Enabled When: The undo position
+   is not at the end of the undo transaction
+   history.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
selectAll

+   
Summary: Selects all the editable content.

+   
Action: The user agent must change the
+   selection so that all the content in the currently focused
+   editing host is selected. If no editing
+   host is focused, then the content of the entire document
+   must be selected.

+   
Enabled When: Always.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
subscript

+   
Summary: Toggles whether the selection is subscripted.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the sub element (or, again,
+   unwrapped, or have that semantic inserted or removed, as defined by
+   the UA).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: True if the selection, or the caret, if
+   there is no selection, is, or is contained within, a
+   sub element. False otherwise.

+   
Value: The string "true"
+   if the expression given for the "State" above is true, the string
+   "false" otherwise.

+
+   
superscript

+   
Summary: Toggles whether the selection is superscripted.

+   
Action: The user agent must act as if the user
+   had requested that the selection be wrapped in the
+   semantics of the sup element (or unwrapped, or, if
+   there is no selection, have that semantic inserted or removed
+   — the exact behavior is UA-defined).

+   
Enabled When: The document is ready for
+   editing host commands.

+   
Indeterminate When: Never.

+   
State: True if the selection, or the caret, if
+   there is no selection, is, or is contained within, a
+   sup element. False otherwise.

+   
Value: The string "true"
+   if the expression given for the "State" above is true, the string
+   "false" otherwise.

+
+   
undo

+   
Summary: Acts as if the user had requested an undo.

+   
Action: The user agent must move back one step in its undo
+   transaction history, restoring the associated state. If the
+   undo position is at the start of the undo
+   transaction history, the user agent must do nothing. See the
+   undo history.

+   
Enabled When: The undo position
+   is not at the start of the undo transaction
+   history.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
unlink

+   
Summary: Removes all links from the selection.

+   
Action: The user agent must remove all
+   a elements that have href attributes and that are partially
+   or completely included in the current selection.

+   
Enabled When: The document has a selection
+   that is entirely within an editing host and that
+   contains (either partially or completely) at least one
+   a element that has an href attribute.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
unselect

+   
Summary: Unselects everything.

+   
Action: The user agent must change the
+   selection so that nothing is selected.

+   
Enabled When: Always.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+   
vendorID-customCommandID

+   
Action: User agents may implement
+   vendor-specific extensions to this API. Vendor-specific extensions
+   to the list of commands should use the syntax vendorID-customCommandID
+   so as to prevent clashes between extensions from different vendors
+   and future additions to this specification.

+   
Enabled When: UA-defined.

+   
Indeterminate When: UA-defined.

+   
State: UA-defined.

+   
Value: UA-defined.

+
+   
Anything else

+   
Action: User agents must do nothing.

+   
Enabled When: Never.

+   
Indeterminate When: Never.

+   
State: Always false.

+   
Value: Always the string "false".

+
+  
9 Communication

+
+  

+
+
+
+  
9.1 Event definitions

+
+  
Messages in server-sent events, Web
+  sockets, cross-document messaging, and
+  channel messaging use the message event.
+  
+  [EVENTSOURCE]
+  [WEBSOCKET]
+  
+  

+
+  
The following interface is defined for this event:

+
+  
interface MessageEvent : Event {
+  readonly attribute any data;
+  readonly attribute DOMString origin;
+  readonly attribute DOMString lastEventId;
+  readonly attribute WindowProxy source;
+  readonly attribute MessagePortArray ports;
+  void initMessageEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dataArg, in DOMString originArg, in DOMString lastEventIdArg, in WindowProxy sourceArg, in MessagePortArray portsArg);
+};

+
+  
event . data

+
+   

+
+    
Returns the data of the message.

+
+   

+
+   
event . origin

+
+   

+
+    
Returns the origin of the message, for server-sent
+    events and cross-document messaging.

+
+   

+
+   
event . lastEventId

+
+   

+
+    
Returns the last event ID, for server-sent
+    events.

+
+   

+
+   
event . source

+
+   

+
+    
Returns the WindowProxy of the source window, for
+    cross-document messaging.

+
+   

+
+   
event . ports

+
+   

+
+    
Returns the MessagePortArray sent with the
+    message, for cross-document messaging and
+    channel messaging.

+
+   

+
+  

+
+  
The initMessageEvent()
+  method must initialize the event in a manner analogous to the
+  similarly-named method in the DOM Events interfaces. [DOMEVENTS]

+
+  
The data
+  attribute represents the message being sent.

+
+  
The origin attribute
+  represents, in server-sent events and
+  cross-document messaging, the origin of
+  the document that sent the message (typically the scheme, hostname,
+  and port of the document, but not its path or fragment
+  identifier).

+
+  
The lastEventId
+  attribute represents, in server-sent events, the last event ID
+  string of the event source.

+
+  
The source attribute
+  represents, in cross-document messaging, the
+  WindowProxy of the browsing context of the
+  Window object from which the message came.

+
+  
The ports
+  attribute represents, in cross-document messaging and
+  channel messaging the MessagePortArray
+  being sent, if any.

+
+  
Except where otherwise specified, when the user agent creates and
+  dispatches a message event in the
+  algorithms described in the following sections, the lastEventId attribute
+  must be the empty string, the origin attribute must be the
+  empty string, the source attribute must be
+  null, and the ports
+  attribute must be null.

+
+  

+
+
+  

+
+
+
+
+  

+
+  
+
+  
9.2 Cross-document messaging

+
+  
Web browsers, for security and privacy reasons, prevent documents
+  in different domains from affecting each other; that is, cross-site
+  scripting is disallowed.

+
+  
While this is an important security feature, it prevents pages
+  from different domains from communicating even when those pages are
+  not hostile. This section introduces a messaging system that allows
+  documents to communicate with each other regardless of their source
+  domain, in a way designed to not enable cross-site scripting
+  attacks.

+
+  

+
+  
The task source for the tasks in cross-document
+  messaging is the posted message task source.

+
+  

+
+
+  
9.2.1 Introduction

+
+  
This section is non-normative.

+
+  

+
+   
For example, if document A contains an iframe
+   element that contains document B, and script in document A calls
+   postMessage() on the
+   Window object of document B, then a message event will
+   be fired on that object, marked as originating from the
+   Window of document A. The script in document A might
+   look like:

+
+   
var o = document.getElementsByTagName('iframe')[0];
+o.contentWindow.postMessage('Hello world', 'http://b.example.org/');

+
+   
To register an event handler for incoming events, the script
+   would use addEventListener() (or similar
+   mechanisms). For example, the script in document B might look
+   like:

+
+   
window.addEventListener('message', receiver, false);
+function receiver(e) {
+  if (e.origin == 'http://example.com') {
+    if (e.data == 'Hello world') {
+      e.source.postMessage('Hello', e.origin);
+    } else {
+      alert(e.data);
+    }
+  }
+}

+
+   
This script first checks the domain is the expected domain, and
+   then looks at the message, which it either displays to the user, or
+   responds to by sending a message back to the document which sent
+   the message in the first place.

+
+  

+
+
+  
9.2.2 Security

+
+  

+
+  
9.2.2.1 Authors

+
+  

+
+  
Use of this API requires extra
+  care to protect users from hostile entities abusing a site for their
+  own purposes.

+
+  
Authors should check the origin attribute to ensure
+  that messages are only accepted from domains that they expect to
+  receive messages from. Otherwise, bugs in the author's message
+  handling code could be exploited by hostile sites.

+
+  
Furthermore, even after checking the origin attribute, authors
+  should also check that the data in question is of the expected
+  format. Otherwise, if the source of the event has been attacked
+  using a cross-site scripting flaw, further unchecked processing of
+  information sent using the postMessage() method could
+  result in the attack being propagated into the receiver.

+
+  
Authors should not use the wildcard keyword (*) in the targetOrigin argument in messages that contain any
+  confidential information, as otherwise there is no way to guarantee
+  that the message is only delivered to the recipient to which it was
+  intended.

+
+
+  

+
+  
9.2.2.2 User agents

+
+  
The integrity of this API is based on the inability for scripts
+  of one origin to post arbitrary events (using dispatchEvent() or otherwise) to objects in other
+  origins (those that are not the same).

+
+  
Implementors are urged to take extra care in the
+  implementation of this feature. It allows authors to transmit
+  information from one domain to another domain, which is normally
+  disallowed for security reasons. It also requires that UAs be
+  careful to allow access to certain properties but not others.

+
+  

+
+
+  
9.2.3 Posting messages

+
+  
window . postMessage(message, targetOrigin [, ports ])

+
+   

+
+    
Posts a message, optionally with an array of ports, to the
+    given window.

+
+    
If the origin of the target window doesn't match the given
+    origin, the message is discarded, to avoid information leakage. To
+    send the message to the target regardless of origin, set the
+    target origin to "*". To restrict the
+    message to same-origin targets only, without needing to explicitly
+    state the origin, set the target origin to "/".

+
+    
Throws an INVALID_STATE_ERR if the ports array is not null and it contains either null
+    entries or duplicate ports.

+
+   

+
+  

+
+  
When a script invokes the postMessage(message, targetOrigin, ports) method (with two or three
+  arguments) on a Window object, the user agent must
+  follow these steps:
+
+  
  1. 
+
+    
    If the value of the targetOrigin argument
+    is neither a single U+002A ASTERISK character (*), a single U+002F
+    SOLIDUS character (/), nor an absolute URL with a
+    <host-specific>
+    component that is either empty or a single U+002F SOLIDUS
+    character (/), then throw a SYNTAX_ERR exception and
+    abort the overall set of steps.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    Let message clone be the result of
+    obtaining a structured clone of the message argument. If this throws an exception, then
+    throw that exception and abort these steps.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If the ports argument is present but either
+    any of the entries in ports are null, or any
+    MessagePort object is listed in ports more than once, or any of the
+    MessagePort objects listed in ports have already been cloned once before, then
+    throw an INVALID_STATE_ERR exception and abort these
+    steps.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Let new ports be an empty array.
    
+
+    
    If the ports argument is present, then for
+    each port in ports in turn, obtain a new port
+    by cloning the port with the
+    Window object on which the method was invoked as the
+    owner of the clone, and append the clone to the new
+    ports array.
    
+
+    
    If the original ports argument
+    was omitted or empty, then the new ports array
+    will be empty.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Return from the postMessage() method, but
+    asynchronously continue running these steps.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    If the targetOrigin argument is a single
+    literal U+002F SOLIDUS character (/), and the
+    Document of the Window object on which
+    the method was invoked does not have the same origin
+    as the entry script's document, then abort these steps silently.
    
+
+    
    Otherwise, if the targetOrigin argument is
+    an absolute URL, and the Document of the
+    Window object on which the method was invoked does
+    not have the same origin as targetOrigin, then abort these steps silently.
    
+
+    
    Otherwise, the targetOrigin argument is a
+    single literal U+002A ASTERISK character (*), and no origin check
+    is made.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Create an event that uses the MessageEvent
+    interface, with the event name message, which does not bubble, is
+    not cancelable, and has no default action. The data attribute must be set to
+    the value of message clone, the origin attribute must be
+    set to the Unicode serialization of the origin of
+    the script that invoked the method, the source attribute must be
+    set to the script's global object's
+    WindowProxy object, and the ports attribute must be set
+    to the new ports array.
     
+
+   
    8. 
+
+   
  8. 
+
+    
    Queue a task to dispatch the event created in the
+    previous step at the Window object on which the
+    method was invoked. The task source for this task is the posted message task
+    source.
    
+
+   
    9. 
+
+  

+
+
+
+  
9.3 Channel messaging

+
+  
9.3.1 Introduction

+
+  
This section is non-normative.

+
+  
To enable independent pieces of code (e.g. running in different
+  browsing contexts) to
+  communicate directly, authors can use channel
+  messaging.

+
+  
Communication channels in this mechanisms are implemented as
+  two-ways pipes, with a port at each end. Messages sent in one port
+  are delivered at the other port, and vice-versa. Messages are
+  asynchronous, and delivered as DOM events.

+
+  
To create a connection (two "entangled" ports), the MessageChannel() constructor is called:

+
+  
var channel = new MessageChannel();

+
+  
One of the ports is kept as the local port, and the other port is
+  sent to the remote code, e.g. using postMessage():

+
+  
otherWindow.postMessage('hello', 'http://example.com', [channel.port2]);

+
+  
To send messages, the postMessage() method on
+  the port is used:

+
+  
channel.port1.postMessage('hello');

+
+  
To receive messages, one listens to message events:

+
+  
channel.port1.onmessage = handleMessage;
+function handleMessage(event) {
+  // message is in event.data
+  // ...
+}

+
+
+  
9.3.2 Message channels

+
+  
[Constructor]
+interface MessageChannel {
+  readonly attribute MessagePort port1;
+  readonly attribute MessagePort port2;
+};

+
+  
channel = new MessageChannel()

+
+   

+
+    
Returns a new MessageChannel object with two new MessagePort objects.

+
+   

+
+   
channel . port1

+
+   

+
+    
Returns the first MessagePort object.

+
+   

+
+   
channel . port2

+
+   

+
+    
Returns the second MessagePort object.

+
+   

+
+  

+
+  
When the MessageChannel()
+  constructor is called, it must run the following algorithm:

+
+  
  1. Create a new MessagePort object
+   owned by the script's global object, and let port1 be that object.
    2. 
+
+   
  2. Create a new MessagePort object
+   owned by the script's global object, and let port2 be that object.
    3. 
+
+   
  3. Entangle the port1 and port2 objects.
    4. 
+
+   
  4. Instantiate a new MessageChannel object, and
+   let channel be that object.
    5. 
+
+   
  5. Let the port1
+   attribute of the channel object be port1.
    
+
+   
  6. Let the port2
+   attribute of the channel object be port2.
    
+
+   
  7. Return channel.
    8. 
+
+  
This constructor must be visible when the script's global
+  object is either a Window object or an object
+  implementing the WorkerUtils interface.

+
+  
The port1 and
+  port2 attributes
+  must return the values they were assigned when the
+  MessageChannel object was created.

+
+  

+
+
+
+  
9.3.3 Message ports

+
+  
Each channel has two message ports. Data sent through one port is
+  received by the other port, and vice versa.

+
+  
typedef sequence<MessagePort> MessagePortArray;
+
+interface MessagePort {
+  void postMessage(in any message, in optional MessagePortArray ports);
+  void start();
+  void close();
+
+  // event handlers
+           attribute Function onmessage;
+};
+MessagePort implements EventTarget;

+
+  
port . postMessage(message [, ports] )

+
+   

+
+    
Posts a message through the channel, optionally with the given
+    ports.

+
+    
Throws an INVALID_STATE_ERR if the ports array is not null and it contains either null
+    entries, duplicate ports, or the source or target port.

+
+   

+
+   
port . start()

+
+   

+
+    
Begins dispatching messages received on the port.

+
+   

+
+   
port . close()

+
+   

+
+    
Disconnects the port, so that it is no longer active.

+
+   

+
+  

+
+  
Each MessagePort object can be entangled with
+  another (a symmetric relationship). Each MessagePort
+  object also has a task source called the port
+  message queue, initial empty. A port message
+  queue can be enabled or disabled, and is initially
+  disabled. Once enabled, a port can never be disabled again (though
+  messages in the queue can get moved to another queue or removed
+  altogether, which has much the same effect).

+
+  
When the user agent is to create a new
+  MessagePort object owned by a script's
+  global object object owner, it must
+  instantiate a new MessagePort object, and let its owner
+  be owner.

+
+  
When the user agent is to entangle two
+  MessagePort objects, it must run the following
+  steps:

+
+  
  1. 
+
+    
    If one of the ports is already entangled, then disentangle it
+    and the port that it was entangled with.
    
+
+    
    If those two previously entangled ports were the
+    two ports of a MessageChannel object, then that
+    MessageChannel object no longer represents an actual
+    channel: the two ports in that object are no longer entangled.
    
+
+   
    2. 
+
+   
  2. Associate the two ports to be entangled, so that they form
+   the two parts of a new channel. (There is no
+   MessageChannel object that represents this
+   channel.)
    3. 
+
+  
When the user agent is to clone a port original port, with the clone being owned by owner, it must run the following steps, which return
+  a new MessagePort object. These steps must be run
+  atomically.

+
+  
  1. Create a new MessagePort object
+   owned by owner, and let new
+   port be that object.
    2. 
+
+   
  2. Move all the events in the port message queue
+   of original port to the port message
+   queue of new port, if any, leaving the
+   new port's port message queue in
+   its initial disabled state.
    3. 
+
+   
  3. 
+
+    
    If the original port is entangled with
+    another port, then run these substeps:
    
+
+    
    1. Let the remote port be the port with
+     which the original port is entangled.
      2. 
+
+     
    2. Entangle the remote port
+     and new port objects. The original port object will be disentangled by this
+     process.
      3. 
+
+    
    4. 
+
+   
  4. Return new port. It is the
+   clone.
    5. 
+
+  
The postMessage()
+  method, when called on a port source port, must
+  cause the user agent to run the following steps:

+
+  
  1. Let target port be the port with which
+   source port is entangled, if any.
    2. 
+
+   
  2. If the method was called with a second argument ports and that argument isn't null, then, if any of
+   the entries in ports are null, if any
+   MessagePort object is listed in ports more than once, if any of the
+   MessagePort objects listed in ports have already been cloned once before, or if
+   any of the entries in ports are either the source port or the target port
+   (if any), then throw an INVALID_STATE_ERR
+   exception.
    3. 
+
+   
  3. If there is no target port (i.e. if source port is not entangled), then abort these
+   steps.
    4. 
+   
+
+   
  4. Create an event that uses the MessageEvent
+   interface, with the name message, which does not bubble, is not
+   cancelable, and has no default action.
    5. 
+
+   
  5. Let message be the method's first
+   argument.
    6. 
+
+   
  6. Let message clone be the result of
+   obtaining a structured clone of message. If this throws an exception, then throw
+   that exception and abort these steps.
    7. 
+
+   
  7. Let the data
+   attribute of the event have the value of message
+   clone.
    8. 
+
+   
  8. If the method was called with a second argument ports and that argument isn't null, then run the
+   following substeps:
    
+
+    
    1. 
+
+      
      Let new ports be an empty array.
      
+
+      
      For each port in ports in turn,
+      obtain a new port by cloning
+      the port with the owner of the target port
+      as the owner of the clone, and append the clone to the new ports array.
      
+
+      
      If the original ports
+      array was empty, then the new ports array will
+      also be empty.
      
+
+     
      2. 
+
+     
    2. Let the ports
+     attribute of the event be the new ports
+     array.
      3. 
+
+    
    9. 
+
+   
  9. Add the event to the port message queue of target port.
    10. 
+
+  
The start()
+  method must enable its port's port message queue, if it
+  is not already enabled.

+
+  
When a port's port message queue is enabled, the
+  event loop must use it as one of its task sources.

+
+  
If the Document of the port's event
+  listeners' global object
+  is not fully active, then the messages are lost.

+  
+
+  
The close()
+  method, when called on a port local port that is
+  entangled with another port, must cause the user agents to
+  disentangle the two ports. If the method is called on a port that is
+  not entangled, then the method must do nothing.

+
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported, as IDL attributes, by
+  all objects implementing the MessagePort interface:

+
+  
Event handler Event handler event type
+   
onmessage  message
+  
The first time a MessagePort object's onmessage IDL attribute
+  is set, the port's port message queue must be enabled,
+  as if the start() method
+  had been called.

+
+  

+
+
+  
9.3.3.1 Ports and garbage collection

+
+  

+
+  
When a MessagePort object o is
+  entangled, user agents must either act as if o's
+  entangled MessagePort object has a strong reference to
+  o, or as if o's owner has a
+  strong reference to o.

+
+  

+
+   
Thus, a message port can be received, given an event listener,
+   and then forgotten, and so long as that event listener could
+   receive a message, the channel will be maintained.

+
+   
Of course, if this was to occur on both sides of the channel,
+   then both ports could be garbage collected, since they would not be
+   reachable from live code, despite having a strong reference to each
+   other.

+
+  

+
+  
Furthermore, a MessagePort object must not be
+  garbage collected while there exists a message in a task
+  queue that is to be dispatched on that
+  MessagePort object, or while the
+  MessagePort object's port message queue is
+  open and there exists a message
+  event in that queue.

+  
+
+  
+
+  

+
+  
Authors are strongly encouraged to explicitly close
+  MessagePort objects to disentangle them, so that their
+  resources can be recollected. Creating many MessagePort
+  objects and discarding them without closing them can lead to high
+  memory usage.

+
+
+
+  

+
+
+
+
+  
10 The HTML syntax

+
+  
This section only describes the rules for resources
+  labeled with an HTML MIME type. Rules for XML resources
+  are discussed in the section below entitled "The XHTML
+  syntax".

+
+
+  
10.1 Writing HTML documents

+
+  

+
+  
This section only applies to documents, authoring tools, and
+  markup generators. In particular, it does not apply to conformance
+  checkers; conformance checkers must use the requirements given in
+  the next section ("parsing HTML documents").

+
+  

+
+  
Documents must consist of the following parts, in the given
+  order:

+
+  
  1. Optionally, a single U+FEFF BYTE ORDER MARK (BOM) character.
    2. 
+
+   
  2. Any number of comments and
+   space characters.
    3. 
+
+   
  3. A DOCTYPE.
+
+   
  4. Any number of comments and
+   space characters.
    5. 
+
+   
  5. The root element, in the form of an html element.
    6. 
+
+   
  6. Any number of comments and
+   space characters.
    7. 
+
+  
The various types of content mentioned above are described in the
+  next few sections.

+
+  
In addition, there are some restrictions on how character encoding
+  declarations are to be serialized, as discussed in the
+  section on that topic.

+
+  

+
+   
Space characters before the root html element, and
+   space characters at the start of the html element and
+   before the head element, will be dropped when the
+   document is parsed; space characters after the root
+   html element will be parsed as if they were at the end
+   of the body element. Thus, space characters around the
+   root element do not round-trip.

+
+   
It is suggested that newlines be inserted after the DOCTYPE,
+   after any comments that are before the root element, after the
+   html element's start tag (if it is not omitted), and after any comments
+   that are inside the html element but before the
+   head element.

+
+  

+
+  
Many strings in the HTML syntax (e.g. the names of elements and
+  their attributes) are case-insensitive, but only for characters in
+  the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL
+  LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL
+  LETTER Z). For convenience, in this section this is just referred to
+  as "case-insensitive".

+
+
+  
10.1.1 The DOCTYPE

+
+  
A DOCTYPE is a  required preamble.

+
+  
DOCTYPEs are required for legacy reasons. When
+  omitted, browsers tend to use a different rendering mode that is
+  incompatible with some specifications. Including the DOCTYPE in a
+  document ensures that the browser makes a best-effort attempt at
+  following the relevant specifications.

+
+  
A DOCTYPE must consist of the following characters, in this
+  order:

+
+  
  1. A string that is an ASCII case-insensitive match for the string "<!DOCTYPE".
    2. 
+   
  2. One or more space characters.
    3. 
+   
  3. A string that is an ASCII case-insensitive match for the string "HTML".
    4. 
+   
  4. Optionally, a DOCTYPE legacy string or an obsolete permitted DOCTYPE string (defined below).
    5. 
+   
  5. Zero or more space characters.
    6. 
+   
  6. A U+003E GREATER-THAN SIGN character (>).
    7. 
+  
In other words, <!DOCTYPE HTML>,
+  case-insensitively.

+
+  
For the purposes of HTML generators that cannot output HTML
+  markup with the short DOCTYPE "<!DOCTYPE
+  HTML>", a DOCTYPE legacy string may be inserted
+  into the DOCTYPE (in the position defined above). This string must
+  consist of:

+
+  
  1. One or more space characters.
    2. 
+   
  2. A string that is an ASCII case-insensitive match for the string "SYSTEM".
    3. 
+   
  3. One or more space characters.
    4. 
+   
  4. A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the quote mark).
    5. 
+   
  5. The literal string "about:legacy-compat".
    6. 
+   
  6. A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step labeled quote mark).
    7. 
+  
In other words, <!DOCTYPE HTML SYSTEM
+  "about:legacy-compat"> or <!DOCTYPE HTML SYSTEM
+  'about:legacy-compat'>, case-insensitively except for the bit
+  in single or double quotes.

+
+  
The DOCTYPE legacy string should not be used unless
+  the document is generated from a system that cannot output the
+  shorter string.

+
+  
To help authors transition from HTML4 and XHTML1, an
+  obsolete permitted DOCTYPE string can be inserted into
+  the DOCTYPE (in the position defined above). This string must
+  consist of:

+
+  
  1. One or more space characters.
    2. 
+   
  2. A string that is an ASCII case-insensitive match for the string "PUBLIC".
    3. 
+   
  3. One or more space characters.
    4. 
+   
  4. A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the first quote mark).
    5. 
+   
  5. The string from one of the cells in the first column of the table below. The row to which this cell belongs is the selected row.
    6. 
+   
  6. A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step labeled first quote mark).
    7. 
+   
  7. If the cell in the second column of the selected row is not blank, one or more space characters.
    8. 
+   
  8. If the cell in the second column of the selected row is not blank, a U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the third quote mark).
    9. 
+   
  9. If the cell in the second column of the selected row is not blank, the string from the cell in the second column of the selected row.
    10. 
+   
  10. If the cell in the second column of the selected row is not blank, a matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step labeled third quote mark).
    11. 
+  

+   

+    Allowed values for public and system identifiers in an obsolete permitted DOCTYPE string.
+   
 Public identifier
+      System identifier
+   
 -//W3C//DTD HTML 4.0//EN
+     
+    
 -//W3C//DTD HTML 4.0//EN
+      http://www.w3.org/TR/REC-html40/strict.dtd
+    
 -//W3C//DTD HTML 4.01//EN
+     
+    
 -//W3C//DTD HTML 4.01//EN
+      http://www.w3.org/TR/html4/strict.dtd
+    
 -//W3C//DTD XHTML 1.0 Strict//EN
+      http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
+    
 -//W3C//DTD XHTML 1.1//EN
+      http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
+  
A DOCTYPE containing an
+  obsolete permitted DOCTYPE string is an obsolete
+  permitted DOCTYPE. Authors should not use obsolete permitted
+  DOCTYPEs, as they are unnecessarily long.

+
+
+
+
+  
10.1.2 Elements

+
+  
There are five different kinds of elements: void elements,
+  raw text elements, RCDATA elements,
+  foreign elements, and normal elements.

+
+  
Void elements

+
+   
area, base, br,
+   col, command, embed,
+   hr, img, input,
+   keygen, link, meta,
+   param, source, track,
+   wbr

+
+   
Raw text elements

+
+   
script, style
 
+
+   
RCDATA elements

+
+   
textarea, title

+
+   
Foreign elements

+
+   
Elements from the MathML namespace
+   and the SVG namespace.

+
+   
Normal elements

+
+   
All other allowed HTML elements are normal
+   elements.

+
+  
Tags are used to delimit the start
+  and end of elements in the markup. Raw text, RCDATA, and normal elements have a start tag to indicate where they
+  begin, and an end tag to
+  indicate where they end. The start and end tags of certain
+  normal elements can be omitted, as described
+  later. Those that cannot be omitted must not be omitted. Void
+  elements only have a start tag; end tags must not be
+  specified for void elements. Foreign
+  elements must either have a start tag and an end tag, or a
+  start tag that is marked as self-closing, in which case they must
+  not have an end tag.

+
+  
The contents of the element must be placed between just after the
+  start tag (which might be implied,
+  in certain cases) and just before the end tag (which again,
+  might be implied in certain
+  cases). The exact allowed contents of each individual element
+  depends on the content model of that element, as described earlier
+  in this specification. Elements must not contain content that their
+  content model disallows. In addition to the restrictions placed on
+  the contents by those content models, however, the five types of
+  elements have additional syntactic requirements.

+
+  
Void elements can't have any contents (since there's
+  no end tag, no content can be put between the start tag and the end
+  tag).

+
+  
Raw text elements can have text, though it has restrictions described
+  below.

+
+  
RCDATA elements can have text and character references, but the text
+  must not contain an ambiguous ampersand.
+  There are also further
+  restrictions described below.

+
+  
Foreign elements whose start tag is marked as
+  self-closing can't have any contents (since, again, as there's no
+  end tag, no content can be put between the start tag and the end
+  tag). Foreign elements whose start tag is not
+  marked as self-closing can have text, character references, CDATA sections, other elements, and comments, but the text must not
+  contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand.

+
+  

+
+   
The HTML syntax does not support namespace
+   declarations, even in foreign elements.

+
+   
For instance, consider the following HTML fragment:

+
+   
<p>
+ <svg>
+  <metadata>
+   <!-- this is invalid -->
+   <cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/>
+  </metadata>
+ </svg>
+</p>

+
+   
The innermost element, cdr:license, is
+   actually in the SVG namespace, as the "xmlns:cdr" attribute has no effect (unlike in
+   XML). In fact, as the comment in the fragment above says, the
+   fragment is actually non-conforming. This is because the SVG
+   specification does not define any elements called "cdr:license" in the SVG namespace.

+
+  

+
+  
Normal elements can have text, character references, other elements, and comments, but the text must not
+  contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand. Some
+  normal elements also have yet more restrictions on what
+  content they are allowed to hold, beyond the restrictions imposed by
+  the content model and those described in this paragraph. Those
+  restrictions are described below.

+
+  
Tags contain a tag name,
+  giving the element's name. HTML elements all have names that only
+  use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+  NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
+  Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER
+  Z. In the HTML syntax, tag names, even those for foreign
+  elements, may be written with any mix of lower- and uppercase
+  letters that, when converted to all-lowercase, matches the element's
+  tag name; tag names are case-insensitive.

+
+
+  
10.1.2.1 Start tags

+
+  
Start tags must have the
+  following format:

+
+  
  1. The first character of a start tag must be a U+003C LESS-THAN
+   SIGN character (<).
    2. 
+
+   
  2. The next few characters of a start tag must be the element's
+   tag name.
    3. 
+
+   
  3. If there are to be any attributes in the next step, there must
+   first be one or more space
+   characters.
    4. 
+
+   
  4. Then, the start tag may have a number of attributes, the syntax for which is described
+   below. Attributes may be separated from each other by one or more
+   space characters.
    5. 
+
+   
  5. After the attributes, or after the tag name if there are no attributes,
+   there may be one or more space
+   characters. (Some attributes are required to be followed by
+   a space. See the attributes
+   section below.)
    6. 
+
+   
  6. Then, if the element is one of the void elements,
+   or if the element is a foreign
+   element, then there may be a single U+002F SOLIDUS character
+   (/). This character has no effect on void elements,
+   but on foreign elements it marks the start tag as
+   self-closing.
    7. 
+
+   
  7. Finally, start tags must be closed by a U+003E GREATER-THAN
+   SIGN character (>).
    8. 
+
+  
10.1.2.2 End tags

+
+  
End tags must have the
+  following format:

+
+  
  1. The first character of an end tag must be a U+003C LESS-THAN
+   SIGN character (<).
    2. 
+
+   
  2. The second character of an end tag must be a U+002F SOLIDUS
+   character (/).
    3. 
+
+   
  3. The next few characters of an end tag must be the element's
+   tag name.
    4. 
+
+   
  4. After the tag name, there may be one or more space characters.
    5. 
+
+   
  5. Finally, end tags must be closed by a U+003E GREATER-THAN SIGN
+   character (>).
    6. 
+
+  
10.1.2.3 Attributes

+
+  
Attributes for an element
+  are expressed inside the element's start tag.

+
+  
Attributes have a name and a value. Attribute names must consist of
+  one or more characters other than the space characters, U+0000 NULL, U+0022 QUOTATION
+  MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN
+  (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters,
+  the control characters, and any characters that are not defined by
+  Unicode. In the HTML syntax, attribute names, even those for
+  foreign elements, may be written with any mix of lower-
+  and uppercase letters that are an ASCII
+  case-insensitive match for the attribute's name.

+
+  
Attribute values are a
+  mixture of text and character references, except with the
+  additional restriction that the text cannot contain an ambiguous ampersand.

+
+  
Attributes can be specified in four different ways:

+
+  
Empty attribute syntax

+
+   

+
+    
Just the attribute
+    name. The value is implicitly the empty string.

+
+    

+
+     
In the following example, the disabled attribute is given with
+     the empty attribute syntax:

+
+     
<input disabled>

+
+    

+
+    
If an attribute using the empty attribute syntax is to be
+    followed by another attribute, then there must be a space
+    character separating the two.

+
+   

+
+   
Unquoted attribute value syntax

+
+   

+
+    
The attribute name,
+    followed by zero or more space
+    characters, followed by a single U+003D EQUALS SIGN
+    character, followed by zero or more space characters, followed by the attribute value, which, in
+    addition to the requirements given above for attribute values,
+    must not contain any literal space
+    characters, any U+0022 QUOTATION MARK characters ("),
+    U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN
+    characters (=), U+003C LESS-THAN SIGN characters (<), U+003E
+    GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT
+    characters (`), and must not be the empty string.

+
+    
+
+
+    

+
+     
In the following example, the value attribute is given
+     with the unquoted attribute value syntax:

+
+     
<input value=yes>

+
+    

+
+    
If an attribute using the unquoted attribute syntax is to be
+    followed by another attribute or by the optional U+002F SOLIDUS
+    character (/) allowed in step 6 of the start tag syntax above, then there
+    must be a space character separating the two.

+
+   

+
+   
Single-quoted attribute value syntax

+
+   

+
+    
The attribute name,
+    followed by zero or more space
+    characters, followed by a single U+003D EQUALS SIGN
+    character, followed by zero or more space characters, followed by a single U+0027
+    APOSTROPHE character ('), followed by the attribute value, which, in
+    addition to the requirements given above for attribute values,
+    must not contain any literal U+0027 APOSTROPHE characters ('), and
+    finally followed by a second single U+0027 APOSTROPHE character
+    (').

+
+    

+
+     
In the following example, the type attribute is given with the
+     single-quoted attribute value syntax:

+
+     
<input type='checkbox'>

+
+    

+
+    
If an attribute using the single-quoted attribute syntax is to
+    be followed by another attribute, then there must be a space
+    character separating the two.

+
+   

+
+   
Double-quoted attribute value syntax

+
+   

+
+    
The attribute name,
+    followed by zero or more space
+    characters, followed by a single U+003D EQUALS SIGN
+    character, followed by zero or more space characters, followed by a single U+0022
+    QUOTATION MARK character ("), followed by the attribute value, which, in
+    addition to the requirements given above for attribute values,
+    must not contain any literal U+0022 QUOTATION MARK characters ("),
+    and finally followed by a second single U+0022 QUOTATION MARK
+    character (").

+
+    

+
+     
In the following example, the name attribute is given with the
+     double-quoted attribute value syntax:

+
+     
<input name="be evil">

+
+    

+
+    
If an attribute using the double-quoted attribute syntax is to
+    be followed by another attribute, then there must be a space
+    character separating the two.

+
+   

+
+  
There must never be two or more attributes on the same start tag
+  whose names are an ASCII case-insensitive match for
+  each other.

+
+  
When a foreign element has
+  one of the namespaced attributes given by the local name and
+  namespace of the first and second cells of a row from the following
+  table, it must be written using the name given by the third cell
+  from the same row.

+
+  
 Local name  Namespace  Attribute name
+   
 actuate  XLink namespace  xlink:actuate
+    
 arcrole  XLink namespace  xlink:arcrole
+    
 href  XLink namespace  xlink:href
+    
 role  XLink namespace  xlink:role
+    
 show  XLink namespace  xlink:show
+    
 title  XLink namespace  xlink:title
+    
 type  XLink namespace  xlink:type
+    
 base  XML namespace   xml:base
+    
 lang  XML namespace  xml:lang
+    
 space  XML namespace  xml:space
+    
 xmlns  XMLNS namespace  xmlns
+    
 xlink  XMLNS namespace  xmlns:xlink
+  
No other namespaced attribute can be expressed in the
+  HTML syntax.

+
+
+  
10.1.2.4 Optional tags

+
+  
Certain tags can be omitted.

+
+  
Omitting an element's start tag does not mean the element
+  is not present; it is implied, but it is still there. An HTML
+  document always has a root html element, even if the
+  string <html> doesn't appear anywhere in
+  the markup.

+
+  
+  
An html element's start tag may be omitted if the
+  first thing inside the html element is not a comment.

+
+  
+  
An html element's end
+  tag may be omitted if the html element is not
+  immediately followed by a comment.

+
+  
+  
A head element's start tag may be omitted if the
+  element is empty, or if the first thing inside the
+  head element is an element.

+
+  
+  
A head element's end
+  tag may be omitted if the head element is not
+  immediately followed by a space character or a comment.

+
+  
+  
A body element's start tag may be omitted if the
+  element is empty, or if the first thing inside the body
+  element is not a space character or a comment, except if the first thing
+  inside the body element is a script or
+  style element. 

+
+  
+  
A body element's end
+  tag may be omitted if the body element is not
+  immediately followed by a comment.

+
+  
+  
A li element's end
+  tag may be omitted if the li element is
+  immediately followed by another li element or if there
+  is no more content in the parent element.

+
+  
+  
A dt element's end
+  tag may be omitted if the dt element is
+  immediately followed by another dt element or a
+  dd element.

+
+  
+  
A dd element's end
+  tag may be omitted if the dd element is
+  immediately followed by another dd element or a
+  dt element, or if there is no more content in the
+  parent element.

+
+  
+  
A p element's end
+  tag may be omitted if the p element is
+  immediately followed by an address,
+  article, aside, blockquote,
+   dir,
+  div, dl, fieldset,
+  footer, form, h1,
+  h2, h3, h4, h5,
+  h6, header, hgroup,
+  hr, menu, nav,
+  ol, p, pre,
+  section, table, or ul,
+  element, or if there is no more content in the parent element and
+  the parent element is not an a element.

+
+  
+  
An rt element's end
+  tag may be omitted if the rt element is
+  immediately followed by an rt or rp
+  element, or if there is no more content in the parent element.

+
+  
+  
An rp element's end
+  tag may be omitted if the rp element is
+  immediately followed by an rt or rp
+  element, or if there is no more content in the parent element.

+
+  
+  
An optgroup element's end tag may be omitted if the
+  optgroup element  is immediately followed by
+  another optgroup element, or if  there is no
+  more content in the parent element.

+  
+
+  
+  
An option element's end
+  tag may be omitted if the option element is
+  immediately followed by another option element, or if
+  it is immediately followed by an optgroup element, or
+  if there is no more content in the parent element.

+
+  
+  
A colgroup element's start tag may be omitted if the
+  first thing inside the colgroup element is a
+  col element, and if the element is not immediately
+  preceded by another colgroup element whose end tag has been omitted. (It can't be
+  omitted if the element is empty.)

+
+  
+  
A colgroup element's end tag may be omitted if the
+  colgroup element is not immediately followed by a
+  space character or a comment.

+
+  
+  
A thead element's end
+  tag may be omitted if the thead element is
+  immediately followed by a tbody or tfoot
+  element.

+
+  
+  
A tbody element's start tag may be omitted if the
+  first thing inside the tbody element is a
+  tr element, and if the element is not immediately
+  preceded by a tbody, thead, or
+  tfoot element whose end
+  tag has been omitted. (It can't be omitted if the element is
+  empty.)

+
+  
+  
A tbody element's end
+  tag may be omitted if the tbody element is
+  immediately followed by a tbody or tfoot
+  element, or if there is no more content in the parent element.

+
+  
+  
A tfoot element's end
+  tag may be omitted if the tfoot element is
+  immediately followed by a tbody element, or if there is
+  no more content in the parent element.

+
+  
+  
A tr element's end
+  tag may be omitted if the tr element is
+  immediately followed by another tr element, or if there
+  is no more content in the parent element.

+
+  
+  
A td element's end
+  tag may be omitted if the td element is
+  immediately followed by a td or th
+  element, or if there is no more content in the parent element.

+
+  
+  
A th element's end
+  tag may be omitted if the th element is
+  immediately followed by a td or th
+  element, or if there is no more content in the parent element.

+
+  
However, a start
+  tag must never be omitted if it has any attributes.

+
+
+  
10.1.2.5 Restrictions on content models

+
+  
For historical reasons, certain elements have extra restrictions
+  beyond even the restrictions given by their content model.

+
+  
A table element must not contain tr
+  elements, even though these elements are technically allowed inside
+  table elements according to the content models
+  described in this specification. (If a tr element is
+  put inside a table in the markup, it will in fact imply
+  a tbody start tag before it.)

+
+  
A single newline may be
+  placed immediately after the start
+  tag of pre and textarea
+  elements. This does not affect the processing of the element. The
+  otherwise optional newline
+  must be included if the element's contents themselves start
+  with a newline (because
+  otherwise the leading newline in the contents would be treated like
+  the optional newline, and ignored).

+
+  

+   
The following two pre blocks are equivalent:

+   
<pre>Hello</pre>

+   
<pre>
Hello</pre>

+  

+
+
+  
10.1.2.6 Restrictions on the contents of raw text and RCDATA elements

+
+  
The text in raw text and
+  RCDATA elements must not contain any occurrences of the
+  string "</" (U+003C LESS-THAN SIGN, U+002F
+  SOLIDUS) followed by characters that case-insensitively match the
+  tag name of the element followed by one of U+0009 CHARACTER
+  TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D
+  CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or
+  U+002F SOLIDUS (/).

+
+
+  
10.1.3 Text

+
+  
Text is allowed inside elements,
+  attributes, and comments. Text must consist of Unicode characters.
+  Text must not contain U+0000 characters. Text must not contain
+  permanently undefined Unicode characters (noncharacters). Text must
+  not contain control characters other than space characters. Extra constraints are placed on
+  what is and what is not allowed in text based on where the text is
+  to be put, as described in the other sections.

+
+
+  
10.1.3.1 Newlines

+
+  
Newlines in HTML may be
+  represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A
+  LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR),
+  U+000A LINE FEED (LF) characters in that order.

+
+  
Where character references
+  are allowed, a character reference of a U+000A LINE FEED (LF)
+  character (but not a U+000D CARRIAGE RETURN (CR) character) also
+  represents a newline.

+
+
+  
10.1.4 Character references

+
+  
In certain cases described in other sections, text may be mixed with character references. These can be used
+  to escape characters that couldn't otherwise legally be included in
+  text.

+
+  
Character references must start with a U+0026 AMPERSAND character
+  (&). Following this, there are three possible kinds of character
+  references:

+
+  
Named character references

+
+   
The ampersand must be followed by one of the names given in the
+   named character references section, using the same
+   case. The name must be one that is terminated by
+   a U+003B SEMICOLON character (;).

+
+
+   
Decimal numeric character reference

+
+   
The ampersand must be followed by a U+0023 NUMBER SIGN
+   character (#), followed by one or more digits in the range U+0030
+   DIGIT ZERO (0) to U+0039 DIGIT NINE (9), representing a base-ten
+   integer that corresponds to a Unicode code point that is allowed
+   according to the definition below. The digits must then be followed
+   by a U+003B SEMICOLON character (;).

+
+
+   
Hexadecimal numeric character reference

+
+   
The ampersand must be followed by a U+0023 NUMBER SIGN
+   character (#), which must be followed by either a U+0078 LATIN
+   SMALL LETTER X character (x) or a U+0058 LATIN CAPITAL LETTER X
+   character (X), which must then be followed by one or more digits in
+   the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061
+   LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041
+   LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F,
+   representing a base-sixteen integer that corresponds to a Unicode
+   code point that is allowed according to the definition below. The
+   digits must then be followed by a U+003B SEMICOLON character
+   (;).

+
+  
The numeric character reference forms described above are allowed
+  to reference any Unicode code point other than U+0000, U+000D,
+  permanently undefined Unicode characters (noncharacters), and
+  control characters other than space
+  characters.

+
+  
An ambiguous
+  ampersand is a U+0026 AMPERSAND character (&) that is
+  followed by one or more characters in the range U+0030 DIGIT ZERO
+  (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A
+  LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A
+  LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character
+  (;), where these characters do not match any of the names given in
+  the named character references section.

+
+
+  
10.1.5 CDATA sections

+
+  
CDATA sections must start with
+  the character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
+  MARK, U+005B LEFT SQUARE BRACKET, U+0043 LATIN CAPITAL LETTER C,
+  U+0044 LATIN CAPITAL LETTER D, U+0041 LATIN CAPITAL LETTER A, U+0054
+  LATIN CAPITAL LETTER T, U+0041 LATIN CAPITAL LETTER A, U+005B LEFT
+  SQUARE BRACKET (<![CDATA[). Following this
+  sequence, the CDATA section may have text, with the additional restriction
+  that the text must not contain the three character sequence U+005D
+  RIGHT SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E
+  GREATER-THAN SIGN (]]>). Finally, the CDATA
+  section must be ended by the three character sequence U+005D RIGHT
+  SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E GREATER-THAN
+  SIGN (]]>).

+
+  

+
+   
CDATA sections can only be used in foreign content (MathML or
+   SVG). In this example, a CDATA section is used to escape the
+   contents of an ms element:

+
+   
<p>You can add a string to a number, but this stringifies the number:</p>
+<math>
+ <ms><![CDATA[x<y]]></ms>
+ <mo>+</mo>
+ <mn>3</mn>
+ <mo>=</mo>
+ <ms><![CDATA[x<y3]]></ms>
+</math>

+
+  

+
+
+  
10.1.6 Comments

+
+  
Comments must start with the
+  four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
+  MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<!--). Following this sequence, the comment may
+  have text, with the additional
+  restriction that the text must not start with a single U+003E
+  GREATER-THAN SIGN character (>), nor start with a U+002D
+  HYPHEN-MINUS character (-) followed by a U+003E GREATER-THAN SIGN
+  (>) character, nor contain two consecutive U+002D HYPHEN-MINUS
+  characters (--), nor end with a U+002D
+  HYPHEN-MINUS character (-). Finally, the comment must be ended by
+  the three character sequence U+002D HYPHEN-MINUS, U+002D
+  HYPHEN-MINUS, U+003E GREATER-THAN SIGN (-->).

+
+
+  

+
+  
10.2 Parsing HTML documents

+
+  
This section only applies to user agents, data mining tools,
+  and conformance checkers.

+
+  
The rules for parsing XML documents into DOM trees
+  are covered by the next section, entitled "The XHTML
+  syntax".

+
+  
For HTML documents, user agents must use the parsing
+  rules described in this section to generate the DOM trees. Together,
+  these rules define what is referred to as the HTML
+  parser.

+
+  

+
+   
While the HTML syntax described in this specification bears a
+   close resemblance to SGML and XML, it is a separate language with
+   its own parsing rules.

+
+   
Some earlier versions of HTML (in particular from HTML2 to
+   HTML4) were based on SGML and used SGML parsing rules. However, few
+   (if any) web browsers ever implemented true SGML parsing for HTML
+   documents; the only user agents to strictly handle HTML as an SGML
+   application have historically been validators. The resulting
+   confusion — with validators claiming documents to have one
+   representation while widely deployed Web browsers interoperably
+   implemented a different representation — has wasted decades
+   of productivity. This version of HTML thus returns to a non-SGML
+   basis.

+
+   
Authors interested in using SGML tools in their authoring
+   pipeline are encouraged to use XML tools and the XML serialization
+   of HTML.

+
+  

+
+  
This specification defines the parsing rules for HTML documents,
+  whether they are syntactically correct or not. Certain points in the
+  parsing algorithm are said to be parse
+  errors. The error handling for parse errors is well-defined:
+  user agents must either act as described below when encountering
+  such problems, or must abort processing at the first error that they
+  encounter for which they do not wish to apply the rules described
+  below.

+
+  
Conformance checkers must report at least one parse error
+  condition to the user if one or more parse error conditions exist in
+  the document and must not report parse error conditions if none
+  exist in the document. Conformance checkers may report more than one
+  parse error condition if more than one parse error condition exists
+  in the document. Conformance checkers are not required to recover
+  from parse errors.

+
+  
Parse errors are only errors with the
+  syntax of HTML. In addition to checking for parse errors,
+  conformance checkers will also verify that the document obeys all
+  the other conformance requirements described in this
+  specification.

+
+  
For the purposes of conformance checkers, if a resource is
+  determined to be in the HTML syntax, then it is an
+  HTML document.

+
+  

+
+
+  

+
+  
10.2.1 Overview of the parsing model

+
+  
The input to the HTML parsing process consists of a stream of
+  Unicode characters, which is passed through a
+  tokenization stage followed by a tree
+  construction stage. The output is a Document
+  object.

+
+  
Implementations that do not
+  support scripting do not have to actually create a DOM
+  Document object, but the DOM tree in such cases is
+  still used as the model for the rest of the specification.

+
+  
In the common case, the data handled by the tokenization stage
+  comes from the network, but it can also come from script, e.g. using the document.write() API.

+
+  

+
+  
There is only one set of states for the
+  tokenizer stage and the tree construction stage, but the tree
+  construction stage is reentrant, meaning that while the tree
+  construction stage is handling one token, the tokenizer might be
+  resumed, causing further tokens to be emitted and processed before
+  the first token's processing is complete.

+
+  

+
+   
In the following example, the tree construction stage will be
+   called upon to handle a "p" start tag token while handling the
+   "script" start tag token:

+
+   
...
+<script>
+ document.write('<p>');
+</script>
+...

+
+  

+
+  
To handle these cases, parsers have a script nesting
+  level, which must be initially set to zero, and a parser
+  pause flag, which must be initially set to false.

+
+  

+
+
+  

+
+  
10.2.2 The input stream

+
+  
The stream of Unicode characters that comprises the input to the
+  tokenization stage will be initially seen by the user agent as a
+  stream of bytes (typically coming over the network or from the local
+  file system). The bytes encode the actual characters according to a
+  particular character encoding, which the user agent must
+  use to decode the bytes into characters.

+
+  
For XML documents, the algorithm user agents must
+  use to determine the character encoding is given by the XML
+  specification. This section does not apply to XML documents. [XML]

+
+
+  
10.2.2.1 Determining the character encoding

+
+  
In some cases, it might be impractical to unambiguously determine
+  the encoding before parsing the document. Because of this, this
+  specification provides for a two-pass mechanism with an optional
+  pre-scan. Implementations are allowed, as described below, to apply
+  a simplified parsing algorithm to whatever bytes they have available
+  before beginning to parse the document. Then, the real parser is
+  started, using a tentative encoding derived from this pre-parse and
+  other out-of-band metadata. If, while the document is being loaded,
+  the user agent discovers an encoding declaration that conflicts with
+  this information, then the parser can get reinvoked to perform a
+  parse of the document with the real encoding.

+
+  
User agents must use the following
+  algorithm (the encoding sniffing algorithm) to determine
+  the character encoding to use when decoding a document in the first
+  pass. This algorithm takes as input any out-of-band metadata
+  available to the user agent (e.g. the Content-Type metadata of the document)
+  and all the bytes available so far, and returns an encoding and a
+  confidence. The
+  confidence is either tentative, certain, or
+  irrelevant. The encoding used, and whether the confidence in
+  that encoding is tentative or certain, is used during the parsing to
+  determine whether to change the encoding. If no
+  encoding is necessary, e.g. because the parser is operating on a
+  stream of Unicode characters and doesn't have to use an encoding at
+  all, then the confidence is
+  irrelevant.

+
+  
  1. If the transport layer specifies an encoding, and it is
+   supported, return that encoding with the confidence
+   certain, and abort these steps.
    2. 
+
+   
  2. The user agent may wait for more bytes of the resource to be
+   available, either in this step or at any later step in this
+   algorithm. For instance, a user agent might wait 500ms or 512
+   bytes, whichever came first. In general preparsing the source to
+   find the encoding improves performance, as it reduces the need to
+   throw away the data structures used when parsing upon finding the
+   encoding information. However, if the user agent delays too long to
+   obtain data to determine the encoding, then the cost of the delay
+   could outweigh any performance improvements from the
+   preparse.
    3. 
+
+   
  3. For each of the rows in the following table, starting with
+   the first one and going down, if there are as many or more bytes
+   available than the number of bytes in the first column, and the
+   first bytes of the file match the bytes given in the first column,
+   then return the encoding given in the cell in the second column of
+   that row, with the confidence
+   certain, and abort these steps:
    
+
+    
+    
    Bytes in Hexadecimal
+       Encoding
+     
    FE FF
+       UTF-16BE
+      
    FF FE
+       UTF-16LE
+      
    EF BB BF
+       UTF-8
+
+    
    This step looks for Unicode Byte Order Marks
+   (BOMs).
    4. 
+
+   
  4. Otherwise, the user agent will have to search for explicit
+   character encoding information in the file itself. This should
+   proceed as follows:
+
+    
    Let position be a pointer to a byte in the
+    input stream, initially pointing at the first byte. If at any
+    point during these substeps the user agent either runs out of
+    bytes or decides that scanning further bytes would not be
+    efficient, then skip to the next step of the overall character
+    encoding detection algorithm. User agents may decide that scanning
+    any bytes is not efficient, in which case these substeps
+    are entirely skipped.
    
+
+    
    Now, repeat the following "two" steps until the algorithm
+    aborts (either because user agent aborts, as described above, or
+    because a character encoding is found):
    
+
+    
    1. If position points to:
      
+
+      
      A sequence of bytes starting with: 0x3C 0x21 0x2D 0x2D (ASCII '<!--')
      
+       
      
+
+        
      Advance the position pointer so that it
+        points at the first 0x3E byte which is preceded by two 0x2D
+        bytes (i.e. at the end of an ASCII '-->' sequence) and comes
+        after the 0x3C byte that was found. (The two 0x2D bytes can be
+        the same as the those in the '<!--' sequence.)
      
+
+       
      
+
+       
      A sequence of bytes starting with: 0x3C, 0x4D or 0x6D, 0x45 or 0x65, 0x54 or 0x74, 0x41 or 0x61, and finally one of 0x09, 0x0A, 0x0C, 0x0D, 0x20, 0x2F (case-insensitive ASCII '<meta' followed by a space or slash)
      
+       
      
+
+        
      1. Advance the position pointer so
+         that it points at the next 0x09, 0x0A, 0x0C, 0x0D, 0x20, or
+         0x2F byte (the one in sequence of characters matched
+         above).
        2. 
+
+         
      2. Let attribute list be an empty
+         list of strings.
        3.  
+
+         
      3. Let got pragma be false.
        4. 
+
+         
      4. Let mode be null.
        5. 
+
+         
      5. Let charset be the null value
+         (which, for the purposes of this algorithm, is distinct from
+         an unrecognised encoding or the empty string).
        6. 
+
+         
      6. Attributes: Get an
+         attribute and its value. If no attribute was sniffed,
+         then jump to the processing step below.
        7. 
+
+         
      7. If the attribute's name is already in attribute list, then return to the step
+         labeled attributes.
        
+
+         
      8. 
+
+          
        Run the appropriate step from the following list, if one
+          applies:
        
+
+          
        If the attribute's name is "http-equiv"
        
+
+           
        If the attribute's value is "content-type", then set got
+           pragma to true.
        
+
+           
        If the attribute's name is "charset"
        
+
+           
        If charset is still set to null,
+           let charset be the encoding
+           corresponding to the attribute's value, and set mode to "charset".
        
+
+           
        If the attribute's name is "content"
        
+
+           
        Apply the algorithm for extracting an encoding
+           from a Content-Type, giving the attribute's value as
+           the string to parse. If an encoding is returned, and if
+           charset is still set to null, let charset be the encoding returned, and set
+           mode to "pragma".
        
+
+          
        9. 
+
+         
      9. Return to the step labeled attributes.
        10. 
+
+         
      10. Processing: If mode is
+         null, then jump to the second step of the overall "two step"
+         algorithm.
        11. 
+
+         
      11. If mode is "pragma" but got pragma is false, then jump to the second
+         step of the overall "two step" algorithm.
        12. 
+
+         
      12. If charset is a UTF-16 encoding,
+         change the value of charset to
+         UTF-8.
        13. 
+
+         
      13. If charset is not a supported
+         character encoding, then jump to the second step of the
+         overall "two step" algorithm.
        14. 
+
+         
      14. Return the encoding given by charset, with confidence
+         tentative, and abort all these steps.
        15. 
+
+        
      
+
+       
      A sequence of bytes starting with a 0x3C byte (ASCII <), optionally a 0x2F byte (ASCII /), and finally a byte in the range 0x41-0x5A or 0x61-0x7A (an ASCII letter)
      
+       
      
+
+        
      1. Advance the position pointer so
+         that it points at the next 0x09 (ASCII TAB), 0x0A (ASCII LF),
+         0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E
+         (ASCII >) byte.
        2. 
+
+         
      2. Repeatedly get an
+         attribute until no further attributes can be found,
+         then jump to the second step in the overall "two step"
+         algorithm.
        3. 
+
+        
      
+
+       
      A sequence of bytes starting with: 0x3C 0x21 (ASCII '<!')
      
+       
      A sequence of bytes starting with: 0x3C 0x2F (ASCII '</')
      
+       
      A sequence of bytes starting with: 0x3C 0x3F (ASCII '<?')
      
+       
      
+
+        
      Advance the position pointer so that it
+        points at the first 0x3E byte (ASCII >) that comes after the
+        0x3C byte that was found.
      
+
+       
      
+
+       
      Any other byte
      
+       
      
+
+        
      Do nothing with that byte.
      
+
+       
      
+
+      
      2. 
+
+     
    2. Move position so it points at the next
+     byte in the input stream, and return to the first step of this
+     "two step" algorithm.
      3. 
+
+    
    When the above "two step" algorithm says to get an
+    attribute, it means doing this:
    
+
+    
    1. If the byte at position is one of 0x09
+     (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR),
+     0x20 (ASCII space), or 0x2F (ASCII /) then advance position to the next byte and redo this
+     substep.
      2. 
+
+     
    2. If the byte at position is 0x3E (ASCII
+     >), then abort the "get an attribute" algorithm. There isn't
+     one.
      3. 
+
+     
    3. Otherwise, the byte at position is the
+     start of the attribute name. Let attribute
+     name and attribute value be the empty
+     string.
      4. 
+
+     
    4. Attribute name: Process the byte at position as follows:
      
+
+      
      If it is 0x3D (ASCII =), and the attribute
+       name is longer than the empty string
      
+
+       
      Advance position to the next byte and
+       jump to the step below labeled value.
      
+
+       
      If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII
+       FF), 0x0D (ASCII CR), or 0x20 (ASCII space)
      
+
+       
      Jump to the step below labeled spaces.
      
+
+       
      If it is 0x2F (ASCII /) or 0x3E (ASCII >)
      
+
+       
      Abort the "get an attribute" algorithm. The attribute's
+       name is the value of attribute name, its
+       value is the empty string.
      
+
+       
      If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
+       Z)
      
+
+       
      Append the Unicode character with code point b+0x20 to attribute
+       name (where b is the value of the
+       byte at position).
      
+
+       
      Anything else
      
+
+       
      Append the Unicode character with the same code point as the
+       value of the byte at position) to attribute name. (It doesn't actually matter how
+       bytes outside the ASCII range are handled here, since only
+       ASCII characters can contribute to the detection of a character
+       encoding.)
      
+
+      
      5. 
+
+     
    5. Advance position to the next byte and
+     return to the previous step.
      6. 
+
+     
    6. Spaces: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII
+     LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then
+     advance position to the next byte, then,
+     repeat this step.
      7. 
+
+     
    7. If the byte at position is
+     not 0x3D (ASCII =), abort the "get an attribute"
+     algorithm. The attribute's name is the value of attribute name, its value is the empty
+     string.
      8. 
+
+     
    8. Advance position past the 0x3D (ASCII
+     =) byte.
      9. 
+
+     
    9. Value: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII
+     LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then
+     advance position to the next byte, then,
+     repeat this step.
      10. 
+
+     
    10. Process the byte at position as
+     follows:
      
+
+      
      If it is 0x22 (ASCII ") or 0x27 (ASCII ')
      
+
+       
      
+
+        
      1. Let b be the value of the byte at
+         position.
        2. 
+
+         
      2. Advance position to the next
+         byte.
        3. 
+
+         
      3. If the value of the byte at position
+         is the value of b, then advance position to the next byte and abort the "get
+         an attribute" algorithm. The attribute's name is the value of
+         attribute name, and its value is the
+         value of attribute value.
        4. 
+
+         
      4. Otherwise, if the value of the byte at position is in the range 0x41 (ASCII A) to
+         0x5A (ASCII Z), then append a Unicode character to attribute value whose code point is 0x20 more
+         than the value of the byte at position.
        5. 
+
+         
      5. Otherwise, append a Unicode character to attribute value whose code point is the same as
+         the value of the byte at position.
        6. 
+
+         
      6. Return to the second step in these substeps.
        7. 
+
+        
      
+
+       
      If it is 0x3E (ASCII >)
      
+
+       
      Abort the "get an attribute" algorithm. The attribute's
+       name is the value of attribute name, its
+       value is the empty string.
      
+
+
+       
      If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
+       Z)
      
+
+       
      Append the Unicode character with code point b+0x20 to attribute
+       value (where b is the value of the
+       byte at position). Advance position to the next byte.
      
+
+       
      Anything else
      
+
+       
      Append the Unicode character with the same code point as the
+       value of the byte at position) to attribute value. Advance position to the next byte.
      
+
+      
      11. 
+
+     
    11. Process the byte at position as
+     follows:
      
+
+      
      If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII
+       FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII
+       >)
      
+
+       
      Abort the "get an attribute" algorithm. The attribute's
+       name is the value of attribute name and its
+       value is the value of attribute value.
      
+
+       
      If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
+       Z)
      
+
+       
      Append the Unicode character with code point b+0x20 to attribute
+       value (where b is the value of the
+       byte at position).
      
+
+       
      Anything else
      
+
+       
      Append the Unicode character with the same code point as the
+       value of the byte at position) to attribute value.
      
+
+      
      12. 
+
+     
    12. Advance position to the next byte and
+     return to the previous step.
      13. 
+
+    
    For the sake of interoperability, user agents should not use a
+    pre-scan algorithm that returns different results than the one
+    described above. (But, if you do, please at least let us know, so
+    that we can improve this algorithm and benefit everyone...)
    
+
+   
    5. 
+
+   
  5. If the user agent has information on the likely encoding for
+   this page, e.g. based on the encoding of the page when it was last
+   visited, then return that encoding, with the confidence
+   tentative, and abort these steps.
    6. 
+
+   
  6. 
+
+    
    The user agent may attempt to autodetect the character encoding
+    from applying frequency analysis or other algorithms to the data
+    stream. Such algorithms may use information about the resource
+    other than the resource's contents, including the address of the
+    resource. If autodetection succeeds in determining a character
+    encoding, then return that encoding, with the confidence
+    tentative, and abort these steps. [UNIVCHARDET]
    
+
+    
    The UTF-8 encoding has a highly detectable bit
+    pattern. Documents that contain bytes with values greater than
+    0x7F which match the UTF-8 pattern are very likely to be UTF-8,
+    while documents with byte sequences that do not match it are very
+    likely not. User-agents are therefore encouraged to search for
+    this common encoding. [PPUTF8] [UTF8DET]
    
+
+   
    7. 
+
+   
  7. 
+
+    
    Otherwise, return an implementation-defined or user-specified
+    default character encoding, with the confidence
+    tentative.
    
+
+    
    In controlled environments or in environments where the
+    encoding of documents can be prescribed (for example, for user
+    agents intended for dedicated use in new networks), the
+    comprehensive UTF-8 encoding is
+    suggested.
    
+
+    
    In other environments, the default encoding is typically
+    dependent on the user's locale (an approximation of the languages,
+    and thus often encodings, of the pages that the user is likely to
+    frequent). The following table gives suggested defaults based on
+    the user's locale, for compatibility with legacy content. Locales
+    are identified by BCP 47 language tags. [BCP47]
    
+
+    
+
+    
    Locale language
+       Suggested default encoding
+     
    ar
+       UTF-8
+
+      
    be
+       ISO-8859-5
+
+      
    bg
+       windows-1251
+
+      
    cs
+       ISO-8859-2
+
+      
    cy
+       UTF-8
+
+      
    fa
+       UTF-8
+
+      
    he
+       windows-1255
+
+      
    hr
+       UTF-8
+
+      
    hu
+       ISO-8859-2
+
+      
    ja 
+       Windows-31J 
+
+      
    kk
+       UTF-8
+
+      
    ko
+       windows-949 
+
+      
    ku
+       windows-1254 
+
+      
    lt
+       windows-1257
+
+      
    lv
+       ISO-8859-13
+
+      
    mk
+       UTF-8
+
+      
    or
+       UTF-8
+
+      
    pl
+       ISO-8859-2
+
+      
    ro
+       UTF-8
+
+      
    ru
+       windows-1251
+
+      
    sk
+       windows-1250
+
+      
    sl
+       ISO-8859-2
+
+      
    sr
+       UTF-8
+
+      
    th
+       windows-874 
+
+      
    tr
+       windows-1254 
+
+      
    uk
+       windows-1251
+
+      
    vi
+       UTF-8
+
+      
    zh-CN
+       GB18030
+
+      
    zh-TW
+       Big5
+
+      
    All other locales
+       windows-1252
+
+    
    8. 
+
+  
The document's character encoding must immediately
+  be set to the value returned from this algorithm, at the same time
+  as the user agent uses the returned value to select the decoder to
+  use for the input stream.

+
+  
This algorithm is a willful violation
+  of the HTTP specification, which requires that the encoding be
+  assumed to be ISO-8859-1 in the absence of a character
+  encoding declaration to the contrary, and of RFC 2046,
+  which requires that the encoding be assumed to be US-ASCII in the
+  absence of a character encoding declaration to the
+  contrary. This specification's third approach is motivated by a
+  desire to be maximally compatible with legacy content. [HTTP] [RFC2046]

+
+
+  
10.2.2.2 Character encodings

+
+  
User agents must at a minimum support the UTF-8 and Windows-1252
+  encodings, but may support more.

+
+  
It is not unusual for Web browsers to support dozens
+  if not upwards of a hundred distinct character encodings.

+
+  
User agents must support the preferred MIME name of
+  every character encoding they support, and should support all the
+  IANA-registered names and aliases of every character encoding they
+  support. [IANACHARSET]

+
+  
When comparing a string specifying a character encoding with the
+  name or alias of a character encoding to determine if they are
+  equal, user agents must remove any leading or trailing space characters in both names, and
+  then perform the comparison in an ASCII
+  case-insensitive manner.

+
+  
When a user agent would otherwise use an encoding given in the
+  first column of the following table to either convert content to
+  Unicode characters or convert Unicode characters to bytes, it must
+  instead use the encoding given in the cell in the second column of
+  the same row. When a byte or sequence of bytes is treated
+  differently due to this encoding aliasing, it is said to have been
+  misinterpreted for compatibility.

+
+  
+   
Character encoding overrides
 Input encoding  Replacement encoding  References
+   
 EUC-KR  windows-949 
+         [EUCKR]
+         [WIN949]
+    
 GB2312  GBK 
+         [RFC1345]
+         [GBK]
+    
 GB_2312-80  GBK 
+         [RFC1345]
+         [GBK]
+    
 ISO-8859-1  windows-1252 
+         [RFC1345]
+         [WIN1252]
+    
 ISO-8859-9  windows-1254 
+         [RFC1345]
+         [WIN1254]
+    
 ISO-8859-11  windows-874 
+         [ISO885911]
+         [WIN874]
+    
 KS_C_5601-1987  windows-949 
+         [RFC1345]
+         [WIN949]
+    
 Shift_JIS  Windows-31J 
+         [SHIFTJIS]
+         [WIN31J]
+    
 TIS-620  windows-874 
+         [TIS620]
+         [WIN874]
+    
 US-ASCII  windows-1252 
+         [RFC1345]
+         [WIN1252]
+   
The requirement to treat certain encodings as other
+  encodings according to the table above is a willful
+  violation of the W3C Character Model specification, motivated
+  by a desire for compatibility with legacy content. [CHARMOD]

+
+  
When a user agent is to use the UTF-16 encoding but no BOM has
+  been found, user agents must default to UTF-16LE.

+
+  
The requirement to default UTF-16 to LE rather than
+  BE is a willful violation of RFC 2781, motivated by a
+  desire for compatibility with legacy content. [RFC2781]

+
+  
User agents must not support the CESU-8, UTF-7, BOCU-1 and SCSU
+  encodings. [CESU8] [UTF7] [BOCU1] [SCSU]

+
+  
Support for encodings based on EBCDIC is not recommended. This
+  encoding is rarely used for publicly-facing Web content.

+
+  
Support for UTF-32 is not recommended. This encoding is rarely
+  used, and frequently implemented incorrectly.

+
+  
This specification does not make any attempt to
+  support EBCDIC-based encodings and UTF-32 in its algorithms; support
+  and use of these encodings can thus lead to unexpected behavior in
+  implementations of this specification.

+
+
+
+  
10.2.2.3 Preprocessing the input stream

+
+  
Given an encoding, the bytes in the input stream must be
+  converted to Unicode characters for the tokenizer, as described by
+  the rules for that encoding, except that the leading U+FEFF BYTE
+  ORDER MARK character, if any, must not be stripped by the encoding
+  layer (it is stripped by the rule below).
 
+
+  
Bytes or sequences of bytes in the original byte stream that
+  could not be converted to Unicode code points must be converted to
+  U+FFFD REPLACEMENT CHARACTERs.

+
+  
Bytes or sequences of bytes in the original byte
+  stream that did not conform to the encoding specification
+  (e.g. invalid UTF-8 byte sequences in a UTF-8 input stream) are
+  errors that conformance checkers are expected to report.

+
+  
Any byte or sequence of bytes in the original byte stream that is
+  misinterpreted for compatibility is a parse
+  error.

+
+  
One leading U+FEFF BYTE ORDER MARK character must be ignored if
+  any are present.

+
+  
The requirement to strip a U+FEFF BYTE ORDER MARK
+  character regardless of whether that character was used to determine
+  the byte order is a willful violation of Unicode,
+  motivated by a desire to increase the resilience of user agents in
+  the face of naïve transcoders.

+
+  
All U+0000 NULL characters and code points in the range U+D800 to
+  U+DFFF in the input must be replaced by U+FFFD REPLACEMENT
+  CHARACTERs. Any occurrences of such characters and code points are
+  parse errors.

+
+  
Any occurrences of any characters in the ranges U+0001 to U+0008,
+     U+000E to U+001F,  U+007F
+   to U+009F, U+FDD0
+  to U+FDEF, and characters U+000B, U+FFFE, U+FFFF, U+1FFFE, U+1FFFF,
+  U+2FFFE, U+2FFFF, U+3FFFE, U+3FFFF, U+4FFFE, U+4FFFF, U+5FFFE,
+  U+5FFFF, U+6FFFE, U+6FFFF, U+7FFFE, U+7FFFF, U+8FFFE, U+8FFFF,
+  U+9FFFE, U+9FFFF, U+AFFFE, U+AFFFF, U+BFFFE, U+BFFFF, U+CFFFE,
+  U+CFFFF, U+DFFFE, U+DFFFF, U+EFFFE, U+EFFFF, U+FFFFE, U+FFFFF,
+  U+10FFFE, and U+10FFFF are parse
+  errors. These are all control characters or permanently
+  undefined Unicode characters (noncharacters).

+
+  
U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF)
+  characters are treated specially. Any CR characters that are
+  followed by LF characters must be removed, and any CR characters not
+  followed by LF characters must be converted to LF characters. Thus,
+  newlines in HTML DOMs are represented by LF characters, and there
+  are never any CR characters in the input to the
+  tokenization stage.

+
+  
The next input character is the first character in the
+  input stream that has not yet been consumed. Initially,
+  the next input character is the first character in the
+  input. The current input character is the last character
+  to have been consumed.

+
+  
The insertion point is the position (just before a
+  character or just before the end of the input stream) where content
+  inserted using document.write() is actually
+  inserted. The insertion point is relative to the position of the
+  character immediately after it, it is not an absolute offset into
+  the input stream. Initially, the insertion point is
+  undefined.

+
+  
The "EOF" character in the tables below is a conceptual character
+  representing the end of the input stream. If the parser
+  is a script-created parser, then the end of the
+  input stream is reached when an explicit "EOF"
+  character (inserted by the document.close() method) is
+  consumed. Otherwise, the "EOF" character is not a real character in
+  the stream, but rather the lack of any further characters.

+
+
+  
10.2.2.4 Changing the encoding while parsing

+
+  
When the parser requires the user agent to change the
+  encoding, it must run the following steps. This might happen
+  if the encoding sniffing algorithm described above
+  failed to find an encoding, or if it found an encoding that was not
+  the actual encoding of the file.

+
+  
  1. If the new encoding is identical or equivalent to the encoding
+   that is already being used to interpret the input stream, then set
+   the confidence to
+   certain and abort these steps. This happens when the
+   encoding information found in the file matches what the
+   encoding sniffing algorithm determined to be the
+   encoding, and in the second pass through the parser if the first
+   pass found that the encoding sniffing algorithm described in the
+   earlier section failed to find the right encoding.
    2. 
+
+   
  2. If the encoding that is already being used to interpret the
+   input stream is a UTF-16 encoding, then set the confidence to
+   certain and abort these steps. The new encoding is ignored;
+   if it was anything but the same encoding, then it would be clearly
+   incorrect.
    3. 
+
+   
  3. If the new encoding is a UTF-16 encoding, change it to
+   UTF-8.
    4. 
+
+   
  4. If all the bytes up to the last byte converted by the current
+   decoder have the same Unicode interpretations in both the current
+   encoding and the new encoding, and if the user agent supports
+   changing the converter on the fly, then the user agent may change
+   to the new converter for the encoding on the fly. Set the
+   document's character encoding and the encoding used to
+   convert the input stream to the new encoding, set the confidence to
+   certain, and abort these steps.
    5. 
+
+   
  5. Otherwise, navigate to the document again, with
+   replacement enabled, and using the same source
+   browsing context, but this time skip the encoding
+   sniffing algorithm and instead just set the encoding to the
+   new encoding and the confidence to
+   certain. Whenever possible, this should be done without
+   actually contacting the network layer (the bytes should be
+   re-parsed from memory), even if, e.g., the document is marked as
+   not being cacheable. If this is not possible and contacting the
+   network layer would involve repeating a request that uses a method
+   other than HTTP GET (or
+   equivalent for non-HTTP URLs), then instead set the confidence to
+   certain and ignore the new encoding. The resource will be
+   misinterpreted. User agents may notify the user of the situation,
+   to aid in application development.
    6. 
+
+  

+
+
+  

+
+  
10.2.3 Parse state

+
+  
10.2.3.1 The insertion mode

+
+  
The insertion mode is a state variable that controls
+  the primary operation of the tree construction stage.

+
+  
Initially, the insertion mode is "initial". It can change to
+  "before html",
+  "before head",
+  "in head", "in head noscript",
+  "after head", "in body", "text",
+  "in table", "in table text", "in caption", "in column group",
+  "in table body",
+  "in row", "in cell", "in select", "in select in
+  table", "in
+  foreign content", "after body", "in frameset", "after frameset", "after after body", and "after after
+  frameset" during the course of the parsing, as described in
+  the tree construction stage. The insertion mode affects
+  how tokens are processed and whether CDATA sections are
+  supported.

+
+  
Seven of these modes, namely "in head", "in
+  body", "in
+  table", "in table
+  body", "in row",
+  "in cell", and "in select", are special, in
+  that the other modes defer to them at various times. When the
+  algorithm below says that the user agent is to do something
+  "using the rules for the m insertion
+  mode", where m is one of these modes, the user
+  agent must use the rules described under the m
+  insertion mode's section, but must leave the
+  insertion mode unchanged unless the rules in m themselves switch the insertion mode
+  to a new value.

+
+  
When the insertion mode is switched to "text" or "in table text", the original insertion mode
+  is also set. This is the insertion mode to which the tree
+  construction stage will return.

+
+  
When the insertion mode is switched to "in foreign content", the
+  secondary insertion mode is also set. This secondary mode
+  is used within the rules for the "in foreign content" mode to handle HTML
+  (i.e. not foreign) content.

+
+  
When the steps below require the UA to reset the insertion
+  mode appropriately, it means the UA must follow these
+  steps:

+
+  
  1. Let last be false.
    2. 
+
+   
  2. Let foreign be false.
    3. 
+
+   
  3. Let node be the last node in the
+   stack of open elements.
    4. 
+
+   
  4. Loop: If node is the first node in
+   the stack of open elements, then set last to
+   true and set node to the context element. (fragment case)
    5. 
+
+   
  5. If node is a select element,
+   then switch the insertion mode to "in select" and jump to the
+   step labeled end. (fragment case)
    6. 
+
+   
  6. If node is a td or
+   th element and last is false, then
+   switch the insertion mode to "in cell" and jump to the step labeled end.
    7. 
+
+   
  7. If node is a tr element, then
+   switch the insertion mode to "in row" and jump to the step labeled end.
    8. 
+
+   
  8. If node is a tbody,
+   thead, or tfoot element, then switch the
+   insertion mode to "in table body" and jump to the step labeled end.
    9. 
+
+   
  9. If node is a caption element,
+   then switch the insertion mode to "in caption" and jump to
+   the step labeled end.
    10. 
+
+   
  10. If node is a colgroup element,
+   then switch the insertion mode to "in column group" and
+   jump to the step labeled end. (fragment
+   case)
    11. 
+
+   
  11. If node is a table element,
+   then switch the insertion mode to "in table" and jump to the
+   step labeled end.
    12. 
+
+   
  12. If node is a head element,
+   then switch the insertion mode to "in body" ("in body"!  not "in head"!) and jump to
+   the step labeled end. (fragment
+   case)
    13.  
+
+   
  13. If node is a body element,
+   then switch the insertion mode to "in body" and jump to the
+   step labeled end.
    14. 
+
+   
  14. If node is a frameset element,
+   then switch the insertion mode to "in frameset" and jump to
+   the step labeled end. (fragment
+   case)
    15. 
+
+   
  15. If node is an html element,
+   then  switch the insertion mode
+   to "before
+   head"
+   Then,  jump to the step labeled end. (fragment case)
    16.  
+
+   
  16. If node is an element from the MathML
+   namespace or the SVG namespace, then set the
+   foreign flag to true.
    17. 
+
+   
  17. If last is true, then switch the
+   insertion mode to "in body" and jump to the step labeled end. (fragment case)
    18. 
+
+   
  18. Let node now be the node before node in the stack of open
+   elements.
    19. 
+
+   
  19. Return to the step labeled loop.
    20. 
+
+   
  20. End: If foreign is true, switch the
+   secondary insertion mode to whatever the
+   insertion mode is set to, and switch the
+   insertion mode to "in foreign content".
    21. 
+
+  
10.2.3.2 The stack of open elements

+
+  
Initially, the stack of open elements is empty. The
+  stack grows downwards; the topmost node on the stack is the first
+  one added to the stack, and the bottommost node of the stack is the
+  most recently added node in the stack (notwithstanding when the
+  stack is manipulated in a random access fashion as part of the handling for misnested tags).

+
+  
The "before
+  html" insertion mode creates the
+  html root element node, which is then added to the
+  stack.

+
+  
In the fragment case, the stack of open
+  elements is initialized to contain an html
+  element that is created as part of that algorithm. (The fragment
+  case skips the "before html" insertion mode.)

+
+  
The html node, however it is created, is the topmost
+  node of the stack. It only gets popped off the stack when the parser
+  finishes.

+
+  
The current node is the bottommost node in this
+  stack.

+
+  
The current table is the last table
+  element in the stack of open elements, if there is
+  one. If there is no table element in the stack of
+  open elements (fragment case), then the
+  current table is the first element in the stack
+  of open elements (the html element).

+
+  
Elements in the stack fall into the following categories:

+
+  
Special

+   
The following HTML elements have varying levels of special
+   parsing rules: address, area,
+   article, aside, base,
+   basefont, bgsound,
+   blockquote, body, br,
+   button, center, col,
+   colgroup, command, , dd, details,
+   dir, div, dl,
+   dt, embed, fieldset,
+   figure, footer, form,
+   frame, frameset, h1,
+   h2, h3, h4, h5,
+   h6, head, header,
+   hgroup, hr, iframe, 
+   img, input, isindex,
+   li, link, listing,
+   menu, meta, nav,
+   noembed, noframes, noscript,
+   ol, p, param,
+   plaintext, pre, script,
+   section, select, style,
+   tbody, textarea, tfoot,
+   thead, title, tr,
+   ul, wbr, and xmp.

+
+   
Scoping

+   
The following HTML elements introduce new scopes for various parts of the
+   parsing: applet, caption,
+   html, marquee, object,
+   table, td, th, and SVG's
+   foreignObject.

+
+   
Formatting

+   
The following HTML elements are those that end up in the
+   list of active formatting elements: a,
+   b, big, code,
+   em, font, i,
+   nobr, s, small,
+   strike, strong, tt, and
+   u.

+
+   
Phrasing

+   
All other elements found while parsing an HTML
+   document.

+
+  
The stack of open elements is said to have an element in a
+  specific scope consisting of a list of element types list when the following algorithm terminates in a
+  match state:

+
+  
  1. Initialize node to be the current
+   node (the bottommost node of the stack).
    2. 
+
+   
  2. If node is the target node, terminate in
+   a match state.
    3. 
+
+   
  3. Otherwise, if node is one of the element
+   types in list, terminate in a failure
+   state.
    4. 
+
+   
  4. Otherwise, set node to the previous
+   entry in the stack of open elements and return to step
+   2. (This will never fail, since the loop will always terminate in
+   the previous step if the top of the stack — an
+   html element — is reached.)
    5. 
+
+  
The stack of open elements is said to have an element in scope when
+  it has an element in the specific scope consisting
+  of the following element types:

+
+  
  • applet in the HTML namespace
    • 
+   
  • caption in the HTML namespace
    • 
+   
  • html in the HTML namespace
    •  
+   
  • table in the HTML namespace
    • 
+   
  • td in the HTML namespace
    • 
+   
  • th in the HTML namespace
    • 
+   
  • button in the HTML namespace
    • 
+   
  • marquee in the HTML namespace
    • 
+   
  • object in the HTML namespace
    • 
+   
  • foreignObject in the SVG namespace
    • 
+  
The stack of open elements is said to have an element in list
+  item scope when it has an element in the specific
+  scope consisting of the following element types:

+
+  
The stack of open elements is said to have an element in table
+  scope when it has an element in the specific
+  scope consisting of the following element types:

+
+  
  • html in the HTML namespace
    •  
+   
  • table in the HTML namespace
    • 
+  
Nothing happens if at any time any of the elements in the
+  stack of open elements are moved to a new location in,
+  or removed from, the Document tree. In particular, the
+  stack is not changed in this situation. This can cause, amongst
+  other strange effects, content to be appended to nodes that are no
+  longer in the DOM.

+
+  
In some cases (namely, when closing misnested formatting elements),
+  the stack is manipulated in a random-access fashion.

+
+
+  
10.2.3.3 The list of active formatting elements

+
+  
Initially, the list of active formatting elements is
+  empty. It is used to handle mis-nested formatting element tags.

+
+  
The list contains elements in the formatting
+  category, and scope markers. The scope markers are inserted when
+  entering applet elements, buttons, object
+  elements, marquees, table cells, and table captions, and are used to
+  prevent formatting from "leaking" into applet
+  elements, buttons, object elements, marquees, and
+  tables.

+
+  
The scope markers are unrelated to the concept of an
+  element being in
+  scope.

+
+  
In addition, each element in the list of active formatting
+  elements is associated with the token for which it was
+  created, so that further elements can be created for that token if
+  necessary.

+
+  
When the steps below require the UA to reconstruct the
+  active formatting elements, the UA must perform the following
+  steps:

+
+  
  1. If there are no entries in the list of active formatting
+   elements, then there is nothing to reconstruct; stop this
+   algorithm.
    2. 
+
+   
  2. If the last (most recently added) entry in the list of
+   active formatting elements is a marker, or if it is an
+   element that is in the stack of open elements, then
+   there is nothing to reconstruct; stop this algorithm.
    3. 
+
+   
  3. Let entry be the last (most recently added)
+   element in the list of active formatting
+   elements.
    4. 
+
+   
  4. If there are no entries before entry in the
+   list of active formatting elements, then jump to step
+   8.
    5. 
+
+   
  5. Let entry be the entry one earlier than
+   entry in the list of active formatting
+   elements.
    6. 
+
+   
  6. If entry is neither a marker nor an element
+   that is also in the stack of open elements, go to step
+   4.
    7. 
+
+   
  7. Let entry be the element one later than
+   entry in the list of active formatting
+   elements.
    8. 
+
+   
  8. Create an element for the token for which the
+   element entry was created, to obtain new element.
    9. 
+
+   
  9. Append new element to the current
+   node and push it onto the stack of open
+   elements so that it is the new current
+   node.
    10. 
+
+   
  10. Replace the entry for entry in the list
+   with an entry for new element.
    11. 
+
+   
  11. If the entry for new element in the
+   list of active formatting elements is not the last
+   entry in the list, return to step 7.
    12. 
+
+  
This has the effect of reopening all the formatting elements that
+  were opened in the current body, cell, or caption (whichever is
+  youngest) that haven't been explicitly closed.

+
+  
The way this specification is written, the
+  list of active formatting elements always consists of
+  elements in chronological order with the least recently added
+  element first and the most recently added element last (except for
+  while steps 8 to 11 of the above algorithm are being executed, of
+  course).

+
+  
When the steps below require the UA to clear the list of
+  active formatting elements up to the last marker, the UA must
+  perform the following steps:

+
+  
  1. Let entry be the last (most recently added)
+   entry in the list of active formatting elements.
    2. 
+
+   
  2. Remove entry from the list of active
+   formatting elements.
    3. 
+
+   
  3. If entry was a marker, then stop the
+   algorithm at this point. The list has been cleared up to the last
+   marker.
    4. 
+
+   
  4. Go to step 1.
    5. 
+
+  
10.2.3.4 The element pointers

+
+  
Initially, the head element
+  pointer and the form element
+  pointer are both null.

+
+  
Once a head element has been parsed (whether
+  implicitly or explicitly) the head
+  element pointer gets set to point to this node.

+
+  
The form element pointer
+  points to the last form element that was opened and
+  whose end tag has not yet been seen. It is used to make form
+  controls associate with forms in the face of dramatically bad
+  markup, for historical reasons.

+
+
+  
10.2.3.5 Other parsing state flags

+
+  
The scripting flag is set to "enabled" if scripting was enabled for the
+  Document with which the parser is associated when the
+  parser was created, and "disabled" otherwise.

+
+  
The scripting flag can be enabled even
+  when the parser was originally created for the HTML fragment
+  parsing algorithm, even though script elements
+  don't execute in that case.

+
+  
The frameset-ok flag is set to "ok" when the parser is
+  created. It is set to "not ok" after certain tokens are seen.

+
+  

+
+
+  

+
+  
10.2.4 Tokenization

+
+  
Implementations must act as if they used the following state
+  machine to tokenize HTML. The state machine must start in the
+  data state. Most states consume a single character,
+  which may have various side-effects, and either switches the state
+  machine to a new state to reconsume the same character, or
+  switches it to a new state (to consume the next character), or
+  repeats the same state (to consume the next character). Some states
+  have more complicated behavior and can consume several characters
+  before switching to another state. In some cases, the tokenizer
+  state is also changed by the tree construction stage.

+
+  
The exact behavior of certain states depends on the
+  insertion mode and the stack of open
+  elements. Certain states also use a temporary
+  buffer to track progress.

+
+  
The output of the tokenization step is a series of zero or more
+  of the following tokens: DOCTYPE, start tag, end tag, comment,
+  character, end-of-file. DOCTYPE tokens have a name, a public
+  identifier, a system identifier, and a force-quirks
+  flag. When a DOCTYPE token is created, its name, public
+  identifier, and system identifier must be marked as missing (which
+  is a distinct state from the empty string), and the force-quirks
+  flag must be set to off (its other state is
+  on). Start and end tag tokens have a tag name, a
+  self-closing flag, and a list of attributes, each of which
+  has a name and a value. When a start or end tag token is created,
+  its self-closing flag must be unset (its other state is that
+  it be set), and its attributes list must be empty. Comment and
+  character tokens have data.

+
+  
When a token is emitted, it must immediately be handled by the
+  tree construction stage. The tree construction stage
+  can affect the state of the tokenization stage, and can insert
+  additional characters into the stream. (For example, the
+  script element can result in scripts executing and
+  using the dynamic markup insertion APIs to insert
+  characters into the stream being tokenized.)

+
+  
When a start tag token is emitted with its self-closing
+  flag set, if the flag is not acknowledged when it is processed by the
+  tree construction stage, that is a parse error.

+
+  
When an end tag token is emitted with attributes, that is a
+  parse error.

+
+  
When an end tag token is emitted with its self-closing
+  flag set, that is a parse error.

+
+  
An appropriate end tag token is an end tag token whose
+  tag name matches the tag name of the last start tag to have been
+  emitted from this tokenizer, if any. If no start tag has been
+  emitted from this tokenizer, then no end tag token is
+  appropriate.

+
+  
Before each step of the tokenizer, the user agent must first
+  check the parser pause flag. If it is true, then the
+  tokenizer must abort the processing of any nested invocations of the
+  tokenizer, yielding control back to the caller.

+
+  
The tokenizer state machine consists of the states defined in the
+  following subsections.

+
+
+  
+
+
+  
10.2.4.1 Data state

+
+  
Consume the next input character:

+
+  
U+0026 AMPERSAND (&)

+   
Switch to the character reference in data
+   state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Switch to the tag open state.

+
+   
EOF

+   
Emit an end-of-file token.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the data state.

+
+  
10.2.4.2 Character reference in data state

+
+  
Attempt to consume a character reference, with no
+  additional allowed character.

+
+  
If nothing is returned, emit a U+0026 AMPERSAND character
+  token.

+
+  
Otherwise, emit the character token that was returned.

+
+  
Finally, switch to the data state.

+
+
+  
10.2.4.3 RCDATA state

+
+  
Consume the next input character:

+
+  
U+0026 AMPERSAND (&)

+   
Switch to the character reference in RCDATA
+   state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Switch to the RCDATA less-than sign state.

+
+   
EOF

+   
Emit an end-of-file token.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the RCDATA state.

+
+  
10.2.4.4 Character reference in RCDATA state

+
+  
Attempt to consume a character reference, with no
+  additional allowed character.

+
+  
If nothing is returned, emit a U+0026 AMPERSAND character
+  token.

+
+  
Otherwise, emit the character token that was returned.

+
+  
Finally, switch to the RCDATA state.

+
+
+  
10.2.4.5 RAWTEXT state

+
+  
Consume the next input character:

+
+  
U+003C LESS-THAN SIGN (<)

+   
Switch to the RAWTEXT less-than sign state.

+
+   
EOF

+   
Emit an end-of-file token.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the RAWTEXT state.

+
+  
10.2.4.6 Script data state

+
+  
Consume the next input character:

+
+  
U+003C LESS-THAN SIGN (<)

+   
Switch to the script data less-than sign state.

+
+   
EOF

+   
Emit an end-of-file token.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the script data state.

+
+  
10.2.4.7 PLAINTEXT state

+
+  
Consume the next input character:

+
+  
EOF

+   
Emit an end-of-file token.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the PLAINTEXT state.

+
+  
10.2.4.8 Tag open state

+
+  
Consume the next input character:

+
+  
U+0021 EXCLAMATION MARK (!)

+   
Switch to the markup declaration open state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the end tag open state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new start tag token, set its tag name to the
+   lowercase version of the current input character (add 0x0020 to the
+   character's code point), then switch to the tag name
+   state. (Don't emit the token yet; further details will
+   be filled in before it is emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new start tag token, set its tag name to the
+   current input character, then switch to the tag
+   name state. (Don't emit the token yet; further details will
+   be filled in before it is emitted.)

+
+   
U+003F QUESTION MARK (?)

+   
Parse error. Switch to the bogus
+   comment state.

+
+   
Anything else

+   
Parse error. Emit a U+003C LESS-THAN SIGN
+   character token and reconsume the current input
+   character in the data state.

+
+  
10.2.4.9 End tag open state

+
+  
Consume the next input character:

+
+  
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new end tag token, set its tag name to the lowercase
+   version of the current input character (add 0x0020 to
+   the character's code point), then switch to the tag name
+   state. (Don't emit the token yet; further details will be
+   filled in before it is emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new end tag token, set its tag name to the
+   current input character, then switch to the tag
+   name state. (Don't emit the token yet; further details will
+   be filled in before it is emitted.)

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Emit a U+003C LESS-THAN SIGN
+   character token and a U+002F SOLIDUS character token. Reconsume
+   the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Switch to the bogus
+   comment state.

+
+  
10.2.4.10 Tag name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before attribute name state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the self-closing start tag state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current tag token's tag name. Stay in the tag name
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   tag token's tag name. Stay in the tag name state.

+
+  
10.2.4.11 RCDATA less-than sign state

+  
+
+  
Consume the next input character:

+
+  
U+002F SOLIDUS (/)

+   
Set the temporary buffer to the empty string. Switch
+   to the RCDATA end tag open state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token and reconsume the
+   current input character in the RCDATA
+   state.

+
+  
10.2.4.12 RCDATA end tag open state

+  
+
+  
Consume the next input character:

+
+  
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   lowercase version of the current input character (add
+   0x0020 to the character's code point). Append the current
+   input character to the temporary buffer. Finally,
+   switch to the RCDATA end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   current input character. Append the current
+   input character to the temporary buffer. Finally,
+   switch to the RCDATA end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, and reconsume the current input
+   character in the RCDATA state.

+
+  
10.2.4.13 RCDATA end tag name state

+  
+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the before attribute name
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+002F SOLIDUS (/)

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the self-closing start tag
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
If the current end tag token is an appropriate end tag
+   token, then emit the current tag token and switch to the
+   data state. Otherwise, treat it as per the "anything
+   else" entry below.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   RCDATA end tag name state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Append the current input character to the current
+   tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   RCDATA end tag name state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, a character token for each of the characters in
+   the temporary buffer (in the order they were added to
+   the buffer), and reconsume the current input character
+   in the RCDATA state.

+
+  
10.2.4.14 RAWTEXT less-than sign state

+  
+
+  
Consume the next input character:

+
+  
U+002F SOLIDUS (/)

+   
Set the temporary buffer to the empty string. Switch
+   to the RAWTEXT end tag open state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token and reconsume the
+   current input character in the RAWTEXT
+   state.

+
+  
10.2.4.15 RAWTEXT end tag open state

+  
+
+  
Consume the next input character:

+
+  
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   lowercase version of the current input character (add
+   0x0020 to the character's code point). Append the current
+   input character to the temporary buffer. Finally,
+   switch to the RAWTEXT end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   current input character. Append the current
+   input character to the temporary buffer. Finally,
+   switch to the RAWTEXT end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, and reconsume the current input
+   character in the RAWTEXT state.

+
+  
10.2.4.16 RAWTEXT end tag name state

+  
+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the before attribute name
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+002F SOLIDUS (/)

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the self-closing start tag
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
If the current end tag token is an appropriate end tag
+   token, then emit the current tag token and switch to the
+   data state. Otherwise, treat it as per the "anything
+   else" entry below.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   RAWTEXT end tag name state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Append the current input character to the current
+   tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   RAWTEXT end tag name state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, a character token for each of the characters in
+   the temporary buffer (in the order they were added to
+   the buffer), and reconsume the current input character
+   in the RAWTEXT state.

+
+  
10.2.4.17 Script data less-than sign state

+
+  
Consume the next input character:

+
+  
U+002F SOLIDUS (/)

+   
Set the temporary buffer to the empty string. Switch
+   to the script data end tag open state.

+
+   
U+0021 EXCLAMATION MARK (!)

+   
Emit a U+003C LESS-THAN SIGN character token and a U+0021
+   EXCLAMATION MARK character token. Switch to the script data
+   escape start state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token and reconsume the
+   current input character in the script data
+   state.

+
+  
10.2.4.18 Script data end tag open state

+  
+
+  
Consume the next input character:

+
+  
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   lowercase version of the current input character (add
+   0x0020 to the character's code point). Append the current
+   input character to the temporary buffer. Finally,
+   switch to the script data end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   current input character. Append the current
+   input character to the temporary buffer. Finally,
+   switch to the script data end tag name state. (Don't emit
+   the token yet; further details will be filled in before it is
+   emitted.)

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, and reconsume the current input
+   character in the script data state.

+
+  
10.2.4.19 Script data end tag name state

+  
+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the before attribute name
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+002F SOLIDUS (/)

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the self-closing start tag
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
If the current end tag token is an appropriate end tag
+   token, then emit the current tag token and switch to the
+   data state. Otherwise, treat it as per the "anything
+   else" entry below.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   script data end tag name state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Append the current input character to the current
+   tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   script data end tag name state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, a character token for each of the characters in
+   the temporary buffer (in the order they were added to
+   the buffer), and reconsume the current input character
+   in the script data state.

+
+  
10.2.4.20 Script data escape start state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data escape start dash state.

+
+   
Anything else

+   
Reconsume the current input character in the
+   script data state.

+
+  
10.2.4.21 Script data escape start dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data escaped dash dash state.

+
+   
Anything else

+   
Reconsume the current input character in the
+   script data state.

+
+  
10.2.4.22 Script data escaped state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data escaped dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Switch to the script data escaped less-than sign
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the script data escaped state.

+
+  
10.2.4.23 Script data escaped dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data escaped dash dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Switch to the script data escaped less-than sign
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Switch to the script data escaped state.

+
+  
10.2.4.24 Script data escaped dash dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Stay in the
+   script data escaped dash dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Switch to the script data escaped less-than sign
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit a U+003E GREATER-THAN SIGN character token. Switch to the
+   script data state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Switch to the script data escaped state.

+
+  
10.2.4.25 Script data escaped less-than sign state

+
+  
Consume the next input character:

+
+  
U+002F SOLIDUS (/)

+   
Set the temporary buffer to the empty string. Switch
+   to the script data escaped end tag open state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Emit a U+003C LESS-THAN SIGN character token and the
+   current input character as a character token. Set the
+   temporary buffer to the empty string. Append the
+   lowercase version of the current input character (add
+   0x0020 to the character's code point) to the temporary
+   buffer. Switch to the script data double escape start
+   state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Emit a U+003C LESS-THAN SIGN character token and the
+   current input character as a character token. Set the
+   temporary buffer to the empty string. Append the
+   current input character to the temporary
+   buffer. Switch to the script data double escape start
+   state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token and reconsume the
+   current input character in the script data
+   escaped state.

+
+  
10.2.4.26 Script data escaped end tag open state

+
+  
Consume the next input character:

+
+  
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   lowercase version of the current input character (add
+   0x0020 to the character's code point). Append the current
+   input character to the temporary buffer. Finally,
+   switch to the script data escaped end tag name
+   state. (Don't emit the token yet; further details will be
+   filled in before it is emitted.)

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Create a new end tag token, and set its tag name to the
+   current input character. Append the current
+   input character to the temporary buffer. Finally,
+   switch to the script data escaped end tag name
+   state. (Don't emit the token yet; further details will be
+   filled in before it is emitted.)

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, and reconsume the current input
+   character in the script data escaped state.

+
+  
10.2.4.27 Script data escaped end tag name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the before attribute name
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+002F SOLIDUS (/)

+   
If the current end tag token is an appropriate end tag
+   token, then switch to the self-closing start tag
+   state. Otherwise, treat it as per the "anything else" entry
+   below.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
If the current end tag token is an appropriate end tag
+   token, then emit the current tag token and switch to the
+   data state. Otherwise, treat it as per the "anything
+   else" entry below.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   script data escaped end tag name state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Append the current input character to the current
+   tag token's tag name. Append the current input
+   character to the temporary buffer. Stay in the
+   script data escaped end tag name state.

+
+   
Anything else

+   
Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
+   character token, a character token for each of the characters in
+   the temporary buffer (in the order they were added to
+   the buffer), and reconsume the current input character
+   in the script data escaped state.

+
+  
10.2.4.28 Script data double escape start state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
U+002F SOLIDUS (/)

+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current input character as a character
+   token. If the temporary buffer is the string "script", then switch to the script data
+   double escaped state. Otherwise, switch to the script
+   data escaped state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Emit the current input character as a character
+   token. Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   temporary buffer. Stay in the script data double
+   escape start state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Emit the current input character as a character
+   token. Append the current input character to the
+   temporary buffer. Stay in the script data double
+   escape start state.

+
+   
Anything else

+   
Reconsume the current input character in the
+   script data escaped state.

+
+  
10.2.4.29 Script data double escaped state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data double escaped dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Emit a U+003C LESS-THAN SIGN character token. Switch to the
+   script data double escaped less-than sign
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Stay in the script data double escaped
+   state.

+
+  
10.2.4.30 Script data double escaped dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Switch to the
+   script data double escaped dash dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Emit a U+003C LESS-THAN SIGN character token. Switch to the
+   script data double escaped less-than sign
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Switch to the script data double escaped
+   state.

+
+  
10.2.4.31 Script data double escaped dash dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Emit a U+002D HYPHEN-MINUS character token. Stay in the
+   script data double escaped dash dash state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
Emit a U+003C LESS-THAN SIGN character token. Switch to the
+   script data double escaped less-than sign
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit a U+003E GREATER-THAN SIGN character token. Switch to the
+   script data state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Emit the current input character as a character
+   token. Switch to the script data double escaped
+   state.

+
+  
10.2.4.32 Script data double escaped less-than sign state

+
+  
Consume the next input character:

+
+  
U+002F SOLIDUS (/)

+   
Emit a U+002F SOLIDUS character token. Set the temporary
+   buffer to the empty string. Switch to the script data
+   double escape end state.

+
+   
Anything else

+   
Reconsume the current input character in the
+   script data double escaped state.

+
+  
10.2.4.33 Script data double escape end state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
U+002F SOLIDUS (/)

+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current input character as a character
+   token. If the temporary buffer is the string "script", then switch to the script data
+   escaped state. Otherwise, switch to the script data
+   double escaped state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Emit the current input character as a character
+   token. Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   temporary buffer. Stay in the script data double
+   escape end state.

+
+   
U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z

+   
Emit the current input character as a character
+   token. Append the current input character to the
+   temporary buffer. Stay in the script data double
+   escape end state.

+
+   
Anything else

+   
Reconsume the current input character in the
+   script data double escaped state.

+
+  
10.2.4.34 Before attribute name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the before attribute name state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the self-closing start tag state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Start a new attribute in the current tag token. Set that
+   attribute's name to the lowercase version of the current input
+   character (add 0x0020 to the character's code point), and its
+   value to the empty string. Switch to the attribute name
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
U+0027 APOSTROPHE (')

+   
U+003C LESS-THAN SIGN (<)

+   
U+003D EQUALS SIGN (=)

+   
Parse error. Treat it as per the "anything else"
+   entry below.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Start a new attribute in the current tag token. Set that
+   attribute's name to the current input character, and its value to
+   the empty string. Switch to the attribute name
+   state.

+
+  
10.2.4.35 Attribute name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the after attribute name state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the self-closing start tag state.

+
+   
U+003D EQUALS SIGN (=)

+   
Switch to the before attribute value state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current attribute's name. Stay in the attribute name
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
U+0027 APOSTROPHE (')

+   
U+003C LESS-THAN SIGN (<)

+   
Parse error. Treat it as per the "anything else"
+   entry below.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   attribute's name. Stay in the attribute name
+   state.

+
+  
When the user agent leaves the attribute name state (and before
+  emitting the tag token, if appropriate), the complete attribute's
+  name must be compared to the other attributes on the same token;
+  if there is already an attribute on the token with the exact same
+  name, then this is a parse error and the new
+  attribute must be dropped, along with the value that gets
+  associated with it (if any).

+
+
+  
10.2.4.36 After attribute name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the after attribute name state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the self-closing start tag state.

+
+   
U+003D EQUALS SIGN (=)

+   
Switch to the before attribute value state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Start a new attribute in the current tag token. Set that
+   attribute's name to the lowercase version of the current
+   input character (add 0x0020 to the character's code point),
+   and its value to the empty string. Switch to the attribute
+   name state.

+
+   
U+0022 QUOTATION MARK (")

+   
U+0027 APOSTROPHE (')

+   
U+003C LESS-THAN SIGN (<)

+   
Parse error. Treat it as per the "anything else"
+   entry below.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Start a new attribute in the current tag token. Set that
+   attribute's name to the current input character, and
+   its value to the empty string. Switch to the attribute name
+   state.

+
+  
10.2.4.37 Before attribute value state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the before attribute value state.

+
+   
U+0022 QUOTATION MARK (")

+   
Switch to the attribute value (double-quoted) state.

+
+   
U+0026 AMPERSAND (&)

+   
Switch to the attribute value (unquoted) state
+   and reconsume this current input character.

+
+   
U+0027 APOSTROPHE (')

+   
Switch to the attribute value (single-quoted) state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Emit the current tag token. Switch to
+   the data state.

+
+   
U+003C LESS-THAN SIGN (<)

+   
U+003D EQUALS SIGN (=)

+   
U+0060 GRAVE ACCENT (`)

+   
Parse error. Treat it as per the "anything else"
+   entry below.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   attribute's value. Switch to the attribute value (unquoted)
+   state.

+
+  
10.2.4.38 Attribute value (double-quoted) state

+
+  
Consume the next input character:

+
+  
U+0022 QUOTATION MARK (")

+   
Switch to the after attribute value (quoted)
+   state.

+
+   
U+0026 AMPERSAND (&)

+   
Switch to the character reference in attribute value
+   state, with the additional allowed character
+   being U+0022 QUOTATION MARK (").

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   attribute's value. Stay in the attribute value
+   (double-quoted) state.

+
+  
10.2.4.39 Attribute value (single-quoted) state

+
+  
Consume the next input character:

+
+  
U+0027 APOSTROPHE (')

+   
Switch to the after attribute value (quoted)
+   state.

+
+   
U+0026 AMPERSAND (&)

+   
Switch to the character reference in attribute value
+   state, with the additional allowed character
+   being U+0027 APOSTROPHE (').

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   attribute's value. Stay in the attribute value
+   (single-quoted) state.

+
+  
10.2.4.40 Attribute value (unquoted) state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before attribute name state.

+
+   
U+0026 AMPERSAND (&)

+   
Switch to the character reference in attribute value
+   state, with the additional allowed character
+   being U+003E GREATER-THAN SIGN (>).

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
U+0027 APOSTROPHE (')

+   
U+003C LESS-THAN SIGN (<)

+   
U+003D EQUALS SIGN (=)

+   
U+0060 GRAVE ACCENT (`)

+   
Parse error. Treat it as per the "anything else"
+   entry below.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Append the current input character to the current
+   attribute's value. Stay in the attribute value (unquoted)
+   state.

+
+  
10.2.4.41 Character reference in attribute value state

+
+  
Attempt to consume a character reference.

+
+  
If nothing is returned, append a U+0026 AMPERSAND character to
+  the current attribute's value.

+
+  
Otherwise, append the returned character token to the current
+  attribute's value.

+
+  
Finally, switch back to the attribute value state that you were
+  in when were switched into this state.

+
+
+  
10.2.4.42 After attribute value (quoted) state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before attribute name state.

+
+   
U+002F SOLIDUS (/)

+   
Switch to the self-closing start tag state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current tag token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Parse error. Reconsume the character in
+   the before attribute name state.

+
+  
10.2.4.43 Self-closing start tag state

+
+  
Consume the next input character:

+
+  
U+003E GREATER-THAN SIGN (>)

+   
Set the self-closing flag of the current tag
+   token. Emit the current tag token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Parse error. Reconsume the character in
+   the before attribute name state.

+
+  
10.2.4.44 Bogus comment state

+
+  
Consume every character up to and including the first U+003E
+  GREATER-THAN SIGN character (>) or the end of the file (EOF),
+  whichever comes first. Emit a comment token whose data is the
+  concatenation of all the characters starting from and including
+  the character that caused the state machine to switch into the
+  bogus comment state, up to and including the character immediately
+  before the last consumed character (i.e. up to the character just
+  before the U+003E or EOF character). (If the comment was started
+  by the end of the file (EOF), the token is empty.)

+
+  
Switch to the data state.

+
+  
If the end of the file was reached, reconsume the EOF
+  character.

+
+
+  
10.2.4.45 Markup declaration open state

+
+  
If the next two characters are both U+002D HYPHEN-MINUS
+  characters (-), consume those two characters, create a comment token
+  whose data is the empty string, and switch to the comment
+  start state.

+
+  
Otherwise, if the next seven characters are an ASCII
+  case-insensitive match for the word "DOCTYPE", then consume
+  those characters and switch to the DOCTYPE state.

+
+  
Otherwise, if the insertion mode is "in foreign
+  content" and the current node is not an element
+  in the HTML namespace and the next seven characters are
+  an case-sensitive match for the string "[CDATA[" (the
+  five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET
+  character before and after), then consume those characters and
+  switch to the CDATA section state.

+
+  
Otherwise, this is a parse error. Switch to the
+  bogus comment state. The next character that is
+  consumed, if any, is the first character that will be in the
+  comment.

+
+
+  
10.2.4.46 Comment start state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Switch to the comment start dash state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Emit the comment token. Switch to the
+   data state.
 
+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume
+   the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the comment
+   token's data. Switch to the comment state.

+
+  
10.2.4.47 Comment start dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Switch to the comment end state

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Emit the comment token. Switch to
+   the data state.

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume the
+   EOF character in the data state.
 
+
+   
Anything else

+   
Append a U+002D HYPHEN-MINUS character (-) and the
+   current input character to the comment token's
+   data. Switch to the comment state.

+
+  
10.2.4.48 Comment state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Switch to the comment end dash state

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume the
+   EOF character in the data state.
 
+
+   
Anything else

+   
Append the current input character to the comment
+   token's data. Stay in the comment state.

+
+  
10.2.4.49 Comment end dash state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Switch to the comment end state

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume the
+   EOF character in the data state.
 
+
+   
Anything else

+   
Append a U+002D HYPHEN-MINUS character (-) and the
+   current input character to the comment token's
+   data. Switch to the comment state.

+
+  
10.2.4.50 Comment end state

+
+  
Consume the next input character:

+
+  
U+003E GREATER-THAN SIGN (>)

+   
Emit the comment token. Switch to the data
+   state.

+
+   
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Parse error. Append two U+002D HYPHEN-MINUS
+   characters (-) and the current input character to the
+   comment token's data. Switch to the comment end space
+   state.

+
+   
U+0021 EXCLAMATION MARK (!)

+   
Parse error. Switch to the comment end bang
+   state.

+
+   
U+002D HYPHEN-MINUS (-)

+   
Parse error. Append a U+002D HYPHEN-MINUS
+   character (-) to the comment token's data. Stay in the
+   comment end state.

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume
+   the EOF character in the data state.
 
+
+   
Anything else

+   
Parse error. Append two U+002D HYPHEN-MINUS
+   characters (-) and the current input character to the
+   comment token's data. Switch to the comment
+   state.

+
+  
10.2.4.51 Comment end bang state

+
+  
Consume the next input character:

+
+  
U+002D HYPHEN-MINUS (-)

+   
Append two U+002D HYPHEN-MINUS characters (-) and a U+0021
+   EXCLAMATION MARK character (!) to the comment token's data. Switch
+   to the comment end dash state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the comment token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume
+   the EOF character in the data state.
 
+
+   
Anything else

+   
Append two U+002D HYPHEN-MINUS characters (-), a U+0021
+   EXCLAMATION MARK character (!), and the current input
+   character to the comment token's data. Switch to the
+   comment state.

+
+  
10.2.4.52 Comment end space state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Append the current input character to the comment token's data. Stay in
+   the comment end space state.

+
+   
U+002D HYPHEN-MINUS (-)

+   
Switch to the comment end dash state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the comment token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Emit the comment token. Reconsume
+   the EOF character in the data state.
 
+
+   
Anything else

+   
Append the current input character to the comment token's data. Switch
+   to the comment state.

+
+  
10.2.4.53 DOCTYPE state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before DOCTYPE name state.

+
+   
EOF

+   
Parse error. Create a new DOCTYPE token. Set its
+   force-quirks flag to on. Emit the token. Reconsume
+   the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Reconsume the character in the
+   before DOCTYPE name state.

+
+  
10.2.4.54 Before DOCTYPE name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the before DOCTYPE name state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Create a new DOCTYPE token. Set the token's name to the
+   lowercase version of the current input character (add 0x0020 to the
+   character's code point). Switch to the DOCTYPE name
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Create a new DOCTYPE token. Set its
+   force-quirks flag to on. Emit the token. Switch to
+   the data state.

+
+   
EOF

+   
Parse error. Create a new DOCTYPE token. Set its
+   force-quirks flag to on. Emit the token. Reconsume
+   the EOF character in the data state.

+
+   
Anything else

+   
Create a new DOCTYPE token. Set the token's name to the
+   current input character. Switch to the DOCTYPE name
+   state.

+
+  
10.2.4.55 DOCTYPE name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the after DOCTYPE name state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current DOCTYPE token. Switch to the data
+   state.

+
+   
U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z

+   
Append the lowercase version of the current input
+   character (add 0x0020 to the character's code point) to the
+   current DOCTYPE token's name. Stay in the DOCTYPE name
+   state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the current
+   DOCTYPE token's name. Stay in the DOCTYPE name
+   state.

+
+  
10.2.4.56 After DOCTYPE name state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the after DOCTYPE name state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current DOCTYPE token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   

+
+    
If the six characters starting from the current input
+    character are an ASCII case-insensitive match
+    for the word "PUBLIC", then consume those characters and switch to
+    the after DOCTYPE public keyword state.

+
+    
Otherwise, if the six characters starting from the
+    current input character are an ASCII
+    case-insensitive match for the word "SYSTEM", then consume
+    those characters and switch to the after DOCTYPE system
+    keyword state.

+
+    
Otherwise, this is the parse error. Set the
+    DOCTYPE token's force-quirks flag to on. Switch to
+    the bogus DOCTYPE state.

+
+   

+
+  
10.2.4.57 After DOCTYPE public keyword state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before DOCTYPE public identifier
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
Parse error. Set the DOCTYPE token's public
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE public identifier (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Parse error. Set the DOCTYPE token's public
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE public identifier (single-quoted) state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.58 Before DOCTYPE public identifier state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the before DOCTYPE public identifier state.

+
+   
U+0022 QUOTATION MARK (")

+   
Set the DOCTYPE token's public identifier to the empty string
+   (not missing), then switch to the DOCTYPE public identifier
+   (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Set the DOCTYPE token's public identifier to the empty string
+   (not missing), then switch to the DOCTYPE public identifier
+   (single-quoted) state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.59 DOCTYPE public identifier (double-quoted) state

+
+  
Consume the next input character:

+
+  
U+0022 QUOTATION MARK (")

+   
Switch to the after DOCTYPE public identifier state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the current DOCTYPE
+   token's public identifier. Stay in the DOCTYPE public
+   identifier (double-quoted) state.

+
+  
10.2.4.60 DOCTYPE public identifier (single-quoted) state

+
+  
Consume the next input character:

+
+  
U+0027 APOSTROPHE (')

+   
Switch to the after DOCTYPE public identifier state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the current DOCTYPE
+   token's public identifier. Stay in the DOCTYPE public
+   identifier (single-quoted) state.

+
+  
10.2.4.61 After DOCTYPE public identifier state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the between DOCTYPE public and system
+   identifiers state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current DOCTYPE token. Switch to the data
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
Parse error. Set the DOCTYPE token's system
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE system identifier (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Parse error. Set the DOCTYPE token's system
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE system identifier (single-quoted) state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.62 Between DOCTYPE public and system identifiers state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the between DOCTYPE public and system identifiers
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current DOCTYPE token. Switch to the data
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
Set the DOCTYPE token's system identifier to the empty string
+   (not missing), then switch to the DOCTYPE system identifier
+   (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Set the DOCTYPE token's system identifier to the empty string
+   (not missing), then switch to the DOCTYPE system identifier
+   (single-quoted) state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.63 After DOCTYPE system keyword state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Switch to the before DOCTYPE system identifier
+   state.

+
+   
U+0022 QUOTATION MARK (")

+   
Parse error. Set the DOCTYPE token's system
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE system identifier (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Parse error. Set the DOCTYPE token's system
+   identifier to the empty string (not missing), then switch to the
+   DOCTYPE system identifier (single-quoted) state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.64 Before DOCTYPE system identifier state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the before DOCTYPE system identifier state.

+
+   
U+0022 QUOTATION MARK (")

+   
Set the DOCTYPE token's system identifier to the empty string
+   (not missing), then switch to the DOCTYPE system identifier
+   (double-quoted) state.

+
+   
U+0027 APOSTROPHE (')

+   
Set the DOCTYPE token's system identifier to the empty string
+   (not missing), then switch to the DOCTYPE system identifier
+   (single-quoted) state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Switch to the bogus
+   DOCTYPE state.

+
+  
10.2.4.65 DOCTYPE system identifier (double-quoted) state

+
+  
Consume the next input character:

+
+  
U+0022 QUOTATION MARK (")

+   
Switch to the after DOCTYPE system identifier
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the current
+   DOCTYPE token's system identifier. Stay in the DOCTYPE system
+   identifier (double-quoted) state.

+
+  
10.2.4.66 DOCTYPE system identifier (single-quoted) state

+
+  
Consume the next input character:

+
+  
U+0027 APOSTROPHE (')

+   
Switch to the after DOCTYPE system identifier
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE
+   token. Switch to the data state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Append the current input character to the current
+   DOCTYPE token's system identifier. Stay in the DOCTYPE system
+   identifier (single-quoted) state.

+
+  
10.2.4.67 After DOCTYPE system identifier state

+
+  
Consume the next input character:

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
Stay in the after DOCTYPE system identifier
+   state.

+
+   
U+003E GREATER-THAN SIGN (>)

+   
Emit the current DOCTYPE token. Switch to the data
+   state.

+
+   
EOF

+   
Parse error. Set the DOCTYPE token's
+   force-quirks flag to on. Emit that DOCTYPE token.
+   Reconsume the EOF character in the data state.

+
+   
Anything else

+   
Parse error. Switch to the bogus DOCTYPE
+   state. (This does not set the DOCTYPE token's
+   force-quirks flag to on.)

+
+  
10.2.4.68 Bogus DOCTYPE state

+
+  
Consume the next input character:

+
+  
U+003E GREATER-THAN SIGN (>)

+   
Emit the DOCTYPE token. Switch to the data
+   state.

+
+   
EOF

+   
Emit the DOCTYPE token. Reconsume the EOF character in the
+   data state.

+
+   
Anything else

+   
Stay in the bogus DOCTYPE state.

+
+  
10.2.4.69 CDATA section state

+
+  
Consume every character up to the next occurrence of the three
+  character sequence U+005D RIGHT SQUARE BRACKET U+005D RIGHT SQUARE
+  BRACKET U+003E GREATER-THAN SIGN (]]>), or the
+  end of the file (EOF), whichever comes first. Emit a series of
+  character tokens consisting of all the characters consumed except
+  the matching three character sequence at the end (if one was found
+  before the end of the file).

+
+  
Switch to the data state.

+
+  
If the end of the file was reached, reconsume the EOF
+  character.

+
+
+
+  
10.2.4.70 Tokenizing character references

+
+  
This section defines how to consume a character
+  reference. This definition is used when parsing character
+  references in
+  text and in attributes.

+
+  
The behavior depends on the identity of the next character (the
+  one immediately after the U+0026 AMPERSAND character):

+
+  
U+0009 CHARACTER TABULATION

+   
U+000A LINE FEED (LF)

+   
U+000C FORM FEED (FF)

+   
+   
U+0020 SPACE

+   
U+003C LESS-THAN SIGN

+   
U+0026 AMPERSAND

+   
EOF

+   
The additional allowed character, if there is one

+
+   
Not a character reference. No characters are consumed, and
+   nothing is returned. (This is not an error, either.)

+
+
+   
U+0023 NUMBER SIGN (#)

+
+   

+
+    
Consume the U+0023 NUMBER SIGN.

+
+    
The behavior further depends on the character after the U+0023
+    NUMBER SIGN:

+
+    
U+0078 LATIN SMALL LETTER X

+     
U+0058 LATIN CAPITAL LETTER X

+
+     

+
+      
Consume the X.

+
+      
Follow the steps below, but using the range of characters
+      U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN
+      SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041 LATIN
+      CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F (in other
+      words, 0-9, A-F, a-f).

+
+      
When it comes to interpreting the number, interpret it as a
+      hexadecimal number.

+
+     

+
+
+     
Anything else

+
+     

+
+      
Follow the steps below, but using the range of characters
+      U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).

+
+      
When it comes to interpreting the number, interpret it as a
+      decimal number.

+
+     

+
+    
Consume as many characters as match the range of characters
+    given above.

+
+    
If no characters match the range, then don't consume any
+    characters (and unconsume the U+0023 NUMBER SIGN character and, if
+    appropriate, the X character). This is a parse
+    error; nothing is returned.

+
+    
Otherwise, if the next character is a U+003B SEMICOLON, consume
+    that too. If it isn't, there is a parse
+    error.

+
+    
If one or more characters match the range, then take them all
+    and interpret the string of characters as a number (either
+    hexadecimal or decimal as appropriate).

+
+    
If that number is one of the numbers in the first column of the
+    following table, then this is a parse error. Find the
+    row with that number in the first column, and return a character
+    token for the Unicode character given in the second column of that
+    row.

+
+    
Number Unicode character
+     
0x00 U+FFFD REPLACEMENT CHARACTER
+      
0x0D U+000D CARRIAGE RETURN (CR)
+      
0x80 U+20AC EURO SIGN (€)
+      
0x81 U+0081 <control>
+      
0x82 U+201A SINGLE LOW-9 QUOTATION MARK (‚)
+      
0x83 U+0192 LATIN SMALL LETTER F WITH HOOK (ƒ)
+      
0x84 U+201E DOUBLE LOW-9 QUOTATION MARK („)
+      
0x85 U+2026 HORIZONTAL ELLIPSIS (…)
+      
0x86 U+2020 DAGGER (†)
+      
0x87 U+2021 DOUBLE DAGGER (‡)
+      
0x88 U+02C6 MODIFIER LETTER CIRCUMFLEX ACCENT (ˆ)
+      
0x89 U+2030 PER MILLE SIGN (‰)
+      
0x8A U+0160 LATIN CAPITAL LETTER S WITH CARON (Š)
+      
0x8B U+2039 SINGLE LEFT-POINTING ANGLE QUOTATION MARK (‹)
+      
0x8C U+0152 LATIN CAPITAL LIGATURE OE (Œ)
+      
0x8D U+008D <control>
+      
0x8E U+017D LATIN CAPITAL LETTER Z WITH CARON (Ž)
+      
0x8F U+008F <control>
+      
0x90 U+0090 <control>
+      
0x91 U+2018 LEFT SINGLE QUOTATION MARK (‘)
+      
0x92 U+2019 RIGHT SINGLE QUOTATION MARK (’)
+      
0x93 U+201C LEFT DOUBLE QUOTATION MARK (“)
+      
0x94 U+201D RIGHT DOUBLE QUOTATION MARK (”)
+      
0x95 U+2022 BULLET (•)
+      
0x96 U+2013 EN DASH (–)
+      
0x97 U+2014 EM DASH (—)
+      
0x98 U+02DC SMALL TILDE (˜)
+      
0x99 U+2122 TRADE MARK SIGN (™)
+      
0x9A U+0161 LATIN SMALL LETTER S WITH CARON (š)
+      
0x9B U+203A SINGLE RIGHT-POINTING ANGLE QUOTATION MARK (›)
+      
0x9C U+0153 LATIN SMALL LIGATURE OE (œ)
+      
0x9D U+009D <control>
+      
0x9E U+017E LATIN SMALL LETTER Z WITH CARON (ž)
+      
0x9F U+0178 LATIN CAPITAL LETTER Y WITH DIAERESIS (Ÿ)
+    
Otherwise, if the number is in the range 0xD800 to 0xDFFF or is greater than 0x10FFFF,
+    then this is a parse error. Return a U+FFFD
+    REPLACEMENT CHARACTER.

+
+    
Otherwise, return a character token for the Unicode character
+    whose code point is that number.
+
+    
+    If the number is in the range 0x0001 to 0x0008,    0x000E to 0x001F,  0x007F  to 0x009F, 0xFDD0 to
+    0xFDEF, or is one of 0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF,
+    0x2FFFE, 0x2FFFF, 0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE,
+    0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF,
+    0x9FFFE, 0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE,
+    0xCFFFF, 0xDFFFE, 0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF,
+    0x10FFFE, or 0x10FFFF, then this is a parse
+    error.

+
+   

+
+
+   
Anything else

+
+   

+
+    
Consume the maximum number of characters possible, with the
+    consumed characters matching one of the identifiers in the first
+    column of the named character references table (in a
+    case-sensitive manner).

+
+    
If no match can be made, then no characters are consumed, and
+    nothing is returned. In this case, if the characters after the
+    U+0026 AMPERSAND character (&) consist of a sequence of one or
+    more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+    NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
+    Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL
+    LETTER Z, followed by a U+003B SEMICOLON character (;), then this
+    is a parse error.

+
+    
If the character reference is being consumed as part of an
+    attribute, and the last character matched is not a U+003B
+    SEMICOLON character (;), and the next character is either a U+003D
+    EQUALS SIGN character (=) or in the range U+0030 DIGIT ZERO (0) to
+    U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+005A
+    LATIN CAPITAL LETTER Z, or U+0061 LATIN SMALL LETTER A to U+007A
+    LATIN SMALL LETTER Z, then, for historical reasons, all the
+    characters that were matched after the U+0026 AMPERSAND character
+    (&) must be unconsumed, and nothing is returned.

+    
+
+    
Otherwise, a character reference is parsed. If the last
+    character matched is not a U+003B SEMICOLON character (;), there
+    is a parse error.

+
+    
Return a character token for the character corresponding to the
+    character reference name (as given by the second column of the
+    named character references table).

+
+    

+
+     
If the markup contains (not in an attribute) the string I'm &notit; I tell you, the character
+     reference is parsed as "not", as in, I'm ¬it;
+     I tell you (and this is a parse error). But if the markup
+     was I'm &notin; I tell you, the
+     character reference would be parsed as "notin;", resulting in
+     I'm ∉ I tell you (and no parse
+     error).

+
+    

+
+   

+
+  

+
+
+  

+
+  
+
+  
10.2.5 Tree construction

+
+  
The input to the tree construction stage is a sequence of tokens
+  from the tokenization stage. The tree construction
+  stage is associated with a DOM Document object when a
+  parser is created. The "output" of this stage consists of
+  dynamically modifying or extending that document's DOM tree.

+
+  
This specification does not define when an interactive user agent
+  has to render the Document so that it is available to
+  the user, or when it has to begin accepting user input.

+
+  
As each token is emitted from the tokenizer, the user agent must
+  process the token according to the rules given in the section
+  corresponding to the current insertion mode.

+
+  
When the steps below require the UA to insert a
+  character into a node, if that node has a child immediately
+  before where the character is to be inserted, and that child is a
+  Text node, and that Text node was the last
+  node that the parser inserted into the document, then the character
+  must be appended to that Text node; otherwise, a new
+  Text node whose data is just that character must be
+  inserted in the appropriate place.

+
+  

+
+   
Here are some sample inputs to the parser and the corresponding
+   number of text nodes that they result in, assuming a user agent
+   that executes scripts.

+
+   
Input Number of text nodes
+    
A<script>
+var script = document.getElementsByTagName('script')[0];
+document.body.removeChild(script);
+</script>B

+      		Two adjacent text nodes in the document, containing "A" and "B".
+     
A<script>
+var text = document.createTextNode('B');
+document.body.appendChild(text);
+</script>C

+      		Four text nodes; "A" before the script, the script's contents, "B" after the script, and then, immediately after that, "C".
+     
A<script>
+var text = document.getElementsByTagName('script')[0].firstChild;
+text.data = 'B';
+document.body.appendChild(text);
+</script>B

+      		Two adjacent text nodes in the document, containing "A" and "BB".
+     
A<table>B<tr>C</tr>C</table>

+      		Three adjacent text nodes before the table, containing "A", "B", and "CC" respectively. (This is caused by foster parenting.)
+     
A<table><tr> B</tr> B</table>

+      		Two adjacent text nodes before the table, containing "A" and " B B" (space-B-space-B) respectively. (This is caused by foster parenting.)
+     
A<table><tr> B</tr> </em>C</table>

+      		Three adjacent text nodes before the table, containing "A", " B" (space-B), and "C" respectively, and one text node inside the table (as a child of a tbody) with a single space character. (Space characters separated from non-space characters by non-character tokens are not affected by foster parenting, even if those other tokens then get ignored.)
+   

+
+  
DOM mutation events must not fire
+  for changes caused by the UA parsing the document. (Conceptually,
+  the parser is not mutating the DOM, it is constructing it.) This
+  includes the parsing of any content inserted using document.write() and document.writeln() calls. [DOMEVENTS]

+
+  
Not all of the tag names mentioned below are
+  conformant tag names in this specification; many are included to
+  handle legacy content. They still form part of the algorithm that
+  implementations are required to implement to claim conformance.

+
+  
The algorithm described below places no limit on the
+  depth of the DOM tree generated, or on the length of tag names,
+  attribute names, attribute values, text nodes, etc. While
+  implementors are encouraged to avoid arbitrary limits, it is
+  recognized that practical
+  concerns will likely force user agents to impose nesting depth
+  constraints.

+
+
+  
10.2.5.1 Creating and inserting elements

+
+  
When the steps below require the UA to create an element for a token in a
+  particular namespace, the UA must create a node implementing the
+  interface appropriate for the element type corresponding to the tag
+  name of the token in the given namespace (as given in the
+  specification that defines that element, e.g. for an a
+  element in the HTML namespace, this specification
+  defines it to be the HTMLAnchorElement interface), with
+  the tag name being the name of that element, with the node being in
+  the given namespace, and with the attributes on the node being those
+  given in the given token.

+
+  
The interface appropriate for an element in the HTML
+  namespace that is not defined in this specification (or
+  other applicable specifications) is
+  HTMLUnknownElement. Element in other namespaces whose
+  interface is not defined by that namespace's specification must use
+  the interface Element.

+
+  
When a resettable element is
+  created in this manner, its reset algorithm must be
+  invoked once the attributes are set. (This initializes the element's
+  value and checkedness based on the element's
+  attributes.)

+
+  
When the steps below require the UA to insert an HTML
+  element for a token, the UA must first create an element
+  for the token in the HTML namespace, and then
+  append this node to the current node, and push it onto
+  the stack of open elements so that it is the new
+  current node.

+
+  
The steps below may also require that the UA insert an HTML
+  element in a particular place, in which case the UA must follow the
+  same steps except that it must insert or append the new node in the
+  location specified instead of appending it to the current
+  node. (This happens in particular during the parsing of
+  tables with invalid content.)

+
+  
If an element created by the insert an HTML element
+  algorithm is a form-associated element, and the
+  form element pointer is not null,
+  and the newly created element doesn't have a form attribute, the user agent must
+  associate the newly
+  created element with the form element pointed to by the
+  form element pointer before
+  inserting it wherever it is to be inserted.

+
+  
When the steps below require the UA to insert a foreign
+  element for a token, the UA must first create an element
+  for the token in the given namespace, and then append this
+  node to the current node, and push it onto the
+  stack of open elements so that it is the new
+  current node. If the newly created element has an xmlns attribute in the XMLNS namespace
+  whose value is not exactly the same as the element's namespace, that
+  is a parse error. Similarly, if the newly created
+  element has an xmlns:xlink attribute in the
+  XMLNS namespace whose value is not the XLink
+  Namespace, that is a parse error.

+
+  
When the steps below require the user agent to adjust MathML
+  attributes for a token, then, if the token has an attribute
+  named definitionurl, change its name to definitionURL (note the case difference).

+
+  
When the steps below require the user agent to adjust SVG
+  attributes for a token, then, for each attribute on the token
+  whose attribute name is one of the ones in the first column of the
+  following table, change the attribute's name to the name given in
+  the corresponding cell in the second column. (This fixes the case of
+  SVG attributes that are not all lowercase.)

+
+  
 Attribute name on token  Attribute name on element
+   
 attributename  attributeName
+    
 attributetype  attributeType
+    
 basefrequency  baseFrequency
+    
 baseprofile  baseProfile
+    
 calcmode  calcMode
+    
 clippathunits  clipPathUnits
+    
 contentscripttype  contentScriptType
+    
 contentstyletype  contentStyleType
+    
 diffuseconstant  diffuseConstant
+    
 edgemode  edgeMode
+    
 externalresourcesrequired  externalResourcesRequired
+    
 filterres  filterRes
+    
 filterunits  filterUnits
+    
 glyphref  glyphRef
+    
 gradienttransform  gradientTransform
+    
 gradientunits  gradientUnits
+    
 kernelmatrix  kernelMatrix
+    
 kernelunitlength  kernelUnitLength
+    
 keypoints  keyPoints
+    
 keysplines  keySplines
+    
 keytimes  keyTimes
+    
 lengthadjust  lengthAdjust
+    
 limitingconeangle  limitingConeAngle
+    
 markerheight  markerHeight
+    
 markerunits  markerUnits
+    
 markerwidth  markerWidth
+    
 maskcontentunits  maskContentUnits
+    
 maskunits  maskUnits
+    
 numoctaves  numOctaves
+    
 pathlength  pathLength
+    
 patterncontentunits  patternContentUnits
+    
 patterntransform  patternTransform
+    
 patternunits  patternUnits
+    
 pointsatx  pointsAtX
+    
 pointsaty  pointsAtY
+    
 pointsatz  pointsAtZ
+    
 preservealpha  preserveAlpha
+    
 preserveaspectratio  preserveAspectRatio
+    
 primitiveunits  primitiveUnits
+    
 refx  refX
+    
 refy  refY
+    
 repeatcount  repeatCount
+    
 repeatdur  repeatDur
+    
 requiredextensions  requiredExtensions
+    
 requiredfeatures  requiredFeatures
+    
 specularconstant  specularConstant
+    
 specularexponent  specularExponent
+    
 spreadmethod  spreadMethod
+    
 startoffset  startOffset
+    
 stddeviation  stdDeviation
+    
 stitchtiles  stitchTiles
+    
 surfacescale  surfaceScale
+    
 systemlanguage  systemLanguage
+    
 tablevalues  tableValues
+    
 targetx  targetX
+    
 targety  targetY
+    
 textlength  textLength
+    
 viewbox  viewBox
+    
 viewtarget  viewTarget
+    
 xchannelselector  xChannelSelector
+    
 ychannelselector  yChannelSelector
+    
 zoomandpan  zoomAndPan
+  
When the steps below require the user agent to adjust
+  foreign attributes for a token, then, if any of the attributes
+  on the token match the strings given in the first column of the
+  following table, let the attribute be a namespaced attribute, with
+  the prefix being the string given in the corresponding cell in the
+  second column, the local name being the string given in the
+  corresponding cell in the third column, and the namespace being the
+  namespace given in the corresponding cell in the fourth
+  column. (This fixes the use of namespaced attributes, in particular
+  lang attributes in
+  the XML namespace.)

+
+  
 Attribute name  Prefix  Local name  Namespace
+   
 xlink:actuate  xlink  actuate  XLink namespace
+    
 xlink:arcrole  xlink  arcrole  XLink namespace
+    
 xlink:href  xlink  href  XLink namespace
+    
 xlink:role  xlink  role  XLink namespace
+    
 xlink:show  xlink  show  XLink namespace
+    
 xlink:title  xlink  title  XLink namespace
+    
 xlink:type  xlink  type  XLink namespace
+    
 xml:base  xml  base  XML namespace 
+    
 xml:lang  xml  lang  XML namespace
+    
 xml:space  xml  space  XML namespace
+    
 xmlns  (none)  xmlns  XMLNS namespace
+    
 xmlns:xlink  xmlns  xlink  XMLNS namespace
+  
The generic raw text element parsing algorithm and the
+  generic RCDATA element parsing algorithm consist of the
+  following steps. These algorithms are always invoked in response to
+  a start tag token.

+
+  
  1. Insert an HTML element for the token.
    2. 
+
+   
  2. If the algorithm that was invoked is the generic raw
+   text element parsing algorithm, switch the tokenizer to the
+   RAWTEXT state; otherwise the algorithm invoked
+   was the generic RCDATA element parsing algorithm,
+   switch the tokenizer to the RCDATA state.
    3. 
+
+   
  3. Let the original insertion mode be the current
+   insertion mode.
    
+
+   
  4. Then, switch the insertion mode to "text".
    5. 
+
+  
10.2.5.2 Closing elements that have implied end tags

+
+  
When the steps below require the UA to generate implied end
+  tags, then, while the current node is a
+  dd element, a dt element, an
+  li element, an option element, an
+  optgroup element, a p element, an
+  rp element, or an rt element, the UA must
+  pop the current node off the stack of open
+  elements.

+
+  
If a step requires the UA to generate implied end tags but lists
+  an element to exclude from the process, then the UA must perform the
+  above steps as if that element was not in the above list.

+
+
+  
10.2.5.3 Foster parenting

+
+  
Foster parenting happens when content is misnested in tables.

+
+  
When a node node is to be foster parented, the node node
+  must be inserted into the foster parent element.

+
+  
The foster parent element is the parent element of the
+  last table element in the stack of open
+  elements, if there is a table element and it has
+  such a parent element. If there is no table element in
+  the stack of open elements (fragment
+  case), then the foster parent element is the first
+  element in the stack of open elements (the
+  html element). Otherwise, if there is a
+  table element in the stack of open
+  elements, but the last table element in the
+  stack of open elements has no parent, or its parent
+  node is not an element, then the foster parent element is
+  the element before the last table element in the
+  stack of open elements.

+
+  
If the foster parent element is the parent element of the
+  last table element in the stack of open
+  elements, then node must be inserted
+  immediately before the last table element in
+  the stack of open elements in the foster parent
+  element; otherwise, node must be
+  appended to the foster parent element.

+
+
+
+  
10.2.5.4 The "initial" insertion mode

+
+  
When the insertion mode is "initial", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Ignore the token.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the Document
+    object with the data attribute set to the
+    data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+
+    
If the DOCTYPE token's name is not a
+    case-sensitive match for the string "html", or the token's public identifier is not
+    missing, or the token's system identifier is neither missing nor a
+    case-sensitive match for the string
+    "about:legacy-compat", and none of the sets of
+    conditions in the following list are matched, then there is a
+    parse error.

+
+    
  • The DOCTYPE token's name is a case-sensitive
+     match for the string "html", the token's
+     public identifier is the case-sensitive string
+     "-//W3C//DTD HTML 4.0//EN", and
+     the token's system identifier is either missing or the
+     case-sensitive string "http://www.w3.org/TR/REC-html40/strict.dtd".
    • 
+
+     
  • The DOCTYPE token's name is a case-sensitive
+     match for the string "html", the token's
+     public identifier is the case-sensitive string
+     "-//W3C//DTD HTML 4.01//EN", and
+     the token's system identifier is either missing or the
+     case-sensitive string "http://www.w3.org/TR/html4/strict.dtd".
    • 
+
+     
  • The DOCTYPE token's name is a case-sensitive
+     match for the string "html", the token's
+     public identifier is the case-sensitive string
+     "-//W3C//DTD XHTML 1.0 Strict//EN",
+     and the token's system identifier is the
+     case-sensitive string "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd".
    • 
+
+     
  • The DOCTYPE token's name is a case-sensitive
+     match for the string "html", the token's
+     public identifier is the case-sensitive string
+     "-//W3C//DTD XHTML 1.1//EN", and
+     the token's system identifier is the case-sensitive
+     string "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd".
    • 
+
+    
Conformance checkers may, based on the values (including
+    presence or lack thereof) of the DOCTYPE token's name, public
+    identifier, or system identifier, switch to a conformance checking
+    mode for another language (e.g. based on the DOCTYPE token a
+    conformance checker could recognize that the document is an
+    HTML4-era document, and defer to an HTML4 conformance
+    checker.)

+
+    
Append a DocumentType node to the
+    Document node, with the name
+    attribute set to the name given in the DOCTYPE token, or the empty
+    string if the name was missing; the publicId
+    attribute set to the public identifier given in the DOCTYPE token,
+    or the empty string if the public identifier was missing; the
+    systemId attribute set to the system
+    identifier given in the DOCTYPE token, or the empty string if the
+    system identifier was missing; and the other attributes specific
+    to DocumentType objects set to null and empty lists
+    as appropriate. Associate the DocumentType node with
+    the Document object so that it is returned as the
+    value of the doctype attribute of the
+    Document object.

+
+    
Then, if the DOCTYPE token matches
+    one of the conditions in the following list, then set the
+    Document to quirks mode:

+
+    
  •  The force-quirks flag is set to on. 
    • 
+     
  •  The name is set to anything other than "html" (compared case-sensitively). 
    • 
+     
  •  The public identifier starts with: "+//Silmaril//dtd html Pro v0r11 19970101//" 
    • 
+     
  •  The public identifier starts with: "-//AdvaSoft Ltd//DTD HTML 3.0 asWedit + extensions//" 
    • 
+     
  •  The public identifier starts with: "-//AS//DTD HTML 3.0 asWedit + extensions//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0 Level 1//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0 Level 2//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0 Strict Level 1//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0 Strict Level 2//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0 Strict//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.0//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 2.1E//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 3.0//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 3.2 Final//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 3.2//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML 3//" 
    • 
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Level 0//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Level 1//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Level 2//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Level 3//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Strict Level 0//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Strict Level 1//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Strict Level 2//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Strict Level 3//" 
    • 
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML Strict//" 
    • 
+   
+   
+     
  •  The public identifier starts with: "-//IETF//DTD HTML//" 
    • 
+   
+   
+     
  •  The public identifier starts with: "-//Metrius//DTD Metrius Presentational//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 2.0 HTML Strict//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 2.0 HTML//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 2.0 Tables//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 3.0 HTML Strict//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 3.0 HTML//" 
    • 
+     
  •  The public identifier starts with: "-//Microsoft//DTD Internet Explorer 3.0 Tables//" 
    • 
+     
  •  The public identifier starts with: "-//Netscape Comm. Corp.//DTD HTML//" 
    • 
+     
  •  The public identifier starts with: "-//Netscape Comm. Corp.//DTD Strict HTML//" 
    • 
+     
  •  The public identifier starts with: "-//O'Reilly and Associates//DTD HTML 2.0//" 
    • 
+     
  •  The public identifier starts with: "-//O'Reilly and Associates//DTD HTML Extended 1.0//" 
    • 
+     
  •  The public identifier starts with: "-//O'Reilly and Associates//DTD HTML Extended Relaxed 1.0//" 
    • 
+     
  •  The public identifier starts with: "-//SoftQuad Software//DTD HoTMetaL PRO 6.0::19990601::extensions to HTML 4.0//" 
    • 
+     
  •  The public identifier starts with: "-//SoftQuad//DTD HoTMetaL PRO 4.0::19971010::extensions to HTML 4.0//" 
    • 
+     
  •  The public identifier starts with: "-//Spyglass//DTD HTML 2.0 Extended//" 
    • 
+     
  •  The public identifier starts with: "-//SQ//DTD HTML 2.0 HoTMetaL + extensions//" 
    • 
+     
  •  The public identifier starts with: "-//Sun Microsystems Corp.//DTD HotJava HTML//" 
    • 
+     
  •  The public identifier starts with: "-//Sun Microsystems Corp.//DTD HotJava Strict HTML//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 3 1995-03-24//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 3.2 Draft//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 3.2 Final//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 3.2//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 3.2S Draft//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 4.0 Frameset//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML 4.0 Transitional//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML Experimental 19960712//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD HTML Experimental 970421//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD W3 HTML//" 
    • 
+     
  •  The public identifier starts with: "-//W3O//DTD W3 HTML 3.0//" 
    • 
+   
+     
  •  The public identifier is set to: "-//W3O//DTD W3 HTML Strict 3.0//EN//" 
    • 
+     
  •  The public identifier starts with: "-//WebTechs//DTD Mozilla HTML 2.0//" 
    • 
+     
  •  The public identifier starts with: "-//WebTechs//DTD Mozilla HTML//" 
    • 
+     
  •  The public identifier is set to: "-/W3C/DTD HTML 4.0 Transitional/EN" 
    • 
+     
  •  The public identifier is set to: "HTML" 
    • 
+     
  •  The system identifier is set to: "http://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd" 
    • 
+     
  •  The system identifier is missing and the public identifier starts with: "-//W3C//DTD HTML 4.01 Frameset//" 
    • 
+     
  •  The system identifier is missing and the public identifier starts with: "-//W3C//DTD HTML 4.01 Transitional//" 
    • 
+    
Otherwise, if the DOCTYPE token matches one of the conditions
+    in the following list, then set the Document to
+    limited-quirks mode:

+
+    
  •  The public identifier starts with: "-//W3C//DTD XHTML 1.0 Frameset//" 
    • 
+     
  •  The public identifier starts with: "-//W3C//DTD XHTML 1.0 Transitional//" 
    • 
+     
  •  The system identifier is not missing and the public identifier starts with: "-//W3C//DTD HTML 4.01 Frameset//" 
    • 
+     
  •  The system identifier is not missing and the public identifier starts with: "-//W3C//DTD HTML 4.01 Transitional//" 
    • 
+    
The system identifier and public identifier strings must be
+    compared to the values given in the lists above in an ASCII
+    case-insensitive manner. A system identifier whose value is
+    the empty string is not considered missing for the purposes of the
+    conditions above.

+
+    
Then, switch the insertion mode to "before html".

+
+   

+
+   
Anything else

+   

+
+    
If the document is not an iframe
+    srcdoc document,
+    then this is a parse error; set the
+    Document to quirks mode.

+
+    
In any case, switch the insertion mode to "before html", then
+    reprocess the current token.

+
+   

+
+  
10.2.5.5 The "before html" insertion mode

+
+  
When the insertion mode is "before html", tokens must be handled as follows:

+
+  
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the Document
+    object with the data attribute set to the
+    data given in the comment token.

+   

+
+   
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+
+    
Create an element for the token in the HTML
+    namespace. Append it to the Document
+    object. Put this element in the stack of open
+    elements.

+
+    
If the Document is being
+    loaded as part of navigation of a
+    browsing context, then: if the newly created element
+    has a manifest attribute
+    whose value is not the empty string, then resolve the value of that attribute to an
+    absolute URL, relative to the newly created element,
+    and if that is successful, run the application cache selection
+    algorithm with the resulting absolute URL with
+    any <fragment> component
+    removed; otherwise, if there is no such attribute, or its value is
+    the empty string, or resolving its value fails, run the application cache selection
+    algorithm with no manifest. The algorithm must be passed
+    the Document object.

+
+    
Switch the insertion mode to "before head".

+
+   

+
+   
An end tag whose tag name is one of: "head", "body", "html", "br"

+   

+    
Act as described in the "anything else" entry below.

+   

+
+   
Any other end tag

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+
+    
Create an html element. Append it to the
+    Document object. Put this element in the stack
+    of open elements.

+
+    
If the Document is being loaded as part of navigation of a browsing
+    context, then: run the application cache selection
+    algorithm with no manifest, passing it the
+    Document object.

+
+    
Switch the insertion mode to "before head", then
+    reprocess the current token.

+
+   

+
+  
The root element can end up being removed from the
+  Document object, e.g. by scripts; nothing in particular
+  happens in such cases, content continues being appended to the nodes
+  as described in the next section.

+
+
+  
10.2.5.6 The "before head" insertion mode

+
+  
When the insertion mode is "before head", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Ignore the token.
 
+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "head"

+   

+
+    
Insert an HTML element for the token.

+
+    
Set the head element pointer
+    to the newly created head element.

+
+    
Switch the insertion mode to "in head".

+
+   

+
+   
An end tag whose tag name is one of: "head", "body", "html", "br"

+   

+
+    
Act as if a start tag token with the tag name "head" and no
+    attributes had been seen, then reprocess the current token.

+
+   

+
+   
Any other end tag

+   

+
+    
Parse error. Ignore the token.

+
+   

+
+   
Anything else

+   

+
+    
Act as if a start tag token with the tag name "head" and no
+    attributes had been seen, then reprocess the current
+    token.

+
+   

+
+  
10.2.5.7 The "in head" insertion mode

+
+  
When the insertion mode is "in head", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Insert the character into
+    the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is one of: "base", "command",
+   "link"

+   

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+   

+
+   
A start tag whose tag name is "meta"

+   

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+    
If the element has a charset attribute, and its
+    value is a supported encoding, and the confidence is
+    currently tentative, then change the
+    encoding to the encoding given by the value of the
+    charset attribute.

+
+    
Otherwise, if the element has an http-equiv attribute whose
+    value is an ASCII case-insensitive match for the
+    string "Content-Type", and the element has a
+    content attribute, and
+    applying the algorithm for extracting an encoding from a
+    Content-Type to that attribute's value returns a supported
+    encoding encoding, and the confidence is currently
+    tentative, then change the encoding to the
+    encoding encoding.

+
+   

+
+   
A start tag whose tag name is "title"

+   

+    
Follow the generic RCDATA element parsing algorithm.

+   

+
+   
A start tag whose tag name is "noscript", if the scripting flag is enabled

+   
A start tag whose tag name is one of: "noframes", "style"

+   

+    
Follow the generic raw text element parsing algorithm.

+   

+
+   
A start tag whose tag name is "noscript", if the scripting flag is disabled

+   

+
+    
Insert an HTML element for the token.

+
+    
Switch the insertion mode to "in head
+    noscript".

+
+   

+
+   
A start tag whose tag name is "script"

+   

+
+    
Run these steps:

+
+    
  1. Create an element for the token in the
+     HTML namespace.
    2. 
+
+     
  2. 
+
+      
    Mark the element as being "parser-inserted".
    
+
+      
    This ensures that, if the script is external,
+      any document.write()
+      calls in the script will execute in-line, instead of blowing the
+      document away, as would happen in most other cases. It also
+      prevents the script from executing until the end tag is
+      seen.
    
+
+     
    3. 
+
+     
  3. If the parser was originally created for the HTML
+     fragment parsing algorithm, then mark the
+     script element as "already
+     started". (fragment case)
    4. 
+
+     
  4. Append the new element to the current node
+     and push it onto the stack of open
+     elements.
    5. 
+
+     
  5. Switch the tokenizer to the script data
+     state.
    6. 
+
+     
  6. Let the original insertion mode be the current
+     insertion mode.
    
+
+     
  7. Switch the insertion mode to "text".
    8. 
+
+    

+
+   
An end tag whose tag name is "head"

+   

+
+    
Pop the current node (which will be the
+    head element) off the stack of open
+    elements.

+
+    
Switch the insertion mode to "after head".

+
+   

+
+   
An end tag whose tag name is one of: "body", "html", "br"

+   

+    
Act as described in the "anything else" entry below.

+   

+
+   
A start tag whose tag name is "head"

+   
Any other end tag

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+
+    
+
+    
Act as if an end tag token with the tag name "head" had
+    been seen, and reprocess the current token.

+
+   

+
+  
10.2.5.8 The "in head noscript" insertion mode

+
+  
When the insertion mode is "in head noscript", tokens must be handled as follows:

+
+  
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
An end tag whose tag name is "noscript"

+   

+
+    
Pop the current node (which will be a
+    noscript element) from the stack of open
+    elements; the new current node will be a
+    head element.

+
+    
Switch the insertion mode to "in head".

+
+   

+
+   
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   
A comment token

+   
A start tag whose tag name is one of: "link", "meta", "noframes", "style"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
An end tag whose tag name is "br"

+   

+    
Act as described in the "anything else" entry below.

+   

+
+   
A start tag whose tag name is one of: "head", "noscript"

+   
Any other end tag

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+
+    
+
+    
Parse error. Act as if an end tag with the tag
+    name "noscript" had been seen and reprocess the current
+    token.

+
+   

+
+  
10.2.5.9 The "after head" insertion mode

+
+  
When the insertion mode is "after head", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Insert the character into
+    the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "body"

+   

+
+    
Insert an HTML element for the token.

+
+    
Set the frameset-ok flag to "not ok".

+
+    
Switch the insertion mode to "in body".

+
+   

+
+   
A start tag whose tag name is "frameset"

+   

+
+    
Insert an HTML element for the token.

+
+    
Switch the insertion mode to "in frameset".

+
+   

+
+   
A start tag token whose tag name is one of: "base", "link",
+   "meta", "noframes", "script", "style", "title"

+   

+
+    
Parse error.

+
+    
Push the node pointed to by the head element pointer onto the
+    stack of open elements.

+
+    
Process the token using the rules for the "in head" insertion
+    mode.

+
+    
Remove the node pointed to by the head element pointer from the stack
+    of open elements.

+
+    
The head element
+    pointer cannot be null at this point.

+
+   

+
+   
An end tag whose tag name is one of: "body", "html", "br"

+   

+    
Act as described in the "anything else" entry below.

+   

+
+   
A start tag whose tag name is "head"

+   
Any other end tag

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+    
Act as if a start tag token with the tag name "body" and no
+    attributes had been seen, then set the frameset-ok
+    flag back to "ok", and then reprocess the current
+    token.

+   

+
+  
10.2.5.10 The "in body" insertion mode

+
+  
When the insertion mode is "in body", tokens must be handled as follows:

+
+  
A character token

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert the token's
+    character into the current node.

+
+    
If the token is not one of U+0009 CHARACTER TABULATION, U+000A
+    LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN
+    (CR), or U+0020 SPACE, then set the frameset-ok
+    flag to "not ok".

+
+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Parse error. For each attribute on the token,
+    check to see if the attribute is already present on the top
+    element of the stack of open elements. If it is not,
+    add the attribute and its corresponding value to that element.

+   

+
+   
A start tag token whose tag name is one of: "base", "command",
+   "link", "meta", "noframes", "script", "style", "title"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "body"

+   

+
+    
Parse error.

+
+    
If the second element on the stack of open
+    elements is not a body element, or, if the
+    stack of open elements has only one node on it,
+    then ignore the token. (fragment case)

+
+    
Otherwise, for each attribute on the token, check to see if
+    the attribute is already present on the body
+    element (the second element) on the stack of open
+    elements. If it is not, add the attribute and its
+    corresponding value to that element.

+
+   

+
+   
A start tag whose tag name is "frameset"

+   

+
+    
Parse error.

+
+    
If the second element on the stack of open
+    elements is not a body element, or, if the
+    stack of open elements has only one node on it,
+    then ignore the token. (fragment case)

+
+    
If the frameset-ok flag is set to "not ok", ignore
+    the token.

+
+    
Otherwise, run the following steps:

+
+    
  1. Remove the second element on the stack of open
+     elements from its parent node, if it has one.
    2. 
+
+     
  2. Pop all the nodes from the bottom of the stack of
+     open elements, from the current node up to,
+     but not including, the root html element.
    
+
+     
  3. Insert an HTML element for the
+     token.
    4. 
+
+     
  4. Switch the insertion mode to "in frameset".
    
+
+    

+
+   
An end-of-file token

+   

+
+    
If there is a node in the stack of open elements
+    that is not either a dd element, a dt
+    element, an li element, a p element, a
+    tbody element, a td element, a
+    tfoot element, a th element, a
+    thead element, a tr element, the
+    body element, or the html element, then
+    this is a parse error.
 
+
+    
Stop parsing.

+
+   

+
+   
An end tag whose tag name is "body"

+   

+
+    
If the stack of open elements does not have a body element
+    in scope, this is a parse error; ignore the
+    token.

+
+    
+
+    
Otherwise, if there is a node in the stack of open
+    elements that is not either a dd element, a
+    dt element, an li element, an
+    optgroup element, an option element, a
+    p element, an rp element, an
+    rt element, a tbody element, a
+    td element, a tfoot element, a
+    th element, a thead element, a
+    tr element, the body element, or the
+    html element, then this is a parse
+    error.
 
+
+    
+
+    
Switch the insertion mode to "after body".

+
+   

+
+   
An end tag whose tag name is "html"

+   

+
+    
Act as if an end tag with tag name "body" had been seen,
+    then, if that token wasn't ignored, reprocess the current
+    token.

+
+   

+
+   
+
+   
+   
A start tag whose tag name is one of: "address", "article",
+   "aside", "blockquote", "center", 
+   "details", "dir", "div", "dl", "fieldset", "figure", "footer",
+   "header", "hgroup", "menu", "nav", "ol", "p", "section", "ul"

+   

+
+    
+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Insert an HTML element for the token.

+
+   

+
+   
+   
A start tag whose tag name is one of: "h1", "h2", "h3", "h4",
+   "h5", "h6"

+   

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
If the current node is an element whose tag name
+    is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a
+    parse error; pop the current node off
+    the stack of open elements.

+    
+
+    
Insert an HTML element for the token.

+
+   

+
+   
+   
A start tag whose tag name is one of: "pre", "listing"

+   

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Insert an HTML element for the token.

+
+    
If the next token is a U+000A LINE FEED (LF) character
+    token, then ignore that token and move on to the next
+    one. (Newlines at the start of pre blocks are
+    ignored as an authoring convenience.)

+
+    
+
+    
Set the frameset-ok flag to "not ok".

+
+   

+
+   
+   
A start tag whose tag name is "form"

+   

+
+    
If the form element
+    pointer is not null, then this is a parse
+    error; ignore the token.

+
+    
Otherwise:

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Insert an HTML element for the token, and set the
+    form element pointer to
+    point to the element created.

+
+   

+
+   
+   
A start tag whose tag name is "li"

+   

+
+    
Run these steps:

+
+    
  1. Set the frameset-ok flag to "not ok".
    2. 
+
+     
  2. Initialize node to be the current
+     node (the bottommost node of the stack).
    3. 
+
+     
  3. Loop: If node is an
+     li element, then act as if an end tag with the tag
+     name "li" had been seen, then jump to the last step.
    4. 
+
+     
  4. If node is not in the
+     formatting category, and is not in the
+     phrasing category, and is not an
+     address, div, or p
+     element, then jump to the last step.
    5.  
+
+     
  5. Otherwise, set node to the previous
+     entry in the stack of open elements and return to
+     the step labeled loop.
    6. 
+
+     
  6. 
+
+      
    This is the last step.
    
+
+      
    If the stack of open elements has a p element in
+      scope, then act as if an end tag with the tag name
+      "p" had been seen.
    
+
+      
    Finally, insert an HTML element for the
+      token.
    
+
+     
    7. 
+
+    

+
+   
+   
A start tag whose tag name is one of: "dd", "dt"

+   

+
+    
Run these steps:

+
+    
  1. Set the frameset-ok flag to "not ok".
    2. 
+
+     
  2. Initialize node to be the current
+     node (the bottommost node of the stack).
    3. 
+
+     
  3. Loop: If node is a
+     dd or dt element, then act as if an end
+     tag with the same tag name as node had been
+     seen, then jump to the last step.
    4. 
+
+     
  4. If node is not in the
+     formatting category, and is not in the
+     phrasing category, and is not an
+     address, div, or p
+     element, then jump to the last step.
    5.  
+
+     
  5. Otherwise, set node to the previous
+     entry in the stack of open elements and return to
+     the step labeled loop.
    6. 
+
+     
  6. 
+
+      
    This is the last step.
    
+
+      
    If the stack of open elements has a p element in
+      scope, then act as if an end tag with the tag name
+      "p" had been seen.
    
+
+      
    Finally, insert an HTML element for the
+      token.
    
+
+     
    7. 
+
+    

+
+   
+   
A start tag whose tag name is "plaintext"

+   

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Insert an HTML element for the token.

+
+    
Switch the tokenizer to the PLAINTEXT state.

+
+    
Once a start tag with the tag name "plaintext" has
+    been seen, that will be the last token ever seen other than
+    character tokens (and the end-of-file token), because there is no
+    way to switch out of the PLAINTEXT state.

+
+   

+
+   
+   
A start tag whose tag name is "button"

+   

+
+    
If the stack of open elements has a button element in
+    scope, then this is a parse error;
+    act as if an end tag with the tag name "button" had been seen,
+    then reprocess the token.

+
+    
Otherwise:

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token.

+
+    
Set the frameset-ok flag to "not ok".

+
+   

+
+   
+
+   
+   
An end tag whose tag name is one of: "address", "article",
+   "aside", "blockquote", "button", "center",
+    "details", "dir", "div", "dl",
+   "fieldset", "figure", "footer", "header", "hgroup", "listing",
+   "menu", "nav", "ol", "pre", "section", "ul"

+   

+
+    
If the stack of open elements does not have an element in scope
+    with the same tag name as that of the token, then this is a
+    parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element with the same tag name as the token has been
+     popped from the stack.
    4. 
+
+    

+
+   
+   
An end tag whose tag name is "form"

+   

+
+    
Let node be the element that the
+    form element pointer is set
+    to.

+
+    
Set the form element pointer
+    to null.

+
+    
If node is null or the stack of open
+    elements does not have node in scope, then this is
+    a parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags.
    2. 
+
+     
  2. If the current node is not node, then this is a parse
+     error.
    3. 
+
+     
  3. Remove node from the stack of
+     open elements.
    4. 
+
+    

+
+   
+   
An end tag whose tag name is "p"

+   

+
+    
If the stack of open elements does not have an element in scope
+    with the same tag name as that of the token, then this is a
+    parse error; act as if a start tag with the tag name
+    "p" had been seen, then reprocess the current token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags, except
+     for elements with the same tag name as the token.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element with the same tag name as the token has been
+     popped from the stack.
    4. 
+
+    

+
+   
+   
An end tag whose tag name is "li"

+   

+
+    
If the stack of open elements does not have an element in list
+    item scope with the same tag name as that of the token,
+    then this is a parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags, except
+     for elements with the same tag name as the token.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element with the same tag name as the token has been
+     popped from the stack.
    4. 
+
+    

+
+   
+   
An end tag whose tag name is one of: "dd", "dt"

+   

+
+    
If the stack of open elements does not have an element in scope
+    with the same tag name as that of the token, then this is a
+    parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags, except
+     for elements with the same tag name as the token.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element with the same tag name as the token has been
+     popped from the stack.
    4. 
+
+    

+
+   
+   
An end tag whose tag name is one of: "h1", "h2", "h3", "h4", "h5", "h6"

+   

+
+    
If the stack of open elements does not have an element in scope
+    whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6",
+    then this is a parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element whose tag name is one of "h1", "h2", "h3", "h4",
+     "h5", or "h6" has been popped from the stack.
    4. 
+
+    

+
+   
+
+   
An end tag whose tag name is "sarcasm"

+   

+    
Take a deep breath, then act as described in the "any other end
+    tag" entry below.

+   

+
+   
+
+   
A start tag whose tag name is "a"

+   

+
+    
If the list of active formatting elements
+    contains an element whose tag name is "a" between the end of
+    the list and the last marker on the list (or the start of the
+    list if there is no marker on the list), then this is a
+    parse error; act as if an end tag with the tag
+    name "a" had been seen, then remove that element from the
+    list of active formatting elements and the
+    stack of open elements if the end tag didn't
+    already remove it (it might not have if the element is not
+    in table
+    scope).

+
+    
In the non-conforming stream
+    <a href="a">a<table><a href="b">b</table>x,
+    the first a element would be closed upon seeing the
+    second one, and the "x" character would be inside a link to "b",
+    not to "a". This is despite the fact that the outer a
+    element is not in table scope (meaning that a regular
+    </a> end tag at the start of the table wouldn't
+    close the outer a element). The result is that the
+    two a elements are indirectly nested inside each
+    other — non-conforming markup will often result in
+    non-conforming DOMs when parsed.

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token. Add that
+    element to the list of active formatting
+    elements.

+
+   

+
+   
A start tag whose tag name is one of: "b", "big", "code", "em",
+   "font", "i", "s", "small", "strike", "strong", "tt", "u"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token. Add that
+    element to the list of active formatting
+    elements.

+
+   

+
+   
A start tag whose tag name is "nobr"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
If the stack of open elements has a nobr element in scope,
+    then this is a parse error; act as if an end tag with
+    the tag name "nobr" had been seen, then once again
+    reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token. Add that
+    element to the list of active formatting
+    elements.

+
+   

+
+   
An end tag whose tag name is one of: "a",
+   "b", "big", "code", "em", "font", "i", "nobr", "s", "small",
+   "strike", "strong", "tt", "u"

+   

+
+    
Run these steps:

+
+    
  1. 
+
+      
    Let the formatting element be the
+      last element in the list of active formatting
+      elements that:
    
+
+      
    • is between the end of the list and the last scope
+       marker in the list, if any, or the start of the list
+       otherwise, and
      • 
+
+       
    • has the same tag name as the token.
      • 
+
+      
    If there is no such node, or, if that node is also in the
+      stack of open elements but the element is not in scope, then this is a
+      parse error; ignore the token, and abort these
+      steps.
    
+
+      
    Otherwise, if there is such a node, but that node is not
+      in the stack of open elements, then this is a
+      parse error; remove the element from the list,
+      and abort these steps.
    
+
+      
    Otherwise, there is a formatting
+      element and that element is in the stack and is in scope. If the element is not the
+      current node, this is a parse
+      error. In any case, proceed with the algorithm as
+      written in the following steps.
    
+
+     
    2. 
+
+     
  2. Let the furthest block be the
+     topmost node in the stack of open elements that
+     is lower in the stack than the formatting
+     element, and is not an element in the
+     phrasing or formatting
+     categories. There might not be one.
    3. 
+
+     
  3. If there is no furthest block,
+     then the UA must skip the subsequent steps and instead just
+     pop all the nodes from the bottom of the stack of open
+     elements, from the current node up to and
+     including the formatting element, and
+     remove the formatting element from the
+     list of active formatting elements.
    4. 
+
+     
  4. Let the common ancestor be the element
+     immediately above the formatting element in the
+     stack of open elements.
    5. 
+
+     
  5. Let a bookmark note the position of the formatting element in the list of active
+     formatting elements relative to the elements on either
+     side of it in the list.
    6. 
+
+     
  6. 
+
+      
    Let node and last node be the
+      furthest block. Follow these steps:
    
+
+      
    1. Let node be the element immediately
+       above node in the stack of open
+       elements, or if node is no longer in
+       the stack of open elements (e.g. because it got
+       removed by the next step), the element that was immediately
+       above node in the stack of open
+       elements before node was
+       removed.
      2. 
+
+       
    2. If node is not in the list of
+       active formatting elements, then remove node from the stack of open
+       elements and then go back to step 1.
      3. 
+
+       
    3. Otherwise, if node is the formatting element, then go to the next step
+       in the overall algorithm.
      4. 
+
+       
    4. Otherwise, if last node is the furthest block, then move the aforementioned
+       bookmark to be immediately after the node in the list of active formatting
+       elements.
      5. 
+
+       
    5. Create an element for the token for which the
+       element node was created, replace the entry
+       for node in the list of active
+       formatting elements with an entry for the new element,
+       replace the entry for node in the
+       stack of open elements with an entry for the new
+       element, and let node be the new
+       element.
      6. 
+
+       
    6. Insert last node into node, first removing it from its previous
+       parent node if any.
      7. 
+
+       
    7. Let last node be node.
      8. 
+
+       
    8. Return to step 1 of this inner set of steps.
      9. 
+
+      
    7. 
+
+     
  7. 
+
+      
    If the common ancestor node is a
+      table, tbody, tfoot,
+      thead, or tr element, then,
+      foster parent whatever last
+      node ended up being in the previous step, first removing
+      it from its previous parent node if any.
    
+
+      
    Otherwise, append whatever last node
+      ended up being in the previous step to the common
+      ancestor node, first removing it from its previous parent
+      node if any.
    
+
+     
    8. 
+
+     
  8. Create an element for the token for which the
+     formatting element was created.
    9. 
+
+     
  9. Take all of the child nodes of the furthest
+     block and append them to the element created in the last
+     step.
    10. 
+
+     
  10. Append that new element to the furthest
+     block.
    11. 
+
+     
  11. Remove the formatting element from the
+     list of active formatting elements, and insert the
+     new element into the list of active formatting
+     elements at the position of the aforementioned
+     bookmark.
    12. 
+
+     
  12. Remove the formatting element from the
+     stack of open elements, and insert the new element
+     into the stack of open elements immediately below
+     the position of the furthest block in that
+     stack.
    13. 
+
+     
  13. Jump back to step 1 in this series of steps.
    14. 
+
+    
Because of the way this algorithm causes elements
+    to change parents, it has been dubbed the "adoption agency
+    algorithm" (in contrast with other possible algorithms for dealing
+    with misnested content, which included the "incest algorithm", the
+    "secret affair algorithm", and the "Heisenberg algorithm").

+
+   

+
+   
A start tag token whose tag name is one of: "applet",
+   "marquee", "object"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token.

+
+    
Insert a marker at the end of the list of active
+    formatting elements.

+
+    
Set the frameset-ok flag to "not ok".

+
+   

+
+   
An end tag token whose tag name is one of: "applet",
+   "marquee", "object"

+   

+
+    
If the stack of open elements does not have an element in scope
+    with the same tag name as that of the token, then this is a
+    parse error; ignore the token.

+
+    
Otherwise, run these steps:

+
+    
  1. Generate implied end tags.
    2. 
+
+     
  2. If the current node is not an element with
+     the same tag name as that of the token, then this is a
+     parse error.
    3. 
+
+     
  3. Pop elements from the stack of open elements
+     until an element with the same tag name as the token has been
+     popped from the stack.
    4. 
+
+     
  4. Clear the list of active formatting elements up to the
+     last marker.
    5. 
+
+    

+
+   
A start tag whose tag name is "table"

+   

+
+    
If the Document is not set to
+    quirks mode, and the stack of open
+    elements has a
+    p element in scope, then act as if an end tag
+    with the tag name "p" had been seen.
 
+
+    
Insert an HTML element for the token.

+
+    
Set the frameset-ok flag to "not ok".

+
+    
Switch the insertion mode to "in table".

+
+   

+
+   
A start tag whose tag name is one of: "area", "basefont",
+   "bgsound", "br", "embed", "img", "input", "keygen", "wbr"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+    
Set the frameset-ok flag to "not ok".
 
+
+   

+
+   
A start tag whose tag name is one of: "param", "source", "track"

+   

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+   

+
+   
A start tag whose tag name is "hr"

+   

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+    
Set the frameset-ok flag to "not ok".

+
+   

+
+   
A start tag whose tag name is "image"

+   

+    
Parse error. Change the token's tag name
+    to "img" and reprocess it. (Don't ask.)
 
+   

+
+   
A start tag whose tag name is "isindex"

+   

+
+    
Parse error.

+
+    
If the form element
+    pointer is not null, then ignore the token.

+
+    
Otherwise:

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.
 
+
+    
Act as if a start tag token with the tag name "form" had been seen.

+
+    
If the token has an attribute called "action", set the
+    action attribute on the
+    resulting form element to the value of the
+    "action" attribute of the token.

+
+    
Act as if a start tag token with the tag name "hr" had been
+    seen.

+
+    
Act as if a start tag token with the tag name "label" had been
+    seen.

+
+    
Act as if a stream of character tokens had been seen (see below
+    for what they should say).

+
+    
Act as if a start tag token with the tag name "input" had been
+    seen, with all the attributes from the "isindex" token except
+    "name", "action", and "prompt". Set the name attribute of the resulting
+    input element to the value "isindex".

+
+    
Act as if a stream of character tokens had been seen (see
+    below for what they should say).

+
+    
Act as if an end tag token with the tag name "label" had been
+    seen.

+
+    
Act as if a start tag token with the tag name "hr" had been
+    seen.

+
+    
Act as if an end tag token with the tag name "form" had been
+    seen.

+
+    
If the token has an attribute with the name "prompt", then the
+    first stream of characters must be the same string as given in
+    that attribute, and the second stream of characters must be
+    empty. Otherwise, the two streams of character tokens together
+    should, together with the input element, express the
+    equivalent of "This is a searchable index. Enter search keywords:
+    (input field)" in the user's preferred language.

+
+   

+
+   
A start tag whose tag name is "textarea"

+   

+
+    
Run these steps:

+
+    
  1. Insert an HTML element for the
+     token.
    2. 
+
+     
  2. If the next token is a U+000A LINE FEED (LF) character
+     token, then ignore that token and move on to the next
+     one. (Newlines at the start of textarea elements are
+     ignored as an authoring convenience.)
    3. 
+
+     
+
+     
  3. Switch the tokenizer to the RCDATA
+     state.
    4. 
+
+     
  4. Let the original insertion mode be the
+     current insertion mode.
    
+
+     
  5. Set the frameset-ok flag to "not
+     ok".
    6. 
+
+     
  6. Switch the insertion mode to "text".
    7. 
+
+    

+
+   
A start tag whose tag name is "xmp"

+   

+
+    
If the stack of open elements has a p element in
+    scope, then act as if an end tag with the tag name
+    "p" had been seen.

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Set the frameset-ok flag to "not ok".

+
+    
Follow the generic raw text element parsing algorithm.

+
+   

+
+   
A start tag whose tag name is "iframe"

+   

+
+    
Set the frameset-ok flag to "not ok".

+
+    
Follow the generic raw text element parsing algorithm.

+
+   

+
+   
A start tag whose tag name is "noembed"

+   
A start tag whose tag name is "noscript", if the scripting flag is enabled

+   

+
+    
Follow the generic raw text element parsing algorithm.

+
+   

+
+   
A start tag whose tag name is "select"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token.

+
+    
Set the frameset-ok flag to "not ok".

+
+    
If the insertion mode is one of in table", "in caption", "in column group",
+    "in table
+    body", "in
+    row", or "in
+    cell", then switch the insertion mode to
+    "in select in
+    table". Otherwise, switch the insertion mode
+    to "in select".

+
+   

+
+   
A start tag whose tag name is one of: "optgroup", "option"

+   

+
+    
If the stack of open elements has an option element in
+    scope, then act as if an end tag with the tag name "option"
+    had been seen.

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token.

+
+   

+
+   
A start tag whose tag name is one of: "rp", "rt"

+   

+
+    
+
+    
If the stack of open elements has a ruby element in scope,
+    then generate implied end tags. If the current
+    node is not then a ruby element, this is a
+    parse error; pop all the nodes from the current
+    node up to the node immediately before the bottommost
+    ruby element on the stack of open
+    elements.

+
+    
Insert an HTML element for the token.

+
+   

+
+   
An end tag whose tag name is "br"

+   

+    
Parse error. Act as if a start tag token with
+    the tag name "br" had been seen. Ignore the end tag token.

+   

+
+   
A start tag whose tag name is "math"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Adjust MathML attributes for the token. (This
+    fixes the case of MathML attributes that are not all
+    lowercase.)

+
+    
Adjust foreign attributes for the token. (This
+    fixes the use of namespaced attributes, in particular XLink.)

+
+    
Insert a foreign element for the token, in the
+    MathML namespace.

+
+    
+
+    
If the token has its self-closing flag set, pop the
+    current node off the stack of open
+    elements and acknowledge the token's self-closing flag.

+
+    
Otherwise, if the insertion mode is not already
+    "in foreign
+    content", let the secondary insertion mode be
+    the current insertion mode, and then switch the
+    insertion mode to "in foreign content".

+
+   

+
+   
A start tag whose tag name is "svg"

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Adjust SVG attributes for the token. (This fixes
+    the case of SVG attributes that are not all lowercase.)

+
+    
Adjust foreign attributes for the token. (This
+    fixes the use of namespaced attributes, in particular XLink in
+    SVG.)

+
+    
Insert a foreign element for the token, in the
+    SVG namespace.

+
+    
+
+    
If the token has its self-closing flag set, pop the
+    current node off the stack of open
+    elements and acknowledge the token's self-closing flag.

+
+    
Otherwise, if the insertion mode is not already
+    "in foreign
+    content", let the secondary insertion mode be
+    the current insertion mode, and then switch the
+    insertion mode to "in foreign content".

+
+   

+
+   
A start  tag whose tag name is one of: "caption",
+   "col", "colgroup", "frame", "head", "tbody", "td", "tfoot", "th",
+   "thead", "tr"

+   
+   
+   

+    
Parse error. Ignore the token.

+    
+   

+
+   
Any other start tag

+   

+
+    
Reconstruct the active formatting elements, if
+    any.

+
+    
Insert an HTML element for the token.

+
+    
This element will be a phrasing
+    element.

+
+   

+
+   
Any other end tag

+   

+
+    
Run these steps:

+
+    
  1. Initialize node to be the current
+     node (the bottommost node of the stack).
    2. 
+
+     
  2. If node has the same tag name as
+     the token, then:
    
+
+      
    1. Generate implied end tags.
      2. 
+
+       
    2. If the tag name of the end tag token does not match
+       the tag name of the current node, this is a
+       parse error.
      3. 
+
+       
    3. Pop all the nodes from the current node up
+       to node, including node, then stop these steps.
      4. 
+
+      
    3. 
+
+     
  3. Otherwise, if node is in neither the
+     formatting category nor the phrasing
+     category, then this is a parse error; ignore the
+     token, and abort these steps.
    4. 
+
+     
  4. Set node to the previous entry in the
+     stack of open elements.
    5. 
+
+     
  5. Return to step 2.
    6. 
+
+    

+
+  
10.2.5.11 The "text" insertion mode

+
+  
When the insertion mode is "text", tokens must be handled as follows:

+
+  
A character token

+   

+
+    
Insert the token's
+    character into the current node.

+
+   

+
+   
An end-of-file token

+   

+
+    
+    
Parse error.

+
+    
If the current node is a script
+    element, mark the script element as "already
+    started".

+
+    
Pop the current node off the stack of open
+    elements.

+
+    
Switch the insertion mode to the original
+    insertion mode and reprocess the current token.

+
+   

+
+   
An end tag whose tag name is "script"

+   

+
+    
Let script be the current node
+    (which will be a script element).

+
+    
Pop the current node off the stack of open
+    elements.

+
+    
Switch the insertion mode to the original
+    insertion mode.

+
+    
Let the old insertion point have the
+    same value as the current insertion point. Let
+    the insertion point be just before the next
+    input character.

+
+    
Increment the parser's script nesting level by
+    one.

+
+    
Run the script. This might cause some script to execute,
+    which might cause new characters
+    to be inserted into the tokenizer, and might cause the
+    tokenizer to output more tokens, resulting in a reentrant invocation of the parser.

+
+    
Decrement the parser's script nesting level by
+    one. If the parser's script nesting level is zero,
+    then set the parser pause flag to false.

+
+    
Let the insertion point have the value of the old insertion point. (In other words, restore the
+    insertion point to its previous value. This value
+    might be the "undefined" value.)

+
+    
At this stage, if there is a
+    pending parsing-blocking script, then:

+
+    
If the script nesting level is not zero:

+
+     

+
+      
Set the parser pause flag to true, and abort the
+      processing of any nested invocations of the tokenizer, yielding
+      control back to the caller. (Tokenization will resume when the
+      caller returns to the "outer" tree construction stage.)

+
+      
The tree construction stage of this particular
+      parser is being called reentrantly,
+      say from a call to document.write().

+
+     

+
+
+     
Otherwise:

+
+     

+
+      
Run these steps:

+
+      
  1. Let the script be the pending
+       parsing-blocking script. There is no longer a pending
+       parsing-blocking script.
    2. 
+
+       
  2. Block the tokenizer
+       for this instance of the HTML parser, such that
+       the event loop will not run tasks that invoke the tokenizer.
    3. 
+
+       
  3. Spin the event loop until there is no style sheet blocking
+       scripts and the script's
+       "ready to be parser-executed" flag is set.
    4. 
+
+       
  4. Unblock the tokenizer
+       for this instance of the HTML parser, such that
+       tasks that invoke the tokenizer can again be
+       run.
    5. 
+
+       
  5. Let the insertion point be just before the
+       next input character.
    6. 
+
+       
  6. Increment the parser's script nesting level
+       by one (it should be zero before this step, so this sets it to
+       one).
    7. 
+
+       
  7. Execute
+       the script.
    8. 
+
+       
  8. Decrement the parser's script nesting level
+       by one. If the parser's script nesting level is
+       zero (which it always should be at this point), then set the
+       parser pause flag to false.
    
+
+       
  9. Let the insertion point be undefined
+       again.
    10. 
+
+       
  10. If there is once again a pending parsing-blocking
+       script, then repeat these steps from step 1.
    11. 
+
+      

+
+    

+
+   
Any other end tag

+   

+
+    
Pop the current node off the stack of open
+    elements.

+
+    
Switch the insertion mode to the original
+    insertion mode.

+
+   

+
+  
10.2.5.12 The "in table" insertion mode

+
+  
When the insertion mode is "in table", tokens must be handled as follows:

+
+  
A character token

+   

+
+     
Let the pending table character tokens
+     be an empty list of tokens.

+
+     
Let the original insertion mode be the current
+     insertion mode.

+
+     
Switch the insertion mode to "in table text" and
+     reprocess the token.

+
+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "caption"

+   

+
+    
Clear the stack back to a table context. (See
+    below.)

+
+    
Insert a marker at the end of the list of active
+    formatting elements.

+
+    
Insert an HTML element for the token, then
+    switch the insertion mode to "in caption".

+
+   

+
+   
A start tag whose tag name is "colgroup"

+   

+
+    
Clear the stack back to a table context. (See
+    below.)

+
+    
Insert an HTML element for the token, then
+    switch the insertion mode to "in column
+    group".

+
+   

+
+   
A start tag whose tag name is "col"

+   

+    
Act as if a start tag token with the tag name "colgroup"
+    had been seen, then reprocess the current token.

+   

+
+   
A start tag whose tag name is one of: "tbody", "tfoot", "thead"

+   

+
+    
Clear the stack back to a table context. (See
+    below.)

+
+    
Insert an HTML element for the token, then
+    switch the insertion mode to "in table
+    body".

+
+   

+
+   
A start tag whose tag name is one of: "td", "th", "tr"

+   

+    
Act as if a start tag token with the tag name "tbody" had
+    been seen, then reprocess the current token.

+   

+
+   
A start tag whose tag name is "table"

+   

+
+    
Parse error. Act as if an end tag token with
+    the tag name "table" had been seen, then, if that token wasn't
+    ignored, reprocess the current token.

+
+    
The fake end tag token here can only be
+    ignored in the fragment case.

+
+   

+
+   
An end tag whose tag name is "table"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token. (fragment
+    case)

+
+    
Otherwise:

+
+    
Pop elements from this stack until a table
+    element has been popped from the stack.

+
+    
Reset the insertion mode appropriately.

+
+   

+
+   
An end tag whose tag name is one of: "body", "caption",
+   "col", "colgroup", "html", "tbody", "td", "tfoot", "th",
+   "thead", "tr"

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is one of: "style", "script"

+   

+
+    
Process the token using the rules for the "in head" insertion
+    mode.

+
+   

+
+   
A start tag whose tag name is "input"

+   

+
+    
If the token does not have an attribute with the name "type",
+    or if it does, but that attribute's value is not an ASCII
+    case-insensitive match for the string "hidden", then: act as described in the "anything
+    else" entry below.

+
+    
Otherwise:

+
+    
Parse error.

+
+    
Insert an HTML element for the token.

+
+    
Pop that input element off the stack of
+    open elements.

+
+   

+
+   
A start tag whose tag name is "form"

+   

+
+    
Parse error.

+
+    
If the form element
+    pointer is not null, ignore the token.

+
+    
Otherwise:

+
+    
Insert an HTML element for the token.

+
+    
Pop that form element off the stack of
+    open elements.

+
+   

+
+   
+
+   
An end-of-file token

+   

+
+    
If the current node is not the root
+    html element, then this is a parse
+    error.

+
+    
It can only be the current node in
+    the fragment case.

+
+    
Stop parsing.

+
+   

+
+   
Anything else

+   

+
+    
Parse error. Process the token using the
+    rules for the "in
+    body" insertion mode, except that if the
+    current node is a table,
+    tbody, tfoot, thead, or
+    tr element, then, whenever a node would be inserted
+    into the current node, it must instead be foster parented.

+
+   

+
+  
When the steps above require the UA to clear the stack
+  back to a table context, it means that the UA must, while
+  the current node is not a table
+  element or an html element, pop elements from the
+  stack of open elements.

+
+  
The current node being an
+  html element after this process is a fragment
+  case.

+
+
+
+  
10.2.5.13 The "in table text" insertion mode

+
+  
When the insertion mode is "in table text", tokens must be handled
+  as follows:

+
+  
A character token

+   

+
+    
Append the character token to the pending table character
+    tokens list.

+
+   

+
+
+   
Anything else

+   

+
+    
If any of the tokens in the pending table character
+    tokens list are character tokens that are not one of U+0009
+    CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED
+    (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE, then
+    reprocess those character tokens using the rules given in the
+    "anything else" entry in the in table" insertion mode.

+
+    
Otherwise, insert the
+    characters given by the pending table character
+    tokens list into the current node.

+
+    
Switch the insertion mode to the original
+    insertion mode and reprocess the token.

+
+   

+
+  
10.2.5.14 The "in caption" insertion mode

+
+  
When the insertion mode is "in caption", tokens must be handled as follows:

+
+  
An end tag whose tag name is "caption"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token. (fragment
+    case)

+
+    
Otherwise:

+
+    
Generate implied end tags.

+
+    
Now, if the current node is not a
+    caption element, then this is a parse
+    error.

+
+    
Pop elements from this stack until a caption
+    element has been popped from the stack.

+
+    
Clear the list of active formatting elements up to
+    the last marker.

+
+    
Switch the insertion mode to "in table".

+
+   

+
+   
A start tag whose tag name is one of: "caption", "col",
+   "colgroup", "tbody", "td", "tfoot", "th", "thead", "tr"

+   
An end tag whose tag name is "table"

+   

+
+    
Parse error. Act as if an end tag with the tag
+    name "caption" had been seen, then, if that token wasn't
+    ignored, reprocess the current token.

+
+    
The fake end tag token here can only be
+    ignored in the fragment case.

+
+   

+
+   
An end tag whose tag name is one of: "body", "col",
+   "colgroup", "html", "tbody", "td", "tfoot", "th", "thead",
+   "tr"

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+  
10.2.5.15 The "in column group" insertion mode

+
+  
When the insertion mode is "in column group", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Insert the character into
+    the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "col"

+   

+
+    
Insert an HTML element for the token. Immediately
+    pop the current node off the stack of open
+    elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+   

+
+   
An end tag whose tag name is "colgroup"

+   

+
+    
If the current node is the root
+    html element, then this is a parse
+    error; ignore the token. (fragment
+    case)

+
+    
Otherwise, pop the current node (which will be
+    a colgroup element) from the stack of open
+    elements. Switch the insertion mode to
+    "in table".

+
+   

+
+   
An end tag whose tag name is "col"

+   

+    
Parse error. Ignore the token.

+   

+
+   
An end-of-file token

+   

+
+    
If the current node is the root html
+    element, then stop parsing. (fragment
+    case)

+
+    
Otherwise, act as described in the "anything else" entry
+    below.

+
+   

+
+   
Anything else

+   

+
+    
Act as if an end tag with the tag name "colgroup" had been
+    seen, and then, if that token wasn't ignored, reprocess the
+    current token.

+
+    
The fake end tag token here can only be
+    ignored in the fragment case.

+
+   

+
+  
10.2.5.16 The "in table body" insertion mode

+
+  
When the insertion mode is "in table body", tokens must be handled as follows:

+
+  
A start tag whose tag name is "tr"

+   

+
+    
Clear the stack back to a table body
+    context. (See below.)

+
+    
Insert an HTML element for the token, then switch
+    the insertion mode to "in row".

+
+   

+
+   
A start tag whose tag name is one of: "th", "td"

+   

+    
Parse error. Act as if a start tag with
+    the tag name "tr" had been seen, then reprocess the current
+    token.

+   

+
+   
An end tag whose tag name is one of: "tbody", "tfoot",
+   "thead"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token.

+
+    
Otherwise:

+
+    
Clear the stack back to a table body
+    context. (See below.)

+
+    
Pop the current node from the stack of
+    open elements. Switch the insertion mode
+    to "in table".

+
+   

+
+   
A start tag whose tag name is one of: "caption", "col",
+   "colgroup", "tbody", "tfoot", "thead"

+   
An end tag whose tag name is "table"

+   

+
+    
If the stack of open elements does not have a
+    tbody, thead, or tfoot
+    element in table scope, this is a parse
+    error. Ignore the token. (fragment
+    case)

+
+    
Otherwise:

+
+    
Clear the stack back to a table body
+    context. (See below.)

+
+    
Act as if an end tag with the same tag name as the
+    current node ("tbody", "tfoot", or "thead") had
+    been seen, then reprocess the current token.

+
+   

+
+   
An end tag whose tag name is one of: "body", "caption",
+   "col", "colgroup", "html", "td", "th", "tr"

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+    
Process the token using the rules for the "in table" insertion
+    mode.

+   

+
+  
When the steps above require the UA to clear the stack
+  back to a table body context, it means that the UA must,
+  while the current node is not a tbody,
+  tfoot, thead, or html
+  element, pop elements from the stack of open
+  elements.

+
+  
The current node being an
+  html element after this process is a fragment
+  case.

+
+
+  
10.2.5.17 The "in row" insertion mode

+
+  
When the insertion mode is "in row", tokens must be handled as follows:

+
+  
A start tag whose tag name is one of: "th", "td"

+   

+
+    
Clear the stack back to a table row
+    context. (See below.)

+
+    
Insert an HTML element for the token, then switch
+    the insertion mode to "in cell".

+
+    
Insert a marker at the end of the list of active
+    formatting elements.

+
+   

+
+   
An end tag whose tag name is "tr"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token. (fragment
+    case)

+
+    
Otherwise:

+
+    
Clear the stack back to a table row
+    context. (See below.)

+
+    
Pop the current node (which will be a
+    tr element) from the stack of open
+    elements. Switch the insertion mode to
+    "in table
+    body".

+
+   

+
+   
A start tag whose tag name is one of: "caption", "col",
+   "colgroup", "tbody", "tfoot", "thead", "tr"

+   
An end tag whose tag name is "table"

+   

+
+    
Act as if an end tag with the tag name "tr" had been seen,
+    then, if that token wasn't ignored, reprocess the current
+    token.

+
+    
The fake end tag token here can only be
+    ignored in the fragment case.

+
+   

+
+   
An end tag whose tag name is one of: "tbody", "tfoot",
+   "thead"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token.

+
+    
Otherwise, act as if an end tag with the tag name "tr" had
+    been seen, then reprocess the current token.

+
+   

+
+   
An end tag whose tag name is one of: "body", "caption",
+   "col", "colgroup", "html", "td", "th"

+   

+    
Parse error. Ignore the token.

+   

+
+   
Anything else

+   

+    
Process the token using the rules for the "in table" insertion
+    mode.

+   

+
+  
When the steps above require the UA to clear the stack
+  back to a table row context, it means that the UA must,
+  while the current node is not a tr
+  element or an html element, pop elements from the
+  stack of open elements.

+
+  
The current node being an
+  html element after this process is a fragment
+  case.

+
+
+  
10.2.5.18 The "in cell" insertion mode

+
+  
When the insertion mode is "in cell", tokens must be handled as follows:

+
+  
An end tag whose tag name is one of: "td", "th"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as that of the token, then
+    this is a parse error and the token must be
+    ignored.

+
+    
Otherwise:

+
+    
Generate implied end tags.

+
+    
Now, if the current node is not an element
+    with the same tag name as the token, then this is a
+    parse error.

+
+    
Pop elements from the stack of open elements stack
+    until an element with the same tag name as the token has been
+    popped from the stack.

+
+    
Clear the list of active formatting elements up to
+    the last marker.

+
+    
Switch the insertion mode to "in row". (The
+    current node will be a tr element at
+    this point.)

+
+   

+
+   
A start tag whose tag name is one of: "caption", "col",
+   "colgroup", "tbody", "td", "tfoot", "th", "thead", "tr"

+   

+
+    
If the stack of open elements does
+    not have
+    a td or th element in table
+    scope, then this is a parse error; ignore
+    the token. (fragment case)

+
+    
Otherwise, close the cell (see below) and
+    reprocess the current token.

+
+   

+
+   
An end tag whose tag name is one of: "body", "caption",
+   "col", "colgroup", "html"

+   

+    
Parse error. Ignore the token.

+   

+
+   
An end tag whose tag name is one of: "table", "tbody",
+   "tfoot", "thead", "tr"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as that of the token
+    (which can only happen for "tbody", "tfoot" and "thead", or,
+    in the fragment case), then this is a parse
+    error and the token must be ignored.

+
+    
Otherwise, close the cell (see below) and
+    reprocess the current token.

+
+   

+
+   
Anything else

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+  
Where the steps above say to close the cell, they
+  mean to run the following algorithm:

+
+  
  1. If the stack of open elements has a td
+   element in table scope, then act as if an end tag token
+   with the tag name "td" had been seen.
    2. 
+
+   
  2. Otherwise, the stack of open elements will
+   have a
+   th element in table scope; act as if an end
+   tag token with the tag name "th" had been seen.
    3. 
+
+  
The stack of open elements cannot
+  have both a td and a th element in table scope at
+  the same time, nor can it have neither when the insertion
+  mode is "in
+  cell".

+
+
+  
10.2.5.19 The "in select" insertion mode

+
+  
When the insertion mode is "in select", tokens must be handled as follows:

+
+  
A character token

+   

+    
Insert the token's
+    character into the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "option"

+   

+
+    
If the current node is an option
+    element, act as if an end tag with the tag name "option" had
+    been seen.

+
+    
Insert an HTML element for the token.

+
+   

+
+   
A start tag whose tag name is "optgroup"

+   

+
+    
If the current node is an option
+    element, act as if an end tag with the tag name "option" had
+    been seen.

+
+    
If the current node is an
+    optgroup element, act as if an end tag with the
+    tag name "optgroup" had been seen.

+
+    
Insert an HTML element for the token.

+
+   

+
+   
An end tag whose tag name is "optgroup"

+   

+
+    
First, if the current node is an
+    option element, and the node immediately before
+    it in the stack of open elements is an
+    optgroup element, then act as if an end tag with
+    the tag name "option" had been seen.

+
+    
If the current node is an
+    optgroup element, then pop that node from the
+    stack of open elements. Otherwise, this is a
+    parse error; ignore the token.

+
+   

+
+   
An end tag whose tag name is "option"

+   

+
+    
If the current node is an option
+    element, then pop that node from the stack of open
+    elements. Otherwise, this is a parse
+    error; ignore the token.

+
+   

+
+   
An end tag whose tag name is "select"

+   

+
+    
If the stack of open elements does not have an element in table
+    scope with the same tag name as the token, this is a
+    parse error. Ignore the token. (fragment
+    case)

+
+    
Otherwise:

+
+    
Pop elements from the stack of open elements
+    until a select element has been popped from the
+    stack.

+
+    
Reset the insertion mode appropriately.

+
+   

+
+   
A start tag whose tag name is "select"

+   

+
+    
Parse error. Act as if the token had been
+    an end tag with the tag name "select" instead.

+
+   

+
+   
A start tag whose tag name is one of: "input", "keygen", "textarea"

+   

+
+    
Parse error.

+
+    
If the stack of open elements does not have a select
+    element in table scope, ignore the token. (fragment
+    case)

+
+    
Otherwise, act as if an end tag with the tag name "select" had
+    been seen, and reprocess the token.

+
+   

+
+   
A start tag token whose tag name is "script"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
An end-of-file token

+   

+
+    
If the current node is not the root
+    html element, then this is a parse
+    error.

+
+    
It can only be the current node in
+    the fragment case.

+
+    
Stop parsing.

+
+   

+
+   
Anything else

+   

+    
Parse error. Ignore the token.

+   

+
+  
10.2.5.20 The "in select in table" insertion mode

+
+  
When the insertion mode is "in select in table", tokens must be handled as follows:

+
+  
A start tag whose tag name is one of: "caption", "table",
+   "tbody", "tfoot", "thead", "tr", "td", "th"

+   

+    
Parse error. Act as if an end tag with the tag
+    name "select" had been seen, and reprocess the token.

+   

+
+   
An end tag whose tag name is one of: "caption", "table",
+   "tbody", "tfoot", "thead", "tr", "td", "th"

+   

+
+    
Parse error.

+
+    
If the stack of open elements has an
+    element in table scope with the same tag name as that
+    of the token, then act as if an end tag with the tag name
+    "select" had been seen, and reprocess the token. Otherwise,
+    ignore the token.

+
+   

+
+   
Anything else

+   

+    
Process the token using the rules for the "in select" insertion
+    mode.

+   

+
+  
10.2.5.21 The "in foreign content" insertion mode

+
+  
When the insertion mode is "in foreign content", tokens must be
+  handled as follows:

+
+  
A character token

+   

+
+    
Insert the token's
+    character into the current node.

+
+    
If the token is not one of U+0009 CHARACTER TABULATION, U+000A
+    LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN
+    (CR), or U+0020 SPACE, then set the frameset-ok
+    flag to "not ok".

+
+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
An end tag whose tag name is "script", if the current node is a script element in the SVG namespace.

+   

+
+    
Pop the current node off the stack of open
+    elements.

+
+    
Let the old insertion point have the
+    same value as the current insertion point. Let
+    the insertion point be just before the next
+    input character.

+
+    
Increment the parser's script nesting level by
+    one. Set the parser pause flag to true.

+
+    
Process
+    the script element according to the SVG
+    rules, if the user agent supports SVG. [SVG]

+
+    
Even if this causes new characters to be inserted into the
+    tokenizer, the parser will not be executed reentrantly,
+    since the parser pause flag is true.

+
+    
Decrement the parser's script nesting level by
+    one. If the parser's script nesting level is zero,
+    then set the parser pause flag to false.

+
+    
Let the insertion point have the value of the old insertion point. (In other words, restore the
+    insertion point to its previous value. This value
+    might be the "undefined" value.)

+
+   

+
+   
An end tag, if the current node is not an element in the HTML namespace.

+
+   

+
+    
Run these steps:

+
+    
  1. Initialize node to be the current
+     node (the bottommost node of the stack).
    2. 
+
+     
  2. If node is not an element with the
+     same tag name as the token, then this is a parse
+     error.
    3. 
+
+     
  3. Loop: If node has the same tag
+     name as the token, pop elements from the stack of
+     open elements until node has been
+     popped from the stack, and then abort these steps.
    4. 
+
+     
  4. Set node to the previous entry in the
+     stack of open elements.
    5. 
+
+     
  5. 
+
+      
    If node is an element in the HTML
+      namespace, process the token using the rules
+      for the secondary insertion mode. If, after
+      doing so, the insertion mode is still "in foreign
+      content", but there is no element in scope that has a namespace other
+      than the HTML namespace, switch the insertion
+      mode to the secondary insertion mode.
    
+
+     
    6. 
+
+     
  6. Return to the step labeled loop.
    7. 
+
+    

+
+   
A start tag whose tag name is neither "mglyph" nor "malignmark", if the current node is an mi element in the MathML namespace.

+   
A start tag whose tag name is neither "mglyph" nor "malignmark", if the current node is an mo element in the MathML namespace.

+   
A start tag whose tag name is neither "mglyph" nor "malignmark", if the current node is an mn element in the MathML namespace.

+   
A start tag whose tag name is neither "mglyph" nor "malignmark", if the current node is an ms element in the MathML namespace.

+   
A start tag whose tag name is neither "mglyph" nor "malignmark", if the current node is an mtext element in the MathML namespace.

+   
A start tag whose tag name is "svg", if the current node is an annotation-xml element in the MathML namespace.

+   
A start tag, if the current node is a foreignObject element in the SVG namespace.

+   
A start tag, if the current node is a desc element in the SVG namespace.

+   
A start tag, if the current node is a title element in the SVG namespace.

+   
A start tag, if the current node is an element in the HTML namespace.

+   
Any other end tag

+   

+
+    
Process the token using the rules for the
+    secondary insertion mode.

+
+    
If, after doing so, the insertion mode is still
+    "in foreign
+    content", but there is no element in scope that has a namespace other than
+    the HTML namespace, switch the insertion
+    mode to the secondary insertion mode.

+
+   

+
+   
A start tag whose tag name is one of:  "b", "big",
+   "blockquote", "body", "br", "center", "code",
+   "dd", "div", "dl", "dt", "em", "embed", "h1", "h2",
+   "h3", "h4", "h5", "h6", "head", "hr", "i", "img",
+   "li", "listing", "menu", "meta", "nobr",
+   "ol", "p", "pre", "ruby", "s",  "small",
+   "span", "strong", "strike",  "sub", "sup",
+   "table", "tt", "u", "ul", "var"
 
+   
A start tag whose tag name is "font", if the token has any
+   attributes named "color", "face", or "size"
 
+   
An end-of-file token
 

+
+    
Parse error.

+
+    
Pop elements from the stack of open elements until
+    either a math element or an svg element
+    has been popped from the stack, and reprocess the token.

+
+   

+
+   
Any other start tag

+   

+
+    
If the current node is an element in the
+    MathML namespace, adjust MathML
+    attributes for the token. (This fixes the case of MathML
+    attributes that are not all lowercase.)

+
+    
If the current node is an element in the SVG
+    namespace, and the token's tag name is one of the ones in
+    the first column of the following table, change the tag name to
+    the name given in the corresponding cell in the second
+    column. (This fixes the case of SVG elements that are not all
+    lowercase.)

+
+    
 Tag name  Element name
+     
 altglyph  altGlyph
+      
 altglyphdef  altGlyphDef
+      
 altglyphitem  altGlyphItem
+      
 animatecolor  animateColor
+      
 animatemotion  animateMotion
+      
 animatetransform  animateTransform
+      
 clippath  clipPath
+      
 feblend  feBlend
+      
 fecolormatrix  feColorMatrix
+      
 fecomponenttransfer  feComponentTransfer
+      
 fecomposite  feComposite
+      
 feconvolvematrix  feConvolveMatrix
+      
 fediffuselighting  feDiffuseLighting
+      
 fedisplacementmap  feDisplacementMap
+      
 fedistantlight  feDistantLight
+      
 feflood  feFlood
+      
 fefunca  feFuncA
+      
 fefuncb  feFuncB
+      
 fefuncg  feFuncG
+      
 fefuncr  feFuncR
+      
 fegaussianblur  feGaussianBlur
+      
 feimage  feImage
+      
 femerge  feMerge
+      
 femergenode  feMergeNode
+      
 femorphology  feMorphology
+      
 feoffset  feOffset
+      
 fepointlight  fePointLight
+      
 fespecularlighting  feSpecularLighting
+      
 fespotlight  feSpotLight
+      
 fetile  feTile
+      
 feturbulence  feTurbulence
+      
 foreignobject  foreignObject
+      
 glyphref  glyphRef
+      
 lineargradient  linearGradient
+      
 radialgradient  radialGradient
+      
+      
 textpath  textPath
+    
If the current node is an element in the SVG
+    namespace, adjust SVG attributes for the
+    token. (This fixes the case of SVG attributes that are not all
+    lowercase.)

+
+    
Adjust foreign attributes for the token. (This
+    fixes the use of namespaced attributes, in particular XLink in
+    SVG.)

+
+    
Insert a foreign element for the token, in the
+    same namespace as the current node.

+
+    
If the token has its self-closing flag set, pop the
+    current node off the stack of open
+    elements and acknowledge the token's self-closing flag.

+
+   

+
+  
10.2.5.22 The "after body" insertion mode

+
+  
When the insertion mode is "after body", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the first element in
+    the stack of open elements (the html
+    element), with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
An end tag whose tag name is "html"

+   

+
+    
If the parser was originally created as part of the HTML
+    fragment parsing algorithm, this is a parse
+    error; ignore the token. (fragment case)

+
+    
Otherwise, switch the insertion mode to "after after
+    body".

+
+   

+
+   
An end-of-file token

+   

+    
Stop parsing.

+   

+
+   
Anything else

+   

+
+    
Parse error. Switch the insertion
+    mode to "in
+    body" and reprocess the token.

+
+   

+
+  
10.2.5.23 The "in frameset" insertion mode

+
+  
When the insertion mode is "in frameset", tokens must be handled as follows:

+
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Insert the character into
+    the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
A start tag whose tag name is "frameset"

+   

+    
Insert an HTML element for the token.

+   

+
+   
An end tag whose tag name is "frameset"

+   

+
+    
If the current node is the root
+    html element, then this is a parse
+    error; ignore the token. (fragment
+    case)

+
+    
Otherwise, pop the current node from the
+    stack of open elements.

+
+    
If the parser was not originally created as part
+    of the HTML fragment parsing algorithm
+    (fragment case), and the current
+    node is no longer a frameset element, then
+    switch the insertion mode to "after
+    frameset".

+
+   

+
+   
A start tag whose tag name is "frame"

+   

+
+    
Insert an HTML element for the token.
+    Immediately pop the current node off the
+    stack of open elements.

+
+    
Acknowledge the
+    token's self-closing flag, if it is set.

+
+   

+
+   
A start tag whose tag name is "noframes"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
An end-of-file token

+   

+
+    
If the current node is not the root
+    html element, then this is a parse
+    error.

+
+    
It can only be the current node in
+    the fragment case.

+
+    
Stop parsing.

+
+   

+
+   
Anything else

+   

+    
Parse error. Ignore the token.

+   

+
+  
10.2.5.24 The "after frameset" insertion mode

+
+  
When the insertion mode is "after frameset", tokens must be handled as follows:

+
+  
+  
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   

+    
Insert the character into
+    the current node.

+   

+
+   
A comment token

+   

+    
Append a Comment node to the current
+    node with the data attribute set to
+    the data given in the comment token.

+   

+
+   
A DOCTYPE token

+   

+    
Parse error. Ignore the token.

+   

+
+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
An end tag whose tag name is "html"

+   

+    
Switch the insertion mode to "after after
+    frameset".

+   

+
+   
A start tag whose tag name is "noframes"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
An end-of-file token

+   

+    
Stop parsing.

+   

+
+   
Anything else

+   

+    
Parse error. Ignore the token.

+   

+
+  
10.2.5.25 The "after after body" insertion mode

+
+  
When the insertion mode is "after after body", tokens must be handled as follows:

+
+  
A comment token

+   

+    
Append a Comment node to the Document
+    object with the data attribute set to the
+    data given in the comment token.

+   

+
+   
A DOCTYPE token

+   
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
An end-of-file token

+   

+    
Stop parsing.

+   

+
+   
Anything else

+   

+    
Parse error. Switch the insertion mode
+    to "in body" and
+    reprocess the token.

+   

+
+  
10.2.5.26 The "after after frameset" insertion mode

+
+  
When the insertion mode is "after after frameset", tokens must be handled as follows:

+
+  
A comment token

+   

+    
Append a Comment node to the Document
+    object with the data attribute set to the
+    data given in the comment token.

+   

+
+   
A DOCTYPE token

+   
A character token that is one of U+0009 CHARACTER
+   TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
+   U+000D CARRIAGE RETURN (CR), or U+0020 SPACE

+   
A start tag whose tag name is "html"

+   

+    
Process the token using the rules for the "in body" insertion
+    mode.

+   

+
+   
An end-of-file token

+   

+    
Stop parsing.

+   

+
+   
A start tag whose tag name is "noframes"

+   

+    
Process the token using the rules for the "in head" insertion
+    mode.

+   

+
+   
Anything else

+   

+    
Parse error. Ignore the token.

+   

+
+  

+
+
+  

+
+  
10.2.6 The end

+
+  
Once the user agent stops parsing
+  the document, the user agent must run the following steps:

+
+  
  1. Set the current document readiness to
+   "interactive"  and
+   the insertion point to undefined.
    2. 
+
+   
  2. Pop all the nodes off the stack of open
+   elements.
    3. 
+
+   
  3. If the list of scripts that will execute when the
+   document has finished parsing is not empty, run these
+   substeps:
    
+
+    
    1. Spin the event loop until the first
+     script in the list of scripts that will
+     execute when the document has finished parsing has its
+     "ready to be parser-executed" flag set and there
+     is no style sheet
+     blocking scripts.
      2. 
+
+     
    2. Execute the
+     first script in the list of scripts that will
+     execute when the document has finished parsing.
      3. 
+
+     
    3. Remove the first script element from the
+     list of scripts that will execute when the document has
+     finished parsing (i.e. shift out the first entry in the
+     list).
      4. 
+
+     
    4. If the list of scripts that will execute when the
+     document has finished parsing is still not empty, repeat
+     these substeps again from substep 1.
      
+
+    
    4. 
+
+   
  4. Queue a task to fire a simple
+   event named DOMContentLoaded at the
+   Document.
    5. 
+
+   
  5. Spin the event loop until the set of
+   scripts that will execute as soon as possible is
+   empty.
    6.  
+
+   
  6. Spin the event loop until there is nothing that
+   delays the load event in
+   the Document.
    7. 
+
+   
  7. Queue a task to set the current document
+   readiness to "complete". 
    8. 
+
+   
  8. If the Document is in a browsing
+   context, then queue a task to fire a
+   simple event named load at
+   the Document's Window object, but with
+   its target set to the
+   Document object (and the currentTarget set to the
+   Window object).
    9. 
+
+   
  9. If the Document is in a browsing
+   context, then queue a task to fire a pageshow event at the
+   Window object of the Document, but with
+   its target set to the
+   Document object (and the currentTarget set to the
+   Window object), using the
+   PageTransitionEvent interface, with the persisted
+   attribute set to false. This event must not bubble, must not be
+   cancelable, and has no default action.
    10. 
+
+   
  10. If the Document has a pending state
+   object, then queue a task to fire a popstate event at the
+   Document's Window object using the
+   PopStateEvent interface, with the state attribute set to the
+   current value of the pending state object. This event
+   must bubble but not be cancelable and has no default
+   action.
    11. 
+
+   
  11. If the Document has any pending
+   application cache download process tasks, then queue each such task in the order they were added to
+   the list of pending application cache download process
+   tasks, and then empty the list of pending application
+   cache download process tasks. The task source
+   for these tasks is the
+   networking task source.
    12. 
+
+   
  12. The Document is now completely
+   loaded.
    13. 
+
+  
When the user agent is to abort an HTML parser, it
+  must run the following steps:

+
+  
  1. Throw away any pending content in the input
+   stream, and discard any future content that would have been
+   added to it.
    2. 
+
+   
  2. Pop all the nodes off the stack of open
+   elements.
    3. 
+
+   
+
+  
Except where otherwise specified, the task source
+  for the tasks mentioned in this
+  section is the DOM manipulation task source.

+
+  

+
+
+  

+
+  
10.2.7 Coercing an HTML DOM into an infoset

+
+  
When an application uses an HTML parser in
+  conjunction with an XML pipeline, it is possible that the
+  constructed DOM is not compatible with the XML tool chain in certain
+  subtle ways. For example, an XML toolchain might not be able to
+  represent attributes with the name xmlns,
+  since they conflict with the Namespaces in XML syntax. There is also
+  some data that the HTML parser generates that isn't
+  included in the DOM itself. This section specifies some rules for
+  handling these issues.

+
+  
If the XML API being used doesn't support DOCTYPEs, the tool may
+  drop DOCTYPEs altogether.

+
+  
If the XML API doesn't support attributes in no namespace that
+  are named "xmlns", attributes whose names
+  start with "xmlns:", or attributes in the
+  XMLNS namespace, then the tool may drop such
+  attributes.

+
+  
The tool may annotate the output with any namespace declarations
+  required for proper operation.

+
+  
If the XML API being used restricts the allowable characters in
+  the local names of elements and attributes, then the tool may map
+  all element and attribute local names that the API wouldn't support
+  to a set of names that are allowed, by replacing any
+  character that isn't supported with the uppercase letter U and the
+  six digits of the character's Unicode code point when expressed in
+  hexadecimal, using digits 0-9 and capital letters A-F as the
+  symbols, in increasing numeric order.

+
+  
For example, the element name foo<bar, which can be output by the HTML
+  parser, though it is neither a legal HTML element name nor a
+  well-formed XML element name, would be converted into fooU00003Cbar, which is a well-formed XML
+  element name (though it's still not legal in HTML by any means).

+
+  
As another example, consider the attribute
+  xlink:href. Used on a MathML element, it becomes, after
+  being adjusted, an
+  attribute with a prefix "xlink" and a local
+  name "href". However, used on an HTML element,
+  it becomes an attribute with no prefix and the local name "xlink:href", which is not a valid NCName, and thus
+  might not be accepted by an XML API. It could thus get converted,
+  becoming "xlinkU00003Ahref".

+
+  
The resulting names from this conversion
+  conveniently can't clash with any attribute generated by the
+  HTML parser, since those are all either lowercase or
+  those listed in the adjust foreign attributes
+  algorithm's table.

+
+  
If the XML API restricts comments from having two consecutive
+  U+002D HYPHEN-MINUS characters (--), the tool may insert a single
+  U+0020 SPACE character between any such offending characters.

+
+  
If the XML API restricts comments from ending in a
+  U+002D HYPHEN-MINUS character (-), the tool may insert a single
+  U+0020 SPACE character at the end of such comments.

+
+  
If the XML API restricts allowed characters in character data,
+  attribute values, or comments, the tool may replace any U+000C FORM
+  FEED (FF) character with a U+0020 SPACE character, and any other
+  literal non-XML character with a U+FFFD REPLACEMENT CHARACTER.

+
+  
If the tool has no way to convey out-of-band information, then
+  the tool may drop the following information:

+
+  
The mutations allowed by this section apply
+  after the HTML parser's rules have been
+  applied. For example, a <a::> start tag
+  will be closed by a </a::> end tag, and
+  never by a </aU00003AU00003A> end tag, even
+  if the user agent is using the rules above to then generate an
+  actual element in the DOM with the name aU00003AU00003A for that start tag.

+
+  

+
+
+  

+
+  
10.2.8 An introduction to error handling and strange cases in the parser

+
+  
This section is non-normative.

+
+  
This section examines some erroneous markup and discusses how
+  the HTML parser handles these cases.

+
+
+  
10.2.8.1 Misnested tags: <b><i></b></i>

+
+  
This section is non-normative.

+
+  
The most-often discussed example of erroneous markup is as
+  follows:

+
+  
<p>1<b>2<i>3</b>4</i>5</p>

+
+  
The parsing of this markup is straightforward up to the "3". At
+  this point, the DOM looks like this:

+
+  
Here, the stack of open elements has five elements
+  on it: html, body, p,
+  b, and i. The list of active
+  formatting elements just has two: b and
+  i. The insertion mode is "in body".

+
+  
Upon receiving the end tag token with the tag name "b", the "adoption agency algorithm" is
+  invoked. This is a simple case, in that the formatting
+  element is the b element, and there is no
+  furthest block. Thus, the stack of open
+  elements ends up with just three elements: html,
+  body, and p, while the list of
+  active formatting elements has just one: i. The
+  DOM tree is unmodified at this point.

+
+  
The next token is a character ("4"), triggers the reconstruction of
+  the active formatting elements, in this case just the
+  i element. A new i element is thus created
+  for the "4" text node. After the end tag token for the "i" is also
+  received, and the "5" text node is inserted, the DOM looks as
+  follows:

+
+  
10.2.8.2 Misnested tags: <b><p></b></p>

+
+  
This section is non-normative.

+
+  
A case similar to the previous one is the following:

+
+  
<b>1<p>2</b>3</p>

+
+  
Up to the "2" the parsing here is straightforward:

+
+  
The interesting part is when the end tag token with the tag name
+  "b" is parsed.

+
+  
Before that token is seen, the stack of open
+  elements has four elements on it: html,
+  body, b, and p. The
+  list of active formatting elements just has the one:
+  b. The insertion mode is "in body".

+
+  
Upon receiving the end tag token with the tag name "b", the "adoption agency algorithm" is invoked, as
+  in the previous example. However, in this case, there is a
+  furthest block, namely the p element. Thus,
+  this time the adoption agency algorithm isn't skipped over.

+
+  
The common ancestor is the body
+  element. A conceptual "bookmark" marks the position of the
+  b in the list of active formatting
+  elements, but since that list has only one element in it,
+  it won't have much effect.

+
+  
As the algorithm progresses, node ends up set
+  to the formatting element (b), and last
+  node ends up set to the furthest block
+  (p).

+
+  
The last node gets appended (moved) to the
+  common ancestor, so that the DOM looks like:

+
+  
A new b element is created, and the children of the
+  p element are moved to it:

+
+  
  • b
    • #text: 2
Finally, the new b element is appended to the
+  p element, so that the DOM looks like:

+
+  
The b element is removed from the list of
+  active formatting elements and the stack of open
+  elements, so that when the "3" is parsed, it is appended to
+  the p element:

+
+  
10.2.8.3 Unexpected markup in tables

+
+  
This section is non-normative.

+
+  
Error handling in tables is, for historical reasons, especially
+  strange. For example, consider the following markup:

+
+  
<table><b><tr><td>aaa</td></tr>bbb</table>ccc

+
+  
The highlighted b element start tag is not allowed
+  directly inside a table like that, and the parser handles this case
+  by placing the element before the table. (This is called foster parenting.) This can be seen by
+  examining the DOM tree as it stands just after the
+  table element's start tag has been seen:

+
+  
...and then immediately after the b element start
+  tag has been seen:

+
+  
At this point, the stack of open elements has on it
+  the elements html, body,
+  table, and b (in that order, despite the
+  resulting DOM tree); the list of active formatting
+  elements just has the b element in it; and the
+  insertion mode is "in table".

+
+  
The tr start tag causes the b element
+  to be popped off the stack and a tbody start tag to be
+  implied; the tbody and tr elements are
+  then handled in a rather straight-forward manner, taking the parser
+  through the "in table
+  body" and "in
+  row" insertion modes, after which the DOM looks as
+  follows:

+
+  
Here, the stack of open elements has on it the
+  elements html, body, table,
+  tbody, and tr; the list of active
+  formatting elements still has the b element in
+  it; and the insertion mode is "in row".

+
+  
The td element start tag token, after putting a
+  td element on the tree, puts a marker on the list
+  of active formatting elements (it also switches to the "in cell" insertion
+  mode).

+
+  
The marker means that when the "aaa" character tokens are seen,
+  no b element is created to hold the resulting text
+  node:

+
+  
The end tags are handled in a straight-forward manner; after
+  handling them, the stack of open elements has on it the
+  elements html, body, table,
+  and tbody; the list of active formatting
+  elements still has the b element in it (the
+  marker having been removed by the "td" end tag token); and the
+  insertion mode is "in table body".

+
+  
Thus it is that the "bbb" character tokens are found. These
+  trigger the "in table
+  text" insertion mode to be used (with the original
+  insertion mode set to "in table body"). The character tokens are collected,
+  and when the next token (the table element end tag) is
+  seen, they are processed as a group. Since they are not all spaces,
+  they are handled as per the "anything else" rules in the "in table" insertion mode,
+  which defer to the "in
+  body" insertion mode but with foster parenting.

+
+  
When the
+  active formatting elements are reconstructed, a
+  b element is created and foster parented, and then the "bbb" text node is
+  appended to it:

+
+  
The stack of open elements has on it the elements
+  html, body, table,
+  tbody, and the new b (again, note that
+  this doesn't match the resulting tree!); the list of active
+  formatting elements has the new b element in it;
+  and the insertion mode is still "in table body".

+
+  
Had the character tokens been only space characters instead of "bbb", then those
+  space characters would just be
+  appended to the tbody element.

+
+  
Finally, the table is closed by a "table" end
+  tag. This pops all the nodes from the stack of open
+  elements up to and including the table element,
+  but it doesn't affect the list of active formatting
+  elements, so the "ccc" character tokens after the table
+  result in yet another b element being created, this
+  time after the table:

+
+  
10.2.8.4 Scripts that modify the page as it is being parsed

+
+  
This section is non-normative.

+
+  
Consider the following markup, which for this example we will
+  assume is the document with URL http://example.com/inner, being rendered as the
+  content of an iframe in another document with the
+  URL http://example.com/outer:

+
+  
<div id=a>
+ <script>
+  var div = document.getElementById('a');
+  parent.document.body.appendChild(div);
+ </script>
+ <script>
+  alert(document.URL);
+ </script>
+</div>
+<script>
+ alert(document.URL);
+</script>

+
+  
Up to the first "script" end tag, before the script is parsed,
+  the result is relatively straightforward:

+
+  
  • html
    • head
    • body
      • div id="a"
        • #text: 
+ 
        • script
          • #text: var div = document.getElementById('a'); ⏎ parent.document.body.appendChild(div);
After the script is parsed, though, the div element
+  and its child script element are gone:

+
+  
They are, at this point, in the Document of the
+  aforementioned outer browsing context. However, the
+  stack of open elements still contains the
+  div element.

+
+  
Thus, when the second script element is parsed, it
+  is inserted into the outer Document
+  object.

+
+  
This also means that the script's global object is
+  the outer browsing context's Window
+  object, not the Window object inside the
+  iframe.

+
+  
This isn't a security problem since the script that
+  moves the div into the outer Document can
+  only do so because the two Document object have the
+  same origin.

+
+  
Thus, the first alert says "http://example.com/outer".

+
+  
Once the div element's end tag is parsed, the
+  div element is popped off the stack, and so the next
+  script element is in the inner Document:

+
+  
This second alert will say "http://example.com/inner".

+
+
+
+
+  
10.3 Serializing HTML fragments

+
+  
The following steps form the HTML fragment serialization
+  algorithm. The algorithm takes as input a DOM
+  Element or Document, referred to as the node, and either returns a string or raises an
+  exception.

+
+  
This algorithm serializes the children of
+  the node being serialized, not the node itself.

+
+  
  1. Let s be a string, and initialize it to
+   the empty string.
    2. 
+
+   
  2. 
+
+    
    For each child node of the node, in
+    tree order, run the following steps:
+
+    
    1. Let current node be the child node
+     being processed.
      2. 
+
+     
    2. 
+
+      
      Append the appropriate string from the following list to
+      s:
      
+
+      
      If current node is an Element
      
+
+       
      
+
+        
      Append a U+003C LESS-THAN SIGN character character (<),
+        followed by the element's tag name. (For nodes created by the
+        HTML parser or Document.createElement(), the tag name will be
+        lowercase.)
      
+
+        
      For each attribute that the element has, append a U+0020
+        SPACE character, the attribute's name (which, for attributes
+        set by the HTML parser or by Element.setAttributeNode() or Element.setAttribute(), will be lowercase), a
+        U+003D EQUALS SIGN character (=), a U+0022 QUOTATION MARK
+        character ("), the attribute's value, escaped as described below in
+        attribute mode, and a second U+0022 QUOTATION MARK
+        character (").
      
+
+        
      While the exact order of attributes is UA-defined, and may
+        depend on factors such as the order that the attributes were
+        given in the original markup, the sort order must be stable,
+        such that consecutive invocations of this algorithm serialize an
+        element's attributes in the same order.
      
+
+        
      Append a U+003E GREATER-THAN SIGN character (>).
      
+
+        
      If current node is an
+        area, base, basefont,
+        bgsound, br, col,
+        embed, frame, hr,
+        img, input, keygen,
+        link, meta, param, or
+        wbr element, then continue on to the next child
+        node at this point.
       
+
+        
      If current node is a pre,
+        textarea, or listing element, append
+        a U+000A LINE FEED (LF) character.
      
+
+        
      Append the value of running the HTML fragment
+        serialization algorithm on the current
+        node element (thus recursing into this algorithm for
+        that element), followed by a U+003C LESS-THAN SIGN character
+        (<), a U+002F SOLIDUS character (/), the element's tag name
+        again, and finally a U+003E GREATER-THAN SIGN character
+        (>).
      
+
+       
      
+
+
+       
      If current node is a Text or CDATASection
+       node
      
+
+       
      
+
+        
      If the parent of current node is a
+        style, script, xmp,
+        iframe, noembed,
+        noframes, or plaintext element, or
+        if the parent of current node is
+        noscript element and scripting is enabled for the
+        node, then append the value of current
+        node's data IDL attribute
+        literally.
      
+
+        
      Otherwise, append the value of current
+        node's data IDL attribute, escaped as described
+        below.
      
+
+       
      
+
+
+       
      If current node is a Comment
      
+
+       
      
+
+        
      Append the literal string <!-- (U+003C
+        LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS,
+        U+002D HYPHEN-MINUS), followed by the value of current node's data IDL
+        attribute, followed by the literal string -->
+        (U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN
+        SIGN).
      
+
+       
      
+
+
+       
      If current node is a ProcessingInstruction
      
+
+       
      
+
+        
      Append the literal string <? (U+003C
+        LESS-THAN SIGN, U+003F QUESTION MARK), followed by the value
+        of current node's target IDL attribute, followed by a single
+        U+0020 SPACE character, followed by the value of current node's data IDL
+        attribute, followed by a single U+003E GREATER-THAN SIGN
+        character (>).
      
+
+       
      
+
+
+       
      If current node is a DocumentType
      
+
+       
      
+
+        
      Append the literal string <!DOCTYPE (U+003C
+        LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+0044 LATIN CAPITAL
+        LETTER D, U+004F LATIN CAPITAL LETTER O, U+0043 LATIN CAPITAL
+        LETTER C, U+0054 LATIN CAPITAL LETTER T, U+0059 LATIN CAPITAL
+        LETTER Y, U+0050 LATIN CAPITAL LETTER P, U+0045 LATIN CAPITAL
+        LETTER E), followed by a space (U+0020 SPACE), followed by the
+        value of current node's name IDL attribute, followed by the literal
+        string > (U+003E GREATER-THAN SIGN).
      
+
+       
      
+
+
+      
      Other node types (e.g. Attr) cannot
+      occur as children of elements. If, despite this, they somehow do
+      occur, this algorithm must raise an
+      INVALID_STATE_ERR exception.
      
+
+     
      3. 
+
+    
    3. 
+
+   
  3. The result of the algorithm is the string s.
    4. 
+
+  
Escaping a string (for the
+  purposes of the algorithm above) consists of replacing any
+  occurrences of the "&" character by the
+  string "&amp;", any occurrences of the
+  U+00A0 NO-BREAK SPACE character by the string "&nbsp;", and, if the algorithm was invoked in
+  the attribute mode, any occurrences of the """ character by the string "&quot;", or if it was not, any occurrences of
+  the "<" character by the string "&lt;", any occurrences of the ">" character by the string "&gt;".

+
+  
Entity reference nodes are assumed to be expanded by the user
+  agent, and are therefore not covered in the algorithm above.

+
+  
It is possible that the output of this algorithm, if
+  parsed with an HTML parser, will not return the
+  original tree structure. For instance, if a textarea
+  element to which a Comment node has been
+  appended is serialized and the output is then reparsed, the comment
+  will end up being displayed in the text field. Similarly, if, as a
+  result of DOM manipulation, an element contains a comment that
+  contains the literal string "-->", then
+  when the result of serializing the element is parsed, the comment
+  will be truncated at that point and the rest of the comment will be
+  interpreted as markup. More examples would be making a
+  script element contain a text node with the text string
+  "</script>", or having a p element that
+  contains a ul element (as the ul element's
+  start tag would imply the end
+  tag for the p).

+
+
+  
10.4 Parsing HTML fragments

+
+  
The following steps form the HTML fragment parsing
+  algorithm. The algorithm optionally takes as input an
+  Element node, referred to as the context element, which gives the context for the
+  parser, as well as input, a string to parse, and
+  returns a list of zero or more nodes.

+
+  
Parts marked fragment case in algorithms
+  in the parser section are parts that only occur if the parser was
+  created for the purposes of this algorithm (and with a context element). The algorithms have been annotated
+  with such markings for informational purposes only; such markings
+  have no normative weight. If it is possible for a condition
+  described as a fragment case to occur even when the
+  parser wasn't created for the purposes of handling this algorithm,
+  then that is an error in the specification.

+
+  
  1. 
+
+    
    Create a new Document node, and mark it as being
+    an HTML document.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If there is a context element, and the
+    Document of the context element
+    is in quirks mode, then let the Document
+    be in quirks mode. Otherwise, if there is a context element, and the Document of
+    the context element is in limited-quirks
+    mode, then let the Document be in
+    limited-quirks mode. Otherwise, leave the
+    Document in no-quirks mode.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Create a new HTML parser, and associate it with
+    the just created Document node.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If there is a context element, run these
+    substeps:
    
+
+    
    1. 
+
+      
      Set the state of the HTML parser's
+      tokenization stage as follows:
      
+
+      
      If it is a title or textarea
+       element
      
+
+       
      Switch the tokenizer to the RCDATA state.
      
+
+
+       
      If it is a style, xmp,
+       iframe, noembed, or
+       noframes element
      
+
+       
      Switch the tokenizer to the RAWTEXT state.
      
+
+
+       
      If it is a script element
      
+
+       
      Switch the tokenizer to the script data state.
      
+
+
+       
      If it is a noscript element
      
+
+       
      If the scripting flag is enabled, switch the
+       tokenizer to the RAWTEXT state.  Otherwise,
+       leave the tokenizer in the data state.
      
+
+
+       
      If it is a plaintext element
      
+
+       
      Switch the tokenizer to the PLAINTEXT
+       state.
      
+
+
+       
      Otherwise
      
+
+       
      Leave the tokenizer in the data state.
      
+
+      
      For performance reasons, an implementation that
+      does not report errors and that uses the actual state machine
+      described in this specification directly could use the PLAINTEXT
+      state instead of the RAWTEXT and script data states where those
+      are mentioned in the list above. Except for rules regarding
+      parse errors, they are equivalent, since there is no
+      appropriate end tag token in the fragment case, yet
+      they involve far fewer state transitions.
      
+
+     
      2. 
+
+     
    2. 
+
+      
      Let root be a new html element
+      with no attributes.
      
+
+     
      3. 
+
+     
    3. 
+
+      
      Append the element root to the
+      Document node created above.
      
+
+     
      4. 
+
+     
    4. 
+
+      
      Set up the parser's stack of open elements so that
+      it contains just the single element root.
      
+
+     
      5. 
+
+     
    5. 
+
+      
      Reset the
+      parser's insertion mode appropriately.
      
+
+      
      The parser will reference the context element as part of that algorithm.
      
+
+     
      6. 
+
+     
    6. 
+
+      
      Set the parser's form element pointer
+      to the nearest node to the context element
+      that is a form element (going straight up the
+      ancestor chain, and including the element itself, if it is a
+      form element), or, if there is no such
+      form element, to null.
      
+
+     
      7. 
+
+    
    5. 
+
+   
  5. 
+
+    
    Place into the input stream for the HTML
+    parser just created the input. The
+    encoding confidence is
+    irrelevant.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Start the parser and let it run until it has consumed all the
+    characters just inserted into the input stream.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    If there is a context element, return the
+    child nodes of root, in tree
+    order.
    
+
+    
    Otherwise, return the children of the Document
+    object, in tree order.
    
+
+   
    8. 
+
+  

+
+
+
+  
10.5 Named character references

+
+  
This table lists the character reference names that are supported
+  by HTML, and the code points to which they refer. It is referenced
+  by the previous sections.

+
+  

+   
 Name   Character   Glyph  
 AElig;   U+000C6   Æ  
 AElig   U+000C6   Æ  
 AMP;   U+00026   &  
 AMP   U+00026   &  
 Aacute;   U+000C1   Á  
 Aacute   U+000C1   Á  
 Abreve;   U+00102   Ă  
 Acirc;   U+000C2   Â  
 Acirc   U+000C2   Â  
 Acy;   U+00410   А  
 Afr;   U+1D504   𝔄  
 Agrave;   U+000C0   À  
 Agrave   U+000C0   À  
 Alpha;   U+00391   Α  
 Amacr;   U+00100   Ā  
 And;   U+02A53   ⩓  
 Aogon;   U+00104   Ą  
 Aopf;   U+1D538   𝔸  
 ApplyFunction;   U+02061   ⁡  
 Aring;   U+000C5   Å  
 Aring   U+000C5   Å  
 Ascr;   U+1D49C   𝒜  
 Assign;   U+02254   ≔  
 Atilde;   U+000C3   Ã  
 Atilde   U+000C3   Ã  
 Auml;   U+000C4   Ä  
 Auml   U+000C4   Ä  
 Backslash;   U+02216   ∖  
 Barv;   U+02AE7   ⫧  
 Barwed;   U+02306   ⌆  
 Bcy;   U+00411   Б  
 Because;   U+02235   ∵  
 Bernoullis;   U+0212C   ℬ  
 Beta;   U+00392   Β  
 Bfr;   U+1D505   𝔅  
 Bopf;   U+1D539   𝔹  
 Breve;   U+002D8   ˘  
 Bscr;   U+0212C   ℬ  
 Bumpeq;   U+0224E   ≎  
 CHcy;   U+00427   Ч  
 COPY;   U+000A9   ©  
 COPY   U+000A9   ©  
 Cacute;   U+00106   Ć  
 Cap;   U+022D2   ⋒  
 CapitalDifferentialD;   U+02145   ⅅ  
 Cayleys;   U+0212D   ℭ  
 Ccaron;   U+0010C   Č  
 Ccedil;   U+000C7   Ç  
 Ccedil   U+000C7   Ç  
 Ccirc;   U+00108   Ĉ  
 Cconint;   U+02230   ∰  
 Cdot;   U+0010A   Ċ  
 Cedilla;   U+000B8   ¸  
 CenterDot;   U+000B7   ·  
 Cfr;   U+0212D   ℭ  
 Chi;   U+003A7   Χ  
 CircleDot;   U+02299   ⊙  
 CircleMinus;   U+02296   ⊖  
 CirclePlus;   U+02295   ⊕  
 CircleTimes;   U+02297   ⊗  
 ClockwiseContourIntegral;   U+02232   ∲  
 CloseCurlyDoubleQuote;   U+0201D   ”  
 CloseCurlyQuote;   U+02019   ’  
 Colon;   U+02237   ∷  
 Colone;   U+02A74   ⩴  
 Congruent;   U+02261   ≡  
 Conint;   U+0222F   ∯  
 ContourIntegral;   U+0222E   ∮  
 Copf;   U+02102   ℂ  
 Coproduct;   U+02210   ∐  
 CounterClockwiseContourIntegral;   U+02233   ∳  
 Cross;   U+02A2F   ⨯  
 Cscr;   U+1D49E   𝒞  
 Cup;   U+022D3   ⋓  
 CupCap;   U+0224D   ≍  
 DD;   U+02145   ⅅ  
 DDotrahd;   U+02911   ⤑  
 DJcy;   U+00402   Ђ  
 DScy;   U+00405   Ѕ  
 DZcy;   U+0040F   Џ  
 Dagger;   U+02021   ‡  
 Darr;   U+021A1   ↡  
 Dashv;   U+02AE4   ⫤  
 Dcaron;   U+0010E   Ď  
 Dcy;   U+00414   Д  
 Del;   U+02207   ∇  
 Delta;   U+00394   Δ  
 Dfr;   U+1D507   𝔇  
 DiacriticalAcute;   U+000B4   ´  
 DiacriticalDot;   U+002D9   ˙  
 DiacriticalDoubleAcute;   U+002DD   ˝  
 DiacriticalGrave;   U+00060   `  
 DiacriticalTilde;   U+002DC   ˜  
 Diamond;   U+022C4   ⋄  
 DifferentialD;   U+02146   ⅆ  
 Dopf;   U+1D53B   𝔻  
 Dot;   U+000A8   ¨  
 DotDot;   U+020DC   ◌⃜  
 DotEqual;   U+02250   ≐  
 DoubleContourIntegral;   U+0222F   ∯  
 DoubleDot;   U+000A8   ¨  
 DoubleDownArrow;   U+021D3   ⇓  
 DoubleLeftArrow;   U+021D0   ⇐  
 DoubleLeftRightArrow;   U+021D4   ⇔  
 DoubleLeftTee;   U+02AE4   ⫤  
 DoubleLongLeftArrow;   U+027F8   ⟸  
 DoubleLongLeftRightArrow;   U+027FA   ⟺  
 DoubleLongRightArrow;   U+027F9   ⟹  
 DoubleRightArrow;   U+021D2   ⇒  
 DoubleRightTee;   U+022A8   ⊨  
 DoubleUpArrow;   U+021D1   ⇑  
 DoubleUpDownArrow;   U+021D5   ⇕  
 DoubleVerticalBar;   U+02225   ∥  
 DownArrow;   U+02193   ↓  
 DownArrowBar;   U+02913   ⤓  
 DownArrowUpArrow;   U+021F5   ⇵  
 DownBreve;   U+00311   ◌̑  
 DownLeftRightVector;   U+02950   ⥐  
 DownLeftTeeVector;   U+0295E   ⥞  
 DownLeftVector;   U+021BD   ↽  
 DownLeftVectorBar;   U+02956   ⥖  
 DownRightTeeVector;   U+0295F   ⥟  
 DownRightVector;   U+021C1   ⇁  
 DownRightVectorBar;   U+02957   ⥗  
 DownTee;   U+022A4   ⊤  
 DownTeeArrow;   U+021A7   ↧  
 Downarrow;   U+021D3   ⇓  
 Dscr;   U+1D49F   𝒟  
 Dstrok;   U+00110   Đ  
 ENG;   U+0014A   Ŋ  
 ETH;   U+000D0   Ð  
 ETH   U+000D0   Ð  
 Eacute;   U+000C9   É  
 Eacute   U+000C9   É  
 Ecaron;   U+0011A   Ě  
 Ecirc;   U+000CA   Ê  
 Ecirc   U+000CA   Ê  
 Ecy;   U+0042D   Э  
 Edot;   U+00116   Ė  
 Efr;   U+1D508   𝔈  
 Egrave;   U+000C8   È  
 Egrave   U+000C8   È  
 Element;   U+02208   ∈  
 Emacr;   U+00112   Ē  
 EmptySmallSquare;   U+025FB   ◻  
 EmptyVerySmallSquare;   U+025AB   ▫  
 Eogon;   U+00118   Ę  
 Eopf;   U+1D53C   𝔼  
 Epsilon;   U+00395   Ε  
 Equal;   U+02A75   ⩵  
 EqualTilde;   U+02242   ≂  
 Equilibrium;   U+021CC   ⇌  
 Escr;   U+02130   ℰ  
 Esim;   U+02A73   ⩳  
 Eta;   U+00397   Η  
 Euml;   U+000CB   Ë  
 Euml   U+000CB   Ë  
 Exists;   U+02203   ∃  
 ExponentialE;   U+02147   ⅇ  
 Fcy;   U+00424   Ф  
 Ffr;   U+1D509   𝔉  
 FilledSmallSquare;   U+025FC   ◼  
 FilledVerySmallSquare;   U+025AA   ▪  
 Fopf;   U+1D53D   𝔽  
 ForAll;   U+02200   ∀  
 Fouriertrf;   U+02131   ℱ  
 Fscr;   U+02131   ℱ  
 GJcy;   U+00403   Ѓ  
 GT;   U+0003E   >  
 GT   U+0003E   >  
 Gamma;   U+00393   Γ  
 Gammad;   U+003DC   Ϝ  
 Gbreve;   U+0011E   Ğ  
 Gcedil;   U+00122   Ģ  
 Gcirc;   U+0011C   Ĝ  
 Gcy;   U+00413   Г  
 Gdot;   U+00120   Ġ  
 Gfr;   U+1D50A   𝔊  
 Gg;   U+022D9   ⋙  
 Gopf;   U+1D53E   𝔾  
 GreaterEqual;   U+02265   ≥  
 GreaterEqualLess;   U+022DB   ⋛  
 GreaterFullEqual;   U+02267   ≧  
 GreaterGreater;   U+02AA2   ⪢  
 GreaterLess;   U+02277   ≷  
 GreaterSlantEqual;   U+02A7E   ⩾  
 GreaterTilde;   U+02273   ≳  
 Gscr;   U+1D4A2   𝒢  
 Gt;   U+0226B   ≫  
 HARDcy;   U+0042A   Ъ  
 Hacek;   U+002C7   ˇ  
 Hat;   U+0005E   ^  
 Hcirc;   U+00124   Ĥ  
 Hfr;   U+0210C   ℌ  
 HilbertSpace;   U+0210B   ℋ  
 Hopf;   U+0210D   ℍ  
 HorizontalLine;   U+02500   ─  
 Hscr;   U+0210B   ℋ  
 Hstrok;   U+00126   Ħ  
 HumpDownHump;   U+0224E   ≎  
 HumpEqual;   U+0224F   ≏  
 IEcy;   U+00415   Е  
 IJlig;   U+00132   IJ  
 IOcy;   U+00401   Ё  
 Iacute;   U+000CD   Í  
 Iacute   U+000CD   Í  
 Icirc;   U+000CE   Î  
 Icirc   U+000CE   Î  
 Icy;   U+00418   И  
 Idot;   U+00130   İ  
 Ifr;   U+02111   ℑ  
 Igrave;   U+000CC   Ì  
 Igrave   U+000CC   Ì  
 Im;   U+02111   ℑ  
 Imacr;   U+0012A   Ī  
 ImaginaryI;   U+02148   ⅈ  
 Implies;   U+021D2   ⇒  
 Int;   U+0222C   ∬  
 Integral;   U+0222B   ∫  
 Intersection;   U+022C2   ⋂  
 InvisibleComma;   U+02063   ⁣  
 InvisibleTimes;   U+02062   ⁢  
 Iogon;   U+0012E   Į  
 Iopf;   U+1D540   𝕀  
 Iota;   U+00399   Ι  
 Iscr;   U+02110   ℐ  
 Itilde;   U+00128   Ĩ  
 Iukcy;   U+00406   І  
 Iuml;   U+000CF   Ï  
 Iuml   U+000CF   Ï  
 Jcirc;   U+00134   Ĵ  
 Jcy;   U+00419   Й  
 Jfr;   U+1D50D   𝔍  
 Jopf;   U+1D541   𝕁  
 Jscr;   U+1D4A5   𝒥  
 Jsercy;   U+00408   Ј  
 Jukcy;   U+00404   Є  
 KHcy;   U+00425   Х  
 KJcy;   U+0040C   Ќ  
 Kappa;   U+0039A   Κ  
 Kcedil;   U+00136   Ķ  
 Kcy;   U+0041A   К  
 Kfr;   U+1D50E   𝔎  
 Kopf;   U+1D542   𝕂  
 Kscr;   U+1D4A6   𝒦  
 LJcy;   U+00409   Љ  
 LT;   U+0003C   <  
 LT   U+0003C   <  
 Lacute;   U+00139   Ĺ  
 Lambda;   U+0039B   Λ  
 Lang;   U+027EA   ⟪  
 Laplacetrf;   U+02112   ℒ  
 Larr;   U+0219E   ↞  
 Lcaron;   U+0013D   Ľ  
 Lcedil;   U+0013B   Ļ  
 Lcy;   U+0041B   Л  
 LeftAngleBracket;   U+027E8   ⟨  
 LeftArrow;   U+02190   ←  
 LeftArrowBar;   U+021E4   ⇤  
 LeftArrowRightArrow;   U+021C6   ⇆  
 LeftCeiling;   U+02308   ⌈  
 LeftDoubleBracket;   U+027E6   ⟦  
 LeftDownTeeVector;   U+02961   ⥡  
 LeftDownVector;   U+021C3   ⇃  
 LeftDownVectorBar;   U+02959   ⥙  
 LeftFloor;   U+0230A   ⌊  
 LeftRightArrow;   U+02194   ↔  
 LeftRightVector;   U+0294E   ⥎  
 LeftTee;   U+022A3   ⊣  
 LeftTeeArrow;   U+021A4   ↤  
 LeftTeeVector;   U+0295A   ⥚  
 LeftTriangle;   U+022B2   ⊲  
 LeftTriangleBar;   U+029CF   ⧏  
 LeftTriangleEqual;   U+022B4   ⊴  
 LeftUpDownVector;   U+02951   ⥑  
 LeftUpTeeVector;   U+02960   ⥠  
 LeftUpVector;   U+021BF   ↿  
 LeftUpVectorBar;   U+02958   ⥘  
 LeftVector;   U+021BC   ↼  
 LeftVectorBar;   U+02952   ⥒  
 Leftarrow;   U+021D0   ⇐  
 Leftrightarrow;   U+021D4   ⇔  
 LessEqualGreater;   U+022DA   ⋚  
 LessFullEqual;   U+02266   ≦  
 LessGreater;   U+02276   ≶  
 LessLess;   U+02AA1   ⪡  
 LessSlantEqual;   U+02A7D   ⩽  
 LessTilde;   U+02272   ≲  
 Lfr;   U+1D50F   𝔏  
 Ll;   U+022D8   ⋘  
 Lleftarrow;   U+021DA   ⇚  
 Lmidot;   U+0013F   Ŀ  
 LongLeftArrow;   U+027F5   ⟵  
 LongLeftRightArrow;   U+027F7   ⟷  
 LongRightArrow;   U+027F6   ⟶  
 Longleftarrow;   U+027F8   ⟸  
 Longleftrightarrow;   U+027FA   ⟺  
 Longrightarrow;   U+027F9   ⟹  
 Lopf;   U+1D543   𝕃  
 LowerLeftArrow;   U+02199   ↙  
 LowerRightArrow;   U+02198   ↘  
 Lscr;   U+02112   ℒ  
 Lsh;   U+021B0   ↰  
 Lstrok;   U+00141   Ł  
 Lt;   U+0226A   ≪  
 Map;   U+02905   ⤅  
 Mcy;   U+0041C   М  
 MediumSpace;   U+0205F      
 Mellintrf;   U+02133   ℳ  
 Mfr;   U+1D510   𝔐  
 MinusPlus;   U+02213   ∓  
 Mopf;   U+1D544   𝕄  
 Mscr;   U+02133   ℳ  
 Mu;   U+0039C   Μ  
 NJcy;   U+0040A   Њ  
 Nacute;   U+00143   Ń  
 Ncaron;   U+00147   Ň  
 Ncedil;   U+00145   Ņ  
 Ncy;   U+0041D   Н  
 NegativeMediumSpace;   U+0200B   ​  
 NegativeThickSpace;   U+0200B   ​  
 NegativeThinSpace;   U+0200B   ​  
 NegativeVeryThinSpace;   U+0200B   ​  
 NestedGreaterGreater;   U+0226B   ≫  
 NestedLessLess;   U+0226A   ≪  
 NewLine;   U+0000A   
+  
 Nfr;   U+1D511   𝔑  
 NoBreak;   U+02060   ⁠  
 NonBreakingSpace;   U+000A0      
 Nopf;   U+02115   ℕ  
 Not;   U+02AEC   ⫬  
 NotCongruent;   U+02262   ≢  
 NotCupCap;   U+0226D   ≭  
 NotDoubleVerticalBar;   U+02226   ∦  
 NotElement;   U+02209   ∉  
 NotEqual;   U+02260   ≠  
 NotExists;   U+02204   ∄  
 NotGreater;   U+0226F   ≯  
 NotGreaterEqual;   U+02271   ≱  
 NotGreaterLess;   U+02279   ≹  
 NotGreaterTilde;   U+02275   ≵  
 NotLeftTriangle;   U+022EA   ⋪  
 NotLeftTriangleEqual;   U+022EC   ⋬  
 NotLess;   U+0226E   ≮  
 NotLessEqual;   U+02270   ≰  
 NotLessGreater;   U+02278   ≸  
 NotLessTilde;   U+02274   ≴  
 NotPrecedes;   U+02280   ⊀  
 NotPrecedesSlantEqual;   U+022E0   ⋠  
 NotReverseElement;   U+0220C   ∌  
 NotRightTriangle;   U+022EB   ⋫  
 NotRightTriangleEqual;   U+022ED   ⋭  
 NotSquareSubsetEqual;   U+022E2   ⋢  
 NotSquareSupersetEqual;   U+022E3   ⋣  
 NotSubsetEqual;   U+02288   ⊈  
 NotSucceeds;   U+02281   ⊁  
 NotSucceedsSlantEqual;   U+022E1   ⋡  
 NotSupersetEqual;   U+02289   ⊉  
 NotTilde;   U+02241   ≁  
 NotTildeEqual;   U+02244   ≄  
 NotTildeFullEqual;   U+02247   ≇  
 NotTildeTilde;   U+02249   ≉  
 NotVerticalBar;   U+02224   ∤  
 Nscr;   U+1D4A9   𝒩  
 Ntilde;   U+000D1   Ñ  
 Ntilde   U+000D1   Ñ  
 Nu;   U+0039D   Ν  
 OElig;   U+00152   Π 
 Oacute;   U+000D3   Ó  
 Oacute   U+000D3   Ó  
 Ocirc;   U+000D4   Ô  
 Ocirc   U+000D4   Ô  
 Ocy;   U+0041E   О  
 Odblac;   U+00150   Ő  
 Ofr;   U+1D512   𝔒  
 Ograve;   U+000D2   Ò  
 Ograve   U+000D2   Ò  
 Omacr;   U+0014C   Ō  
 Omega;   U+003A9   Ω  
 Omicron;   U+0039F   Ο  
 Oopf;   U+1D546   𝕆  
 OpenCurlyDoubleQuote;   U+0201C   “  
 OpenCurlyQuote;   U+02018   ‘  
 Or;   U+02A54   ⩔  
 Oscr;   U+1D4AA   𝒪  
 Oslash;   U+000D8   Ø  
 Oslash   U+000D8   Ø  
 Otilde;   U+000D5   Õ  
 Otilde   U+000D5   Õ  
 Otimes;   U+02A37   ⨷  
 Ouml;   U+000D6   Ö  
 Ouml   U+000D6   Ö  
 OverBar;   U+0203E   ‾  
 OverBrace;   U+023DE   ⏞  
 OverBracket;   U+023B4   ⎴  
 OverParenthesis;   U+023DC   ⏜  
 PartialD;   U+02202   ∂  
 Pcy;   U+0041F   П  
 Pfr;   U+1D513   𝔓  
 Phi;   U+003A6   Φ  
 Pi;   U+003A0   Π  
 PlusMinus;   U+000B1   ±  
 Poincareplane;   U+0210C   ℌ  
 Popf;   U+02119   ℙ  
 Pr;   U+02ABB   ⪻  
 Precedes;   U+0227A   ≺  
 PrecedesEqual;   U+02AAF   ⪯  
 PrecedesSlantEqual;   U+0227C   ≼  
 PrecedesTilde;   U+0227E   ≾  
 Prime;   U+02033   ″  
 Product;   U+0220F   ∏  
 Proportion;   U+02237   ∷  
 Proportional;   U+0221D   ∝  
 Pscr;   U+1D4AB   𝒫  
 Psi;   U+003A8   Ψ  
 QUOT;   U+00022   "  
 QUOT   U+00022   "  
 Qfr;   U+1D514   𝔔  
 Qopf;   U+0211A   ℚ  
 Qscr;   U+1D4AC   𝒬  
 RBarr;   U+02910   ⤐  
 REG;   U+000AE   ®  
 REG   U+000AE   ®  
 Racute;   U+00154   Ŕ  
 Rang;   U+027EB   ⟫  
 Rarr;   U+021A0   ↠  
 Rarrtl;   U+02916   ⤖  
 Rcaron;   U+00158   Ř  
 Rcedil;   U+00156   Ŗ  
 Rcy;   U+00420   Р  
 Re;   U+0211C   ℜ  
 ReverseElement;   U+0220B   ∋  
 ReverseEquilibrium;   U+021CB   ⇋  
 ReverseUpEquilibrium;   U+0296F   ⥯  
 Rfr;   U+0211C   ℜ  
 Rho;   U+003A1   Ρ  
 RightAngleBracket;   U+027E9   ⟩  
 RightArrow;   U+02192   →  
 RightArrowBar;   U+021E5   ⇥  
 RightArrowLeftArrow;   U+021C4   ⇄  
 RightCeiling;   U+02309   ⌉  
 RightDoubleBracket;   U+027E7   ⟧  
 RightDownTeeVector;   U+0295D   ⥝  
 RightDownVector;   U+021C2   ⇂  
 RightDownVectorBar;   U+02955   ⥕  
 RightFloor;   U+0230B   ⌋  
 RightTee;   U+022A2   ⊢  
 RightTeeArrow;   U+021A6   ↦  
 RightTeeVector;   U+0295B   ⥛  
 RightTriangle;   U+022B3   ⊳  
 RightTriangleBar;   U+029D0   ⧐  
 RightTriangleEqual;   U+022B5   ⊵  
 RightUpDownVector;   U+0294F   ⥏  
 RightUpTeeVector;   U+0295C   ⥜  
 RightUpVector;   U+021BE   ↾  
 RightUpVectorBar;   U+02954   ⥔  
 RightVector;   U+021C0   ⇀  
 RightVectorBar;   U+02953   ⥓  
 Rightarrow;   U+021D2   ⇒  
 Ropf;   U+0211D   ℝ  
 RoundImplies;   U+02970   ⥰  
 Rrightarrow;   U+021DB   ⇛  
 Rscr;   U+0211B   ℛ  
 Rsh;   U+021B1   ↱  
 RuleDelayed;   U+029F4   ⧴  
 SHCHcy;   U+00429   Щ  
 SHcy;   U+00428   Ш  
 SOFTcy;   U+0042C   Ь  
 Sacute;   U+0015A   Ś  
 Sc;   U+02ABC   ⪼  
 Scaron;   U+00160   Š  
 Scedil;   U+0015E   Ş  
 Scirc;   U+0015C   Ŝ  
 Scy;   U+00421   С  
 Sfr;   U+1D516   𝔖  
 ShortDownArrow;   U+02193   ↓  
 ShortLeftArrow;   U+02190   ←  
 ShortRightArrow;   U+02192   →  
 ShortUpArrow;   U+02191   ↑  
 Sigma;   U+003A3   Σ  
 SmallCircle;   U+02218   ∘  
 Sopf;   U+1D54A   𝕊  
 Sqrt;   U+0221A   √  
 Square;   U+025A1   □  
 SquareIntersection;   U+02293   ⊓  
 SquareSubset;   U+0228F   ⊏  
 SquareSubsetEqual;   U+02291   ⊑  
 SquareSuperset;   U+02290   ⊐  
 SquareSupersetEqual;   U+02292   ⊒  
 SquareUnion;   U+02294   ⊔  
 Sscr;   U+1D4AE   𝒮  
 Star;   U+022C6   ⋆  
 Sub;   U+022D0   ⋐  
 Subset;   U+022D0   ⋐  
 SubsetEqual;   U+02286   ⊆  
 Succeeds;   U+0227B   ≻  
 SucceedsEqual;   U+02AB0   ⪰  
 SucceedsSlantEqual;   U+0227D   ≽  
 SucceedsTilde;   U+0227F   ≿  
 SuchThat;   U+0220B   ∋  
 Sum;   U+02211   ∑  
 Sup;   U+022D1   ⋑  
 Superset;   U+02283   ⊃  
 SupersetEqual;   U+02287   ⊇  
 Supset;   U+022D1   ⋑  
 THORN;   U+000DE   Þ  
 THORN   U+000DE   Þ  
 TRADE;   U+02122   ™  
 TSHcy;   U+0040B   Ћ  
 TScy;   U+00426   Ц  
 Tab;   U+00009   	  
 Tau;   U+003A4   Τ  
 Tcaron;   U+00164   Ť  
 Tcedil;   U+00162   Ţ  
 Tcy;   U+00422   Т  
 Tfr;   U+1D517   𝔗  
 Therefore;   U+02234   ∴  
 Theta;   U+00398   Θ  
 ThinSpace;   U+02009      
 Tilde;   U+0223C   ∼  
 TildeEqual;   U+02243   ≃  
 TildeFullEqual;   U+02245   ≅  
 TildeTilde;   U+02248   ≈  
 Topf;   U+1D54B   𝕋  
 TripleDot;   U+020DB   ◌⃛  
 Tscr;   U+1D4AF   𝒯  
 Tstrok;   U+00166   Ŧ  
 Uacute;   U+000DA   Ú  
 Uacute   U+000DA   Ú  
 Uarr;   U+0219F   ↟  
 Uarrocir;   U+02949   ⥉  
 Ubrcy;   U+0040E   Ў  
 Ubreve;   U+0016C   Ŭ  
 Ucirc;   U+000DB   Û  
 Ucirc   U+000DB   Û  
 Ucy;   U+00423   У  
 Udblac;   U+00170   Ű  
 Ufr;   U+1D518   𝔘  
 Ugrave;   U+000D9   Ù  
 Ugrave   U+000D9   Ù  
 Umacr;   U+0016A   Ū  
 UnderBar;   U+0005F   _  
 UnderBrace;   U+023DF   ⏟  
 UnderBracket;   U+023B5   ⎵  
 UnderParenthesis;   U+023DD   ⏝  
 Union;   U+022C3   ⋃  
 UnionPlus;   U+0228E   ⊎  
 Uogon;   U+00172   Ų  
 Uopf;   U+1D54C   𝕌  
 UpArrow;   U+02191   ↑  
 UpArrowBar;   U+02912   ⤒  
 UpArrowDownArrow;   U+021C5   ⇅  
 UpDownArrow;   U+02195   ↕  
 UpEquilibrium;   U+0296E   ⥮  
 UpTee;   U+022A5   ⊥  
 UpTeeArrow;   U+021A5   ↥  
 Uparrow;   U+021D1   ⇑  
 Updownarrow;   U+021D5   ⇕  
 UpperLeftArrow;   U+02196   ↖  
 UpperRightArrow;   U+02197   ↗  
 Upsi;   U+003D2   ϒ  
 Upsilon;   U+003A5   Υ  
 Uring;   U+0016E   Ů  
 Uscr;   U+1D4B0   𝒰  
 Utilde;   U+00168   Ũ  
 Uuml;   U+000DC   Ü  
 Uuml   U+000DC   Ü  
 VDash;   U+022AB   ⊫  
 Vbar;   U+02AEB   ⫫  
 Vcy;   U+00412   В  
 Vdash;   U+022A9   ⊩  
 Vdashl;   U+02AE6   ⫦  
 Vee;   U+022C1   ⋁  
 Verbar;   U+02016   ‖  
 Vert;   U+02016   ‖  
 VerticalBar;   U+02223   ∣  
 VerticalLine;   U+0007C   |  
 VerticalSeparator;   U+02758   ❘  
 VerticalTilde;   U+02240   ≀  
 VeryThinSpace;   U+0200A      
 Vfr;   U+1D519   𝔙  
 Vopf;   U+1D54D   𝕍  
 Vscr;   U+1D4B1   𝒱  
 Vvdash;   U+022AA   ⊪  
 Wcirc;   U+00174   Ŵ  
 Wedge;   U+022C0   ⋀  
 Wfr;   U+1D51A   𝔚  
 Wopf;   U+1D54E   𝕎  
 Wscr;   U+1D4B2   𝒲  
 Xfr;   U+1D51B   𝔛  
 Xi;   U+0039E   Ξ  
 Xopf;   U+1D54F   𝕏  
 Xscr;   U+1D4B3   𝒳  
 YAcy;   U+0042F   Я  
 YIcy;   U+00407   Ї  
 YUcy;   U+0042E   Ю  
 Yacute;   U+000DD   Ý  
 Yacute   U+000DD   Ý  
 Ycirc;   U+00176   Ŷ  
 Ycy;   U+0042B   Ы  
 Yfr;   U+1D51C   𝔜  
 Yopf;   U+1D550   𝕐  
 Yscr;   U+1D4B4   𝒴  
 Yuml;   U+00178   Ÿ  
 ZHcy;   U+00416   Ж  
 Zacute;   U+00179   Ź  
 Zcaron;   U+0017D   Ž  
 Zcy;   U+00417   З  
 Zdot;   U+0017B   Ż  
 ZeroWidthSpace;   U+0200B   ​  
 Zeta;   U+00396   Ζ  
 Zfr;   U+02128   ℨ  
 Zopf;   U+02124   ℤ  
 Zscr;   U+1D4B5   𝒵  
 aacute;   U+000E1   á  
 aacute   U+000E1   á  
 abreve;   U+00103   ă  
 ac;   U+0223E   ∾  
 acd;   U+0223F   ∿  
 acirc;   U+000E2   â  
 acirc   U+000E2   â  
 acute;   U+000B4   ´  
 acute   U+000B4   ´  
 acy;   U+00430   а  
 aelig;   U+000E6   æ  
 aelig   U+000E6   æ  
 af;   U+02061   ⁡  
 afr;   U+1D51E   𝔞  
 agrave;   U+000E0   à  
 agrave   U+000E0   à  
 alefsym;   U+02135   ℵ  
 aleph;   U+02135   ℵ  
 alpha;   U+003B1   α  
 amacr;   U+00101   ā  
 amalg;   U+02A3F   ⨿  
 amp;   U+00026   &  
 amp   U+00026   &  
 and;   U+02227   ∧  
 andand;   U+02A55   ⩕  
 andd;   U+02A5C   ⩜  
 andslope;   U+02A58   ⩘  
 andv;   U+02A5A   ⩚  
 ang;   U+02220   ∠  
 ange;   U+029A4   ⦤  
 angle;   U+02220   ∠  
 angmsd;   U+02221   ∡  
 angmsdaa;   U+029A8   ⦨  
 angmsdab;   U+029A9   ⦩  
 angmsdac;   U+029AA   ⦪  
 angmsdad;   U+029AB   ⦫  
 angmsdae;   U+029AC   ⦬  
 angmsdaf;   U+029AD   ⦭  
 angmsdag;   U+029AE   ⦮  
 angmsdah;   U+029AF   ⦯  
 angrt;   U+0221F   ∟  
 angrtvb;   U+022BE   ⊾  
 angrtvbd;   U+0299D   ⦝  
 angsph;   U+02222   ∢  
 angst;   U+000C5   Å  
 angzarr;   U+0237C   ⍼  
 aogon;   U+00105   ą  
 aopf;   U+1D552   𝕒  
 ap;   U+02248   ≈  
 apE;   U+02A70   ⩰  
 apacir;   U+02A6F   ⩯  
 ape;   U+0224A   ≊  
 apid;   U+0224B   ≋  
 apos;   U+00027   '  
 approx;   U+02248   ≈  
 approxeq;   U+0224A   ≊  
 aring;   U+000E5   å  
 aring   U+000E5   å  
 ascr;   U+1D4B6   𝒶  
 ast;   U+0002A   *  
 asymp;   U+02248   ≈  
 asympeq;   U+0224D   ≍  
 atilde;   U+000E3   ã  
 atilde   U+000E3   ã  
 auml;   U+000E4   ä  
 auml   U+000E4   ä  
 awconint;   U+02233   ∳  
 awint;   U+02A11   ⨑  
 bNot;   U+02AED   ⫭  
 backcong;   U+0224C   ≌  
 backepsilon;   U+003F6   ϶  
 backprime;   U+02035   ‵  
 backsim;   U+0223D   ∽  
 backsimeq;   U+022CD   ⋍  
 barvee;   U+022BD   ⊽  
 barwed;   U+02305   ⌅  
 barwedge;   U+02305   ⌅  
 bbrk;   U+023B5   ⎵  
 bbrktbrk;   U+023B6   ⎶  
 bcong;   U+0224C   ≌  
 bcy;   U+00431   б  
 bdquo;   U+0201E   „  
 becaus;   U+02235   ∵  
 because;   U+02235   ∵  
 bemptyv;   U+029B0   ⦰  
 bepsi;   U+003F6   ϶  
 bernou;   U+0212C   ℬ  
 beta;   U+003B2   β  
 beth;   U+02136   ℶ  
 between;   U+0226C   ≬  
 bfr;   U+1D51F   𝔟  
 bigcap;   U+022C2   ⋂  
 bigcirc;   U+025EF   ◯  
 bigcup;   U+022C3   ⋃  
 bigodot;   U+02A00   ⨀  
 bigoplus;   U+02A01   ⨁  
 bigotimes;   U+02A02   ⨂  
 bigsqcup;   U+02A06   ⨆  
 bigstar;   U+02605   ★  
 bigtriangledown;   U+025BD   ▽  
 bigtriangleup;   U+025B3   △  
 biguplus;   U+02A04   ⨄  
 bigvee;   U+022C1   ⋁  
 bigwedge;   U+022C0   ⋀  
 bkarow;   U+0290D   ⤍  
 blacklozenge;   U+029EB   ⧫  
 blacksquare;   U+025AA   ▪  
 blacktriangle;   U+025B4   ▴  
 blacktriangledown;   U+025BE   ▾  
 blacktriangleleft;   U+025C2   ◂  
 blacktriangleright;   U+025B8   ▸  
 blank;   U+02423   ␣  
 blk12;   U+02592   ▒  
 blk14;   U+02591   ░  
 blk34;   U+02593   ▓  
 block;   U+02588   █  
 bnot;   U+02310   ⌐  
 bopf;   U+1D553   𝕓  
 bot;   U+022A5   ⊥  
 bottom;   U+022A5   ⊥  
 bowtie;   U+022C8   ⋈  
 boxDL;   U+02557   ╗  
 boxDR;   U+02554   ╔  
 boxDl;   U+02556   ╖  
 boxDr;   U+02553   ╓  
 boxH;   U+02550   ═  
 boxHD;   U+02566   ╦  
 boxHU;   U+02569   ╩  
 boxHd;   U+02564   ╤  
 boxHu;   U+02567   ╧  
 boxUL;   U+0255D   ╝  
 boxUR;   U+0255A   ╚  
 boxUl;   U+0255C   ╜  
 boxUr;   U+02559   ╙  
 boxV;   U+02551   ║  
 boxVH;   U+0256C   ╬  
 boxVL;   U+02563   ╣  
 boxVR;   U+02560   ╠  
 boxVh;   U+0256B   ╫  
 boxVl;   U+02562   ╢  
 boxVr;   U+0255F   ╟  
 boxbox;   U+029C9   ⧉  
 boxdL;   U+02555   ╕  
 boxdR;   U+02552   ╒  
 boxdl;   U+02510   ┐  
 boxdr;   U+0250C   ┌  
 boxh;   U+02500   ─  
 boxhD;   U+02565   ╥  
 boxhU;   U+02568   ╨  
 boxhd;   U+0252C   ┬  
 boxhu;   U+02534   ┴  
 boxminus;   U+0229F   ⊟  
 boxplus;   U+0229E   ⊞  
 boxtimes;   U+022A0   ⊠  
 boxuL;   U+0255B   ╛  
 boxuR;   U+02558   ╘  
 boxul;   U+02518   ┘  
 boxur;   U+02514   └  
 boxv;   U+02502   │  
 boxvH;   U+0256A   ╪  
 boxvL;   U+02561   ╡  
 boxvR;   U+0255E   ╞  
 boxvh;   U+0253C   ┼  
 boxvl;   U+02524   ┤  
 boxvr;   U+0251C   ├  
 bprime;   U+02035   ‵  
 breve;   U+002D8   ˘  
 brvbar;   U+000A6   ¦  
 brvbar   U+000A6   ¦  
 bscr;   U+1D4B7   𝒷  
 bsemi;   U+0204F   ⁏  
 bsim;   U+0223D   ∽  
 bsime;   U+022CD   ⋍  
 bsol;   U+0005C   \  
 bsolb;   U+029C5   ⧅  
 bsolhsub;   U+027C8   ⟈  
 bull;   U+02022   •  
 bullet;   U+02022   •  
 bump;   U+0224E   ≎  
 bumpE;   U+02AAE   ⪮  
 bumpe;   U+0224F   ≏  
 bumpeq;   U+0224F   ≏  
 cacute;   U+00107   ć  
 cap;   U+02229   ∩  
 capand;   U+02A44   ⩄  
 capbrcup;   U+02A49   ⩉  
 capcap;   U+02A4B   ⩋  
 capcup;   U+02A47   ⩇  
 capdot;   U+02A40   ⩀  
 caret;   U+02041   ⁁  
 caron;   U+002C7   ˇ  
 ccaps;   U+02A4D   ⩍  
 ccaron;   U+0010D   č  
 ccedil;   U+000E7   ç  
 ccedil   U+000E7   ç  
 ccirc;   U+00109   ĉ  
 ccups;   U+02A4C   ⩌  
 ccupssm;   U+02A50   ⩐  
 cdot;   U+0010B   ċ  
 cedil;   U+000B8   ¸  
 cedil   U+000B8   ¸  
 cemptyv;   U+029B2   ⦲  
 cent;   U+000A2   ¢  
 cent   U+000A2   ¢  
 centerdot;   U+000B7   ·  
 cfr;   U+1D520   𝔠  
 chcy;   U+00447   ч  
 check;   U+02713   ✓  
 checkmark;   U+02713   ✓  
 chi;   U+003C7   χ  
 cir;   U+025CB   ○  
 cirE;   U+029C3   ⧃  
 circ;   U+002C6   ˆ  
 circeq;   U+02257   ≗  
 circlearrowleft;   U+021BA   ↺  
 circlearrowright;   U+021BB   ↻  
 circledR;   U+000AE   ®  
 circledS;   U+024C8   Ⓢ  
 circledast;   U+0229B   ⊛  
 circledcirc;   U+0229A   ⊚  
 circleddash;   U+0229D   ⊝  
 cire;   U+02257   ≗  
 cirfnint;   U+02A10   ⨐  
 cirmid;   U+02AEF   ⫯  
 cirscir;   U+029C2   ⧂  
 clubs;   U+02663   ♣  
 clubsuit;   U+02663   ♣  
 colon;   U+0003A   :  
 colone;   U+02254   ≔  
 coloneq;   U+02254   ≔  
 comma;   U+0002C   ,  
 commat;   U+00040   @  
 comp;   U+02201   ∁  
 compfn;   U+02218   ∘  
 complement;   U+02201   ∁  
 complexes;   U+02102   ℂ  
 cong;   U+02245   ≅  
 congdot;   U+02A6D   ⩭  
 conint;   U+0222E   ∮  
 copf;   U+1D554   𝕔  
 coprod;   U+02210   ∐  
 copy;   U+000A9   ©  
 copy   U+000A9   ©  
 copysr;   U+02117   ℗  
 crarr;   U+021B5   ↵  
 cross;   U+02717   ✗  
 cscr;   U+1D4B8   𝒸  
 csub;   U+02ACF   ⫏  
 csube;   U+02AD1   ⫑  
 csup;   U+02AD0   ⫐  
 csupe;   U+02AD2   ⫒  
 ctdot;   U+022EF   ⋯  
 cudarrl;   U+02938   ⤸  
 cudarrr;   U+02935   ⤵  
 cuepr;   U+022DE   ⋞  
 cuesc;   U+022DF   ⋟  
 cularr;   U+021B6   ↶  
 cularrp;   U+0293D   ⤽  
 cup;   U+0222A   ∪  
 cupbrcap;   U+02A48   ⩈  
 cupcap;   U+02A46   ⩆  
 cupcup;   U+02A4A   ⩊  
 cupdot;   U+0228D   ⊍  
 cupor;   U+02A45   ⩅  
 curarr;   U+021B7   ↷  
 curarrm;   U+0293C   ⤼  
 curlyeqprec;   U+022DE   ⋞  
 curlyeqsucc;   U+022DF   ⋟  
 curlyvee;   U+022CE   ⋎  
 curlywedge;   U+022CF   ⋏  
 curren;   U+000A4   ¤  
 curren   U+000A4   ¤  
 curvearrowleft;   U+021B6   ↶  
 curvearrowright;   U+021B7   ↷  
 cuvee;   U+022CE   ⋎  
 cuwed;   U+022CF   ⋏  
 cwconint;   U+02232   ∲  
 cwint;   U+02231   ∱  
 cylcty;   U+0232D   ⌭  
 dArr;   U+021D3   ⇓  
 dHar;   U+02965   ⥥  
 dagger;   U+02020   †  
 daleth;   U+02138   ℸ  
 darr;   U+02193   ↓  
 dash;   U+02010   ‐  
 dashv;   U+022A3   ⊣  
 dbkarow;   U+0290F   ⤏  
 dblac;   U+002DD   ˝  
 dcaron;   U+0010F   ď  
 dcy;   U+00434   д  
 dd;   U+02146   ⅆ  
 ddagger;   U+02021   ‡  
 ddarr;   U+021CA   ⇊  
 ddotseq;   U+02A77   ⩷  
 deg;   U+000B0   °  
 deg   U+000B0   °  
 delta;   U+003B4   δ  
 demptyv;   U+029B1   ⦱  
 dfisht;   U+0297F   ⥿  
 dfr;   U+1D521   𝔡  
 dharl;   U+021C3   ⇃  
 dharr;   U+021C2   ⇂  
 diam;   U+022C4   ⋄  
 diamond;   U+022C4   ⋄  
 diamondsuit;   U+02666   ♦  
 diams;   U+02666   ♦  
 die;   U+000A8   ¨  
 digamma;   U+003DD   ϝ  
 disin;   U+022F2   ⋲  
 div;   U+000F7   ÷  
 divide;   U+000F7   ÷  
 divide   U+000F7   ÷  
 divideontimes;   U+022C7   ⋇  
 divonx;   U+022C7   ⋇  
 djcy;   U+00452   ђ  
 dlcorn;   U+0231E   ⌞  
 dlcrop;   U+0230D   ⌍  
 dollar;   U+00024   $  
 dopf;   U+1D555   𝕕  
 dot;   U+002D9   ˙  
 doteq;   U+02250   ≐  
 doteqdot;   U+02251   ≑  
 dotminus;   U+02238   ∸  
 dotplus;   U+02214   ∔  
 dotsquare;   U+022A1   ⊡  
 doublebarwedge;   U+02306   ⌆  
 downarrow;   U+02193   ↓  
 downdownarrows;   U+021CA   ⇊  
 downharpoonleft;   U+021C3   ⇃  
 downharpoonright;   U+021C2   ⇂  
 drbkarow;   U+02910   ⤐  
 drcorn;   U+0231F   ⌟  
 drcrop;   U+0230C   ⌌  
 dscr;   U+1D4B9   𝒹  
 dscy;   U+00455   ѕ  
 dsol;   U+029F6   ⧶  
 dstrok;   U+00111   đ  
 dtdot;   U+022F1   ⋱  
 dtri;   U+025BF   ▿  
 dtrif;   U+025BE   ▾  
 duarr;   U+021F5   ⇵  
 duhar;   U+0296F   ⥯  
 dwangle;   U+029A6   ⦦  
 dzcy;   U+0045F   џ  
 dzigrarr;   U+027FF   ⟿  
 eDDot;   U+02A77   ⩷  
 eDot;   U+02251   ≑  
 eacute;   U+000E9   é  
 eacute   U+000E9   é  
 easter;   U+02A6E   ⩮  
 ecaron;   U+0011B   ě  
 ecir;   U+02256   ≖  
 ecirc;   U+000EA   ê  
 ecirc   U+000EA   ê  
 ecolon;   U+02255   ≕  
 ecy;   U+0044D   э  
 edot;   U+00117   ė  
 ee;   U+02147   ⅇ  
 efDot;   U+02252   ≒  
 efr;   U+1D522   𝔢  
 eg;   U+02A9A   ⪚  
 egrave;   U+000E8   è  
 egrave   U+000E8   è  
 egs;   U+02A96   ⪖  
 egsdot;   U+02A98   ⪘  
 el;   U+02A99   ⪙  
 elinters;   U+023E7   ⏧  
 ell;   U+02113   ℓ  
 els;   U+02A95   ⪕  
 elsdot;   U+02A97   ⪗  
 emacr;   U+00113   ē  
 empty;   U+02205   ∅  
 emptyset;   U+02205   ∅  
 emptyv;   U+02205   ∅  
 emsp13;   U+02004      
 emsp14;   U+02005      
 emsp;   U+02003      
 eng;   U+0014B   ŋ  
 ensp;   U+02002      
 eogon;   U+00119   ę  
 eopf;   U+1D556   𝕖  
 epar;   U+022D5   ⋕  
 eparsl;   U+029E3   ⧣  
 eplus;   U+02A71   ⩱  
 epsi;   U+003B5   ε  
 epsilon;   U+003B5   ε  
 epsiv;   U+003F5   ϵ  
 eqcirc;   U+02256   ≖  
 eqcolon;   U+02255   ≕  
 eqsim;   U+02242   ≂  
 eqslantgtr;   U+02A96   ⪖  
 eqslantless;   U+02A95   ⪕  
 equals;   U+0003D   =  
 equest;   U+0225F   ≟  
 equiv;   U+02261   ≡  
 equivDD;   U+02A78   ⩸  
 eqvparsl;   U+029E5   ⧥  
 erDot;   U+02253   ≓  
 erarr;   U+02971   ⥱  
 escr;   U+0212F   ℯ  
 esdot;   U+02250   ≐  
 esim;   U+02242   ≂  
 eta;   U+003B7   η  
 eth;   U+000F0   ð  
 eth   U+000F0   ð  
 euml;   U+000EB   ë  
 euml   U+000EB   ë  
 euro;   U+020AC   €  
 excl;   U+00021   !  
 exist;   U+02203   ∃  
 expectation;   U+02130   ℰ  
 exponentiale;   U+02147   ⅇ  
 fallingdotseq;   U+02252   ≒  
 fcy;   U+00444   ф  
 female;   U+02640   ♀  
 ffilig;   U+0FB03   ffi  
 fflig;   U+0FB00   ff  
 ffllig;   U+0FB04   ffl  
 ffr;   U+1D523   𝔣  
 filig;   U+0FB01   fi  
 flat;   U+0266D   ♭  
 fllig;   U+0FB02   fl  
 fltns;   U+025B1   ▱  
 fnof;   U+00192   ƒ  
 fopf;   U+1D557   𝕗  
 forall;   U+02200   ∀  
 fork;   U+022D4   ⋔  
 forkv;   U+02AD9   ⫙  
 fpartint;   U+02A0D   ⨍  
 frac12;   U+000BD   ½  
 frac12   U+000BD   ½  
 frac13;   U+02153   ⅓  
 frac14;   U+000BC   ¼  
 frac14   U+000BC   ¼  
 frac15;   U+02155   ⅕  
 frac16;   U+02159   ⅙  
 frac18;   U+0215B   ⅛  
 frac23;   U+02154   ⅔  
 frac25;   U+02156   ⅖  
 frac34;   U+000BE   ¾  
 frac34   U+000BE   ¾  
 frac35;   U+02157   ⅗  
 frac38;   U+0215C   ⅜  
 frac45;   U+02158   ⅘  
 frac56;   U+0215A   ⅚  
 frac58;   U+0215D   ⅝  
 frac78;   U+0215E   ⅞  
 frasl;   U+02044   ⁄  
 frown;   U+02322   ⌢  
 fscr;   U+1D4BB   𝒻  
 gE;   U+02267   ≧  
 gEl;   U+02A8C   ⪌  
 gacute;   U+001F5   ǵ  
 gamma;   U+003B3   γ  
 gammad;   U+003DD   ϝ  
 gap;   U+02A86   ⪆  
 gbreve;   U+0011F   ğ  
 gcirc;   U+0011D   ĝ  
 gcy;   U+00433   г  
 gdot;   U+00121   ġ  
 ge;   U+02265   ≥  
 gel;   U+022DB   ⋛  
 geq;   U+02265   ≥  
 geqq;   U+02267   ≧  
 geqslant;   U+02A7E   ⩾  
 ges;   U+02A7E   ⩾  
 gescc;   U+02AA9   ⪩  
 gesdot;   U+02A80   ⪀  
 gesdoto;   U+02A82   ⪂  
 gesdotol;   U+02A84   ⪄  
 gesles;   U+02A94   ⪔  
 gfr;   U+1D524   𝔤  
 gg;   U+0226B   ≫  
 ggg;   U+022D9   ⋙  
 gimel;   U+02137   ℷ  
 gjcy;   U+00453   ѓ  
 gl;   U+02277   ≷  
 glE;   U+02A92   ⪒  
 gla;   U+02AA5   ⪥  
 glj;   U+02AA4   ⪤  
 gnE;   U+02269   ≩  
 gnap;   U+02A8A   ⪊  
 gnapprox;   U+02A8A   ⪊  
 gne;   U+02A88   ⪈  
 gneq;   U+02A88   ⪈  
 gneqq;   U+02269   ≩  
 gnsim;   U+022E7   ⋧  
 gopf;   U+1D558   𝕘  
 grave;   U+00060   `  
 gscr;   U+0210A   ℊ  
 gsim;   U+02273   ≳  
 gsime;   U+02A8E   ⪎  
 gsiml;   U+02A90   ⪐  
 gt;   U+0003E   >  
 gt   U+0003E   >  
 gtcc;   U+02AA7   ⪧  
 gtcir;   U+02A7A   ⩺  
 gtdot;   U+022D7   ⋗  
 gtlPar;   U+02995   ⦕  
 gtquest;   U+02A7C   ⩼  
 gtrapprox;   U+02A86   ⪆  
 gtrarr;   U+02978   ⥸  
 gtrdot;   U+022D7   ⋗  
 gtreqless;   U+022DB   ⋛  
 gtreqqless;   U+02A8C   ⪌  
 gtrless;   U+02277   ≷  
 gtrsim;   U+02273   ≳  
 hArr;   U+021D4   ⇔  
 hairsp;   U+0200A      
 half;   U+000BD   ½  
 hamilt;   U+0210B   ℋ  
 hardcy;   U+0044A   ъ  
 harr;   U+02194   ↔  
 harrcir;   U+02948   ⥈  
 harrw;   U+021AD   ↭  
 hbar;   U+0210F   ℏ  
 hcirc;   U+00125   ĥ  
 hearts;   U+02665   ♥  
 heartsuit;   U+02665   ♥  
 hellip;   U+02026   …  
 hercon;   U+022B9   ⊹  
 hfr;   U+1D525   𝔥  
 hksearow;   U+02925   ⤥  
 hkswarow;   U+02926   ⤦  
 hoarr;   U+021FF   ⇿  
 homtht;   U+0223B   ∻  
 hookleftarrow;   U+021A9   ↩  
 hookrightarrow;   U+021AA   ↪  
 hopf;   U+1D559   𝕙  
 horbar;   U+02015   ―  
 hscr;   U+1D4BD   𝒽  
 hslash;   U+0210F   ℏ  
 hstrok;   U+00127   ħ  
 hybull;   U+02043   ⁃  
 hyphen;   U+02010   ‐  
 iacute;   U+000ED   í  
 iacute   U+000ED   í  
 ic;   U+02063   ⁣  
 icirc;   U+000EE   î  
 icirc   U+000EE   î  
 icy;   U+00438   и  
 iecy;   U+00435   е  
 iexcl;   U+000A1   ¡  
 iexcl   U+000A1   ¡  
 iff;   U+021D4   ⇔  
 ifr;   U+1D526   𝔦  
 igrave;   U+000EC   ì  
 igrave   U+000EC   ì  
 ii;   U+02148   ⅈ  
 iiiint;   U+02A0C   ⨌  
 iiint;   U+0222D   ∭  
 iinfin;   U+029DC   ⧜  
 iiota;   U+02129   ℩  
 ijlig;   U+00133   ij  
 imacr;   U+0012B   ī  
 image;   U+02111   ℑ  
 imagline;   U+02110   ℐ  
 imagpart;   U+02111   ℑ  
 imath;   U+00131   ı  
 imof;   U+022B7   ⊷  
 imped;   U+001B5   Ƶ  
 in;   U+02208   ∈  
 incare;   U+02105   ℅  
 infin;   U+0221E   ∞  
 infintie;   U+029DD   ⧝  
 inodot;   U+00131   ı  
 int;   U+0222B   ∫  
 intcal;   U+022BA   ⊺  
 integers;   U+02124   ℤ  
 intercal;   U+022BA   ⊺  
 intlarhk;   U+02A17   ⨗  
 intprod;   U+02A3C   ⨼  
 iocy;   U+00451   ё  
 iogon;   U+0012F   į  
 iopf;   U+1D55A   𝕚  
 iota;   U+003B9   ι  
 iprod;   U+02A3C   ⨼  
 iquest;   U+000BF   ¿  
 iquest   U+000BF   ¿  
 iscr;   U+1D4BE   𝒾  
 isin;   U+02208   ∈  
 isinE;   U+022F9   ⋹  
 isindot;   U+022F5   ⋵  
 isins;   U+022F4   ⋴  
 isinsv;   U+022F3   ⋳  
 isinv;   U+02208   ∈  
 it;   U+02062   ⁢  
 itilde;   U+00129   ĩ  
 iukcy;   U+00456   і  
 iuml;   U+000EF   ï  
 iuml   U+000EF   ï  
 jcirc;   U+00135   ĵ  
 jcy;   U+00439   й  
 jfr;   U+1D527   𝔧  
 jmath;   U+00237   ȷ  
 jopf;   U+1D55B   𝕛  
 jscr;   U+1D4BF   𝒿  
 jsercy;   U+00458   ј  
 jukcy;   U+00454   є  
 kappa;   U+003BA   κ  
 kappav;   U+003F0   ϰ  
 kcedil;   U+00137   ķ  
 kcy;   U+0043A   к  
 kfr;   U+1D528   𝔨  
 kgreen;   U+00138   ĸ  
 khcy;   U+00445   х  
 kjcy;   U+0045C   ќ  
 kopf;   U+1D55C   𝕜  
 kscr;   U+1D4C0   𝓀  
 lAarr;   U+021DA   ⇚  
 lArr;   U+021D0   ⇐  
 lAtail;   U+0291B   ⤛  
 lBarr;   U+0290E   ⤎  
 lE;   U+02266   ≦  
 lEg;   U+02A8B   ⪋  
 lHar;   U+02962   ⥢  
 lacute;   U+0013A   ĺ  
 laemptyv;   U+029B4   ⦴  
 lagran;   U+02112   ℒ  
 lambda;   U+003BB   λ  
 lang;   U+027E8   ⟨  
 langd;   U+02991   ⦑  
 langle;   U+027E8   ⟨  
 lap;   U+02A85   ⪅  
 laquo;   U+000AB   «  
 laquo   U+000AB   «  
 larr;   U+02190   ←  
 larrb;   U+021E4   ⇤  
 larrbfs;   U+0291F   ⤟  
 larrfs;   U+0291D   ⤝  
 larrhk;   U+021A9   ↩  
 larrlp;   U+021AB   ↫  
 larrpl;   U+02939   ⤹  
 larrsim;   U+02973   ⥳  
 larrtl;   U+021A2   ↢  
 lat;   U+02AAB   ⪫  
 latail;   U+02919   ⤙  
 late;   U+02AAD   ⪭  
 lbarr;   U+0290C   ⤌  
 lbbrk;   U+02772   ❲  
 lbrace;   U+0007B   {  
 lbrack;   U+0005B   [  
 lbrke;   U+0298B   ⦋  
 lbrksld;   U+0298F   ⦏  
 lbrkslu;   U+0298D   ⦍  
 lcaron;   U+0013E   ľ  
 lcedil;   U+0013C   ļ  
 lceil;   U+02308   ⌈  
 lcub;   U+0007B   {  
 lcy;   U+0043B   л  
 ldca;   U+02936   ⤶  
 ldquo;   U+0201C   “  
 ldquor;   U+0201E   „  
 ldrdhar;   U+02967   ⥧  
 ldrushar;   U+0294B   ⥋  
 ldsh;   U+021B2   ↲  
 le;   U+02264   ≤  
 leftarrow;   U+02190   ←  
 leftarrowtail;   U+021A2   ↢  
 leftharpoondown;   U+021BD   ↽  
 leftharpoonup;   U+021BC   ↼  
 leftleftarrows;   U+021C7   ⇇  
 leftrightarrow;   U+02194   ↔  
 leftrightarrows;   U+021C6   ⇆  
 leftrightharpoons;   U+021CB   ⇋  
 leftrightsquigarrow;   U+021AD   ↭  
 leftthreetimes;   U+022CB   ⋋  
 leg;   U+022DA   ⋚  
 leq;   U+02264   ≤  
 leqq;   U+02266   ≦  
 leqslant;   U+02A7D   ⩽  
 les;   U+02A7D   ⩽  
 lescc;   U+02AA8   ⪨  
 lesdot;   U+02A7F   ⩿  
 lesdoto;   U+02A81   ⪁  
 lesdotor;   U+02A83   ⪃  
 lesges;   U+02A93   ⪓  
 lessapprox;   U+02A85   ⪅  
 lessdot;   U+022D6   ⋖  
 lesseqgtr;   U+022DA   ⋚  
 lesseqqgtr;   U+02A8B   ⪋  
 lessgtr;   U+02276   ≶  
 lesssim;   U+02272   ≲  
 lfisht;   U+0297C   ⥼  
 lfloor;   U+0230A   ⌊  
 lfr;   U+1D529   𝔩  
 lg;   U+02276   ≶  
 lgE;   U+02A91   ⪑  
 lhard;   U+021BD   ↽  
 lharu;   U+021BC   ↼  
 lharul;   U+0296A   ⥪  
 lhblk;   U+02584   ▄  
 ljcy;   U+00459   љ  
 ll;   U+0226A   ≪  
 llarr;   U+021C7   ⇇  
 llcorner;   U+0231E   ⌞  
 llhard;   U+0296B   ⥫  
 lltri;   U+025FA   ◺  
 lmidot;   U+00140   ŀ  
 lmoust;   U+023B0   ⎰  
 lmoustache;   U+023B0   ⎰  
 lnE;   U+02268   ≨  
 lnap;   U+02A89   ⪉  
 lnapprox;   U+02A89   ⪉  
 lne;   U+02A87   ⪇  
 lneq;   U+02A87   ⪇  
 lneqq;   U+02268   ≨  
 lnsim;   U+022E6   ⋦  
 loang;   U+027EC   ⟬  
 loarr;   U+021FD   ⇽  
 lobrk;   U+027E6   ⟦  
 longleftarrow;   U+027F5   ⟵  
 longleftrightarrow;   U+027F7   ⟷  
 longmapsto;   U+027FC   ⟼  
 longrightarrow;   U+027F6   ⟶  
 looparrowleft;   U+021AB   ↫  
 looparrowright;   U+021AC   ↬  
 lopar;   U+02985   ⦅  
 lopf;   U+1D55D   𝕝  
 loplus;   U+02A2D   ⨭  
 lotimes;   U+02A34   ⨴  
 lowast;   U+02217   ∗  
 lowbar;   U+0005F   _  
 loz;   U+025CA   ◊  
 lozenge;   U+025CA   ◊  
 lozf;   U+029EB   ⧫  
 lpar;   U+00028   (  
 lparlt;   U+02993   ⦓  
 lrarr;   U+021C6   ⇆  
 lrcorner;   U+0231F   ⌟  
 lrhar;   U+021CB   ⇋  
 lrhard;   U+0296D   ⥭  
 lrm;   U+0200E   ‎  
 lrtri;   U+022BF   ⊿  
 lsaquo;   U+02039   ‹  
 lscr;   U+1D4C1   𝓁  
 lsh;   U+021B0   ↰  
 lsim;   U+02272   ≲  
 lsime;   U+02A8D   ⪍  
 lsimg;   U+02A8F   ⪏  
 lsqb;   U+0005B   [  
 lsquo;   U+02018   ‘  
 lsquor;   U+0201A   ‚  
 lstrok;   U+00142   ł  
 lt;   U+0003C   <  
 lt   U+0003C   <  
 ltcc;   U+02AA6   ⪦  
 ltcir;   U+02A79   ⩹  
 ltdot;   U+022D6   ⋖  
 lthree;   U+022CB   ⋋  
 ltimes;   U+022C9   ⋉  
 ltlarr;   U+02976   ⥶  
 ltquest;   U+02A7B   ⩻  
 ltrPar;   U+02996   ⦖  
 ltri;   U+025C3   ◃  
 ltrie;   U+022B4   ⊴  
 ltrif;   U+025C2   ◂  
 lurdshar;   U+0294A   ⥊  
 luruhar;   U+02966   ⥦  
 mDDot;   U+0223A   ∺  
 macr;   U+000AF   ¯  
 macr   U+000AF   ¯  
 male;   U+02642   ♂  
 malt;   U+02720   ✠  
 maltese;   U+02720   ✠  
 map;   U+021A6   ↦  
 mapsto;   U+021A6   ↦  
 mapstodown;   U+021A7   ↧  
 mapstoleft;   U+021A4   ↤  
 mapstoup;   U+021A5   ↥  
 marker;   U+025AE   ▮  
 mcomma;   U+02A29   ⨩  
 mcy;   U+0043C   м  
 mdash;   U+02014   —  
 measuredangle;   U+02221   ∡  
 mfr;   U+1D52A   𝔪  
 mho;   U+02127   ℧  
 micro;   U+000B5   µ  
 micro   U+000B5   µ  
 mid;   U+02223   ∣  
 midast;   U+0002A   *  
 midcir;   U+02AF0   ⫰  
 middot;   U+000B7   ·  
 middot   U+000B7   ·  
 minus;   U+02212   −  
 minusb;   U+0229F   ⊟  
 minusd;   U+02238   ∸  
 minusdu;   U+02A2A   ⨪  
 mlcp;   U+02ADB   ⫛  
 mldr;   U+02026   …  
 mnplus;   U+02213   ∓  
 models;   U+022A7   ⊧  
 mopf;   U+1D55E   𝕞  
 mp;   U+02213   ∓  
 mscr;   U+1D4C2   𝓂  
 mstpos;   U+0223E   ∾  
 mu;   U+003BC   μ  
 multimap;   U+022B8   ⊸  
 mumap;   U+022B8   ⊸  
 nLeftarrow;   U+021CD   ⇍  
 nLeftrightarrow;   U+021CE   ⇎  
 nRightarrow;   U+021CF   ⇏  
 nVDash;   U+022AF   ⊯  
 nVdash;   U+022AE   ⊮  
 nabla;   U+02207   ∇  
 nacute;   U+00144   ń  
 nap;   U+02249   ≉  
 napos;   U+00149   ʼn  
 napprox;   U+02249   ≉  
 natur;   U+0266E   ♮  
 natural;   U+0266E   ♮  
 naturals;   U+02115   ℕ  
 nbsp;   U+000A0      
 nbsp   U+000A0      
 ncap;   U+02A43   ⩃  
 ncaron;   U+00148   ň  
 ncedil;   U+00146   ņ  
 ncong;   U+02247   ≇  
 ncup;   U+02A42   ⩂  
 ncy;   U+0043D   н  
 ndash;   U+02013   –  
 ne;   U+02260   ≠  
 neArr;   U+021D7   ⇗  
 nearhk;   U+02924   ⤤  
 nearr;   U+02197   ↗  
 nearrow;   U+02197   ↗  
 nequiv;   U+02262   ≢  
 nesear;   U+02928   ⤨  
 nexist;   U+02204   ∄  
 nexists;   U+02204   ∄  
 nfr;   U+1D52B   𝔫  
 nge;   U+02271   ≱  
 ngeq;   U+02271   ≱  
 ngsim;   U+02275   ≵  
 ngt;   U+0226F   ≯  
 ngtr;   U+0226F   ≯  
 nhArr;   U+021CE   ⇎  
 nharr;   U+021AE   ↮  
 nhpar;   U+02AF2   ⫲  
 ni;   U+0220B   ∋  
 nis;   U+022FC   ⋼  
 nisd;   U+022FA   ⋺  
 niv;   U+0220B   ∋  
 njcy;   U+0045A   њ  
 nlArr;   U+021CD   ⇍  
 nlarr;   U+0219A   ↚  
 nldr;   U+02025   ‥  
 nle;   U+02270   ≰  
 nleftarrow;   U+0219A   ↚  
 nleftrightarrow;   U+021AE   ↮  
 nleq;   U+02270   ≰  
 nless;   U+0226E   ≮  
 nlsim;   U+02274   ≴  
 nlt;   U+0226E   ≮  
 nltri;   U+022EA   ⋪  
 nltrie;   U+022EC   ⋬  
 nmid;   U+02224   ∤  
 nopf;   U+1D55F   𝕟  
 not;   U+000AC   ¬  
 not   U+000AC   ¬  
 notin;   U+02209   ∉  
 notinva;   U+02209   ∉  
 notinvb;   U+022F7   ⋷  
 notinvc;   U+022F6   ⋶  
 notni;   U+0220C   ∌  
 notniva;   U+0220C   ∌  
 notnivb;   U+022FE   ⋾  
 notnivc;   U+022FD   ⋽  
 npar;   U+02226   ∦  
 nparallel;   U+02226   ∦  
 npolint;   U+02A14   ⨔  
 npr;   U+02280   ⊀  
 nprcue;   U+022E0   ⋠  
 nprec;   U+02280   ⊀  
 nrArr;   U+021CF   ⇏  
 nrarr;   U+0219B   ↛  
 nrightarrow;   U+0219B   ↛  
 nrtri;   U+022EB   ⋫  
 nrtrie;   U+022ED   ⋭  
 nsc;   U+02281   ⊁  
 nsccue;   U+022E1   ⋡  
 nscr;   U+1D4C3   𝓃  
 nshortmid;   U+02224   ∤  
 nshortparallel;   U+02226   ∦  
 nsim;   U+02241   ≁  
 nsime;   U+02244   ≄  
 nsimeq;   U+02244   ≄  
 nsmid;   U+02224   ∤  
 nspar;   U+02226   ∦  
 nsqsube;   U+022E2   ⋢  
 nsqsupe;   U+022E3   ⋣  
 nsub;   U+02284   ⊄  
 nsube;   U+02288   ⊈  
 nsubseteq;   U+02288   ⊈  
 nsucc;   U+02281   ⊁  
 nsup;   U+02285   ⊅  
 nsupe;   U+02289   ⊉  
 nsupseteq;   U+02289   ⊉  
 ntgl;   U+02279   ≹  
 ntilde;   U+000F1   ñ  
 ntilde   U+000F1   ñ  
 ntlg;   U+02278   ≸  
 ntriangleleft;   U+022EA   ⋪  
 ntrianglelefteq;   U+022EC   ⋬  
 ntriangleright;   U+022EB   ⋫  
 ntrianglerighteq;   U+022ED   ⋭  
 nu;   U+003BD   ν  
 num;   U+00023   #  
 numero;   U+02116   №  
 numsp;   U+02007      
 nvDash;   U+022AD   ⊭  
 nvHarr;   U+02904   ⤄  
 nvdash;   U+022AC   ⊬  
 nvinfin;   U+029DE   ⧞  
 nvlArr;   U+02902   ⤂  
 nvrArr;   U+02903   ⤃  
 nwArr;   U+021D6   ⇖  
 nwarhk;   U+02923   ⤣  
 nwarr;   U+02196   ↖  
 nwarrow;   U+02196   ↖  
 nwnear;   U+02927   ⤧  
 oS;   U+024C8   Ⓢ  
 oacute;   U+000F3   ó  
 oacute   U+000F3   ó  
 oast;   U+0229B   ⊛  
 ocir;   U+0229A   ⊚  
 ocirc;   U+000F4   ô  
 ocirc   U+000F4   ô  
 ocy;   U+0043E   о  
 odash;   U+0229D   ⊝  
 odblac;   U+00151   ő  
 odiv;   U+02A38   ⨸  
 odot;   U+02299   ⊙  
 odsold;   U+029BC   ⦼  
 oelig;   U+00153   œ  
 ofcir;   U+029BF   ⦿  
 ofr;   U+1D52C   𝔬  
 ogon;   U+002DB   ˛  
 ograve;   U+000F2   ò  
 ograve   U+000F2   ò  
 ogt;   U+029C1   ⧁  
 ohbar;   U+029B5   ⦵  
 ohm;   U+003A9   Ω  
 oint;   U+0222E   ∮  
 olarr;   U+021BA   ↺  
 olcir;   U+029BE   ⦾  
 olcross;   U+029BB   ⦻  
 oline;   U+0203E   ‾  
 olt;   U+029C0   ⧀  
 omacr;   U+0014D   ō  
 omega;   U+003C9   ω  
 omicron;   U+003BF   ο  
 omid;   U+029B6   ⦶  
 ominus;   U+02296   ⊖  
 oopf;   U+1D560   𝕠  
 opar;   U+029B7   ⦷  
 operp;   U+029B9   ⦹  
 oplus;   U+02295   ⊕  
 or;   U+02228   ∨  
 orarr;   U+021BB   ↻  
 ord;   U+02A5D   ⩝  
 order;   U+02134   ℴ  
 orderof;   U+02134   ℴ  
 ordf;   U+000AA   ª  
 ordf   U+000AA   ª  
 ordm;   U+000BA   º  
 ordm   U+000BA   º  
 origof;   U+022B6   ⊶  
 oror;   U+02A56   ⩖  
 orslope;   U+02A57   ⩗  
 orv;   U+02A5B   ⩛  
 oscr;   U+02134   ℴ  
 oslash;   U+000F8   ø  
 oslash   U+000F8   ø  
 osol;   U+02298   ⊘  
 otilde;   U+000F5   õ  
 otilde   U+000F5   õ  
 otimes;   U+02297   ⊗  
 otimesas;   U+02A36   ⨶  
 ouml;   U+000F6   ö  
 ouml   U+000F6   ö  
 ovbar;   U+0233D   ⌽  
 par;   U+02225   ∥  
 para;   U+000B6     
 para   U+000B6     
 parallel;   U+02225   ∥  
 parsim;   U+02AF3   ⫳  
 parsl;   U+02AFD   ⫽  
 part;   U+02202   ∂  
 pcy;   U+0043F   п  
 percnt;   U+00025   %  
 period;   U+0002E   .  
 permil;   U+02030   ‰  
 perp;   U+022A5   ⊥  
 pertenk;   U+02031   ‱  
 pfr;   U+1D52D   𝔭  
 phi;   U+003C6   φ  
 phiv;   U+003D5   ϕ  
 phmmat;   U+02133   ℳ  
 phone;   U+0260E   ☎  
 pi;   U+003C0   π  
 pitchfork;   U+022D4   ⋔  
 piv;   U+003D6   ϖ  
 planck;   U+0210F   ℏ  
 planckh;   U+0210E   ℎ  
 plankv;   U+0210F   ℏ  
 plus;   U+0002B   +  
 plusacir;   U+02A23   ⨣  
 plusb;   U+0229E   ⊞  
 pluscir;   U+02A22   ⨢  
 plusdo;   U+02214   ∔  
 plusdu;   U+02A25   ⨥  
 pluse;   U+02A72   ⩲  
 plusmn;   U+000B1   ±  
 plusmn   U+000B1   ±  
 plussim;   U+02A26   ⨦  
 plustwo;   U+02A27   ⨧  
 pm;   U+000B1   ±  
 pointint;   U+02A15   ⨕  
 popf;   U+1D561   𝕡  
 pound;   U+000A3   £  
 pound   U+000A3   £  
 pr;   U+0227A   ≺  
 prE;   U+02AB3   ⪳  
 prap;   U+02AB7   ⪷  
 prcue;   U+0227C   ≼  
 pre;   U+02AAF   ⪯  
 prec;   U+0227A   ≺  
 precapprox;   U+02AB7   ⪷  
 preccurlyeq;   U+0227C   ≼  
 preceq;   U+02AAF   ⪯  
 precnapprox;   U+02AB9   ⪹  
 precneqq;   U+02AB5   ⪵  
 precnsim;   U+022E8   ⋨  
 precsim;   U+0227E   ≾  
 prime;   U+02032   ′  
 primes;   U+02119   ℙ  
 prnE;   U+02AB5   ⪵  
 prnap;   U+02AB9   ⪹  
 prnsim;   U+022E8   ⋨  
 prod;   U+0220F   ∏  
 profalar;   U+0232E   ⌮  
 profline;   U+02312   ⌒  
 profsurf;   U+02313   ⌓  
 prop;   U+0221D   ∝  
 propto;   U+0221D   ∝  
 prsim;   U+0227E   ≾  
 prurel;   U+022B0   ⊰  
 pscr;   U+1D4C5   𝓅  
 psi;   U+003C8   ψ  
 puncsp;   U+02008      
 qfr;   U+1D52E   𝔮  
 qint;   U+02A0C   ⨌  
 qopf;   U+1D562   𝕢  
 qprime;   U+02057   ⁗  
 qscr;   U+1D4C6   𝓆  
 quaternions;   U+0210D   ℍ  
 quatint;   U+02A16   ⨖  
 quest;   U+0003F   ?  
 questeq;   U+0225F   ≟  
 quot;   U+00022   "  
 quot   U+00022   "  
 rAarr;   U+021DB   ⇛  
 rArr;   U+021D2   ⇒  
 rAtail;   U+0291C   ⤜  
 rBarr;   U+0290F   ⤏  
 rHar;   U+02964   ⥤  
 racute;   U+00155   ŕ  
 radic;   U+0221A   √  
 raemptyv;   U+029B3   ⦳  
 rang;   U+027E9   ⟩  
 rangd;   U+02992   ⦒  
 range;   U+029A5   ⦥  
 rangle;   U+027E9   ⟩  
 raquo;   U+000BB   »  
 raquo   U+000BB   »  
 rarr;   U+02192   →  
 rarrap;   U+02975   ⥵  
 rarrb;   U+021E5   ⇥  
 rarrbfs;   U+02920   ⤠  
 rarrc;   U+02933   ⤳  
 rarrfs;   U+0291E   ⤞  
 rarrhk;   U+021AA   ↪  
 rarrlp;   U+021AC   ↬  
 rarrpl;   U+02945   ⥅  
 rarrsim;   U+02974   ⥴  
 rarrtl;   U+021A3   ↣  
 rarrw;   U+0219D   ↝  
 ratail;   U+0291A   ⤚  
 ratio;   U+02236   ∶  
 rationals;   U+0211A   ℚ  
 rbarr;   U+0290D   ⤍  
 rbbrk;   U+02773   ❳  
 rbrace;   U+0007D   }  
 rbrack;   U+0005D   ]  
 rbrke;   U+0298C   ⦌  
 rbrksld;   U+0298E   ⦎  
 rbrkslu;   U+02990   ⦐  
 rcaron;   U+00159   ř  
 rcedil;   U+00157   ŗ  
 rceil;   U+02309   ⌉  
 rcub;   U+0007D   }  
 rcy;   U+00440   р  
 rdca;   U+02937   ⤷  
 rdldhar;   U+02969   ⥩  
 rdquo;   U+0201D   ”  
 rdquor;   U+0201D   ”  
 rdsh;   U+021B3   ↳  
 real;   U+0211C   ℜ  
 realine;   U+0211B   ℛ  
 realpart;   U+0211C   ℜ  
 reals;   U+0211D   ℝ  
 rect;   U+025AD   ▭  
 reg;   U+000AE   ®  
 reg   U+000AE   ®  
 rfisht;   U+0297D   ⥽  
 rfloor;   U+0230B   ⌋  
 rfr;   U+1D52F   𝔯  
 rhard;   U+021C1   ⇁  
 rharu;   U+021C0   ⇀  
 rharul;   U+0296C   ⥬  
 rho;   U+003C1   ρ  
 rhov;   U+003F1   ϱ  
 rightarrow;   U+02192   →  
 rightarrowtail;   U+021A3   ↣  
 rightharpoondown;   U+021C1   ⇁  
 rightharpoonup;   U+021C0   ⇀  
 rightleftarrows;   U+021C4   ⇄  
 rightleftharpoons;   U+021CC   ⇌  
 rightrightarrows;   U+021C9   ⇉  
 rightsquigarrow;   U+0219D   ↝  
 rightthreetimes;   U+022CC   ⋌  
 ring;   U+002DA   ˚  
 risingdotseq;   U+02253   ≓  
 rlarr;   U+021C4   ⇄  
 rlhar;   U+021CC   ⇌  
 rlm;   U+0200F   ‏  
 rmoust;   U+023B1   ⎱  
 rmoustache;   U+023B1   ⎱  
 rnmid;   U+02AEE   ⫮  
 roang;   U+027ED   ⟭  
 roarr;   U+021FE   ⇾  
 robrk;   U+027E7   ⟧  
 ropar;   U+02986   ⦆  
 ropf;   U+1D563   𝕣  
 roplus;   U+02A2E   ⨮  
 rotimes;   U+02A35   ⨵  
 rpar;   U+00029   )  
 rpargt;   U+02994   ⦔  
 rppolint;   U+02A12   ⨒  
 rrarr;   U+021C9   ⇉  
 rsaquo;   U+0203A   ›  
 rscr;   U+1D4C7   𝓇  
 rsh;   U+021B1   ↱  
 rsqb;   U+0005D   ]  
 rsquo;   U+02019   ’  
 rsquor;   U+02019   ’  
 rthree;   U+022CC   ⋌  
 rtimes;   U+022CA   ⋊  
 rtri;   U+025B9   ▹  
 rtrie;   U+022B5   ⊵  
 rtrif;   U+025B8   ▸  
 rtriltri;   U+029CE   ⧎  
 ruluhar;   U+02968   ⥨  
 rx;   U+0211E   ℞  
 sacute;   U+0015B   ś  
 sbquo;   U+0201A   ‚  
 sc;   U+0227B   ≻  
 scE;   U+02AB4   ⪴  
 scap;   U+02AB8   ⪸  
 scaron;   U+00161   š  
 sccue;   U+0227D   ≽  
 sce;   U+02AB0   ⪰  
 scedil;   U+0015F   ş  
 scirc;   U+0015D   ŝ  
 scnE;   U+02AB6   ⪶  
 scnap;   U+02ABA   ⪺  
 scnsim;   U+022E9   ⋩  
 scpolint;   U+02A13   ⨓  
 scsim;   U+0227F   ≿  
 scy;   U+00441   с  
 sdot;   U+022C5   ⋅  
 sdotb;   U+022A1   ⊡  
 sdote;   U+02A66   ⩦  
 seArr;   U+021D8   ⇘  
 searhk;   U+02925   ⤥  
 searr;   U+02198   ↘  
 searrow;   U+02198   ↘  
 sect;   U+000A7   §  
 sect   U+000A7   §  
 semi;   U+0003B   ;  
 seswar;   U+02929   ⤩  
 setminus;   U+02216   ∖  
 setmn;   U+02216   ∖  
 sext;   U+02736   ✶  
 sfr;   U+1D530   𝔰  
 sfrown;   U+02322   ⌢  
 sharp;   U+0266F   ♯  
 shchcy;   U+00449   щ  
 shcy;   U+00448   ш  
 shortmid;   U+02223   ∣  
 shortparallel;   U+02225   ∥  
 shy;   U+000AD   ­  
 shy   U+000AD   ­  
 sigma;   U+003C3   σ  
 sigmaf;   U+003C2   ς  
 sigmav;   U+003C2   ς  
 sim;   U+0223C   ∼  
 simdot;   U+02A6A   ⩪  
 sime;   U+02243   ≃  
 simeq;   U+02243   ≃  
 simg;   U+02A9E   ⪞  
 simgE;   U+02AA0   ⪠  
 siml;   U+02A9D   ⪝  
 simlE;   U+02A9F   ⪟  
 simne;   U+02246   ≆  
 simplus;   U+02A24   ⨤  
 simrarr;   U+02972   ⥲  
 slarr;   U+02190   ←  
 smallsetminus;   U+02216   ∖  
 smashp;   U+02A33   ⨳  
 smeparsl;   U+029E4   ⧤  
 smid;   U+02223   ∣  
 smile;   U+02323   ⌣  
 smt;   U+02AAA   ⪪  
 smte;   U+02AAC   ⪬  
 softcy;   U+0044C   ь  
 sol;   U+0002F   /  
 solb;   U+029C4   ⧄  
 solbar;   U+0233F   ⌿  
 sopf;   U+1D564   𝕤  
 spades;   U+02660   ♠  
 spadesuit;   U+02660   ♠  
 spar;   U+02225   ∥  
 sqcap;   U+02293   ⊓  
 sqcup;   U+02294   ⊔  
 sqsub;   U+0228F   ⊏  
 sqsube;   U+02291   ⊑  
 sqsubset;   U+0228F   ⊏  
 sqsubseteq;   U+02291   ⊑  
 sqsup;   U+02290   ⊐  
 sqsupe;   U+02292   ⊒  
 sqsupset;   U+02290   ⊐  
 sqsupseteq;   U+02292   ⊒  
 squ;   U+025A1   □  
 square;   U+025A1   □  
 squarf;   U+025AA   ▪  
 squf;   U+025AA   ▪  
 srarr;   U+02192   →  
 sscr;   U+1D4C8   𝓈  
 ssetmn;   U+02216   ∖  
 ssmile;   U+02323   ⌣  
 sstarf;   U+022C6   ⋆  
 star;   U+02606   ☆  
 starf;   U+02605   ★  
 straightepsilon;   U+003F5   ϵ  
 straightphi;   U+003D5   ϕ  
 strns;   U+000AF   ¯  
 sub;   U+02282   ⊂  
 subE;   U+02AC5   ⫅  
 subdot;   U+02ABD   ⪽  
 sube;   U+02286   ⊆  
 subedot;   U+02AC3   ⫃  
 submult;   U+02AC1   ⫁  
 subnE;   U+02ACB   ⫋  
 subne;   U+0228A   ⊊  
 subplus;   U+02ABF   ⪿  
 subrarr;   U+02979   ⥹  
 subset;   U+02282   ⊂  
 subseteq;   U+02286   ⊆  
 subseteqq;   U+02AC5   ⫅  
 subsetneq;   U+0228A   ⊊  
 subsetneqq;   U+02ACB   ⫋  
 subsim;   U+02AC7   ⫇  
 subsub;   U+02AD5   ⫕  
 subsup;   U+02AD3   ⫓  
 succ;   U+0227B   ≻  
 succapprox;   U+02AB8   ⪸  
 succcurlyeq;   U+0227D   ≽  
 succeq;   U+02AB0   ⪰  
 succnapprox;   U+02ABA   ⪺  
 succneqq;   U+02AB6   ⪶  
 succnsim;   U+022E9   ⋩  
 succsim;   U+0227F   ≿  
 sum;   U+02211   ∑  
 sung;   U+0266A   ♪  
 sup1;   U+000B9   ¹  
 sup1   U+000B9   ¹  
 sup2;   U+000B2   ²  
 sup2   U+000B2   ²  
 sup3;   U+000B3   ³  
 sup3   U+000B3   ³  
 sup;   U+02283   ⊃  
 supE;   U+02AC6   ⫆  
 supdot;   U+02ABE   ⪾  
 supdsub;   U+02AD8   ⫘  
 supe;   U+02287   ⊇  
 supedot;   U+02AC4   ⫄  
 suphsol;   U+027C9   ⟉  
 suphsub;   U+02AD7   ⫗  
 suplarr;   U+0297B   ⥻  
 supmult;   U+02AC2   ⫂  
 supnE;   U+02ACC   ⫌  
 supne;   U+0228B   ⊋  
 supplus;   U+02AC0   ⫀  
 supset;   U+02283   ⊃  
 supseteq;   U+02287   ⊇  
 supseteqq;   U+02AC6   ⫆  
 supsetneq;   U+0228B   ⊋  
 supsetneqq;   U+02ACC   ⫌  
 supsim;   U+02AC8   ⫈  
 supsub;   U+02AD4   ⫔  
 supsup;   U+02AD6   ⫖  
 swArr;   U+021D9   ⇙  
 swarhk;   U+02926   ⤦  
 swarr;   U+02199   ↙  
 swarrow;   U+02199   ↙  
 swnwar;   U+0292A   ⤪  
 szlig;   U+000DF   ß  
 szlig   U+000DF   ß  
 target;   U+02316   ⌖  
 tau;   U+003C4   τ  
 tbrk;   U+023B4   ⎴  
 tcaron;   U+00165   ť  
 tcedil;   U+00163   ţ  
 tcy;   U+00442   т  
 tdot;   U+020DB   ◌⃛  
 telrec;   U+02315   ⌕  
 tfr;   U+1D531   𝔱  
 there4;   U+02234   ∴  
 therefore;   U+02234   ∴  
 theta;   U+003B8   θ  
 thetasym;   U+003D1   ϑ  
 thetav;   U+003D1   ϑ  
 thickapprox;   U+02248   ≈  
 thicksim;   U+0223C   ∼  
 thinsp;   U+02009      
 thkap;   U+02248   ≈  
 thksim;   U+0223C   ∼  
 thorn;   U+000FE   þ  
 thorn   U+000FE   þ  
 tilde;   U+002DC   ˜  
 times;   U+000D7   ×  
 times   U+000D7   ×  
 timesb;   U+022A0   ⊠  
 timesbar;   U+02A31   ⨱  
 timesd;   U+02A30   ⨰  
 tint;   U+0222D   ∭  
 toea;   U+02928   ⤨  
 top;   U+022A4   ⊤  
 topbot;   U+02336   ⌶  
 topcir;   U+02AF1   ⫱  
 topf;   U+1D565   𝕥  
 topfork;   U+02ADA   ⫚  
 tosa;   U+02929   ⤩  
 tprime;   U+02034   ‴  
 trade;   U+02122   ™  
 triangle;   U+025B5   ▵  
 triangledown;   U+025BF   ▿  
 triangleleft;   U+025C3   ◃  
 trianglelefteq;   U+022B4   ⊴  
 triangleq;   U+0225C   ≜  
 triangleright;   U+025B9   ▹  
 trianglerighteq;   U+022B5   ⊵  
 tridot;   U+025EC   ◬  
 trie;   U+0225C   ≜  
 triminus;   U+02A3A   ⨺  
 triplus;   U+02A39   ⨹  
 trisb;   U+029CD   ⧍  
 tritime;   U+02A3B   ⨻  
 trpezium;   U+023E2   ⏢  
 tscr;   U+1D4C9   𝓉  
 tscy;   U+00446   ц  
 tshcy;   U+0045B   ћ  
 tstrok;   U+00167   ŧ  
 twixt;   U+0226C   ≬  
 twoheadleftarrow;   U+0219E   ↞  
 twoheadrightarrow;   U+021A0   ↠  
 uArr;   U+021D1   ⇑  
 uHar;   U+02963   ⥣  
 uacute;   U+000FA   ú  
 uacute   U+000FA   ú  
 uarr;   U+02191   ↑  
 ubrcy;   U+0045E   ў  
 ubreve;   U+0016D   ŭ  
 ucirc;   U+000FB   û  
 ucirc   U+000FB   û  
 ucy;   U+00443   у  
 udarr;   U+021C5   ⇅  
 udblac;   U+00171   ű  
 udhar;   U+0296E   ⥮  
 ufisht;   U+0297E   ⥾  
 ufr;   U+1D532   𝔲  
 ugrave;   U+000F9   ù  
 ugrave   U+000F9   ù  
 uharl;   U+021BF   ↿  
 uharr;   U+021BE   ↾  
 uhblk;   U+02580   ▀  
 ulcorn;   U+0231C   ⌜  
 ulcorner;   U+0231C   ⌜  
 ulcrop;   U+0230F   ⌏  
 ultri;   U+025F8   ◸  
 umacr;   U+0016B   ū  
 uml;   U+000A8   ¨  
 uml   U+000A8   ¨  
 uogon;   U+00173   ų  
 uopf;   U+1D566   𝕦  
 uparrow;   U+02191   ↑  
 updownarrow;   U+02195   ↕  
 upharpoonleft;   U+021BF   ↿  
 upharpoonright;   U+021BE   ↾  
 uplus;   U+0228E   ⊎  
 upsi;   U+003C5   υ  
 upsih;   U+003D2   ϒ  
 upsilon;   U+003C5   υ  
 upuparrows;   U+021C8   ⇈  
 urcorn;   U+0231D   ⌝  
 urcorner;   U+0231D   ⌝  
 urcrop;   U+0230E   ⌎  
 uring;   U+0016F   ů  
 urtri;   U+025F9   ◹  
 uscr;   U+1D4CA   𝓊  
 utdot;   U+022F0   ⋰  
 utilde;   U+00169   ũ  
 utri;   U+025B5   ▵  
 utrif;   U+025B4   ▴  
 uuarr;   U+021C8   ⇈  
 uuml;   U+000FC   ü  
 uuml   U+000FC   ü  
 uwangle;   U+029A7   ⦧  
 vArr;   U+021D5   ⇕  
 vBar;   U+02AE8   ⫨  
 vBarv;   U+02AE9   ⫩  
 vDash;   U+022A8   ⊨  
 vangrt;   U+0299C   ⦜  
 varepsilon;   U+003F5   ϵ  
 varkappa;   U+003F0   ϰ  
 varnothing;   U+02205   ∅  
 varphi;   U+003D5   ϕ  
 varpi;   U+003D6   ϖ  
 varpropto;   U+0221D   ∝  
 varr;   U+02195   ↕  
 varrho;   U+003F1   ϱ  
 varsigma;   U+003C2   ς  
 vartheta;   U+003D1   ϑ  
 vartriangleleft;   U+022B2   ⊲  
 vartriangleright;   U+022B3   ⊳  
 vcy;   U+00432   в  
 vdash;   U+022A2   ⊢  
 vee;   U+02228   ∨  
 veebar;   U+022BB   ⊻  
 veeeq;   U+0225A   ≚  
 vellip;   U+022EE   ⋮  
 verbar;   U+0007C   |  
 vert;   U+0007C   |  
 vfr;   U+1D533   𝔳  
 vltri;   U+022B2   ⊲  
 vopf;   U+1D567   𝕧  
 vprop;   U+0221D   ∝  
 vrtri;   U+022B3   ⊳  
 vscr;   U+1D4CB   𝓋  
 vzigzag;   U+0299A   ⦚  
 wcirc;   U+00175   ŵ  
 wedbar;   U+02A5F   ⩟  
 wedge;   U+02227   ∧  
 wedgeq;   U+02259   ≙  
 weierp;   U+02118   ℘  
 wfr;   U+1D534   𝔴  
 wopf;   U+1D568   𝕨  
 wp;   U+02118   ℘  
 wr;   U+02240   ≀  
 wreath;   U+02240   ≀  
 wscr;   U+1D4CC   𝓌  
 xcap;   U+022C2   ⋂  
 xcirc;   U+025EF   ◯  
 xcup;   U+022C3   ⋃  
 xdtri;   U+025BD   ▽  
 xfr;   U+1D535   𝔵  
 xhArr;   U+027FA   ⟺  
 xharr;   U+027F7   ⟷  
 xi;   U+003BE   ξ  
 xlArr;   U+027F8   ⟸  
 xlarr;   U+027F5   ⟵  
 xmap;   U+027FC   ⟼  
 xnis;   U+022FB   ⋻  
 xodot;   U+02A00   ⨀  
 xopf;   U+1D569   𝕩  
 xoplus;   U+02A01   ⨁  
 xotime;   U+02A02   ⨂  
 xrArr;   U+027F9   ⟹  
 xrarr;   U+027F6   ⟶  
 xscr;   U+1D4CD   𝓍  
 xsqcup;   U+02A06   ⨆  
 xuplus;   U+02A04   ⨄  
 xutri;   U+025B3   △  
 xvee;   U+022C1   ⋁  
 xwedge;   U+022C0   ⋀  
 yacute;   U+000FD   ý  
 yacute   U+000FD   ý  
 yacy;   U+0044F   я  
 ycirc;   U+00177   ŷ  
 ycy;   U+0044B   ы  
 yen;   U+000A5   ¥  
 yen   U+000A5   ¥  
 yfr;   U+1D536   𝔶  
 yicy;   U+00457   ї  
 yopf;   U+1D56A   𝕪  
 yscr;   U+1D4CE   𝓎  
 yucy;   U+0044E   ю  
 yuml;   U+000FF   ÿ  
 yuml   U+000FF   ÿ  
 zacute;   U+0017A   ź  
 zcaron;   U+0017E   ž  
 zcy;   U+00437   з  
 zdot;   U+0017C   ż  
 zeetrf;   U+02128   ℨ  
 zeta;   U+003B6   ζ  
 zfr;   U+1D537   𝔷  
 zhcy;   U+00436   ж  
 zigrarr;   U+021DD   ⇝  
 zopf;   U+1D56B   𝕫  
 zscr;   U+1D4CF   𝓏  
 zwj;   U+0200D   ‍  
 zwnj;   U+0200C   ‌  

+
+  
The glyphs displayed above are non-normative. Refer to the
+  Unicode specifications for formal definitions of the characters
+  listed above.

+
+
+
+  
11 The XHTML syntax

+
+  
This section only describes the rules for XML
+  resources. Rules for text/html resources are discussed
+  in the section above entitled "The HTML syntax".

+
+
+  

+
+  
11.1 Writing XHTML documents

+
+  

+
+  
The syntax for using HTML with XML, whether in XHTML documents or
+  embedded in other XML documents, is defined in the XML and
+  Namespaces in XML specifications. [XML] [XMLNS]

+
+  
This specification does not define any syntax-level requirements
+  beyond those defined for XML proper.

+
+  
XML documents may contain a DOCTYPE if desired, but
+  this is not required to conform to this specification. This
+  specification does not define a public or system identifier, nor
+  provide a format DTD.

+
+  
According to the XML specification, XML processors
+  are not guaranteed to process the external DTD subset referenced in
+  the DOCTYPE. This means, for example, that using entity references
+  for characters in XHTML documents is unsafe if they are defined in
+  an external file (except for &lt;, &gt;, &amp;, &quot; and &apos;).

+
+
+  

+
+  
11.2 Parsing XHTML documents

+
+  
This section describes the relationship between XML and the DOM,
+  with a particular emphasis on how this interacts with HTML.

+
+  
An XML parser, for the purposes of this specification,
+  is a construct that follows the rules given in the XML specification
+  to map a string of bytes or characters into a Document
+  object.

+
+  
An XML parser is either associated with a
+  Document object when it is created, or creates one
+  implicitly.

+
+  
This Document must then be populated with DOM nodes
+  that represent the tree structure of the input passed to the parser,
+  as defined by the XML specification, the Namespaces in XML
+  specification, and the DOM Core specification. DOM mutation events
+  must not fire for the operations that the XML parser
+  performs on the Document's tree, but the user agent
+  must act as if elements and attributes were individually appended
+  and set respectively so as to trigger rules in this specification
+  regarding what happens when an element in inserted into a document
+  or has its attributes set. [XML] [XMLNS] [DOMCORE]
+  [DOMEVENTS]

+
+  
Between the time an element's start tag is parsed and the time
+  either the element's end tag is parsed on the parser detects a
+  well-formedness error, the user agent must act as if the element was
+  in a stack of open elements.

+
+  
This is used by the object element to
+  avoid instantiating plugins before the param element
+  children have been parsed.

+
+  
This specification provides the following additional information
+  that user agents should use when retrieving an external entity: the
+  public identifiers given in the following list all correspond to the URL given by this
+  link.

+
+  
  • -//W3C//DTD XHTML 1.0 Transitional//EN
    • 
+   
  • -//W3C//DTD XHTML 1.1//EN
    • 
+   
  • -//W3C//DTD XHTML 1.0 Strict//EN
    • 
+   
  • -//W3C//DTD XHTML 1.0 Frameset//EN
    • 
+   
  • -//W3C//DTD XHTML Basic 1.0//EN
    • 
+   
  • -//W3C//DTD XHTML 1.1 plus MathML 2.0//EN
    • 
+   
  • -//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN
    • 
+   
  • -//W3C//DTD MathML 2.0//EN
    • 
+   
  • -//WAPFORUM//DTD XHTML Mobile 1.0//EN
    • 
+  
Furthermore, user agents should attempt to retrieve the above
+  external entity's content when one of the above public identifiers
+  is used, and should not attempt to retrieve any other external
+  entity's content.

+
+  
This is not strictly a violation of the XML specification, but it does
+  contradict the spirit of the XML specification's requirements. This
+  is motivated by a desire for user agents to all handle entities in
+  an interoperable fashion without requiring any network access for
+  handling external subsets. [XML]

+
+  
When an XML parser creates a
+  script element, it must be marked as being
+  "parser-inserted".  If the parser was originally
+  created for the XML fragment parsing algorithm, then
+  the element must be marked as "already started"
+  also. When the element's end tag is parsed, the user agent must
+  run the script
+  element. If this causes there to be a pending parsing-blocking
+  script, then the user agent must run the following steps:

+
+  
  1. Block this instance of the XML parser, such
+   that the event loop will not run tasks that invoke it.
    2. 
+
+   
  2. Spin the event loop until there is no style sheet blocking
+   scripts and the pending parsing-blocking
+   script's "ready to be parser-executed" flag is
+   set.
    3. 
+
+   
  3. Unblock this instance of the XML parser, such
+   that tasks that invoke it can
+   again be run.
    4. 
+
+   
  4. Execute the
+   pending parsing-blocking script.
    5. 
+
+   
  5. There is no longer a pending parsing-blocking
+   script.
    6. 
+
+  
Since the document.write() API is not
+  available for XML documents, much of the complexity in
+  the HTML parser is not needed in the XML
+  parser.

+
+  
Certain algorithms in this specification spoon-feed the parser characters one string at a
+  time. In such cases, the XML parser must act as it
+  would have if faced with a single string consisting of the
+  concatenation of all those characters.

+
+  
When an XML parser reaches the end of its input, it
+  must stop parsing, following the same rules as the
+  HTML parser.

+
+  
For the purposes of conformance checkers, if a resource is
+  determined to be in the XHTML syntax, then it is an
+  XML document.

+
+
+
+  
11.3 Serializing XHTML fragments

+
+  
The XML fragment serialization algorithm for a
+  Document or Element node either returns a
+  fragment of XML that represents that node or raises an
+  exception.

+
+  
For Documents, the algorithm must return a string in
+  the form of a document
+  entity, if none of the error cases below apply.

+
+  
For Elements, the algorithm must return a string in
+  the form of an internal general parsed
+  entity, if none of the error cases below apply.

+
+  
In both cases, the string returned must be XML
+  namespace-well-formed and must be an isomorphic serialization of all
+  of that node's child nodes, in tree order. User agents
+  may adjust prefixes and namespace declarations in the serialization
+  (and indeed might be forced to do so in some cases to obtain
+  namespace-well-formed XML). User agents may use a combination of
+  regular text, character references, and CDATA sections to represent
+  text nodes in the DOM (and indeed
+  might be forced to use representations that don't match the DOM's,
+  e.g. if a CDATASection node contains the string "]]>").

+
+  
For Elements, if any of the elements in the
+  serialization are in no namespace, the default namespace in scope
+  for those elements must be explicitly declared as the empty
+  string. (This doesn't
+  apply in the Document case.) [XML] [XMLNS]

+
+  
For the purposes of this section, an internal general parsed
+  entity is considered XML namespace-well-formed if a document
+  consisting of an element with no namespace declarations whose
+  contents are the internal general parsed entity would itself be XML
+  namespace-well-formed.

+
+  
If any of the following error cases are found in the DOM subtree
+  being serialized, then the algorithm must raise an
+  INVALID_STATE_ERR exception instead of returning a
+  string:

+
+  
  • A Document node with no child element nodes.
    • 
+
+   
  • A DocumentType node that has an external subset
+   public identifier that contains characters that are not matched by
+   the XML PubidChar production. [XML]
    • 
+
+   
  • A DocumentType node that has an external subset
+   system identifier that contains both a U+0022 QUOTATION MARK (")
+   and a U+0027 APOSTROPHE (') or that contains characters that are
+   not matched by the XML Char production. [XML]
    • 
+
+   
  • A node with a  local name containing a U+003A
+   COLON (:).
    •  
+
+   
  • A node with a  local name that does not match
+   the XML Name production. [XML]
    •  
+
+   
  • An Attr node with no namespace whose local name is
+   the lowercase string "xmlns". [XMLNS]
    • 
+
+   
  • An Element node with two or more attributes with
+   the same local name and namespace.
    • 
+
+   
  • An Attr node, Text node,
+   CDATASection node, Comment node, or
+   ProcessingInstruction node whose data contains
+   characters that are not matched by the XML Char production. [XML]
    • 
+
+   
+
+   
  • A Comment node whose data contains two adjacent
+   U+002D HYPHEN-MINUS characters (-) or ends with such a
+   character.
    • 
+
+   
  • A ProcessingInstruction node whose target name is
+   an ASCII case-insensitive match for the string "xml".
    • 
+
+   
  • A ProcessingInstruction node whose target name
+   contains a U+003A COLON (:).
    • 
+
+   
  • A ProcessingInstruction node whose data contains
+   the string "?>".
    • 
+
+  
These are the only ways to make a DOM
+  unserializable. The DOM enforces all the other XML constraints; for
+  example, trying to append two elements to a Document
+  node will raise a HIERARCHY_REQUEST_ERR exception.

+
+
+
+  
11.4 Parsing XHTML fragments

+
+  
The XML fragment parsing algorithm for either returns
+  a Document or raises a SYNTAX_ERR
+  exception. Given a string input and an optional
+  context element context, the algorithm is as
+  follows:

+
+  
  1. 
+
+    
    Create a new XML parser.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    If there is a context element, feed
+    the parser just created the string corresponding to the
+    start tag of that element, declaring all the namespace prefixes
+    that are in scope on that element in the DOM, as well as declaring
+    the default namespace (if any) that is in scope on that element in
+    the DOM.
    
+
+    
    A namespace prefix is in scope if the DOM Core lookupNamespaceURI() method on the element would
+    return a non-null value for that prefix.
    
+
+    
    The default namespace is the namespace for which the DOM Core
+    isDefaultNamespace() method on the element
+    would return true.
    
+
+    
    If there is a context element,
+    no DOCTYPE is passed to the parser, and
+    therefore no external subset is referenced, and therefore no
+    entities will be recognized.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    Feed the parser just created the string input.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If there is a context element, feed
+    the parser just created the string corresponding to the
+    end tag of that element.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If there is an XML well-formedness or XML namespace
+    well-formedness error, then raise a SYNTAX_ERR
+    exception and abort these steps.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    If there is a context element, then return
+    the child nodes of the root element of the resulting
+    Document, in tree order.
    
+
+    
    Otherwise, return the children of the Document
+    object, in tree order.
    
+
+   
    7. 
+
+  

+
+
+  

+
+  
12 Rendering

+
+  
User agents are not required to present HTML documents in any
+  particular way. However, this section provides a set of suggestions
+  for rendering HTML documents that, if followed, are likely to lead
+  to a user experience that closely resembles the experience intended
+  by the documents' authors. So as to avoid confusion regarding the
+  normativity of this section, RFC2119 terms have not been used.
+  Instead, the term "expected" is used to indicate behavior that will
+  lead to this experience.

+
+
+  
12.1 Introduction

+
+  
In general, user agents are expected to support CSS, and many of
+  the suggestions in this section are expressed in CSS terms. User
+  agents that use other presentation mechanisms can derive their
+  expected behavior by translating from the CSS rules given in this
+  section.

+
+  
In the absence of style-layer rules to the contrary (e.g. author
+  style sheets), user agents are expected to render an element so that
+  it conveys to the user the meaning that the element
+  represents, as described by this specification.

+
+  
The suggestions in this section generally assume a visual output
+  medium with a resolution of 96dpi or greater, but HTML is intended
+  to apply to multiple media (it is a media-independent
+  language). User agents are encouraged to adapt the suggestions in
+  this section to their target media.

+
+  
An element is being rendered if it is in a
+  Document, either its parent node is itself
+  being rendered or it is the Document node,
+  and it is not explicitly excluded from the rendering using either:

+  
  • the CSS 'display' property's 'none' value, or
    • 
+   
  • the 'visibility' property's 'collapse' value unless it is being treated as equivalent to the 'hidden' value, or
    • 
+   
  • some equivalent in other styling languages.
    • 
+  
Just being off-screen does not mean the element is
+  not being rendered. The presence of the hidden attribute normally means the
+  element is not being rendered, though this might be
+  overriden by the style sheets.

+
+  

+
+
+  

+
+  
12.2 The CSS user agent style sheet and presentational hints

+
+  
12.2.1 Introduction

+
+  
The CSS rules given in these subsections are, except where
+  otherwise specified, expected to be used as part of the user-agent
+  level style sheet defaults for all documents that contain HTML
+  elements.

+
+  
Some rules are intended for the author-level zero-specificity
+  presentational hints part of the CSS cascade; these are explicitly
+  called out as presentational hints.

+
+  
Some of the rules regarding left and right margins are given here
+  as appropriate for elements whose 'direction' property is 'ltr', and
+  are expected to be flipped around on elements whose 'direction'
+  property is 'rtl'. These are marked "LTR-specific".

+
+  
For the purpose of the
+  rules marked "case-sensitive", user agents are expected to use
+  case-sensitive matching of attribute values rather than
+  case-insensitive matching, regardless of whether a case-insensitive
+  matching is normally required for the given attribute.

+
+  
Similarly, for the
+  purpose of the rules marked "case-insensitive", user agents are
+  expected to use ASCII case-insensitive matching of
+  attribute values rather than case-sensitive matching, even for
+  attributes in XHTML documents.

+
+  
These markings only affect the handling of attribute
+  values, not attribute names or element names.

+
+  
When the text below says that an attribute attribute on an element element
+  maps to the pixel length property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute's value
+  using the rules for parsing non-negative integers
+  doesn't generate an error, then the user agent is expected to use
+  the parsed value as a pixel length for a presentational hint for properties.

+
+  
When the text below says that an attribute attribute on an element element
+  maps to the dimension property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute's value
+  using the rules for parsing dimension values doesn't
+  generate an error, then the user agent is expected to use the parsed
+  dimension as the value for a presentational hint for properties, with the value given as a pixel length if
+  the dimension was an integer, and with the value given as a
+  percentage if the dimension was a percentage.

+
+  

+
+
+  

+
+  
12.2.2 Display types

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+[hidden], area, base, basefont, command, datalist, head,
+input[type=hidden], link, menu[type=context], meta, noembed, noframes,
+param, rp, script, source, style, track, title { /* case-insensitive */
+  display: none;
+}
+
+address, article, aside, blockquote, body, center, dd, dir, div, dl,
+dt, figure, figcaption, footer, form, h1, h2, h3, h4, h5, h6, header,
+hgroup, hr, html, legend, listing, menu, nav, ol, p, plaintext, pre,
+section, summary, ul, xmp { display: block; }
+
+table { display: table; }
+caption { display: table-caption; }
+colgroup { display: table-column-group; }
+col { display: table-column; }
+thead { display: table-header-group; }
+tbody { display: table-row-group; }
+tfoot { display: table-footer-group; }
+tr { display: table-row; }
+td, th { display: table-cell; }
+
+li { display: list-item; }
+
+ruby { display: ruby; }
+rt { display: ruby-text; }

+
+  
+
+  
For the purposes of the CSS table model, the col
+  element is expected to be treated as if it was present as many times
+  as its span attribute specifies.

+
+  
For the purposes of the CSS table model, the
+  colgroup element, if it contains no col
+  element, is expected to be treated as if it had as many such
+  children as its span
+  attribute specifies.

+
+  
For the purposes of the CSS table model, the colspan and rowspan attributes on
+  td and th elements are expected to provide the
+  special knowledge regarding cells spanning rows and
+  columns.

+
+  
For the purposes of the CSS ruby model, runs of children of
+  ruby elements that are not rt or
+  rp elements are expected to be wrapped in anonymous
+  boxes whose 'display' property has the value 'ruby-base'.

+
+  
User agents that do not support correct ruby rendering are
+  expected to render parentheses around the text of rt
+  elements in the absence of rp elements.

+
+  
The br element is expected to render as if its
+  contents were a single U+000A LINE FEED (LF) character and its
+  'white-space' property was 'pre'. User agents are expected to
+  support the 'clear' property on inline elements (in order to render
+  br elements with clear attributes) in the manner
+  described in the non-normative note to this effect in CSS2.1.

+  
+
+  
The user agent is expected to hide noscript elements
+  for whom scripting is enabled,
+  irrespective of CSS rules.

+
+  
In HTML documents, the user agent is expected to
+  hide form elements that are children of
+  table, thead, tbody,
+  tfoot, or tr elements, irrespective of CSS
+  rules.

+
+  

+
+
+  

+
+  
12.2.3 Margins and padding

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+blockquote, dir, dl, figure, listing, menu, ol, p, plaintext,
+pre, ul, xmp {
+  margin-top: 1em; margin-bottom: 1em;
+}
+
+dir dir, dir dl, dir menu, dir ol, dir ul,
+dl dir, dl dl, dl menu, dl ol, dl ul,
+menu dir, menu dl, menu menu, menu ol, menu ul,
+ol dir, ol dl, ol menu, ol ol, ol ul,
+ul dir, ul dl, ul menu, ul ol, ul ul {
+  margin-top: 0; margin-bottom: 0;
+}
+
+h1 { margin-top: 0.67em; margin-bottom; 0.67em; }
+h2 { margin-top: 0.83em; margin-bottom; 0.83em; }
+h3 { margin-top: 1.00em; margin-bottom; 1.00em; }
+h4 { margin-top: 1.33em; margin-bottom; 1.33em; }
+h5 { margin-top: 1.67em; margin-bottom; 1.67em; }
+h6 { margin-top: 2.33em; margin-bottom; 2.33em; }
+
+dd { margin-left: 40px; } /* LTR-specific: use 'margin-right' for rtl elements */
+dir, menu, ol, ul { padding-left: 40px; } /* LTR-specific: use 'padding-right' for rtl elements */
+blockquote, figure { margin-left: 40px; margin-right: 40px; }
+
+table { border-spacing: 2px; border-collapse: separate; }
+td, th { padding: 1px; }

+
+  
The article, aside, nav,
+  and section elements are expected to affect the margins
+  of h1 elements, based on the nesting depth. If x is a selector that matches elements that are either
+  article, aside, nav, or
+  section elements, then the following rules capture what
+  is expected:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+x h1 { margin-top: 0.83em; margin-bottom: 0.83em; }
+x x h1 { margin-top: 1.00em; margin-bottom: 1.00em; }
+x x x h1 { margin-top: 1.33em; margin-bottom: 1.33em; }
+x x x x h1 { margin-top: 1.67em; margin-bottom: 1.67em; }
+x x x x x h1 { margin-top: 2.33em; margin-bottom: 2.33em; }

+
+  
For each property in the table below, given a body
+  element, the first attribute that exists maps to the pixel
+  length property on the body element. If none of
+  the attributes for a property are found, or if the value of the
+  attribute that was found cannot be parsed successfully, then a
+  default value of 8px is expected to be used for that property
+  instead.

+
+  
Property
+     Source
+   
'margin-top'
+     body element's marginheight attribute
+    
The body element's container frame element's marginheight attribute
+    
body element's topmargin attribute
+   
'margin-right'
+     body element's marginwidth attribute
+    
The body element's container frame element's marginwidth attribute
+    
body element's rightmargin attribute
+   
'margin-bottom'
+     body element's marginheight attribute
+    
The body element's container frame element's marginheight attribute
+    
body element's topmargin attribute
+   
'margin-left'
+     body element's marginwidth attribute
+    
The body element's container frame element's marginwidth attribute
+    
body element's rightmargin attribute
+  
If the body element's Document's
+  browsing context is a nested browsing
+  context, and the browsing context container of
+  that nested browsing context is a frame or
+  iframe element, then the container frame
+  element of the body element is that
+  frame or iframe element. Otherwise, there
+  is no container frame element.

+
+  
The above requirements imply that a page can
+  change the margins of another page (including one from another
+  origin) using, for example, an
+  iframe. This is potentially a security risk, as it
+  might in some cases allow an attack to contrive a situation in which
+  a page is rendered not as the author intended, possibly for the
+  purposes of phishing or otherwise misleading the user.

+
+  
If the Document has a root element, and
+  the Document's browsing context is a
+  nested browsing context, and the browsing context
+  container of that nested browsing context is a
+  frame or iframe element, and that element
+  has a scrolling
+  attribute, then the user agent is expected to compare the value of
+  the attribute in an ASCII case-insensitive manner to
+  the values in the first column of the following table, and if one of
+  them matches, then the user agent is expected to treat that
+  attribute as a presentational
+  hint for the aforementioned root element's 'overflow'
+  property, setting it to the value given in the corresponding cell on
+  the same row in the second column:

+
+  
 Attribute value
+      'overflow' value
+   
on
+     'scroll'
+    
scroll
+     'scroll'
+    
yes
+     'scroll'
+    
off
+     'hidden'
+    
noscroll
+     'hidden'
+    
no
+     'hidden'
+    
auto
+     'auto'
+  
The table element's cellspacing attribute
+  maps to the pixel length property 'border-spacing' on the
+  element.

+
+  
The table element's cellpadding attribute maps to the pixel length
+  properties 'padding-top', 'padding-right', 'padding-bottom',
+  and 'padding-left' of any td and th
+  elements that have corresponding cells in the table corresponding to the
+  table element.

+
+  
The table element's hspace attribute maps to the dimension properties
+  'margin-left' and 'margin-right' on the table
+  element.

+
+  
The table element's vspace attribute maps to the dimension properties
+  'margin-top' and 'margin-bottom' on the table
+  element.

+
+  
The table element's height attribute maps to the
+  dimension property 'height' on the table
+  element.

+
+  
The table element's width attribute maps to the
+  dimension property 'width' on the table
+  element.

+
+  
The col element's width attribute maps to the
+  dimension property 'width' on the col
+  element.

+
+  
The tr element's height attribute maps to the
+  dimension property 'height' on the tr
+  element.

+
+  
The td and th elements' height attributes map to the dimension property 'height'
+  on the element.

+
+  
The td and th elements' width attributes map to the dimension property 'width'
+  on the element.

+
+  
In quirks mode, the following rules are also
+  expected to apply:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+form { margin-bottom: 1em; }

+
+  
When a Document is in quirks mode,
+  margins on HTML elements at the top or bottom of
+  body, td, or th elements are
+  expected to be collapsed to zero.

+
+  

+
+
+  

+
+  
12.2.4 Alignment

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+thead, tbody, tfoot, table > tr { vertical-align: middle; }
+tr, td, th { vertical-align: inherit; }
+sub { vertical-align: sub; }
+sup { vertical-align: super; }
+th { text-align: center; }

+
+  
The following rules are also expected to apply, as
+  presentational hints:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+table[align=left] { float: left; } /* case-insensitive */
+table[align=right] { float: right; } /* case-insensitive */
+table[align=center], table[align=abscenter],
+table[align=absmiddle], table[align=middle] { /* case-insensitive */
+  margin-left: auto; margin-right: auto;
+}
+thead[align=absmiddle], tbody[align=absmiddle], tfoot[align=absmiddle],
+tr[align=absmiddle], td[align=absmiddle], th[align=absmiddle] {
+  text-align: center;
+}
+
+caption[align=bottom] { caption-side: bottom; } /* case-insensitive */
+p[align=left], h1[align=left], h2[align=left], h3[align=left],
+h4[align=left], h5[align=left], h6[align=left] { /* case-insensitive */
+  text-align: left;
+}
+p[align=right], h1[align=right], h2[align=right], h3[align=right],
+h4[align=right], h5[align=right], h6[align=right] { /* case-insensitive */
+  text-align: right;
+}
+p[align=center], h1[align=center], h2[align=center], h3[align=center],
+h4[align=center], h5[align=center], h6[align=center] { /* case-insensitive */
+  text-align: center;
+}
+p[align=justify], h1[align=justify], h2[align=justify], h3[align=justify],
+h4[align=justify], h5[align=justify], h6[align=justify] { /* case-insensitive */
+  text-align: justify;
+}
+col[valign=top], thead[valign=top], tbody[valign=top],
+tfoot[valign=top], tr[valign=top], td[valign=top], th[valign=top] { /* case-insensitive */
+  vertical-align: top;
+}
+col[valign=middle], thead[valign=middle], tbody[valign=middle],
+tfoot[valign=middle], tr[valign=middle], td[valign=middle], th[valign=middle] { /* case-insensitive */
+  vertical-align: middle;
+}
+col[valign=bottom], thead[valign=bottom], tbody[valign=bottom],
+tfoot[valign=bottom], tr[valign=bottom], td[valign=bottom], th[valign=bottom] { /* case-insensitive */
+  vertical-align: bottom;
+}
+col[valign=baseline], thead[valign=baseline], tbody[valign=baseline],
+tfoot[valign=baseline], tr[valign=baseline], td[valign=baseline], th[valign=baseline] { /* case-insensitive */
+  vertical-align: baseline;
+}

+
+  
The center element, the caption element
+  unless specified otherwise below, and the div,
+  thead, tbody, tfoot,
+  tr, td, and th elements when
+  they have an align attribute
+  whose value is an ASCII case-insensitive match for
+  either the string "center" or the string
+  "middle", are expected to center text within
+  themselves, as if they had their 'text-align' property set to
+  'center' in a presentational
+  hint, and to align descendants to the
+  center.

+
+  
The div, caption, thead,
+  tbody, tfoot, tr,
+  td, and th elements, when they have an
+  align attribute whose value is an
+  ASCII case-insensitive match for the string "left", are expected to left-align text within
+  themselves, as if they had their 'text-align' property set to 'left'
+  in a presentational hint,
+  and to align descendants to the left.

+
+  
The div, caption, thead,
+  tbody, tfoot, tr,
+  td, and th elements, when they have an
+  align attribute whose value is an
+  ASCII case-insensitive match for the string "right", are expected to right-align text within
+  themselves, as if they had their 'text-align' property set to
+  'right' in a presentational
+  hint, and to align descendants to the right.

+
+  
The div, caption, thead,
+  tbody, tfoot, tr,
+  td, and th elements, when they have an
+  align attribute whose value is an
+  ASCII case-insensitive match for the string "justify", are expected to full-justify text within
+  themselves, as if they had their 'text-align' property set to
+  'justify' in a presentational
+  hint, and to align descendants to the left.

+
+  
When a user agent is to align descendants of a node,
+  the user agent is expected to align only those descendants that have
+  both their 'margin-left' and 'margin-right' properties computing to
+  a value other than 'auto', that are over-constrained and that have
+  one of those two margins with a used value forced to a greater
+  value, and that do not themselves have an applicable align attribute. When multiple elements
+  are to align a particular
+  descendant, the most deeply nested such element is expected to
+  override the others.

+
+  

+
+
+  

+
+  
12.2.5 Fonts and colors

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+address, cite, dfn, em, i, var { font-style: italic; }
+b, strong, th { font-weight: bold; }
+code, kbd, listing, plaintext, pre, samp, tt, xmp { font-family: monospace; }
+h1 { font-size: 2.00em; font-weight: bold; }
+h2 { font-size: 1.50em; font-weight: bold; }
+h3 { font-size: 1.17em; font-weight: bold; }
+h4 { font-size: 1.00em; font-weight: bold; }
+h5 { font-size: 0.83em; font-weight: bold; }
+h6 { font-size: 0.67em; font-weight: bold; }
+big { font-size: larger; }
+small, sub, sup { font-size: smaller; }
+sub, sup { line-height: normal; }
+
+:link { color: blue; }
+:visited { color: purple; }
+mark { background: yellow; color: black; }
+
+table, td, th { border-color: gray; }
+thead, tbody, tfoot, tr { border-color: inherit; }
+table[rules=none], table[rules=groups], table[rules=rows],
+table[rules=cols], table[rules=all], table[frame=void],
+table[frame=above], table[frame=below], table[frame=hsides],
+table[frame=lhs], table[frame=rhs], table[frame=vsides],
+table[frame=box], table[frame=border],
+table[rules=none] > tr > td, table[rules=none] > tr > th,
+table[rules=groups] > tr > td, table[rules=groups] > tr > th,
+table[rules=rows] > tr > td, table[rules=rows] > tr > th,
+table[rules=cols] > tr > td, table[rules=cols] > tr > th,
+table[rules=all] > tr > td, table[rules=all] > tr > th,
+table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th,
+table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th,
+table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th,
+table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th,
+table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th,
+table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th,
+table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th,
+table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th,
+table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th,
+table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th,
+table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th,
+table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th,
+table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th,
+table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th,
+table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th { /* case-insensitive */
+  border-color: black;
+}

+
+  
The initial value for the 'color' property is expected to be
+  black. The initial value for the 'background-color' property is
+  expected to be 'transparent'. The canvas's background is expected to
+  be white.

+
+  
The article, aside, nav,
+  and section elements are expected to affect the font
+  size of h1 elements, based on the nesting depth. If
+  x is a selector that matches elements that are
+  either article, aside, nav,
+  or section elements, then the following rules capture
+  what is expected:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+x h1 { font-size: 1.50em; }
+x x h1 { font-size: 1.17em; }
+x x x h1 { font-size: 1.00em; }
+x x x x h1 { font-size: 0.83em; }
+x x x x x h1 { font-size: 0.67em; }

+
+  
When a body, table, thead,
+  tbody, tfoot, tr,
+  td, or th element has a background attribute set to a
+  non-empty value, the new value is expected to be resolved relative to the element, and
+  if this is successful, the user agent is expected to treat the
+  attribute as a presentational
+  hint setting the element's 'background-image' property to the
+  resulting absolute URL.

+
+  
When a body, table, thead,
+  tbody, tfoot, tr,
+  td, or th element has a bgcolor attribute set, the new value is expected to
+  be parsed using the rules for parsing a legacy color
+  value, and if that does not return an error, the user agent
+  is expected to treat the attribute as a presentational hint setting the element's
+  'background-color' property to the resulting color.

+
+  
When a body element has a text attribute, its value is expected
+  to be parsed using the rules for parsing a legacy color
+  value, and if that does not return an error, the user
+  agent is expected to treat the attribute as a presentational hint setting the
+  element's 'color' property to the resulting color.

+
+  
When a body element has a link attribute, its value is expected
+  to be parsed using the rules for parsing a legacy color
+  value, and if that does not return an error, the user agent
+  is expected to treat the attribute as a presentational hint setting the 'color' property of
+  any element in the Document matching the ':link'
+  pseudo-class to the resulting color.

+
+  
When a body element has a vlink attribute, its value is
+  expected to be parsed using the rules for parsing a legacy
+  color value, and if that does not return an error, the user
+  agent is expected to treat the attribute as a presentational hint setting the
+  'color' property of any element in the Document
+  matching the ':visited' pseudo-class to the resulting color.

+
+  
When a body element has a alink attribute, its value is
+  expected to be parsed using the rules for parsing a legacy
+  color value, and if that does not return an error, the user
+  agent is expected to treat the attribute as a presentational hint setting the
+  'color' property of any element in the Document
+  matching the ':active' pseudo-class and either the ':link'
+  pseudo-class or the ':visited' pseudo-class to the resulting
+  color.

+
+  
When a table element has a bordercolor attribute, its
+  value is expected to be parsed using the rules for parsing a
+  legacy color value, and if that does not return an error, the
+  user agent is expected to treat the attribute as a presentational hint setting the
+  element's 'border-top-color', 'border-right-color',
+  'border-bottom-color', and 'border-right-color' properties to the
+  resulting color.

+
+  
When a font element has a color attribute, its value is
+  expected to be parsed using the rules for parsing a legacy
+  color value, and if that does not return an error, the user
+  agent is expected to treat the attribute as a presentational hint setting the
+  element's 'color' property to the resulting color.

+
+  
When a font element has a face attribute, the user agent is
+  expected to treat the attribute as a presentational hint setting the element's
+  'font-family' property to the attribute's value.

+
+  
+
+  
When a font element has a size attribute, the user agent is
+  expected to use the following steps to treat the attribute as a
+  presentational hint
+  setting the element's 'font-size' property:

+
+  
  1. Let input be the attribute's
+   value.
    2. 
+
+   
  2. Let position be a pointer into input, initially pointing at the start of the
+   string.
    3. 
+
+   
  3. Skip whitespace.
    4. 
+
+   
  4. If position is past the end of input, there is no presentational hint. Abort these steps.
    5. 
+
+   
  5. If the character at position is a U+002B
+   PLUS SIGN character (+), then let mode be
+   relative-plus, and advance position to
+   the next character. Otherwise, if the character at position is a U+002D HYPHEN-MINUS character (-),
+   then let mode be relative-minus, and
+   advance position to the next
+   character. Otherwise, let mode be
+   absolute.
    6. 
+
+   
  6. Collect a sequence of characters in the range
+   U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and let the
+   resulting sequence be digits.
    7. 
+
+   
  7. If digits is the empty string, there is
+   no presentational
+   hint. Abort these steps.
    8. 
+
+   
  8. Interpret digits as a base-ten
+   integer. Let value be the resulting
+   number.
    9. 
+
+   
  9. 
+
+    
+
+    
    If mode is relative-plus, then
+    increment value by 3. If mode is relative-minus, then let value be the result of subtracting value from 3.
    
+
+   
    10. 
+
+   
  10. If value is greater than 7, let it be
+   7.
    11. 
+
+   
  11. If value is less than 1, let it be
+   1.
    12. 
+
+   
  12. 
+
+    
    Set 'font-size' to the keyword corresponding to the value of
+    value according to the following table:
    
+
+    
    value
+       'font-size' keyword
+       Notes
+     
    1
+       xx-small
+       
+      
    2
+       small
+       
+      
    3
+       medium
+       
+      
    4
+       large
+       
+      
    5
+       x-large
+       
+      
    6
+       xx-large
+       
+      
    7
+       xxx-large
+       see below
+    
    The 'xxx-large' value is a non-CSS value used here to
+    indicate a font size one "step" larger than 'xx-large'.
    
+
+   
    13. 
+
+  

+
+
+  

+
+  
12.2.6 Punctuation and decorations

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+:link, :visited, ins, u { text-decoration: underline; }
+abbr[title], acronym[title] { text-decoration: dotted underline; }
+del, s, strike { text-decoration: line-through; }
+blink { text-decoration: blink; }
+
+:focus { outline: auto; }
+
+q:before { content: open-quote; }
+q:after { content: close-quote; }
+
+nobr { white-space: nowrap; }
+listing, plaintext, pre, xmp { white-space: pre; }
+
+ol { list-style-type: decimal; }
+
+dir, menu, ul {
+  list-style-type: disc;
+}
+
+dir dl, dir menu, dir ul,
+menu dl, menu menu, menu ul,
+ol dl, ol menu, ol ul,
+ul dl, ul menu, ul ul {
+  list-style-type: circle;
+}
+
+dir dir dl, dir dir menu, dir dir ul,
+dir menu dl, dir menu menu, dir menu ul,
+dir ol dl, dir ol menu, dir ol ul,
+dir ul dl, dir ul menu, dir ul ul,
+menu dir dl, menu dir menu, menu dir ul,
+menu menu dl, menu menu menu, menu menu ul,
+menu ol dl, menu ol menu, menu ol ul,
+menu ul dl, menu ul menu, menu ul ul,
+ol dir dl, ol dir menu, ol dir ul,
+ol menu dl, ol menu menu, ol menu ul,
+ol ol dl, ol ol menu, ol ol ul,
+ol ul dl, ol ul menu, ol ul ul,
+ul dir dl, ul dir menu, ul dir ul,
+ul menu dl, ul menu menu, ul menu ul,
+ul ol dl, ul ol menu, ul ol ul,
+ul ul dl, ul ul menu, ul ul ul {
+  list-style-type: square;
+}
+
+table { border-style: outset; }
+td, th { border-style: inset; }
+
+[dir=ltr] { direction: ltr; unicode-bidi: embed; } /* case-insensitive */
+[dir=rtl] { direction: rtl; unicode-bidi: embed; } /* case-insensitive */
+bdo[dir=ltr], bdo[dir=rtl] { unicode-bidi: bidi-override; } /* case-insensitive */

+
+  
In addition, rules setting the 'quotes' property appropriately
+  for the locales and languages understood by the user are expected to
+  be present.

+
+  
The following rules are also expected to apply, as
+  presentational hints:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+td[nowrap], th[nowrap] { white-space: nowrap; }
+pre[wrap] { white-space: pre-wrap; }
+
+br[clear=left] { clear: left; } /* case-insensitive */
+br[clear=right] { clear: right; } /* case-insensitive */
+br[clear=all], br[clear=both] { clear: both; } /* case-insensitive */
+
+ol[type=1], li[type=1] { list-style-type: decimal; }
+ol[type=a], li[type=a] { list-style-type: lower-alpha; } /* case-sensitive */
+ol[type=A], li[type=A] { list-style-type: upper-alpha; } /* case-sensitive */
+ol[type=i], li[type=i] { list-style-type: lower-roman; } /* case-sensitive */
+ol[type=I], li[type=I] { list-style-type: upper-roman; } /* case-sensitive */
+ul[type=disc], li[type=disc] { list-style-type: disc; }
+ul[type=circle], li[type=circle] { list-style-type: circle; }
+ul[type=square], li[type=square] { list-style-type: square; }
+
+table[rules=none], table[rules=groups], table[rules=rows],
+table[rules=cols], table[rules=all] {
+  border-style: none;
+  border-collapse: collapse;
+}
+
+table[frame=void] { border-style: hidden hidden hidden hidden; }
+table[frame=above] { border-style: solid hidden hidden hidden; }
+table[frame=below] { border-style: hidden hidden solid hidden; }
+table[frame=hsides] { border-style: solid hidden solid hidden; }
+table[frame=lhs] { border-style: hidden hidden hidden solid; }
+table[frame=rhs] { border-style: hidden solid hidden hidden; }
+table[frame=vsides] { border-style: hidden solid hidden solid; }
+table[frame=box],
+table[frame=border] { border-style: solid solid solid solid; }
+
+table[rules=none] > tr > td, table[rules=none] > tr > th,
+table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th,
+table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th,
+table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th,
+table[rules=groups] > tr > td, table[rules=groups] > tr > th,
+table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th,
+table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th,
+table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th,
+table[rules=rows] > tr > td, table[rules=rows] > tr > th,
+table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th,
+table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th,
+table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th {
+  border-style: none;
+}
+
+table[rules=groups] > colgroup, table[rules=groups] > thead,
+table[rules=groups] > tbody, table[rules=groups] > tfoot {
+  border-style: solid;
+}
+
+table[rules=rows] > tr, table[rules=rows] > thead > tr,
+table[rules=rows] > tbody > tr, table[rules=rows] > tfoot > tr {
+  border-style: solid;
+}
+
+table[rules=cols] > tr > td, table[rules=cols] > tr > th,
+table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th,
+table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th,
+table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th {
+  border-style: none solid none solid;
+}
+
+table[rules=all] > tr > td, table[rules=all] > tr > th,
+table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th,
+table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th,
+table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th {
+  border-style: solid;
+}
+
+table[border] > tr > td, table[border] > tr > th,
+table[border] > thead > tr > td, table[border] > thead > tr > th,
+table[border] > tbody > tr > td, table[border] > tbody > tr > th,
+table[border] > tfoot > tr > td, table[border] > tfoot > tr > th {
+  border-width: 1px;
+}

+
+  
When rendering li elements, user agents are expected
+  to use the ordinal value of the li element to render
+  the counter in the list item marker.

+
+  
The table element's border attribute maps to the pixel length
+  properties 'border-top-width', 'border-right-width',
+  'border-bottom-width', 'border-left-width' on the element. If the
+  attribute is present but parsing the attribute's value using the
+  rules for parsing non-negative integers generates an
+  error, a default value of 1px is expected to be used for that
+  property instead.

+
+  
The wbr element is expected to override the
+  'white-space' property and always provide a line-breaking
+  opportunity.

+
+  

+
+
+  

+
+  
12.2.7 Resetting rules for inherited properties

+
+  
The following rules are also expected to be in play, resetting
+  certain properties to block inheritance by default.

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+table, input, select, option, optgroup, button, textarea, keygen {
+  text-indent: initial;
+}

+
+  
+
+  
In quirks mode, the following rules are also
+  expected to apply:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+table {
+  font-weight: initial;
+  font-style: initial;
+  font-variant: initial;
+  font-size: initial;
+  line-height: initial;
+  white-space: initial;
+  text-align: initial;
+}
+
+input { box-sizing: border-box; }

+
+  

+
+
+  

+
+  
12.2.8 The hr element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+hr { color: gray; border-style: inset; border-width: 1px; margin: 0.5em auto; }

+
+  
The following rules are also expected to apply, as
+  presentational hints:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+hr[align=left] { margin-left: 0; margin-right: auto; } /* case-insensitive */
+hr[align=right] { margin-left: auto; margin-right: 0; } /* case-insensitive */
+hr[align=center] { margin-left: auto; margin-right: auto; } /* case-insensitive */
+hr[color], hr[noshade] { border-style: solid; }

+
+  
If an hr element has either a color attribute or a noshade attribute, and furthermore
+  also has a size attribute, and
+  parsing that attribute's value using the rules for parsing
+  non-negative integers doesn't generate an error, then the
+  user agent is expected to use the parsed value divided by two as a
+  pixel length for presentational hints for the properties
+  'border-top-width', 'border-right-width', 'border-bottom-width', and
+  'border-left-width' on the element.

+
+  
Otherwise, if an hr element has neither a color attribute nor a noshade attribute, but does have a
+  size attribute, and parsing that
+  attribute's value using the rules for parsing non-negative
+  integers doesn't generate an error, then: if the parsed value
+  is one, then the user agent is expected to use the attribute as a
+  presentational hint
+  setting the element's 'border-bottom-width' to 0; otherwise, if the
+  parsed value is greater than one, then the user agent is expected to
+  use the parsed value minus two as a pixel length for
+  presentational hints for the 'height' property on the
+  element.

+
+  
The width attribute on an
+  hr element maps to the dimension property
+  'width' on the element.

+
+  
When an hr element has a color attribute, its value is expected
+  to be parsed using the rules for parsing a legacy color
+  value, and if that does not return an error, the user agent
+  is expected to treat the attribute as a presentational hint setting the element's 'color'
+  property to the resulting color.

+
+  

+
+
+  

+
+  
12.2.9 The fieldset element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+fieldset {
+  margin-left: 2px; margin-right: 2px;
+  border: groove 2px ThreeDFace;
+  padding: 0.35em 0.625em 0.75em;
+}

+
+  
The fieldset element is expected to establish a new
+  block formatting context.

+
+  
The first legend element child of a
+  fieldset element, if any, is expected to be rendered
+  over the top border edge of the fieldset element. If
+  the legend element in question has an align attribute, and its value is
+  an ASCII case-insensitive match for one of the strings
+  in the first column of the following table, then the
+  legend is expected to be rendered horizontally aligned
+  over the border edge in the position given in the corresponding cell
+  on the same row in the second column. If the attribute is absent or
+  has a value that doesn't match any of the cases in the table, then
+  the position is expected to be on the right if the 'direction'
+  property on this element has a computed value of 'rtl', and on the
+  left otherwise.

+
+  
Attribute value
+     Alignment position
+   
left
+     On the left
+    
right
+     On the right
+    
center
+     In the middle
+  

+
+
+  

+
+  
12.3 Replaced elements

+
+  
12.3.1 Embedded content

+
+  
The embed, iframe, and
+  video elements are expected to be treated as replaced
+  elements.

+
+  
A canvas element that represents
+  embedded content is expected to be treated as a
+  replaced element. Other canvas elements are expected to
+  be treated as ordinary elements in the rendering model.

+
+  
An object element that represents an
+  image, plugin, or nested browsing context is expected
+  to be treated as a replaced element. Other object
+  elements are expected to be treated as ordinary elements in the
+  rendering model.

+
+  
An applet element that represents a
+  plugin is expected to be treated as a replaced
+  element. Other applet elements are expected to be
+  treated as ordinary elements in the rendering model.

+
+  
The audio element, when it is exposing a user interface, is
+  expected to be treated as a replaced element about one line high, as
+  wide as is necessary to expose the user agent's user interface
+  features. When an audio element is not exposing a user
+  interface, the user agent is expected to hide it,
+  irrespective of CSS rules.

+
+  
Whether a video element is exposing a user interface is not
+  expected to affect the size of the rendering; controls are expected
+  to be overlaid with the page content without causing any layout
+  changes, and are expected to disappear when the user does not need
+  them.

+
+  
When a video element represents a poster frame or
+  frame of video, the poster frame or frame of video is expected to be
+  rendered at the largest size that maintains the aspect ratio of that
+  poster frame or frame of video without being taller or wider than
+  the video element itself, and is expected to be
+  centered in the video element.

+
+  
pointer to rendering model for timed tracks

+
+  
Resizing video and canvas
+  elements does not interrupt video playback or clear the canvas.

+
+  
The following CSS rules are expected to apply:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+iframe { border: 2px inset; }

+
+  

+
+
+  

+
+  
12.3.2 Timed tracks

+
+  
rendering model for timed tracks

+
+  
CSS extensions

+
+  

+
+
+  

+
+  
12.3.3 Images

+
+  
When an img element or an input element
+  when its type attribute is in
+  the Image Button state
+  represents an image, it is expected to be treated as a
+  replaced element.

+
+  
When an img element or an input element
+  when its type attribute is in
+  the Image Button state
+  does not represent an image, but the
+  element already has intrinsic dimensions (e.g. from the
+  dimension attributes or CSS rules), and either the user
+  agent has reason to believe that the image will become available
+  and be rendered in due course or the Document is in
+  quirks mode, the element is expected to be treated as a
+  replaced element whose content is the text that the element
+  represents, if any, optionally alongside an icon indicating that the
+  image is being obtained. For input elements, the text
+  is expected to appear button-like to indicate that the element is a
+  button.

+
+  
When an img element represents some
+  text and the user agent does not expect this to change, the element
+  is expected to be treated as an inline element whose content is the
+  text, optionally with an icon indicating that an image is
+  missing.

+
+  
When an img element represents nothing
+  and the user agent does not expect this to change, the element is
+  expected to not be rendered at all.

+
+  
When an img element might be a key part of the
+  content, but neither the image nor any kind of alternative text is
+  available, and the user agent does not expect this to change, the
+  element is expected to be treated as an inline element whose content
+  is an icon indicating that an image is missing.
 
+
+  
When an input element whose type attribute is in the Image Button state does not
+  represent an image and the user
+  agent does not expect this to change, the element is expected to be
+  treated as a replaced element consisting of a button whose content
+  is the element's alternative text. The intrinsic dimensions of the
+  button are expected to be about one line in height and whatever
+  width is necessary to render the text on one line.

+
+  
The icons mentioned above are expected to be relatively small so
+  as not to disrupt most text but be easily clickable. In a visual
+  environment, for instance, icons could be 16 pixels by 16 pixels
+  square, or 1em by 1em if the images are scalable. In an audio
+  environment, the icon could be a short bleep. The icons are intended
+  to indicate to the user that they can be used to get to whatever
+  options the UA provides for images, and, where appropriate, are
+  expected to provide access to the context menu that would have come
+  up if the user interacted with the actual image.

+
+  
The following CSS rules are expected to apply when the
+  Document is in quirks mode:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+img[align=left] { margin-right: 3px; } /* case-insensitive */
+img[align=right] { margin-left: 3px; } /* case-insensitive */

+
+  

+
+
+  

+
+  
12.3.4 Attributes for embedded content and images

+
+  
The following CSS rules are expected to apply as
+  presentational hints:

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+iframe[frameborder=0], iframe[frameborder=no] { border: none; } /* case-insensitive */
+
+applet[align=left], embed[align=left], iframe[align=left],
+img[align=left], input[type=image][align=left], object[align=left] { /* case-insensitive */
+  float: left;
+}
+
+applet[align=right], embed[align=right], iframe[align=right],
+img[align=right], input[type=image][align=right], object[align=right] { /* case-insensitive */
+  float: right;
+}
+
+applet[align=top], embed[align=top], iframe[align=top],
+img[align=top], input[type=image][align=top], object[align=top] { /* case-insensitive */
+  vertical-align: top;
+}
+
+applet[align=bottom], embed[align=bottom], iframe[align=bottom],
+img[align=bottom], input[type=image][align=bottom], object[align=bottom],
+applet[align=baseline], embed[align=baseline], iframe[align=baseline],
+img[align=baseline], input[type=image][align=baseline], object[align=baseline] { /* case-insensitive */
+  vertical-align: baseline;
+}
+
+applet[align=texttop], embed[align=texttop], iframe[align=texttop],
+img[align=texttop], input[type=image][align=texttop], object[align=texttop] { /* case-insensitive */
+  vertical-align: text-top;
+}
+
+applet[align=absmiddle], embed[align=absmiddle], iframe[align=absmiddle],
+img[align=absmiddle], input[type=image][align=absmiddle], object[align=absmiddle],
+applet[align=abscenter], embed[align=abscenter], iframe[align=abscenter],
+img[align=abscenter], input[type=image][align=abscenter], object[align=abscenter] { /* case-insensitive */
+  vertical-align: middle;
+}
+
+applet[align=bottom], embed[align=bottom], iframe[align=bottom],
+img[align=bottom], input[type=image][align=bottom],
+object[align=bottom] { /* case-insensitive */
+  vertical-align: bottom;
+}

+
+  
When an applet, embed,
+  iframe, img, or object
+  element, or an input element whose type attribute is in the Image Button state, has an
+  align attribute whose value is
+  an ASCII case-insensitive match for the string "center" or the string "middle", the user agent is expected to act as if the
+  element's 'vertical-align' property was set to a value that aligns
+  the vertical middle of the element with the parent element's
+  baseline.

+
+  
The hspace attribute of
+  applet, embed, iframe,
+  img, or object elements, and
+  input elements with a type attribute in the Image Button state, maps to the dimension
+  properties 'margin-left' and 'margin-right' on the
+  element.

+
+  
The vspace attribute of
+  applet, embed, iframe,
+  img, or object elements, and
+  input elements with a type attribute in the Image Button state, maps to the dimension
+  properties 'margin-top' and 'margin-bottom' on the
+  element.

+
+  
When an img element, object element, or
+  input element with a type attribute in the Image Button state is contained
+  within a hyperlink and has a border attribute whose value, when
+  parsed using the rules for parsing non-negative
+  integers, is found to be a number greater than zero, the user
+  agent is expected to use the parsed value for eight
+  presentational hints: four setting the parsed value as
+  a pixel length for the element's 'border-top-width',
+  'border-right-width', 'border-bottom-width', and 'border-left-width'
+  properties, and four setting the element's 'border-top-style',
+  'border-right-style', 'border-bottom-style', and 'border-left-style'
+  properties to the value 'solid'.

+
+  
The width
+  and height attributes on
+  applet, embed, iframe,
+  img, object or video
+  elements, and input elements with a type attribute in the Image Button state, map to the dimension
+  properties 'width' and 'height' on the element
+  respectively.

+
+  

+
+
+  

+
+  
12.3.5 Image maps

+
+  
Shapes on an image map are expected to act, for the
+  purpose of the CSS cascade, as elements independent of the original
+  area element that happen to match the same style rules
+  but inherit from the img or object
+  element.

+
+  
For the purposes of the rendering, only the 'cursor' property is
+  expected to have any effect on the shape.

+
+  
Thus, for example, if an area
+  element has a style attribute that
+  sets the 'cursor' property to 'help', then when the user designates
+  that shape, the cursor would change to a Help cursor.

+
+  
Similarly, if an area element had a
+  CSS rule that set its 'cursor' property to 'inherit' (or if no rule
+  setting the 'cursor' property matched the element at all), the
+  shape's cursor would be inherited from the img or
+  object element of the image map, not from
+  the parent of the area element.

+
+  

+
+
+  

+
+  
12.3.6 Toolbars

+
+  
When a menu element's type attribute is in the toolbar state, the element is
+  expected to be treated as a replaced element with a height about two
+  lines high and a width derived from the contents of the element.

+
+  
The element is expected to have, by default, the appearance of a
+  toolbar on the user agent's platform. It is expected to contain the
+  menu that is built
+  from the element.

+
+  

+
+
+  

+
+  
12.4 Bindings

+
+  
12.4.1 Introduction

+
+  
A number of elements have their rendering defined in terms of the
+  'binding' property. [BECSS]

+
+  
The CSS snippets below set the 'binding' property to a
+  user-agent-defined value, represented below by keywords like button. The rules then described for
+  these bindings are only expected to apply if the element's 'binding'
+  property has not been overridden (e.g. by the author) to have
+  another value.

+
+  
Exactly how the bindings are implemented is not specified by this
+  specification. User agents are encouraged to make their bindings set
+  the 'appearance' CSS property appropriately to achieve
+  platform-native appearances for widgets, and are expected to
+  implement any relevant animations, etc, that are appropriate for the
+  platform. [CSSUI]

+
+  

+
+
+  

+
+  
12.4.2 The button element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+button { binding: button; }

+
+  
When the button binding applies to a
+  button element, the element is expected to render as an
+  'inline-block' box rendered as a button whose contents are the
+  contents of the element.

+
+  

+
+
+
+
+  

+
+  
12.4.3 The details element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+details { binding: details; }

+
+  
When the details binding applies to a
+  details element, the element is expected to render as a
+  'block' box with its 'padding-left' property set to '40px' for
+  left-to-right elements (LTR-specific) and with its
+  'padding-right' property set to '40px' for right-to-left
+  elements. The element's shadow tree is expected to take the
+  element's first child summary element, if any, and
+  place it in a first 'block' box container, and then take the
+  element's remaining descendants, if any, and place them in a second
+  'block' box container.

+
+  
The first container is expected to contain at least one line box,
+  and that line box is expected to contain a disclosure widget
+  (typically a triangle), horizontally positioned within the left
+  padding of the details element. That widget is expected
+  to allow the user to request that the details be shown or
+  hidden.

+
+  
The second container is expected to have its 'overflow' property
+  set to 'hidden'. When the details element does not have
+  an open attribute, this
+  second container is expected to be removed from the rendering.

+
+  
+
+  

+
+  

+
+  
12.4.4 The input element as a text entry widget

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input { binding: input-textfield; }
+input[type=password] { binding: input-password; } /* case-insensitive */
+/* later rules override this for other values of type="" */

+
+  
When the input-textfield binding applies to an
+  input element whose type attribute is in the Text, Search, Telephone, URL, or E-mail state, the element is
+  expected to render as an 'inline-block' box rendered as a text
+  field.

+
+  
When the input-password binding applies, to an
+  input element whose type attribute is in the Password state, the element
+  is expected to render as an 'inline-block' box rendered as a text
+  field whose contents are obscured.

+
+  
If an input element whose type attribute is in one of the above
+  states has a size attribute,
+  and parsing that attribute's value using the rules for parsing
+  non-negative integers doesn't generate an error, then the
+  user agent is expected to use the attribute as a presentational hint for the
+  'width' property on the element, with the value obtained from
+  applying the converting a character width to pixels
+  algorithm to the value of the attribute.

+
+  
If an input element whose type attribute is in one of the above
+  states does not have a size attribute, then the user agent
+  is expected to act as if it had a user-agent-level style sheet rule
+  setting the 'width' property on the element to the value obtained
+  from applying the converting a character width to
+  pixels algorithm to the number 20.

+
+  
The converting a character width to pixels algorithm
+  returns (size-1)×avg + max, where
+  size is the character width to convert, avg is the average character width of the primary
+  font for the element for which the algorithm is being run, in
+  pixels, and max is the maximum character width
+  of that same font, also in pixels. (The element's 'letter-spacing'
+  property does not affect the result.)

+
+  

+
+
+  

+
+  
12.4.5 The input element as domain-specific widgets

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=datetime] { binding: input-datetime; } /* case-insensitive */
+input[type=date] { binding: input-date; } /* case-insensitive */
+input[type=month] { binding: input-month; } /* case-insensitive */
+input[type=week] { binding: input-week; } /* case-insensitive */
+input[type=time] { binding: input-time; } /* case-insensitive */
+input[type=datetime-local] { binding: input-datetime-local; } /* case-insensitive */
+input[type=number] { binding: input-number; } /* case-insensitive */

+
+  
When the input-datetime binding applies to an
+  input element whose type attribute is in the Date and Time state, the
+  element is expected to render as an 'inline-block' box depicting a
+  Date and Time control.

+
+  
When the input-date binding applies to an
+  input element whose type attribute is in the Date state, the element is
+  expected to render as an 'inline-block' box depicting a Date
+  control.

+
+  
When the input-month binding applies to an
+  input element whose type attribute is in the Month state, the element is
+  expected to render as an 'inline-block' box depicting a Month
+  control.

+
+  
When the input-week binding applies to an
+  input element whose type attribute is in the Week state, the element is
+  expected to render as an 'inline-block' box depicting a Week
+  control.

+
+  
When the input-time binding applies to an
+  input element whose type attribute is in the Time state, the element is
+  expected to render as an 'inline-block' box depicting a Time
+  control.

+
+  
When the input-datetime-local binding applies to an
+  input element whose type attribute is in the Local Date and Time
+  state, the element is expected to render as an 'inline-block' box
+  depicting a Local Date and Time control.

+
+  
When the input-number binding applies to an
+  input element whose type attribute is in the Number state, the element is
+  expected to render as an 'inline-block' box depicting a Number
+  control.

+
+  
These controls are all expected to be about one line high, and
+  about as wide as necessary to show the widest possible value.

+
+  

+
+
+  

+
+  
12.4.6 The input element as a range control

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=range] { binding: input-range; } /* case-insensitive */

+
+  
When the input-range binding applies to an
+  input element whose type attribute is in the Range state, the element is
+  expected to render as an 'inline-block' box depicting a slider
+  control.

+
+  
When the control is wider than it is tall (or square), the
+  control is expected to be a horizontal slider, with the lowest value
+  on the right if the 'direction' property on this element has a
+  computed value of 'rtl', and on the left otherwise. When the control
+  is taller than it is wide, it is expected to be a vertical slider,
+  with the lowest value on the bottom.

+
+  
Predefined suggested values (provided by the list attribute) are expected to be
+  shown as tick marks on the slider, which the slider can snap to.

+
+  

+
+
+  

+
+  
12.4.7 The input element as a color well

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=color] { binding: input-color; } /* case-insensitive */

+
+  
When the input-color binding applies to an
+  input element whose type attribute is in the Color state, the element is
+  expected to render as an 'inline-block' box depicting a color well,
+  which, when activated, provides the user with a color picker (e.g. a
+  color wheel or color palette) from which the color can be
+  changed.

+
+  
Predefined suggested values (provided by the list attribute) are expected to be
+  shown in the color picker interface, not on the color well
+  itself.

+
+  

+
+
+  

+
+  
12.4.8 The input element as a check box and radio button widgets

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=checkbox] { binding: input-checkbox; } /* case-insensitive */
+input[type=radio] { binding: input-radio; } /* case-insensitive */

+
+  
When the input-checkbox binding applies to an
+  input element whose type attribute is in the Checkbox state, the element
+  is expected to render as an 'inline-block' box containing a single
+  check box control, with no label.

+
+  
When the input-radio binding applies to an
+  input element whose type attribute is in the Radio Button state, the element
+  is expected to render as an 'inline-block' box containing a single
+  radio button control, with no label.

+
+  

+
+
+  

+
+  
12.4.9 The input element as a file upload control

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=file] { binding: input-file; } /* case-insensitive */

+
+  
When the input-file binding applies to an
+  input element whose type attribute is in the File Upload state, the element
+  is expected to render as an 'inline-block' box containing a span of
+  text giving the filename(s) of the selected files, if
+  any, followed by a button that, when activated, provides the user
+  with a file picker from which the selection can be changed.

+
+  

+
+
+  

+
+  
12.4.10 The input element as a button

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+input[type=submit], input[type=reset], input[type=button] { /* case-insensitive */
+  binding: input-button;
+}

+
+  
When the input-button binding applies to an
+  input element whose type attribute is in the Submit Button, Reset Button, or Button state, the element is
+  expected to render as an 'inline-block' box rendered as a button,
+  about one line high, containing the contents of the element's value attribute, if any, or text
+  derived from the element's type
+  attribute in a user-agent-defined (and probably locale-specific)
+  fashion, if not.

+
+  

+
+
+  

+
+  
12.4.11 The marquee element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+marquee {
+  binding: marquee;
+}

+
+  
When the marquee binding applies to a
+  marquee element, while the element is turned on, the element is expected
+  to render in an animated fashion according to its attributes as
+  follows:

+
+  
If the element's behavior attribute is in the
+   scroll state

+
+   

+
+    
Slide the contents of the element in the direction described by
+    the direction
+    attribute as defined below, such that it begins off the start side
+    of the marquee, and ends flush with the inner end
+    side.

+
+    
For example, if the direction attribute is left (the default),
+    then the contents would start such that their left edge are off
+    the side of the right edge of the marquee's content
+    area, and the contents would then slide up to the point where the
+    left edge of the contents are flush with the left inner edge of
+    the marquee's content area.

+
+    
Once the animation has ended, the user agent is expected to
+    increment the marquee current loop index. If the
+    element is still turned on
+    after this, then the user agent is expected to restart the
+    animation.

+
+   

+
+   
If the element's behavior attribute is in the
+   slide state

+
+   

+
+    
Slide the contents of the element in the direction described by
+    the direction
+    attribute as defined below, such that it begins off the start side
+    of the marquee, and ends off the end side of the
+    marquee.

+
+    
For example, if the direction attribute is left (the default),
+    then the contents would start such that their left edge are off
+    the side of the right edge of the marquee's content
+    area, and the contents would then slide up to the point where the
+    right edge of the contents are flush with the left inner
+    edge of the marquee's content area.

+
+    
Once the animation has ended, the user agent is expected to
+    increment the marquee current loop index. If the
+    element is still turned on
+    after this, then the user agent is expected to restart the
+    animation.

+
+   

+
+   
If the element's behavior attribute is in the
+   alternate
+   state

+
+   

+
+    
When the marquee current loop index is even (or
+    zero), slide the contents of the element in the direction
+    described by the direction attribute as
+    defined below, such that it begins flush with the start side of
+    the marquee, and ends flush with the end side of the
+    marquee.

+
+    
When the marquee current loop index is odd, slide
+    the contents of the element in the opposite direction than that
+    described by the direction attribute as
+    defined below, such that it begins flush with the end side of the
+    marquee, and ends flush with the start side of the
+    marquee.

+
+    
For example, if the direction attribute is left (the default),
+    then the contents would with their right edge flush with the right
+    inner edge of the marquee's content area, and the
+    contents would then slide up to the point where the left
+    edge of the contents are flush with the left inner edge of the
+    marquee's content area.

+
+    
Once the animation has ended, the user agent is expected to
+    increment the marquee current loop index. If the
+    element is still turned on
+    after this, then the user agent is expected to continue the
+    animation.

+
+   

+
+  
The direction
+  attribute has the meanings described in the following table:

+
+  
direction attribute state
+     Direction of animation
+     Start edge
+     End edge
+     Opposite direction
+   
left
+     ← Right to left
+     Right
+     Left
+     → Left to Right
+    
right
+     → Left to Right
+     Left
+     Right
+     ← Right to left
+    
up
+     ↑ Up (Bottom to Top)
+     Bottom
+     Top
+     ↓ Down (Top to Bottom)
+    
down
+     ↓ Down (Top to Bottom)
+     Top
+     Bottom
+     ↑ Up (Bottom to Top)
+  
In any case, the animation should proceed such that there is a
+  delay given by the marquee scroll interval between each
+  frame, and such that the content moves at most the distance given by
+  the marquee scroll distance with each frame.

+
+  
When a marquee element has a bgcolor attribute set, the value
+  is expected to be parsed using the rules for parsing a legacy
+  color value, and if that does not return an error, the user
+  agent is expected to treat the attribute as a presentational hint setting the
+  element's 'background-color' property to the resulting color.

+
+  
The width and height attributes on a
+  marquee element map to the dimension properties 'width' and
+  'height' on the element respectively.

+
+  
The intrinsic height of a marquee element with its
+  direction attribute in
+  the up or down states is 200 CSS
+  pixels.

+
+  
The vspace attribute of
+  a marquee element maps to the dimension properties 'margin-top' and
+  'margin-bottom' on the element. The hspace attribute of a
+  marquee element maps to the dimension properties 'margin-left' and
+  'margin-right' on the element.

+
+  
The 'overflow' property on the marquee element is
+  expected to be ignored; overflow is expected to always be
+  hidden.

+
+  

+
+
+  

+
+  
12.4.12 The meter element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+meter {
+  binding: meter;
+}

+
+  
When the meter binding applies to a
+  meter element, the element is expected to render as an
+  'inline-block' box with a 'height' of '1em' and a 'width' of '5em',
+  a 'vertical-align' of '-0.2em', and with its contents depicting a
+  gauge.

+
+  
When the element is wider than it is tall (or square), the
+  depiction is expected to be of a horizontal gauge, with the minimum
+  value on the right if the 'direction' property on this element has a
+  computed value of 'rtl', and on the left otherwise. When the element
+  is taller than it is wide, it is expected to depict a vertical
+  gauge, with the minimum value on the bottom.

+
+  
User agents are expected to use a presentation consistent with
+  platform conventions for gauges, if any.

+
+  
Requirements for what must be depicted in the gauge
+  are included in the definition of the meter
+  element.

+
+  

+
+
+  

+
+  
12.4.13 The progress element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+progress {
+  binding: progress;
+}

+
+  
When the progress binding applies to a
+  progress element, the element is expected to render as
+  an 'inline-block' box with a 'height' of '1em' and a 'width' of
+  '10em', a 'vertical-align' of '-0.2em', and with its contents
+  depicting a horizontal progress bar, with the start on the right and
+  the end on the left if the 'direction' property on this element has
+  a computed value of 'rtl', and with the start on the left and the
+  end on the right otherwise.

+
+  
User agents are expected to use a presentation consistent with
+  platform conventions for progress bars. In particular, user agents
+  are expected to use different presentations for determinate and
+  indeterminate progress bars. User agents are also expected to vary
+  the presentation based on the dimensions of the element.

+
+  
For example, on some platforms for showing
+  indeterminate progress there is an asynchronous progress indicator
+  with square dimensions, which could be used when the element is
+  square, and an indeterminate progress bar, which could be used when
+  the element is wide.

+
+  
Requirements for how to determine if the progress
+  bar is determinate or indeterminate, and what progress a determinate
+  progress bar is to show, are included in the definition of the
+  progress element.

+
+  

+
+
+  

+
+  
12.4.14 The select element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+select {
+  binding: select;
+}

+
+  
When the select binding applies to a
+  select element whose multiple attribute is present,
+  the element is expected to render as a multi-select list box.

+
+  
When the select binding applies to a
+  select element whose multiple attribute is absent,
+  and the element's display
+  size is greater than 1, the element is expected to render as
+  a single-select list box.

+
+  
When the element renders as a list box, it is expected to render
+  as an 'inline-block' box whose 'height' is the height necessary to
+  contain as many rows for items as given by the element's display size, or four rows if the
+  attribute is absent, and whose 'width' is the width of the
+  select's labels plus the width of a
+  scrollbar.

+
+  
When the select binding applies to a
+  select element whose multiple attribute is absent,
+  and the element's display
+  size is 1, the element is expected to render as a one-line
+  drop down box whose width is the width of the
+  select's labels.

+
+  
In either case (list box or drop-down box), the element's items
+  are expected to be the element's list of options, with the
+  element's optgroup element children providing headers
+  for groups of options where applicable.

+
+  
The width of the select's labels is the
+  wider of the width necessary to render the widest
+  optgroup, and the width necessary to render the widest
+  option element in the element's list of options (including
+  its indent, if any).

+
+  
An optgroup element is expected to be rendered by
+  displaying the element's label attribute.

+
+  
An option element is expected to be rendered by
+  displaying the element's label, indented under its
+  optgroup element if it has one.

+
+  

+
+
+  

+
+  
12.4.15 The textarea element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+textarea { binding: textarea; }

+
+  
When the textarea binding applies to a
+  textarea element, the element is expected to render as
+  an 'inline-block' box rendered as a multiline text field.

+
+  
If the element has a cols
+  attribute, and parsing that attribute's value using the rules
+  for parsing non-negative integers doesn't generate an error,
+  then the user agent is expected to use the attribute as a presentational hint for the
+  'width' property on the element, with the value being the
+  textarea effective width (as defined below). Otherwise,
+  the user agent is expected to act as if it had a user-agent-level
+  style sheet rule setting the 'width' property on the element to the
+  textarea effective width.

+
+  
The textarea effective width of a
+  textarea element is size×avg + sbw, where size is the
+  element's character
+  width, avg is the average character width
+  of the primary font of the element, in CSS pixels, and sbw is the width of a scroll bar, in CSS pixels. (The
+  element's 'letter-spacing' property does not affect the result.)

+
+  
If the element has a rows
+  attribute, and parsing that attribute's value using the rules
+  for parsing non-negative integers doesn't generate an error,
+  then the user agent is expected to use the attribute as a presentational hint for the
+  'height' property on the element, with the value being the
+  textarea effective height (as defined
+  below). Otherwise, the user agent is expected to act as if it had a
+  user-agent-level style sheet rule setting the 'height' property on
+  the element to the textarea effective height.

+
+  
The textarea effective height of a
+  textarea element is the height in CSS pixels of the
+  number of lines specified the element's character height, plus the
+  height of a scrollbar in CSS pixels.

+
+  
For historical reasons, if the element has a wrap attribute whose value is an
+  ASCII case-insensitive match for the string "off", then the user agent is
+  expected to not wrap the rendered value; otherwise, the value of the
+  control is expected to be wrapped to the width of the control.

+
+  

+
+
+  

+
+  
12.4.16 The keygen element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+keygen { binding: keygen; }

+
+  
When the keygen binding applies to a
+  keygen element, the element is expected to render as an
+  'inline-block' box containing a user interface to configure the key
+  pair to be generated.

+
+  

+
+
+  

+
+  
12.4.17 The time element

+
+  
@namespace url(http://www.w3.org/1999/xhtml);
+
+time[datetime] { binding: time; }

+
+  
When the time binding applies to a
+  time element, the element is expected to render as if
+  it contained text conveying the date (if known), time (if known), and time-zone offset (if known)
+  represented by the element, in the fashion most convenient for the
+  user.

+
+  
+
+  

+
+
+
+  

+
+  
12.5 Frames and framesets

+
+  
When an html element's second child element is a
+  frameset element, the user agent is expected to render
+  the frameset element as described below across the
+  surface of the viewport, instead of applying the usual CSS rendering
+  rules.

+
+  
When rendering a frameset on a surface, the user
+  agent is expected to use the following layout algorithm:

+
+  
  1. 
+
+    
    The cols and rows
+    variables are lists of zero or more pairs consisting of a number
+    and a unit, the unit being one of percentage,
+    relative, and absolute.
    
+
+    
    Use the rules for parsing a list of dimensions to
+    parse the value of the element's cols attribute, if there is
+    one. Let cols be the result, or an empty list
+    if there is no such attribute.
    
+
+    
    Use the rules for parsing a list of dimensions to
+    parse the value of the element's rows attribute, if there is
+    one. Let rows be the result, or an empty list
+    if there is no such attribute.
    
+
+   
    2. 
+
+   
  2. 
+
+    
    For any of the entries in cols or rows that have the number zero and the unit
+    relative, change the entry's number to one.
    
+
+   
    3. 
+
+   
  3. 
+
+    
    If cols has no entries, then add a single
+    entry consisting of the value 1 and the unit relative to
+    cols.
    
+
+    
    If rows has no entries, then add a single
+    entry consisting of the value 1 and the unit relative to
+    rows.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    Invoke the algorithm defined below to convert a list of
+    dimensions to a list of pixel values using cols as the input list, and the width of the
+    surface that the frameset is being rendered into, in
+    CSS pixels, as the input dimension. Let sized
+    cols be the resulting list.
    
+
+    
    Invoke the algorithm defined below to convert a list of
+    dimensions to a list of pixel values using rows as the input list, and the height of the
+    surface that the frameset is being rendered into, in
+    CSS pixels, as the input dimension. Let sized
+    rows be the resulting list.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    Split the surface into a grid of w×h rectangles,
+    where w is the number of entries in sized cols and h is the number
+    of entries in sized rows.
    
+
+    
    Size the columns so that each column in the grid is as many CSS
+    pixels wide as the corresponding entry in the sized
+    cols list.
    
+
+    
    Size the rows so that each row in the grid is as many CSS
+    pixels high as the corresponding entry in the sized
+    rows list.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    Let children be the list of
+    frame and frameset elements that are
+    children of the frameset element for which the
+    algorithm was invoked.
    
+
+   
    7. 
+
+   
  7. 
+
+    
    For each row of the grid of rectangles created in the previous
+    step, from top to bottom, run these substeps:
    
+
+    
    1. 
+
+      
      For each rectangle in the row, from left to right, run these
+      substeps:
      
+
+      
      1. 
+
+        
        If there are any elements left in children, take the first element in the list,
+        and assign it to the rectangle.
        
+
+        
        If this is a frameset element, then recurse
+        the entire frameset layout algorithm for that
+        frameset element, with the rectangle as the
+        surface.
        
+
+        
        Otherwise, it is a frame element; create a
+        nested browsing context sized to fit the
+        rectangle.
        
+
+       
        2. 
+
+       
      2. 
+
+        
        If there are any elements left in children, remove the first element from children.
        
+
+      
      2. 
+
+    
    8. 
+
+   
  8. 
+
+    
    If the frameset element has a border,
+    draw an outer set of borders around the rectangles, using the
+    element's frame border color.
    
+
+    
    For each rectangle, if there is an element assigned to that
+    rectangle, and that element has a border, draw an
+    inner set of borders around that rectangle, using the
+    element's frame border color.
    
+
+    
    For each (visible) border that does not abut a rectangle that
+    is assigned a frame element with a noresize attribute (including
+    rectangles in further nested frameset elements), the
+    user agent is expected to allow the user to move the border,
+    resizing the rectangles within, keeping the proportions of any
+    nested frameset grids.
    
+
+    
    A frameset or frame element has
+    a border if the following algorithm returns true:
    
+
+    
    1. If the element has a frameborder attribute
+     whose value is not the empty string and whose first character is
+     either a U+0031 DIGIT ONE (1) character, a U+0079 LATIN SMALL
+     LETTER Y character (y), or a U+0059 LATIN CAPITAL LETTER Y
+     character (Y), then return true.
      2. 
+
+     
    2. Otherwise, if the element has a frameborder attribute,
+     return false.
      3. 
+
+     
    3. Otherwise, if the element has a parent element that is a
+     frameset element, then return true if that
+     element has a border, and false if it does
+     not.
      4. 
+
+     
    4. Otherwise, return true.
      5. 
+
+    
    The frame border color of a frameset or
+    frame element is the color obtained from the
+    following algorithm:
    
+
+    
    1. If the element has a bordercolor attribute, and
+     applying the rules for parsing a legacy color value
+     to that attribute's value does not result in an error, then
+     return the color so obtained.
      2. 
+
+     
    2. Otherwise, if the element has a parent element that is a
+     frameset element, then the frame border
+     color of that element.
      
+
+     
    3. Otherwise, return gray.
      4. 
+
+    
    9. 
+
+  
The algorithm to convert a list of dimensions to a list of
+  pixel values consists of the following steps:

+
+  
  1. 
+
+    
    Let input list be the list of numbers and
+    units passed to the algorithm.
    
+
+    
    Let output list be a list of numbers the
+    same length as input list, all zero.
    
+
+    
    Entries in output list correspond to the
+    entries in input list that have the same
+    position.
    
+
+   
    2. 
+
+   
  2. Let input dimension be the size passed
+   to the algorithm.
    
+
+   
  3. 
+
+    
    Let count percentage be the number of
+    entries in input list whose unit is
+    percentage.
    
+
+    
    Let total percentage be the sum of all the
+    numbers in input list whose unit is
+    percentage.
    
+
+    
    Let count relative be the number of
+    entries in input list whose unit is
+    relative.
    
+
+    
    Let total relative be the sum of all the
+    numbers in input list whose unit is
+    relative.
    
+
+    
    Let count absolute be the number of
+    entries in input list whose unit is
+    absolute.
    
+
+    
    Let total absolute be the sum of all the
+    numbers in input list whose unit is
+    absolute.
    
+
+    
    Let remaining space be the value of input dimension.
    
+
+   
    4. 
+
+   
  4. 
+
+    
    If total absolute is greater than remaining space, then for each entry in input list whose unit is absolute, set the
+    corresponding value in output list to the
+    number of the entry in input list multiplied
+    by remaining space and divided by total absolute. Then, set remaining
+    space to zero.
    
+
+    
    Otherwise, for each entry in input list
+    whose unit is absolute, set the corresponding value in output list to the number of the entry in input list. Then, decrement remaining
+    space by total absolute.
    
+
+   
    5. 
+
+   
  5. 
+
+    
    If total percentage multiplied by the input dimension and divided by 100 is greater than
+    remaining space, then for each entry in input list whose unit is percentage, set the
+    corresponding value in output list to the
+    number of the entry in input list multiplied
+    by remaining space and divided by total percentage. Then, set remaining
+    space to zero.
    
+
+    
    Otherwise, for each entry in input list
+    whose unit is percentage, set the corresponding value in
+    output list to the number of the entry in input list multiplied by the input
+    dimension and divided by 100. Then, decrement remaining space by total
+    percentage multiplied by the input
+    dimension and divided by 100.
    
+
+   
    6. 
+
+   
  6. 
+
+    
    For each entry in input list whose unit is
+    relative, set the corresponding value in output list to the number of the entry in input list multiplied by remaining
+    space and divided by total relative.
    
+
+   
    7. 
+
+   
  7. Return output list.
    8. 
+
+  
User agents working with integer values for frame widths (as
+  opposed to user agents that can lay frames out with subpixel
+  accuracy) are expected to distribute the remainder first to the last
+  entry whose unit is relative, then equally (not
+  proportionally) to each entry whose unit is percentage, then
+  equally (not proportionally) to each entry whose unit is
+  absolute, and finally, failing all else, to the last
+  entry.

+
+
+  

+
+
+  

+
+  
12.6 Interactive media

+
+  
12.6.1 Links, forms, and navigation

+
+  
User agents are expected to allow the user to control aspects of
+  hyperlink activation and form submission,
+  such as which browsing context is to be used for the
+  subsequent navigation.

+
+  
User agents are expected to allow users to discover the
+  destination of hyperlinks and of
+  forms before triggering their navigation.

+
+
+  
User agents are expected to inform the user of whether a
+  hyperlink includes hyperlink auditing, and
+  to let them know at a minimum which domains will be contacted as
+  part of such auditing.

+
+
+  
User agents are expected to allow users to navigate
+  browsing contexts to the
+  resources indicated by the cite attributes on q,
+  blockquote, section, article,
+  ins, and del elements.

+
+  
User agents are expected to surface hyperlinks created by link
+  elements in their user interface.

+
+  
While link elements that create hyperlinks will match the ':link' or
+  ':visited' pseudo-classes, will react to clicks if visible, and so
+  forth, this does not extend to any browser interface constructs that
+  expose those same links. Activating a link through the browser's
+  interface, rather than in the page itself, does not trigger click events and the like.

+
+
+
+
+  
12.6.2 The title attribute

+
+  
Given an element (e.g. the element designated by the mouse
+  cursor), if the element, or one of its ancestors, has a title attribute, and the nearest such
+  attribute has a value that is not the empty string, it is expected
+  that the user agent will expose the contents of that attribute as a
+  tooltip.

+
+  
User agents are encouraged to make it possible to view tooltips
+  without the use of a pointing device, since not all users are able
+  to use pointing devices.

+
+  
U+000A LINE FEED (LF) characters are expected to cause line
+  breaks in the tooltip.

+
+
+  
12.6.3 Editing hosts

+
+  
The current text editing caret (the one at the caret
+  position in a focused editing host) is expected
+  to act like an inline replaced element with the vertical dimensions
+  of the caret and with zero width for the purposes of the CSS
+  rendering model.

+
+  
This means that even an empty block can have the
+  caret inside it, and that when the caret is in such an element, it
+  prevents margins from collapsing through the element.

+
+
+
+
+  
+
+  
User agents are expected to allow the user to request the
+  opportunity to obtain a physical form (or a
+  representation of a physical form) of a Document. For
+  example, selecting the option to print a page or convert it to PDF
+  format.

+
+  
When the user actually obtains a physical form (or a representation of a
+  physical form) of a Document, the user agent is
+  expected to create a new rendering of the Document for
+  the print media.

+
+
+
+  

+
+
+
+  
13 Obsolete features

+
+  
13.1 Obsolete but conforming features

+
+  
Features listed in this section will trigger warnings in
+  conformance checkers.

+
+  
Authors should not specify an http-equiv attribute in the
+  Content
+  Language state on a meta element. The lang attribute should be used instead.

+
+  
Authors should not specify a border attribute on an
+  img element. If the attribute is present, its value
+  must be the string "0". CSS should be used
+  instead.

+
+  
Authors should not specify a language attribute on a
+  script element. If the attribute is present, its value
+  must be an ASCII case-insensitive match for the string
+  "JavaScript" and either the type attribute must be omitted or
+  its value must be an ASCII case-insensitive match for
+  the string "text/javascript". The attribute
+  should be entirely omitted instead (with the value "JavaScript", it has no effect), or replaced with use
+  of the type attribute.

+
+  
Authors should not specify the name attribute on a
+  elements. If the attribute is present, its value must not be the
+  empty string and must neither be equal to the value of any of the
+  IDs in the element's home
+  subtree other than the element's own ID, if any, nor be equal to the value of
+  any of the other name attributes on
+  a elements in the element's home
+  subtree. If this attribute is present and the element has an
+  ID, then the attribute's value must
+  be equal to the element's ID. In
+  earlier versions of the language, this attribute was intended as a
+  way to specify possible targets for fragment identifiers in URLs. The id
+  attribute should be used instead.

+
+  
In the HTML syntax, specifying a DOCTYPE that is an obsolete
+  permitted DOCTYPE will also trigger a warning.

+
+  
The summary
+  attribute, defined in the table section, will also
+  trigger a warning.

+
+
+  

+
+  
13.1.1 Warnings for obsolete but conforming features

+
+  
To ease the transition from HTML4 Transitional documents to the
+  language defined in this specification, and to discourage
+  certain features that are only allowed in very few circumstances,
+  conformance checkers are required to warn the user when the
+  following features are used in a document. These are generally old
+  obsolete features that have no effect, and are allowed only to
+  distinguish between likely mistakes (regular conformance errors) and
+  mere vestigial markup or unusual and discouraged practices (these
+  warnings).

+
+  
The following features must be categorized as described
+  above:

+
+  
Conformance checkers must distinguish between pages that have no
+  conformance errors and have none of these obsolete features, and
+  pages that have no conformance errors but do have some of these
+  obsolete features.

+
+  
For example, a validator could report some pages
+  as "Valid HTML" and others as "Valid HTML with warnings".

+
+  

+
+
+  
13.2 Non-conforming features

+
+  
Elements in the following list are entirely obsolete, and must
+  not be used by authors:

+
+  
applet

+   
Use embed or object instead.

+
+   
acronym

+   
Use abbr instead.

+
+   
bgsound

+   
Use audio instead.

+
+   
dir

+   
Use ul instead.

+
+   
frame

+   
frameset

+   
noframes

+   
Either use iframe and CSS instead, or use server-side includes to generate complete pages with the various invariant parts merged in.

+
+   
isindex

+   
Use an explicit form and text field combination instead.

+
+   
listing

+   
xmp

+   
Use pre and code instead.

+
+   
nextid

+   
Use GUIDs instead.

+
+   
noembed

+   
Use object instead of embed when fallback is necessary.

+
+   
plaintext

+   
Use the "text/plain" MIME type instead.

+
+   
rb

+   
Providing the ruby base directly inside the ruby element is sufficient; the rb element is unnecessary. Omit it altogether.

+
+   
basefont

+   
big

+   
blink

+   
center

+   
font

+   
marquee

+   
multicol

+   
nobr

+   
s

+   
spacer

+   
strike

+   
tt

+   
u

+
+   

+
+    
Use appropriate elements and/or CSS instead.

+
+    
For the s and strike elements, if
+    they are marking up a removal from the element, consider using the
+    del element instead.

+
+    
Where the tt element would have been used for
+    marking up keyboard input, consider the kbd element;
+    for variables, consider the var element; for computer
+    code, consider the code element; and for computer
+    output, consider the samp element.

+
+    
Similarly, if the u element is being used to
+    indicate emphasis, consider using the em element; if
+    it is being used for marking up keywords, consider the
+    b element; and if it is being used for highlighting
+    text for reference purposes, consider the mark
+    element.

+
+    
See also the text-level semantics
+    usage summary for more suggestions with examples.

+
+   

+
+  
The following attributes are obsolete (though the elements are
+  still part of the language), and must not be used by authors:

+
+  
charset on a elements

+   
charset on link elements

+   
Use an HTTP Content-Type header on the linked resource instead.

+
+   
coords on a elements

+   
shape on a elements

+   
Use area instead of a for image maps.

+
+   
methods on a elements

+   
methods on link elements

+   
Use the HTTP OPTIONS feature instead.

+
+   
name on a elements (except as noted in the previous section)

+   
name on embed elements

+   
name on img elements

+   
name on option elements

+   
Use the id attribute instead.

+
+   
rev on a elements

+   
rev on link elements

+   
Use the rel
+   attribute instead, with an opposite term. (For example, instead of
+   rev="made", use rel="author".)

+
+   
urn on a elements

+   
urn on link elements

+   
Specify the preferred persistent identifier using the href attribute instead.

+
+   
nohref on area elements

+   
Omitting the href
+   attribute is sufficient; the nohref attribute is
+   unnecessary. Omit it altogether.

+
+   
profile on head elements

+   
When used for declaring which meta terms are
+   used in the document, unnecessary; omit it altogether, and register the names.

+   
When used for triggering specific user agent behaviors: use
+   a link element instead.

+
+   
version on html elements

+   
Unnecessary. Omit it altogether.

+
+   
usemap on input elements

+   
Use img instead of input for image maps.

+
+   
longdesc on iframe elements

+   
longdesc on img elements

+   
Use a regular a element to link to the description.

+
+   
target on link elements

+   
Unnecessary. Omit it altogether.

+
+   
scheme on meta elements

+   
Use only one scheme per field, or make the scheme declaration part of the value.

+
+   
archive on object elements

+   
classid on object elements

+   
code on object elements

+   
codebase on object elements

+   
codetype on object elements

+   
Use the data and type attributes to invoke plugins. To set parameters with these names
+   in particular, the param element can be used.

+
+   
declare on object elements

+   
Repeat the object element completely each time the resource is to be reused.

+
+   
standby on object elements

+   
Optimize the linked resource so that it loads quickly or, at least, incrementally.

+
+   
type on param elements

+   
valuetype on param elements

+   
Use the name and value attributes without declaring
+   value types.

+
+   
language on script elements (except as noted in the previous section)

+   
Use the type attribute
+   instead.

+
+   
event on script elements

+   
for on script elements

+   
Use DOM Events mechanisms to register event listeners. [DOMEVENTS]

+
+   
datapagesize on table elements

+   
Unnecessary. Omit it altogether.

+
+   
abbr on td and th elements

+   
Use text that begins in an unambiguous and terse manner, and include any more elaborate text after that. The title attribute can also be useful in including more detailed text, so that the cell's contents can be made terse.

+
+   
axis on td and th elements

+   
Use the scope attribute on the relevant th.

+
+   
datasrc on a, applet, button, div, frame, iframe, img, input, label, legend, marquee, object, option, select, span, table, and textarea elements

+   
datafld on a, applet, button, div, fieldset, frame, iframe, img, input, label, legend, marquee, object, param, select, span, and textarea elements

+   
dataformatas on button, div, input, label, legend, marquee, object, option, select, span, table

+   
Use script and a mechanism such as XMLHttpRequest to populate the page dynamically. [XHR]

+
+   
alink on body elements

+   
bgcolor on body elements

+   
link on body elements

+   
marginbottom on body elements

+   
marginheight on body elements

+   
marginleft on body elements

+   
marginright on body elements

+   
margintop on body elements

+   
marginwidth on body elements

+   
text on body elements

+   
vlink on body elements

+   
clear on br elements

+   
align on caption elements

+   
align on col elements

+   
char on col elements

+   
charoff on col elements

+   
valign on col elements

+   
width on col elements

+   
align on div elements

+   
compact on dl elements

+   
align on embed elements

+   
hspace on embed elements

+   
vspace on embed elements

+   
align on hr elements

+   
color on hr elements

+   
noshade on hr elements

+   
size on hr elements

+   
width on hr elements

+   
align on h1—h6 elements

+   
align on iframe elements

+   
allowtransparency on iframe elements

+   
frameborder on iframe elements

+   
hspace on iframe elements

+   
marginheight on iframe elements

+   
marginwidth on iframe elements

+   
scrolling on iframe elements

+   
vspace on iframe elements

+   
align on input elements

+   
hspace on input elements

+   
vspace on input elements

+   
align on img elements

+   
border on img elements (except as noted in the previous section)

+   
hspace on img elements

+   
vspace on img elements

+   
align on legend elements

+   
type on li elements

+   
compact on menu elements

+   
align on object elements

+   
border on object elements

+   
hspace on object elements

+   
vspace on object elements

+   
compact on ol elements

+   
type on ol elements

+   
align on p elements

+   
width on pre elements

+   
align on table elements

+   
bgcolor on table elements

+   
border on table elements

+   
cellpadding on table elements

+   
cellspacing on table elements

+   
frame on table elements

+   
rules on table elements

+   
width on table elements

+   
align on tbody, thead, and tfoot elements

+   
char on tbody, thead, and tfoot elements

+   
charoff on tbody, thead, and tfoot elements

+   
valign on tbody, thead, and tfoot elements

+   
align on td and th elements

+   
bgcolor on td and th elements

+   
char on td and th elements

+   
charoff on td and th elements

+   
height on td and th elements

+   
nowrap on td and th elements

+   
valign on td and th elements

+   
width on td and th elements

+   
align on tr elements

+   
bgcolor on tr elements

+   
char on tr elements

+   
charoff on tr elements

+   
valign on tr elements

+   
compact on ul elements

+   
type on ul elements

+   
background on body, table, thead, tbody, tfoot, tr, td, and th elements

+   
Use CSS instead.

+
+  

+
+  
13.3 Requirements for implementations

+
+  
13.3.1 The applet element

+
+  
The applet element is a Java-specific variant of the
+  embed element. The applet element is now
+  obsoleted so that all extension frameworks (Java, .NET, Flash, etc)
+  are handled in a consistent manner.

+
+  
When the element is still in the
+  stack of open elements of an HTML parser
+  or XML parser, and when the element is not in a
+  Document, and when the element's document is not
+  fully active, and when the element's
+  Document's browsing context had its
+  sandboxed plugins browsing context flag when that
+  Document was created, and when the element's
+  Document was parsed from a resource whose sniffed type as determined
+  during navigation is
+  text/html-sandboxed, and when the element has an
+  ancestor media element, and when the element has an
+  ancestor object element that is not showing
+  its fallback content, and when no Java Language runtime
+  plugin is available, and when one is available
+  but it is disabled, the element represents its
+  contents.

+
+  
Otherwise, the user agent should instantiate a Java Language
+  runtime plugin, and should pass the names and values of
+  all the attributes on the element, in the order they were added to
+  the element, with the attributes added by the parser being ordered
+  in source order, and then a parameter named "PARAM" whose value is
+  null, and then all the names and values of parameters given by
+  param elements that are children of the
+  applet element, in tree order, to the
+  plugin used. If the plugin supports a
+  scriptable interface, the HTMLAppletElement object
+  representing the element should expose that interface. The
+  applet element represents the
+  plugin.

+
+  
+
+  
The applet element is unaffected by the
+  CSS 'display' property. The Java Language runtime is instantiated
+  even if the element is hidden with a 'display:none' CSS style.

+
+  
The applet element must implement the
+  HTMLAppletElement interface.

+
+  
interface HTMLAppletElement : HTMLElement {
+           attribute DOMString align;
+           attribute DOMString alt;
+           attribute DOMString archive;
+           attribute DOMString code;
+           attribute DOMString codeBase;
+           attribute DOMString height;
+           attribute unsigned long hspace;
+           attribute DOMString name;
+           attribute DOMString _object; // the underscore is not part of the identifier 
+           attribute unsigned long vspace;
+           attribute DOMString width;
+};

+
+  
The align, alt, archive, code, height, hspace, name, object, vspace, and width IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  
The codeBase
+  IDL attribute must reflect the codebase content attribute.

+
+
+  
13.3.2 The marquee element

+
+  
The marquee element is a presentational element that
+  animates content. CSS transitions and animations are a more
+  appropriate mechanism.

+
+  
The task source for tasks mentioned in this section
+  is the DOM manipulation task source.

+
+  
The marquee element must implement the
+  HTMLMarqueeElement interface.

+
+  
interface HTMLMarqueeElement : HTMLElement {
+           attribute DOMString behavior;
+           attribute DOMString bgColor;
+           attribute DOMString direction;
+           attribute DOMString height;
+           attribute unsigned long hspace;
+           attribute long loop;
+           attribute unsigned long scrollAmount;
+           attribute unsigned long scrollDelay;
+           attribute DOMString trueSpeed;
+           attribute unsigned long vspace;
+           attribute DOMString width;
+
+           attribute Function onbounce;
+           attribute Function onfinish;
+           attribute Function onstart;
+
+  void start();
+  void stop();
+};

+
+  
A marquee element can be turned on or turned off. When it is created, it
+  is turned on.

+
+  
When the start() method is
+  called, the marquee element must be turned on.

+
+  
When the stop()
+  method is called, the marquee element must be turned off.

+
+  
When a marquee element is created, the user agent
+  must queue a task to fire a simple event
+  named start at the element.

+
+  
The behavior content
+  attribute on marquee elements is an enumerated
+  attribute with the following keywords (all
+  non-conforming):

+
+  
Keyword
+     State
+   
scroll
+     scroll
+    
slide
+     slide
+    
alternate
+     alternate
+  
The missing value default is the scroll state.

+
+  
The direction content
+  attribute on marquee elements is an enumerated
+  attribute with the following keywords (all
+  non-conforming):

+
+  
Keyword
+     State
+   
left
+     left
+    
right
+     right
+    
up
+     up
+    
down
+     down
+  
The missing value default is the left state.

+
+  
The truespeed content
+  attribute on marquee elements is an enumerated
+  attribute with the following keywords (all
+  non-conforming):

+
+  
Keyword
+     State
+   
true
+     true
+    
false
+     false
+  
The missing value default is the false state.

+
+  
A marquee element has a marquee scroll
+  interval, which is obtained as follows:

+
+  
  1. If the element has a scrolldelay attribute, and
+   parsing its value using the rules for parsing non-negative
+   integers does not return an error, then let delay be the parsed value. Otherwise, let delay be 85.
    2. 
+
+   
  2. If the element does not have a truespeed attribute, or if it
+   does but that attribute is in the false state, and the
+   delay value is less than 60, then let delay be 60 instead.
    3. 
+
+   
  3. The marquee scroll interval is delay, interpreted in milliseconds.
    4. 
+
+  
A marquee element has a marquee scroll
+  distance, which, if the element has a scrollamount attribute, and
+  parsing its value using the rules for parsing non-negative
+  integers does not return an error, is the parsed value
+  interpreted in CSS pixels, and otherwise is 6 CSS pixels.

+
+  
A marquee element has a marquee loop
+  count, which, if the element has a loop attribute, and parsing its
+  value using the rules for parsing integers does not
+  return an error or a number less than 1, is the parsed value, and
+  otherwise is −1.

+
+  
The loop IDL
+  attribute, on getting, must return the element's marquee loop
+  count; and on setting, if the new value is different than the
+  element's marquee loop count and either greater than
+  zero or equal to −1, must set the element's loop content attribute (adding it
+  if necessary) to the valid integer that represents the
+  new value. (Other values are ignored.)

+
+  
A marquee element also has a marquee current
+  loop index, which is zero when the element is created.

+
+  
The rendering layer will occasionally increment the marquee
+  current loop index, which must cause the following steps to be
+  run:

+
+  
  1. If the marquee loop count is −1, then
+   abort these steps.
    
+
+   
  2. Increment the marquee current loop index by
+   one.
    3. 
+
+   
  3. 
+
+    
    If the marquee current loop index is now equal to
+    or greater than the element's marquee loop count,
+    turn off the
+    marquee element and queue a task to
+    fire a simple event named finish at the marquee
+    element.
    
+
+    
    Otherwise, if the behavior attribute is in the
+    alternate
+    state, then queue a task to fire a simple
+    event named bounce at
+    the marquee element.
    
+
+    
    Otherwise, queue a task to fire a simple
+    event named start at the
+    marquee element.
    
+
+   
    4. 
+
+  
The following are the event handlers (and their
+  corresponding event handler
+  event types) that must be supported, as content and IDL
+  attributes, by marquee elements:

+
+  
Event handler Event handler event type
+   
onbounce  bounce
+    
onfinish  finish
+    
onstart  start
+  
The behavior, direction, height, hspace, vspace, and width IDL attributes
+  must reflect the respective content attributes of the
+  same name.

+
+  
The bgColor
+  IDL attribute must reflect the bgcolor content attribute.

+
+  
The scrollAmount
+  IDL attribute must reflect the scrollamount content
+  attribute. The default value is 6.

+
+  
The scrollDelay IDL
+  attribute must reflect the scrolldelay content
+  attribute. The default value is 85.

+
+  
The trueSpeed IDL
+  attribute must reflect the truespeed content
+  attribute.

+
+
+  
13.3.3 Frames

+
+  
The frameset element acts as the
+  body element in documents that use frames.

+
+  
The frameset element must implement the
+  HTMLFrameSetElement interface.

+
+  
interface HTMLFrameSetElement : HTMLElement {
+           attribute DOMString cols;
+           attribute DOMString rows;
+           attribute Function onafterprint;
+           attribute Function onbeforeprint;
+           attribute Function onbeforeunload;
+           attribute Function onblur;
+           attribute Function onerror;
+           attribute Function onfocus;
+           attribute Function onhashchange;
+           attribute Function onload;
+           attribute Function onmessage;
+           attribute Function onoffline;
+           attribute Function ononline;
+           attribute Function onpagehide;
+           attribute Function onpageshow;
+           attribute Function onpopstate;
+           attribute Function onredo;
+           attribute Function onresize;
+           attribute Function onstorage;
+           attribute Function onundo;
+           attribute Function onunload;
+};

+
+  
The cols and
+  rows IDL
+  attributes of the frameset element must
+  reflect the respective content attributes of the same
+  name.

+
+  
The frameset element must support the following
+  event handler content attributes exposing the
+  event handlers of the Window object:

+
+  
The DOM interface also exposes event handler IDL
+  attributes that mirror those on the Window
+  element.

+
+  
The onblur, onerror, onfocus, and onload event handler IDL
+  attributes of the Window object, exposed on the
+  frameset element, shadow the generic event
+  handler IDL attributes with the same names normally supported
+  by HTML elements.

+
+  
The frame element defines a nested
+  browsing context similar to the iframe element,
+  but rendered within a frameset element.

+
+  
When the browsing context is created, if a src attribute is present, the user
+  agent must resolve the value of
+  that attribute, relative to the element, and if that is successful,
+  must then navigate the element's browsing context to
+  the resulting absolute URL, with replacement
+  enabled, and with the frame element's
+  document's browsing context as the source
+  browsing context.

+
+  
Whenever the src attribute
+  is set, the user agent must resolve the value of that attribute, relative to the
+  element, and if that is successful, the nested browsing
+  context must be navigated to
+  the resulting absolute URL, with the
+  frame element's document's browsing
+  context as the source browsing context.

+
+  
When the browsing context is created, if a name attribute is present, the
+  browsing context name must be set to the value of this
+  attribute; otherwise, the browsing context name must be
+  set to the empty string.

+
+  
Whenever the name attribute
+  is set, the nested browsing context's name must be changed to the new
+  value. If the attribute is removed, the browsing context
+  name must be set to the empty string.

+
+  
When content loads in a frame, after any load events are fired within the content
+  itself, the user agent must queue a task to fire
+  a simple event named load at
+  the frame element. When content fails to load (e.g. due
+  to a network error), then the user agent must queue a
+  task to fire a simple event named error at the element instead.

+
+  
The task source for the tasks above is the DOM
+  manipulation task source.

+
+  
When there is an active parser in the
+  frame, and when anything in the frame is
+  delaying the load event of
+  the frame's browsing context's
+  active document, the frame must
+  delay the load event of its document.

+
+  
The frame element must implement the
+  HTMLFrameElement interface.

+
+  
interface HTMLFrameElement : HTMLElement {
+           attribute DOMString frameBorder;
+           attribute DOMString longDesc;
+           attribute DOMString marginHeight;
+           attribute DOMString marginWidth;
+           attribute DOMString name;
+           attribute boolean noResize;
+           attribute DOMString scrolling;
+           attribute DOMString src;
+  readonly attribute Document contentDocument;
+};

+
+  
The name, scrolling, and src IDL attributes of the
+  frame element must reflect the respective
+  content attributes of the same name.

+
+  
The frameBorder IDL
+  attribute of the frame element must
+  reflect the element's frameborder content
+  attribute.

+
+  
The longDesc
+  IDL attribute of the frame element must
+  reflect the element's longdesc content attribute.

+
+  
The marginHeight IDL
+  attribute of the frame element must
+  reflect the element's marginheight content
+  attribute.

+
+  
The marginWidth IDL
+  attribute of the frame element must
+  reflect the element's marginwidth content
+  attribute.

+
+  
The noResize
+  IDL attribute of the frame element must
+  reflect the element's noresize content attribute.

+
+  
The contentDocument
+  IDL attribute of the frame element must return the
+  Document object of the active document of
+  the frame element's nested browsing
+  context.

+
+
+
+  
13.3.4 Other elements, attributes and APIs
 
+
+  
User agents must treat acronym elements in a manner
+  equivalent to abbr elements.

+
+  
[Supplemental]
+interface HTMLAnchorElement {
+           attribute DOMString coords;
+           attribute DOMString charset;
+           attribute DOMString name;
+           attribute DOMString rev;
+           attribute DOMString shape;
+};

+
+  
The coords, charset, name, rev, and shape IDL attributes of the
+  a element must reflect the respective
+  content attributes of the same name.

+
+  
[Supplemental]
+interface HTMLAreaElement {
+           attribute boolean noHref;
+};

+
+  
The noHref IDL
+  attribute of the area element must reflect
+  the element's nohref content
+  attribute.

+
+  
The basefont element must implement the
+  HTMLBaseFontElement interface.

+
+  
interface HTMLBaseFontElement : HTMLElement {
+           attribute DOMString color;
+           attribute DOMString face;
+           attribute long size; 
+};

+
+  
The color,
+  face, and size IDL attributes of
+  the basefont element must reflect the
+  respective content attributes of the same name.

+
+  
[Supplemental]
+interface HTMLBodyElement {
+           attribute DOMString text;
+           attribute DOMString bgColor;
+           attribute DOMString background;
+           attribute DOMString link;
+           attribute DOMString vLink;
+           attribute DOMString aLink;
+};

+
+  
The text IDL
+  attribute of the body element must reflect
+  the element's text content
+  attribute.

+
+  
The bgColor IDL
+  attribute of the body element must reflect
+  the element's bgcolor content
+  attribute.

+
+  
The background IDL
+  attribute of the body element must reflect
+  the element's background
+  content attribute. (The background content is not
+  defined to contain a URL, despite rules regarding its
+  handling in the rendering section above.)

+
+  
The link IDL
+  attribute of the body element must reflect
+  the element's link content
+  attribute.

+
+  
The aLink IDL
+  attribute of the body element must reflect
+  the element's alink content
+  attribute.

+
+  
The vLink IDL
+  attribute of the body element must reflect
+  the element's vlink content
+  attribute.

+
+  
[Supplemental]
+interface HTMLBRElement {
+           attribute DOMString clear;
+};

+
+  
The clear IDL
+  attribute of the br element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLTableCaptionElement {
+           attribute DOMString align;
+};

+
+  
The align IDL
+  attribute of the caption element must
+  reflect the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLTableColElement {
+           attribute DOMString align;
+           attribute DOMString ch;
+           attribute DOMString chOff;
+           attribute DOMString vAlign;
+           attribute DOMString width;
+};

+
+  
The align and width IDL attributes of
+  the col element must reflect the
+  respective content attributes of the same name.

+
+  
The ch IDL attribute
+  of the col element must reflect the
+  element's char content
+  attribute.

+
+  
The chOff IDL
+  attribute of the col element must reflect
+  the element's charoff content
+  attribute.

+
+  
The vAlign IDL
+  attribute of the col element must reflect
+  the element's valign content
+  attribute.

+
+  
User agents must treat dir elements in a manner
+  equivalent to ul elements.

+
+  
The dir element must implement the
+  HTMLDirectoryElement interface.

+
+  
interface HTMLDirectoryElement : HTMLElement {
+           attribute boolean compact;
+};

+
+  
The compact IDL
+  attribute of the dir element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLDivElement {
+           attribute DOMString align;
+};

+
+  
The align IDL
+  attribute of the div element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLDListElement {
+           attribute boolean compact;
+};

+
+  
The compact IDL
+  attribute of the dl element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLEmbedElement {
+           attribute DOMString align;
+           attribute DOMString name;
+};

+
+  
The name and align IDL attributes of
+  the embed element must reflect the
+  respective content attributes of the same name.

+
+  
The font element must implement the
+  HTMLFontElement interface.

+
+  
interface HTMLFontElement : HTMLElement {
+           attribute DOMString color;
+           attribute DOMString face;
+           attribute DOMString size; 
+};

+
+  
The color,
+  face, and size IDL attributes of
+  the font element must reflect the
+  respective content attributes of the same name.

+
+  
[Supplemental]
+interface HTMLHeadingElement {
+           attribute DOMString align;
+};

+
+  
The align IDL
+  attribute of the h1–h6 elements must
+  reflect the content attribute of the same name.

+
+  
The profile IDL attribute on
+  head elements (with the HTMLHeadElement
+  interface) is intentionally omitted. Unless so required by another applicable
+  specification, implementations would therefore not support
+  this attribute. (It is mentioned here as it was defined in a
+  previous version of the DOM specifications.)

+
+  
[Supplemental]
+interface HTMLHRElement {
+           attribute DOMString align;
+           attribute DOMString color;
+           attribute boolean noShade;
+           attribute DOMString size;
+           attribute DOMString width;
+};

+
+  
The align, color, size, and width IDL attributes of the
+  hr element must reflect the respective
+  content attributes of the same name.

+
+  
The noShade IDL
+  attribute of the hr element must reflect
+  the element's noshade
+  content attribute.

+
+  
[Supplemental]
+interface HTMLHtmlElement {
+           attribute DOMString version;
+};

+
+  
The version IDL
+  attribute of the html element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLIFrameElement {
+           attribute DOMString align;
+           attribute DOMString frameBorder;
+           attribute DOMString longDesc;
+           attribute DOMString marginHeight;
+           attribute DOMString marginWidth;
+           attribute DOMString scrolling;
+};

+
+  
The align and
+  scrolling IDL
+  attributes of the iframe element must
+  reflect the respective content attributes of the same
+  name.

+
+  
The frameBorder IDL
+  attribute of the iframe element must
+  reflect the element's frameborder content
+  attribute.

+
+  
The longDesc
+  IDL attribute of the iframe element must
+  reflect the element's longdesc content attribute.

+
+  
The marginHeight IDL
+  attribute of the iframe element must
+  reflect the element's marginheight content
+  attribute.

+
+  
The marginWidth IDL
+  attribute of the iframe element must
+  reflect the element's marginwidth content
+  attribute.

+
+  
[Supplemental]
+interface HTMLImageElement {
+           attribute DOMString name;
+           attribute DOMString align;
+           attribute DOMString border;
+           attribute unsigned long hspace;
+           attribute DOMString longDesc;
+           attribute unsigned long vspace;
+};

+
+  
The name, align, border, hspace, and vspace IDL attributes of
+  the img element must reflect the
+  respective content attributes of the same name.

+
+  
The longDesc IDL
+  attribute of the img element must reflect
+  the element's longdesc content
+  attribute.

+
+  
[Supplemental]
+interface HTMLInputElement {
+           attribute DOMString align;
+           attribute DOMString useMap;
+};

+
+  
The align IDL
+  attribute of the input element must reflect
+  the content attribute of the same name.

+
+  
The useMap IDL
+  attribute of the input element must
+  reflect the element's usemap content attribute.

+
+  
[Supplemental]
+interface HTMLLegendElement {
+           attribute DOMString align;
+};

+
+  
The align IDL
+  attribute of the legend element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLLIElement {
+           attribute DOMString type;
+};

+
+  
The type IDL
+  attribute of the li element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLLinkElement {
+           attribute DOMString charset;
+           attribute DOMString rev;
+           attribute DOMString target;
+};

+
+  
The charset,
+  rev, and target IDL attributes of
+  the link element must reflect the
+  respective content attributes of the same name.

+
+  
User agents must treat listing elements in a manner
+  equivalent to pre elements.

+
+  
[Supplemental]
+interface HTMLMenuElement {
+           attribute boolean compact;
+};

+
+  
The compact IDL
+  attribute of the menu element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLMetaElement {
+           attribute DOMString scheme;
+};

+
+  
User agents may treat the scheme content attribute on the
+  meta element as an extension of the element's name content attribute when processing
+  a meta element with a name attribute whose value is one that
+  the user agent recognizes as supporting the scheme attribute.

+
+  
User agents are encouraged to ignore the scheme attribute and instead process
+  the value given to the metadata name as if it had been specified for
+  each expected value of the scheme attribute.

+
+  

+
+   
For example, if the user agent acts on meta
+   elements with name attributes
+   having the value "eGMS.subject.keyword", and knows that the scheme attribute is used with this
+   metadata name, then it could take the scheme attribute into account,
+   acting as if it was an extension of the name attribute. Thus the following
+   two meta elements could be treated as two elements
+   giving values for two different metadata names, one consisting of a
+   combination of "eGMS.subject.keyword" and "LGCL", and the other
+   consisting of a combination of "eGMS.subject.keyword" and
+   "ORLY":

+
+   
<!-- this markup is invalid -->
+<meta name="eGMS.subject.keyword" scheme="LGCL" content="Abandoned vehicles">
+<meta name="eGMS.subject.keyword" scheme="ORLY" content="Mah car: kthxbye">

+
+   
The recommended processing of this markup, however, would be
+   equivalent to the following:

+
+   
<meta name="eGMS.subject.keyword" content="Abandoned vehicles">
+<meta name="eGMS.subject.keyword" content="Mah car: kthxbye">

+
+  

+
+  
The scheme IDL
+  attribute of the meta element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLObjectElement {
+           attribute DOMString align;
+           attribute DOMString archive;
+           attribute DOMString border;
+           attribute DOMString code;
+           attribute DOMString codeBase;
+           attribute DOMString codeType;
+           attribute boolean declare;
+           attribute unsigned long hspace;
+           attribute DOMString standby;
+           attribute unsigned long vspace;
+};

+
+  
The align, archive, border, code, declare, hspace, standby, and vspace IDL attributes
+  of the object element must reflect the
+  respective content attributes of the same name.

+
+  
The codeBase IDL
+  attribute of the object element must reflect
+  the element's codebase content
+  attribute.

+
+  
The codeType IDL
+  attribute of the object element must reflect
+  the element's codetype content
+  attribute.

+
+  
[Supplemental]
+interface HTMLOListElement {
+           attribute boolean compact;
+           attribute DOMString type;
+};

+
+  
The compact and
+  type IDL attributes of
+  the ol element must reflect the respective
+  content attributes of the same name.

+
+  
[Supplemental]
+interface HTMLParagraphElement {
+           attribute DOMString align;
+};

+
+  
The align IDL
+  attribute of the p element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLParamElement {
+           attribute DOMString type;
+           attribute DOMString valueType;
+};

+
+  
The type IDL
+  attribute of the param element must
+  reflect the content attribute of the same name.

+
+  
The valueType
+  IDL attribute of the param element must
+  reflect the element's valuetype content attribute.

+
+  
User agents must treat plaintext elements in a
+  manner equivalent to pre elements.

+
+  
[Supplemental]
+interface HTMLPreElement {
+           attribute unsigned long width;
+};

+
+  
The width IDL
+  attribute of the pre element must reflect
+  the content attribute of the same name.

+
+  
[Supplemental]
+interface HTMLScriptElement {
+           attribute DOMString event;
+           attribute DOMString htmlFor;
+};

+
+  
The event and
+  htmlFor IDL
+  attributes of the script element must return the empty
+  string on getting, and do nothing on setting.

+
+  
[Supplemental]
+interface HTMLTableElement {
+           attribute DOMString align;
+           attribute DOMString bgColor;
+           attribute DOMString border;
+           attribute DOMString cellPadding;
+           attribute DOMString cellSpacing;
+           attribute DOMString frame;
+           attribute DOMString rules;
+           attribute DOMString width;
+};

+
+  
The align, border, frame, rules, and width, IDL attributes of
+  the table element must reflect the
+  respective content attributes of the same name.

+
+  
The bgColor IDL
+  attribute of the table element must reflect
+  the element's bgcolor content
+  attribute.

+
+  
The cellPadding IDL
+  attribute of the table element must reflect
+  the element's cellpadding content
+  attribute.

+
+  
The cellSpacing IDL
+  attribute of the table element must reflect
+  the element's cellspacing content
+  attribute.

+
+  
[Supplemental]
+interface HTMLTableSectionElement {
+           attribute DOMString align;
+           attribute DOMString ch;
+           attribute DOMString chOff;
+           attribute DOMString vAlign;
+};

+
+  
The align IDL
+  attribute of the tbody, thead, and
+  tfoot elements must reflect the content
+  attribute of the same name.

+
+  
The ch IDL attribute
+  of the tbody, thead, and
+  tfoot elements must reflect the elements'
+  char content attributes.

+
+  
The chOff IDL
+  attribute of the tbody, thead, and
+  tfoot elements must reflect the elements'
+  charoff content attributes.

+
+  
The vAlign IDL
+  attribute of the tbody, thead, and
+  tfoot element must reflect the elements'
+  valign content
+  attributes.

+
+  
[Supplemental]
+interface HTMLTableCellElement {
+           attribute DOMString abbr;
+           attribute DOMString align;
+           attribute DOMString axis;
+           attribute DOMString bgColor;
+           attribute DOMString ch;
+           attribute DOMString chOff;
+           attribute DOMString height;
+           attribute boolean noWrap;
+           attribute DOMString vAlign;
+           attribute DOMString width;
+};

+
+  
The abbr, align, axis, height, and width IDL attributes of
+  the td and th elements must
+  reflect the respective content attributes of the same
+  name.

+
+  
The bgColor IDL
+  attribute of the td and th elements must
+  reflect the elements' bgcolor content attributes.

+
+  
The ch IDL
+  attribute of the td and th elements must
+  reflect the elements' char content attributes.

+
+  
The chOff IDL
+  attribute of the td and th elements must
+  reflect the elements' charoff content attributes.

+
+  
The noWrap IDL
+  attribute of the td and th elements must
+  reflect the elements' nowrap content attributes.

+
+  
The vAlign IDL
+  attribute of the td and th element must
+  reflect the elements' valign content attributes.

+
+  
[Supplemental]
+interface HTMLTableRowElement {
+           attribute DOMString align;
+           attribute DOMString bgColor;
+           attribute DOMString ch;
+           attribute DOMString chOff;
+           attribute DOMString vAlign;
+};

+
+  
The align IDL
+  attribute of the tr element must reflect
+  the content attribute of the same name.

+
+  
The bgColor IDL
+  attribute of the tr element must reflect
+  the element's bgcolor content
+  attribute.

+
+  
The ch IDL attribute of
+  the tr element must reflect the element's
+  char content attribute.

+
+  
The chOff IDL
+  attribute of the tr element must reflect
+  the element's charoff content
+  attribute.

+
+  
The vAlign IDL
+  attribute of the tr element must reflect
+  the element's valign content
+  attribute.

+
+  
[Supplemental]
+interface HTMLUListElement {
+           attribute boolean compact;
+           attribute DOMString type;
+};

+
+  
The compact and
+  type IDL attributes of
+  the ul element must reflect the respective
+  content attributes of the same name.

+
+  
User agents must treat xmp elements in a manner
+  equivalent to pre elements.

+
+  
The bgsound, isindex,
+  multicol, nextid, rb, and
+  spacer elements must use the
+  HTMLUnknownElement interface.
 
+
+  
[Supplemental]
+interface HTMLDocument {
+           attribute DOMString fgColor;
+           attribute DOMString bgColor;
+           attribute DOMString linkColor;
+           attribute DOMString vlinkColor;
+           attribute DOMString alinkColor;
+
+  readonly attribute HTMLCollection anchors;
+  readonly attribute HTMLCollection applets;
+
+  void clear();
+
+  readonly attribute HTMLAllCollection all;
+};

+
+  
The attributes of the Document object listed in the
+  first column of the following table must reflect the
+  content attribute on the body element with the name
+  given in the corresponding cell in the second column on the same
+  row, if the body element is a body element
+  (as opposed to a frameset element). When there is no
+  body element or if it is a
+  frameset element, the attributes must instead return
+  the empty string on getting and do nothing on setting.

+
+  
 IDL attribute
+      Content attribute
+   
fgColor
+     text
+    
bgColor
+     bgcolor
+    
linkColor
+     link
+    
vLinkColor
+     vlink
+    
aLinkColor
+     alink
+  
The anchors
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only a
+  elements with name
+  attributes.

+
+  
The applets
+  attribute must return an HTMLCollection rooted at the
+  Document node, whose filter matches only
+  applet elements.

+
+  
The clear()
+  method must do nothing.

+
+  
The all
+  attribute must return an HTMLAllCollection rooted at the
+  Document node, whose filter matches all elements.

+
+  
The object returned for all
+  has several unusual behaviors:

+
+  
  • The user agent must act as if the ToBoolean() operator in
+   JavaScript converts the object returned for all to the false value.
    • 
+
+   
  • The user agent must act as if, for the purposes of the == and != operators in
+   JavaScript, the object returned for all is equal to the undefined value.
    • 
+
+   
  • The user agent must act such that the typeof operator in JavaScript returns the string
+   undefined when applied to the object returned
+   for all.
    • 
+
+  
These requirements are a willful
+  violation of the JavaScript specification current at the time
+  of writing (ECMAScript edition 3). The JavaScript specification
+  requires that the ToBoolean() operator convert all objects to the
+  true value, and does not have provisions for objects acting as if
+  they were undefined for the purposes of
+  certain operators. This violation is motivated by a desire for
+  compatibility with two classes of legacy content: one that uses the
+  presence of document.all as a
+  way to detect legacy user agents, and one that only supports those
+  legacy user agents and uses the document.all object without testing
+  for its presence first. [ECMA262]

+
+  

+
+
+
+
+  
14 IANA considerations

+
+  
+
+
+
+  
14.1 text/html

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
+
+  
Type name:

+   
text

+   
Subtype name:

+   
html

+   
Required parameters:

+   
No required parameters

+   
Optional parameters:

+   

+    
charset

+     

+      
The charset parameter may be provided
+      to definitively specify the document's character
+      encoding, overriding any character encoding declarations in the
+      document. The parameter's value must be the name of the
+      character encoding used to serialize the file, must be a valid
+      character encoding name, and must be an ASCII
+      case-insensitive match for the preferred MIME
+      name for that encoding. [IANACHARSET]

+     

+    

+   
Encoding considerations:

+   
See the section on character encoding declarations.

+   
Security considerations:

+   

+
+    
Entire novels have been written about the security
+    considerations that apply to HTML documents. Many are listed in
+    this document, to which the reader is referred for more
+    details. Some general concerns bear mentioning here, however:

+
+    
HTML is scripted language, and has a large number of APIs (some
+    of which are described in this document). Script can expose the
+    user to potential risks of information leakage, credential
+    leakage, cross-site scripting attacks, cross-site request
+    forgeries, and a host of other problems. While the designs in this
+    specification are intended to be safe if implemented correctly, a
+    full implementation is a massive undertaking and, as with any
+    software, user agents are likely to have security bugs.

+
+    
Even without scripting, there are specific features in HTML
+    which, for historical reasons, are required for broad
+    compatibility with legacy content but that expose the user to
+    unfortunate security problems. In particular, the img
+    element can be used in conjunction with some other features as a
+    way to effect a port scan from the user's location on the
+    Internet. This can expose local network topologies that the
+    attacker would otherwise not be able to determine.

+
+    
HTML relies on a compartmentalization scheme sometimes known as
+    the same-origin policy. An origin in most
+    cases consists of all the pages served from the same host, on the
+    same port, using the same protocol.

+
+    
It is critical, therefore, to ensure that any untrusted content
+    that forms part of a site be hosted on a different
+    origin than any sensitive content on that site.
+    Untrusted content can easily spoof any other page on the same
+    origin, read data from that origin, cause scripts in that origin
+    to execute, submit forms to and from that origin even if they are
+    protected from cross-site request forgery attacks by unique
+    tokens, and make use of any third-party resources exposed to or
+    rights granted to that origin.

+
+   

+   
Interoperability considerations:

+   

+    Rules for processing both conforming and non-conforming content
+    are defined in this specification.
+   

+   
Published specification:

+   

+    This document is the relevant specification. Labeling a resource
+    with the text/html type asserts that the resource is
+    an HTML document using
+    the HTML syntax.
+   

+   
Applications that use this media type:

+   

+    Web browsers, tools for processing Web content, HTML authoring
+    tools, search engines, validators.
+   

+   
Additional information:

+   

+    
Magic number(s):

+     
No sequence of bytes can uniquely identify an HTML
+     document. More information on detecting HTML documents is
+     available in the Content-Type Processing Model specification. [MIMESNIFF]

+     
File extension(s):

+     
"html" and "htm"
+     are commonly, but certainly not exclusively, used as the
+     extension for HTML documents.

+     
Macintosh file type code(s):

+     
TEXT

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
W3C

+  
Fragment identifiers used with text/html resources
+  refer to the indicated part of the document.

+
+
+  
14.2 text/html-sandboxed

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
Type name:

+   
text

+   
Subtype name:

+   
html-sandboxed

+   
Required parameters:

+   
No required parameters

+   
Optional parameters:

+   
Same as for text/html

+   
Encoding considerations:

+   
Same as for text/html

+   
Security considerations:

+   

+    
The purpose of the text/html-sandboxed MIME type
+    is to provide a way for content providers to indicate that they
+    want the file to be interpreted in a manner that does not give the
+    file's contents access to the rest of the site. This is achieved
+    by assigning the Document objects generated from
+    resources labeled as text/html-sandboxed unique
+    origins.

+    
To avoid having legacy user agents treating resources labeled
+    as text/html-sandboxed as regular
+    text/html files, authors should avoid using the .html or .htm extensions for
+    resources labeled as text/html-sandboxed.

+    
Beyond this, the type is identical to text/html,
+    and the same considerations apply.

+   

+   
Interoperability considerations:

+   
Same as for text/html

+   
Published specification:

+   

+    This document is the relevant specification. Labeling a resource
+    with the text/html-sandboxed type asserts that the
+    resource is an HTML document
+    using the HTML syntax.
+   

+   
Applications that use this media type:

+   
Same as for text/html

+   
Additional information:

+   

+    
Magic number(s):

+     
Documents labeled as text/html-sandboxed are
+     heuristically indistinguishable from those labeled as
+     text/html.

+     
File extension(s):

+     
"sandboxed"

+     
Macintosh file type code(s):

+     
TEXT

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
WHATWG

+  
Fragment identifiers used with text/html-sandboxed
+  resources refer to the indicated part of the
+  document.

+
+
+  
14.3 application/xhtml+xml

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
+
+  
Type name:

+   
application

+   
Subtype name:

+   
xhtml+xml

+   
Required parameters:

+   
Same as for application/xml [RFC3023]

+   
Optional parameters:

+   
Same as for application/xml [RFC3023]

+   
Encoding considerations:

+   
Same as for application/xml [RFC3023]

+   
Security considerations:

+   
Same as for application/xml [RFC3023]

+   
Interoperability considerations:

+   
Same as for application/xml [RFC3023]

+   
Published specification:

+   

+    Labeling a resource with the application/xhtml+xml
+    type asserts that the resource is an XML document that likely has
+    a root element from the HTML namespace. As such, the
+    relevant specifications are the XML specification, the Namespaces
+    in XML specification, and this specification. [XML] [XMLNS]
+   

+   
Applications that use this media type:

+   
Same as for application/xml [RFC3023]

+   
Additional information:

+   

+    
Magic number(s):

+     
Same as for application/xml [RFC3023]

+     
File extension(s):

+     
"xhtml" and "xht"
+     are sometimes used as extensions for XML resources that have a
+     root element from the HTML namespace.

+     
Macintosh file type code(s):

+     
TEXT

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
W3C

+  
Fragment identifiers used with application/xhtml+xml
+  resources have the same semantics as with any XML MIME
+  type. [RFC3023]

+
+
+  
14.4 text/cache-manifest

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
Type name:

+   
text

+   
Subtype name:

+   
cache-manifest

+   
Required parameters:

+   
No parameters

+   
Optional parameters:

+   
No parameters

+   
Encoding considerations:

+   
Always UTF-8.

+   
Security considerations:

+   

+    
Cache manifests themselves pose no immediate risk unless
+    sensitive information is included within the
+    manifest. Implementations, however, are required to follow
+    specific rules when populating a cache based on a cache manifest,
+    to ensure that certain origin-based restrictions are
+    honored. Failure to correctly implement these rules can result in
+    information leakage, cross-site scripting attacks, and the
+    like.

+   

+   
Interoperability considerations:

+   

+    Rules for processing both conforming and non-conforming content
+    are defined in this specification.
+   

+   
Published specification:

+   

+    This document is the relevant specification.
+   

+   
Applications that use this media type:

+   

+    Web browsers.
+   

+   
Additional information:

+   

+    
Magic number(s):

+     
Cache manifests begin with the string "CACHE
+     MANIFEST", followed by either a U+0020 SPACE character, a
+     U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED
+     (LF) character, or a U+000D CARRIAGE RETURN (CR) character.

+     
File extension(s):

+     
"manifest"

+     
Macintosh file type code(s):

+     
No specific Macintosh file type codes are recommended for this type.

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
WHATWG

+  
Fragment identifiers have no meaning with
+  text/cache-manifest resources.

+
+
+
+  
14.5 text/ping

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
Type name:

+   
text

+   
Subtype name:

+   
ping

+   
Required parameters:

+   
No parameters

+   
Optional parameters:

+   
No parameters

+   
Encoding considerations:

+   
Not applicable.

+   
Security considerations:

+   

+    
If used exclusively in the fashion described in the context of
+    hyperlink auditing, this type introduces no new
+    security concerns.

+   

+   
Interoperability considerations:

+   

+    Rules applicable to this type are defined in this specification.
+   

+   
Published specification:

+   

+    This document is the relevant specification.
+   

+   
Applications that use this media type:

+   

+    Web browsers.
+   

+   
Additional information:

+   

+    
Magic number(s):

+     
text/ping resources always consist of the four
+     bytes 0x50 0x49 0x4E 0x47 (ASCII 'PING').

+     
File extension(s):

+     
No specific file extension is recommended for this type.

+     
Macintosh file type code(s):

+     
No specific Macintosh file type codes are recommended for this type.

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
Only intended for use with HTTP POST requests generated as part
+   of a Web browser's processing of the ping attribute.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
WHATWG

+  
Fragment identifiers have no meaning with
+  text/ping resources.

+
+
+  
14.6 text/srt

+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
Type name:

+   
text

+   
Subtype name:

+   
srt

+   
Required parameters:

+   
No parameters

+   
Optional parameters:

+   
No parameters

+   
Encoding considerations:

+   
Always UTF-8.

+   
Security considerations:

+   

+    
Timed track files themselves pose no immediate risk unless
+    sensitive information is included within the
+    data. Implementations, however, are required to follow specific
+    rules when processing timed tracks, to ensure that certain
+    origin-based restrictions are honored. Failure to correctly
+    implement these rules can result in information leakage,
+    cross-site scripting attacks, and the like.

+   

+   
Interoperability considerations:

+   

+    Rules for processing both conforming and non-conforming content
+    are defined in this specification.
+   

+   
Published specification:

+   

+    This document is the relevant specification.
+   

+   
Applications that use this media type:

+   

+    Web browsers and other video players.
+   

+   
Additional information:

+   

+    
Magic number(s):

+     
No sequence of bytes can uniquely identify a WebSRT timed
+     track file.

+     
File extension(s):

+     
"srt"

+     
Macintosh file type code(s):

+     
No specific Macintosh file type codes are recommended for this type.

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
WHATWG

+  
Fragment identifiers have no meaning with
+  text/srt resources.

+
+
+
+  
14.7 application/microdata+json

+
+
+  
This registration is for community review and will be submitted
+  to the IESG for review, approval, and registration with IANA.

+
+  
+
+  
Type name:

+   
application

+   
Subtype name:

+   
microdata+json

+   
Required parameters:

+   
Same as for application/json [JSON]

+   
Optional parameters:

+   
Same as for application/json [JSON]

+   
Encoding considerations:

+   
Always UTF-8.

+   
Security considerations:

+   
Same as for application/json [JSON]

+   
Interoperability considerations:

+   
Same as for application/json [JSON]

+   
Published specification:

+   

+
+    Labeling a resource with the
+    application/microdata+json type asserts that the
+    resource is a JSON text that consists of an object with a single
+    entry called "items" consisting of an array
+    of entries, each of which consists of an object with two entries,
+    one called "type" whose value is an array of
+    strings, and one called "properties" whose
+    value is an object whose entries each have a value consisting of
+    an array of either objects or strings, the objects being of the
+    same form as the objects in the aforementioned "items" entry. As such, the relevant specifications
+    are the JSON specification and this specification. [JSON]
+
+   

+   
Applications that use this media type:

+   
Same as for application/json [JSON]

+   
Additional information:

+   

+    
Magic number(s):

+     
Same as for application/json [JSON]

+     
File extension(s):

+     
Same as for application/json [JSON]

+     
Macintosh file type code(s):

+     
Same as for application/json [JSON]

+    

+   
Person & email address to contact for further information:

+   
Ian Hickson <ian@hixie.ch>

+   
Intended usage:

+   
Common

+   
Restrictions on usage:

+   
No restrictions apply.

+   
Author:

+   
Ian Hickson <ian@hixie.ch>

+   
Change controller:

+   
WHATWG

+  
Fragment identifiers used with
+  application/microdata+json resources have the same
+  semantics as when used with application/json. [JSON]

+
+
+
+
+  
14.8 Ping-From

+
+  
This section describes a header field for registration in the
+  Permanent Message Header Field Registry.  [RFC3864]

+
+  
Header field name

+   
Ping-From

+   
Applicable protocol

+   
http

+   
Status

+   
standard

+   
Author/Change controller

+   
WHATWG

+   
Specification document(s)

+   

+    This document is the relevant specification.
+   

+   
Related information

+   
None.

+  
14.9 Ping-To

+
+  
This section describes a header field for registration in the
+  Permanent Message Header Field Registry.  [RFC3864]

+
+  
Header field name

+   
Ping-To

+   
Applicable protocol

+   
http

+   
Status

+   
standard

+   
Author/Change controller

+   
WHATWG

+   
Specification document(s)

+   

+    This document is the relevant specification.
+   

+   
Related information

+   
None.

+  
Index

+
+  

+
+  
The following sections only cover conforming elements and features.

+
+  

+
+  
Elements

+
+  
This section is non-normative.

+
+  
+   
+     
+     
+     
+     
+     
+     
+    
+     
+     
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+     
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+    
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+    
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+    
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+     
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+     
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+    
+     
+     
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+    
+     
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+     
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+    
+     
+     
+     
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+    
+     
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+     
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+     
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+    
+     
+     
+     
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+    
+     
+     
+     
+     
+     
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+    
+     
+     
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+    
+     
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+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
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+    
+     
+     
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+     
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+    
+     
+     
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+     
+     
+     
+    
+     
+     
+     
+     
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+     
+    
+     
+     
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+     
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+     
+    
+     
+     
+     
+     
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+    
+     
+     
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+     
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+     
+    
+     
+     
+     
+     
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+     
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+     
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+     
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+     
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+    
+     
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+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
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+     
+     
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+     
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+     
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+     
+     
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+     
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+     
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+     
+     
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+     
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+     
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+    
+     
+     
+     
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+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
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+    
+     
+     
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+     
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+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
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+     
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+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
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+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
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+     
+     
+     
+     
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+     
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+     
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+    
+     
+     
+     
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+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
+     
+     
+     
+     
+     
+     
+    
List of elements
 Element
+      Description
+      Categories
+      Parents
+      Children
+      Attributes
+      Interface
+   
aHyperlinkflow;
+         phrasing*;
+         interactivephrasingtransparent*globals;
+         href;
+         target;
+
+         ping;
+
+         rel;
+         media;
+         hreflang;
+         typeHTMLAnchorElement
abbrAbbreviationflow;
+         phrasingphrasingphrasingglobalsHTMLElement
addressContact information for a page or sectionflow;
+         formatBlock candidateflowflow*globalsHTMLElement
areaHyperlink or dead area on an image mapflow;
+         phrasingphrasing*emptyglobals;
+         alt;
+         coords;
+         shape;
+         href;
+         target;
+
+         ping;
+
+         rel;
+         media;
+         hreflang;
+         typeHTMLAreaElement
articleSelf-contained syndicatable or reusable compositionflow;
+         sectioning;
+         formatBlock candidateflowflowglobalsHTMLElement
asideSidebar for tangentially related contentflow;
+         sectioning;
+         formatBlock candidateflowflowglobalsHTMLElement
audioAudio playerflow;
+         phrasing;
+         embedded;
+         interactivephrasingsource*;
+         transparent*globals;
+         src;
+         preload;
+         autoplay;
+         loop;
+         controlsHTMLAudioElement
bKeywordsflow;
+         phrasingphrasingphrasingglobalsHTMLElement
baseBase URL and default target browsing context for hyperlinks and formsmetadataheademptyglobals;
+         href;
+         targetHTMLBaseElement
bdoText directionality formattingflow;
+         phrasingphrasingphrasingglobalsHTMLElement
blockquoteA section quoted from another sourceflow;
+         sectioning root;
+         formatBlock candidateflowflowglobals;
+         citeHTMLQuoteElement
bodyDocument bodysectioning roothtmlflowglobals;
+         onafterprint;
+         onbeforeprint;
+         onbeforeunload;
+         onblur;
+         onerror;
+         onfocus;
+         onhashchange;
+         onload;
+         onmessage;
+         onoffline;
+         ononline;
+         onpagehide;
+         onpageshow;
+         onpopstate;
+         onredo;
+         onresize;
+         onstorage;
+         onundo;
+         onunloadHTMLBodyElement
brLine break, e.g. in poem or postal addressflow;
+         phrasingphrasingemptyglobalsHTMLBRElement
buttonButton controlflow;
+         phrasing;
+         interactive;
+         listed;
+         labelable;
+         submittable;
+         form-associatedphrasingPhrasing content*globals;
+         autofocus;
+         disabled;
+         form;
+         formaction;
+         formenctype;
+         formmethod;
+         formnovalidate;
+         formtarget;
+         name;
+         type;
+         valueHTMLButtonElement
canvasScriptable bitmap canvasflow;
+         phrasing;
+         embeddedphrasingtransparentglobals;
+         width;
+         heightHTMLCanvasElement
captionTable captionnonetableflow*globalsHTMLTableCaptionElement
citeTitle of a workflow;
+         phrasingphrasingphrasingglobalsHTMLElement
codeComputer codeflow;
+         phrasingphrasingphrasingglobalsHTMLElement
colTable columnnonecolgroupemptyglobals;
+         spanHTMLTableColElement
colgroupGroup of columns in a tablenonetablecolglobals;
+         spanHTMLTableColElement
commandMenu commandmetadata;
+         flow;
+         phrasinghead;
+         phrasingemptyglobals;
+         type;
+         label;
+         icon;
+         disabled;
+         checked;
+         radiogroupHTMLCommandElement
datalistContainer for options for combo box controlflow;
+         phrasingphrasingphrasing;
+         optionglobalsHTMLDataListElement
ddContent for corresponding dt element(s)nonedlflowglobalsHTMLElement
delA removal from the documentflow;
+         phrasing*phrasingtransparentglobals;
+         cite;
+         datetimeHTMLModElement
detailsDisclosure control for hiding detailsflow;
+         sectioning root;
+         interactiveflowsummary*;
+         flowglobals;
+         openHTMLDetailsElement
dfnDefining instanceflow;
+         phrasingphrasingphrasing*globalsHTMLElement
divGeneric flow containerflow;
+         formatBlock candidateflowflowglobalsHTMLDivElement
dlAssociation list consisting of zero or more name-value groupsflowflowdt*;
+         dd*globalsHTMLDListElement
dtLegend for corresponding dd element(s)nonedlvaries*globalsHTMLElement
emStress emphasisflow;
+         phrasingphrasingphrasingglobalsHTMLElement
embedPluginflow;
+         phrasing;
+         embedded;
+         interactivephrasingemptyglobals;
+         src;
+         type;
+         width;
+         height;
+         any*HTMLEmbedElement
fieldsetGroup of form controlsflow;
+         sectioning root;
+         listed;
+         form-associatedflowlegend*;
+         flowglobals;
+         disabled;
+         form;
+         nameHTMLFieldSetElement
figcaptionCaption for figurenonefigureflowglobalsHTMLElement
figureFigure with optional captionflow;
+         sectioning rootflowfigcaption*;
+         flowglobalsHTMLElement
footerFooter for a page or sectionflow;
+         formatBlock candidateflowflow*globalsHTMLElement
formUser-submittable formflowflowflow*globals;
+         accept-charset;
+         action;
+         autocomplete;
+         enctype;
+         method;
+         name;
+         novalidate;
+         targetHTMLFormElement
h1, h2, h3, h4, h5, h6Section headingflow;
+         heading;
+         formatBlock candidatehgroup;
+         flowphrasingglobalsHTMLHeadingElement
headContainer for document metadatanonehtmlmetadata content*globalsHTMLHeadElement
headerIntroductory or navigational aids for a page or sectionflow;
+         formatBlock candidateflowflow*globalsHTMLElement
hgroupheading groupflow;
+         heading;
+         formatBlock candidateflowOne or more h1, h2, h3, h4, h5, and/or h6globalsHTMLElement
hrThematic breakflowflowemptyglobalsHTMLHRElement
htmlRoot elementnonenone*head*;
+         body*globals;
+         manifestHTMLHtmlElement
iAlternate voiceflow;
+         phrasingphrasingphrasingglobalsHTMLElement
iframeNested browsing contextflow;
+         phrasing;
+         embedded;
+         interactivephrasingtext*globals;
+         src;
+         srcdoc;
+         name;
+         sandbox;
+         seamless;
+         width;
+         heightHTMLIFrameElement
imgImageflow;
+         phrasing;
+         embedded;
+         interactive*phrasingemptyglobals;
+         alt;
+         src;
+         usemap;
+         ismap;
+         width;
+         heightHTMLImageElement
inputForm controlflow;
+         phrasing;
+         interactive*;
+         listed;
+         labelable;
+         submittable;
+         resettable;
+         form-associatedphrasingemptyglobals;
+         accept;
+         alt;
+         autocomplete;
+         autofocus;
+         checked;
+         disabled;
+         form;
+         formaction;
+         formenctype;
+         formmethod;
+         formnovalidate;
+         formtarget;
+         height;
+         list;
+         max;
+         maxlength;
+         min;
+         multiple;
+         name;
+         pattern;
+         placeholder;
+         readonly;
+         required;
+         size;
+         src;
+         step;
+         type;
+         value;
+         widthHTMLInputElement
insAn addition to the documentflow;
+         phrasing*phrasingtransparentglobals;
+         cite;
+         datetimeHTMLModElement
kbdUser inputflow;
+         phrasingphrasingphrasingglobalsHTMLElement
keygenCryptographic key-pair generator form controlflow;
+         phrasing;
+         interactive;
+         listed;
+         labelable;
+         submittable;
+         resettable;
+         form-associatedphrasingemptyglobals;
+         autofocus;
+         challenge;
+         disabled;
+         form;
+         keytype;
+         nameHTMLKeygenElement
labelCaption for a form controlflow;
+         phrasing;
+         interactive;
+         form-associatedphrasingphrasing*globals;
+         form;
+         forHTMLLabelElement
legendCaption for fieldsetnonefieldsetphrasingglobalsHTMLLegendElement
liList itemnoneol; ul; menuflowglobals;
+         value*HTMLLIElement
linkLink metadatametadata;
+         flow*;
+         phrasing*head;
+         noscript*;
+         phrasing*emptyglobals;
+         href;
+         rel;
+         media;
+         hreflang;
+         type;
+         sizesHTMLLinkElement
mapImage mapflow;
+         phrasing*phrasingtransparent;
+         area*globals;
+         nameHTMLMapElement
markHighlightflow;
+         phrasingphrasingphrasingglobalsHTMLElement
menuMenu of commandsflow;
+         interactive*flowli*;
+         flowglobals;
+         type;
+         labelHTMLMenuElement
metaText metadatametadata;
+         flow*;
+         phrasing*head;
+         noscript*;
+         phrasing*emptyglobals;
+         name;
+         http-equiv;
+         content;
+         charsetHTMLMetaElement
meterGaugeflow;
+         phrasing;
+         labelable;
+         form-associatedphrasingphrasing*globals;
+         value;
+         min;
+         max;
+         low;
+         high;
+         optimum;
+         formHTMLMeterElement
navSection with navigational linksflow;
+         sectioning;
+         formatBlock candidateflowflowglobalsHTMLElement
noscriptFallback content for scriptmetadata;
+         flow;
+         phrasinghead*;
+         phrasing*varies*globalsHTMLElement
objectImage, nested browsing context, or pluginflow;
+         phrasing;
+         embedded;
+         interactive*;
+         listed;
+         submittable;
+         form-associatedphrasingparam*;
+         transparentglobals;
+         data;
+         type;
+         name;
+         usemap;
+         form;
+         width;
+         heightHTMLObjectElement
olOrdered listflowflowliglobals;
+         reversed;
+         startHTMLOListElement
optgroupGroup of options in a list boxnoneselectoptionglobals;
+         disabled;
+         labelHTMLOptGroupElement
optionOption in a list box or combo box controlnoneselect;
+         datalist;
+         optgrouptextglobals;
+         disabled;
+         label;
+         selected;
+         valueHTMLOptionElement
outputCalculated output valueflow;
+         phrasing;
+         listed;
+         labelable;
+         resettable;
+         form-associatedphrasingphrasingglobals;
+         for;
+         form;
+         nameHTMLOutputElement
pParagraphflow;
+         formatBlock candidateflowphrasingglobalsHTMLParagraphElement
paramParameter for objectnoneobjectemptyglobals;
+         name;
+         valueHTMLParamElement
preBlock of preformatted textflow;
+         formatBlock candidateflowphrasingglobalsHTMLPreElement
progressProgress barflow;
+         phrasing;
+         labelable;
+         form-associatedphrasingphrasing*globals;
+         value;
+         max;
+         formHTMLProgressElement
qQuotationflow;
+         phrasingphrasingphrasingglobals;
+         citeHTMLQuoteElement
rpParenthesis for ruby annotation textnonerubyphrasingglobalsHTMLElement
rtRuby annotation textnonerubyphrasingglobalsHTMLElement
rubyRuby annotation(s)flow;
+         phrasingphrasingphrasing;
+         rt element;
+         rp element*globalsHTMLElement
sampComputer outputflow;
+         phrasingphrasingphrasingglobalsHTMLElement
scriptEmbedded scriptmetadata;
+         flow;
+         phrasinghead;
+         phrasingscript, data, or script documentation*globals;
+         src;
+         async;
+         defer;
+         type;
+         charsetHTMLScriptElement
sectionGeneric document or application sectionflow;
+         sectioning;
+         formatBlock candidateflowflowglobalsHTMLElement
selectList box controlflow;
+         phrasing;
+         interactive;
+         listed;
+         labelable;
+         submittable;
+         resettable;
+         form-associatedphrasingoption, optgroupglobals;
+         autofocus;
+         disabled;
+         form;
+         multiple;
+         name;
+         sizeHTMLSelectElement
smallSide commentflow;
+         phrasingphrasingphrasingglobalsHTMLElement
sourceMedia source for video or audiononevideo;
+         audioemptyglobals;
+         src;
+         type;
+         mediaHTMLSourceElement
spanGeneric phrasing containerflow;
+         phrasingphrasingphrasingglobalsHTMLSpanElement
strongImportanceflow;
+         phrasingphrasingphrasingglobalsHTMLElement
styleEmbedded styling informationmetadata;
+         flowhead;
+         noscript*;
+         flow*varies*globals;
+         media;
+         type;
+         scopedHTMLStyleElement
subSubscriptflow;
+         phrasingphrasingphrasingglobalsHTMLElement
summaryCaption for detailsnonedetailsphrasingglobalsHTMLElement
supSuperscriptflow;
+         phrasingphrasingphrasingglobalsHTMLElement
tableTableflowflowcaption*;
+         colgroup*;
+         thead*;
+         tbody*;
+         tfoot*;
+         tr*globals;
+         summaryHTMLTableElement
tbodyGroup of rows in a tablenonetabletrglobalsHTMLTableSectionElement
tdTable cellsectioning roottrflowglobals;
+         colspan;
+         rowspan;
+         headersHTMLTableDataCellElement
textareaMultiline text fieldflow;
+         phrasing;
+         interactive;
+         listed;
+         labelable;
+         submittable;
+         resettable;
+         form-associatedphrasingtextglobals;
+         autofocus;
+         cols;
+         disabled;
+         form;
+         maxlength;
+         name;
+         placeholder;
+         readonly;
+         required;
+         rows;
+         wrapHTMLTextAreaElement
tfootGroup of footer rows in a tablenonetabletrglobalsHTMLTableSectionElement
thTable header cellnonetrphrasingglobals;
+         colspan;
+         rowspan;
+         headers;
+         scopeHTMLTableHeaderCellElement
theadGroup of heading rows in a tablenonetabletrglobalsHTMLTableSectionElement
timeDate and/or timeflow;
+         phrasingphrasingphrasing*globals;
+         datetime;
+         pubdateHTMLTimeElement
titleDocument titlemetadataheadtextglobalsHTMLTitleElement
trTable rownonetable;
+         thead;
+         tbody;
+         tfootth*;
+         tdglobalsHTMLTableRowElement
trackTimed tracknoneaudio;
+         videoemptyglobals;
+         kind;
+         label;
+         src;
+         srclangHTMLTrackElement
ulListflowflowliglobalsHTMLUListElement
varVariableflow;
+         phrasingphrasingphrasingglobalsHTMLElement
videoVideo playerflow;
+         phrasing;
+         embedded;
+         interactivephrasingsource*;
+         transparent*globals;
+         src;
+         poster;
+         preload;
+         autoplay;
+         loop;
+         controls;
+         width;
+         heightHTMLVideoElement
wbrLine breaking opportunityflow;
+         phrasingphrasingemptyglobalsHTMLElement
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.

+
+
+
+
+  
Element content categories

+
+  
This section is non-normative.

+
+  
+
+  
+   
List of element content categories
 Category
+      Elements
+      Elements with exceptions
+   
 Metadata content
+     
+      base;
+      command;
+      link;
+      meta;
+      noscript;
+      script;
+      style;
+      title
+     
+      —
+
+    
 Flow content
+     
+      a;
+      abbr;
+      address;
+      article;
+      aside;
+      audio;
+      b;
+      bdo;
+      blockquote;
+      br;
+      button;
+      canvas;
+      cite;
+      code;
+      command;
+      
+      datalist;
+      del;
+      details;
+      dfn;
+      div;
+      dl;
+      em;
+      embed;
+      fieldset;
+      figure;
+      footer;
+      form;
+      h1;
+      h2;
+      h3;
+      h4;
+      h5;
+      h6;
+      header;
+      hgroup;
+      hr;
+      i;
+      iframe;
+      img;
+      input;
+      ins;
+      kbd;
+      keygen;
+      label;
+      map;
+      mark;
+      math;
+      menu;
+      meter;
+      nav;
+      noscript;
+      object;
+      ol;
+      output;
+      p;
+      pre;
+      progress;
+      q;
+      ruby;
+      samp;
+      script;
+      section;
+      select;
+      small;
+      span;
+      strong;
+      sub;
+      sup;
+      svg;
+      table;
+      textarea;
+      time;
+      ul;
+      var;
+      video;
+      wbr;
+      Text
+     
+      area (if it is a descendant of a map element);
+      
+      link (if the itemprop attribute is present);
+      meta (if the itemprop attribute is present);
+      
+      style (if the scoped attribute is present)
+
+    
 Sectioning content
+     
+      article;
+      aside;
+      nav;
+      section
+     
+      —
+
+    
 Heading content
+     
+      h1;
+      h2;
+      h3;
+      h4;
+      h5;
+      h6;
+      hgroup
+     
+      —
+
+    
 Phrasing content
+     
+      abbr;
+      audio;
+      b;
+      bdo;
+      br;
+      button;
+      canvas;
+      cite;
+      code;
+      command;
+      datalist;
+      dfn;
+      em;
+      embed;
+      i;
+      iframe;
+      img;
+      input;
+      kbd;
+      keygen;
+      label;
+      mark;
+      math;
+      meter;
+      noscript;
+      object;
+      output;
+      progress;
+      q;
+      ruby;
+      samp;
+      script;
+      select;
+      small;
+      span;
+      strong;
+      sub;
+      sup;
+      svg;
+      textarea;
+      time;
+      var;
+      video;
+      wbr;
+      Text
+     
+      a (if it contains only phrasing content);
+      area (if it is a descendant of a  map element);
+      del (if it contains only phrasing content);
+      ins (if it contains only phrasing content);
+      
+      link (if the itemprop attribute is present);
+      
+      map (if it contains only phrasing content); meta (if the itemprop attribute is present)
+
+    
 Embedded content
+     
+      audio
+      canvas
+      embed
+      iframe
+      img
+      math
+      object
+      svg
+      video
+     
+      —
+
+    
 Interactive content
+     
+      a;
+      button;
+      
+      details;
+      embed;
+      iframe;
+      keygen;
+      label;
+      select;
+      textarea;
+     
+      audio (if the controls attribute is present);
+      img (if the usemap attribute is present);
+      input (if the type attribute is not in the Hidden state);
+      menu (if the type attribute is in the toolbar state);
+      object (if the usemap attribute is present);
+      video (if the controls attribute is present)
+
+    
 Sectioning roots
+     
+      blockquote;
+      body;
+      
+      details;
+      fieldset;
+      figure;
+      td
+     
+      —
+
+    
 Form-associated elements
+     
+      button;
+      fieldset;
+      input;
+      keygen;
+      label;
+      meter;
+      object;
+      output;
+      progress;
+      select;
+      textarea
+     
+      —
+
+    
 Listed elements
+     
+      button;
+      fieldset;
+      input;
+      keygen;
+      object;
+      output;
+      select;
+      textarea
+     
+      —
+
+    
 Labelable elements
+     
+      button;
+      input;
+      keygen;
+      meter;
+      output;
+      progress;
+      select;
+      textarea
+     
+      —
+
+    
 Submittable elements
+     
+      button;
+      input;
+      keygen;
+      object;
+      select;
+      textarea
+     
+      —
+
+    
 Resettable elements
+     
+      input;
+      keygen;
+      output;
+      select;
+      textarea
+     
+      —
+
+    
 formatBlock candidates
+     
+      section;
+      nav;
+      article;
+      aside;
+      h1;
+      h2;
+      h3;
+      h4;
+      h5;
+      h6;
+      hgroup;
+      header;
+      footer;
+      address;
+      p;
+      pre;
+      blockquote;
+      div
+     
+      —
+
+  
Attributes

+
+  
This section is non-normative.

+
+  
+   
List of attributes (excluding event handler content attributes)
 Attribute
+      Element(s)
+      Description
+      Value
+   
 accept
+      input
+      Hint for expected file type in file upload controls
+      Set of comma-separated tokens* consisting of valid MIME types with no parameters or audio/*, video/*, or image/*
+    
 accept-charset
+      form
+      Character encodings to use for form submission
+      Ordered set of unique space-separated tokens consisting of preferred MIME names of ASCII-compatible character encodings*
+    
 accesskey
+      HTML elements
+      Keyboard shortcut to activate or focus element
+      Ordered set of unique space-separated tokens consisting of one Unicode code point in length
+    
 action
+      form
+      URL to use for form submission
+      Valid URL potentially surrounded by spaces
+    
 alt
+      area;
+          img;
+          input
+      Replacement text for use when images are not available
+      Text*
+    
 async
+      script
+      Execute script asynchronously
+      Boolean attribute
+    
 autocomplete
+      form;
+          input
+      Prevent the user agent from providing autocompletions for the form control(s)
+      "on"; "off"
+    
 autofocus
+      button;
+          input;
+          keygen;
+          select;
+          textarea
+      Automatically focus the form control when the page is loaded
+      Boolean attribute
+    
 autoplay
+      audio;
+          video
+      Hint that the media resource can be started automatically when the page is loaded
+      Boolean attribute
+    
 challenge
+      keygen
+      String to package with the generated and signed public key
+      Text
+    
 charset
+      meta
+      Character encoding declaration
+      Preferred MIME name of an encoding*
+    
 charset
+      script
+      Character encoding of the external script resource
+      Preferred MIME name of an encoding*
+    
 checked
+      command;
+          input
+      Whether the command or control is checked
+      Boolean attribute
+    
 cite
+      blockquote;
+          del;
+          ins;
+          q
+      Link to the source of the quotation or more information about the edit
+      Valid URL potentially surrounded by spaces
+    
 class
+      HTML elements
+      Classes to which the element belongs
+      Unordered set of unique space-separated tokens
+    
 cols
+      textarea
+      Maximum number of characters per line
+      Valid non-negative integer greater than zero
+    
 colspan
+      td;
+          th
+      Number of columns that the cell is to span
+      Valid non-negative integer greater than zero
+    
 content
+      meta
+      Value of the element
+      Text*
+    
 contenteditable
+      HTML elements
+      Whether the element is editable
+      "true"; "false"
+    
 contextmenu
+      HTML elements
+      The element's context menu
+      ID*
+    
 controls
+      audio;
+          video
+      Show user agent controls
+      Boolean attribute
+    
 coords
+      area
+      Coordinates for the shape to be created in an image map
+      Valid list of integers*
+    
 data
+      object
+      Address of the resource
+      Valid non-empty URL potentially surrounded by spaces
+    
 datetime
+      del;
+          ins
+      Time and date of the change
+      Valid global date and time string
+    
 datetime
+      time
+      Value of the element
+      Valid date or time string*
+    
 defer
+      script
+      Defer script execution
+      Boolean attribute
+    
 dir
+      HTML elements
+      The text directionality of the element
+      "ltr"; "rtl"
+    
 disabled
+      button;
+          command;
+          fieldset;
+          input;
+          keygen;
+          optgroup;
+          option;
+          select;
+          textarea
+      Whether the form control is disabled
+      Boolean attribute
+    
 draggable
+      HTML elements
+      Whether the element is draggable
+      "true"; "false"
+    
 enctype
+      form
+      Form data set encoding type to use for form submission
+      "application/x-www-form-urlencoded"; "multipart/form-data"; "text/plain"
+    
 for
+      label
+      Associate the label with form control
+      ID*
+    
 for
+      output
+      Specifies controls from which the output was calculated
+      Unordered set of unique space-separated tokens consisting of IDs*
+    
 form
+      button;
+          fieldset;
+          input;
+          keygen;
+          label;
+          meter;
+          object;
+          output;
+          progress;
+          select;
+          textarea
+      Associates the control with a form element
+      ID*
+    
 formaction
+      button;
+          input
+      URL to use for form submission
+      Valid URL potentially surrounded by spaces
+    
 formenctype
+      button;
+          input
+      Form data set encoding type to use for form submission
+      "application/x-www-form-urlencoded"; "multipart/form-data"; "text/plain"
+    
 formmethod
+      button;
+          input
+      HTTP method to use for form submission
+      "GET"; "POST"; "PUT"; "DELETE"
+    
 formnovalidate
+      button;
+          input
+      Bypass form control validation for form submission
+      Boolean attribute
+    
 formtarget
+      button;
+          input
+      Browsing context for form submission
+      Valid browsing context name or keyword
+    
 headers
+      td;
+          th
+      The header cells for this cell
+      Unordered set of unique space-separated tokens consisting of IDs*
+    
 height
+      canvas;
+          embed;
+          iframe;
+          img;
+          input;
+          object;
+          video
+      Vertical dimension
+      Valid non-negative integer
+    
 hidden
+      HTML elements
+      Whether the element is relevant
+      Boolean attribute
+    
 high
+      meter
+      Low limit of high range
+      Valid floating point number*
+    
 href
+      a;
+          area
+      Address of the hyperlink
+      Valid URL potentially surrounded by spaces
+    
 href
+      link
+      Address of the hyperlink
+      Valid non-empty URL potentially surrounded by spaces
+    
 href
+      base
+      Document base URL
+      Valid URL potentially surrounded by spaces
+    
 hreflang
+      a;
+          area;
+          link
+      Language of the linked resource
+      Valid BCP 47 language tag
+    
 http-equiv
+      meta
+      Pragma directive
+      Text*
+    
 icon
+      command
+      Icon for the command
+      Valid non-empty URL potentially surrounded by spaces
+    
 id
+      HTML elements
+      The element's ID
+      Text*
+    
 ismap
+      img
+      Whether the image is a server-side image map
+      Boolean attribute
+
+    
 itemid
+      HTML elements
+      Global identifier for a microdata item
+      Valid URL potentially surrounded by spaces
+    
 itemprop
+      HTML elements
+      Property names of a microdata item
+      Unordered set of unique space-separated tokens consisting of valid absolute URLs, defined property names, or text*
+    
 itemref
+      itemref
+      Referenced elements
+      Unordered set of unique space-separated tokens consisting of IDs*
+    
 itemscope
+      HTML elements
+      Introduces a microdata item
+      Boolean attribute
+    
 itemtype
+      HTML elements
+      Item type of a microdata item
+      Valid absolute URL*
+
+    
 keytype
+      keygen
+      The type of cryptographic key to generate
+      Text*
+
+    
 kind
+      track
+      The type of timed track
+      "subtitles";
+          "captions";
+          "descriptions";
+          "chapters";
+          "metadata"
+
+    
 label
+      command;
+          menu;
+          optgroup;
+          option;
+
+          track
+
+      User-visible label
+      Text
+    
 lang
+      HTML elements
+      Language of the element
+      Valid BCP 47 language tag or the empty string
+    
 list
+      input
+      List of autocomplete options
+      ID*
+    
 loop
+      audio;
+          video
+      Whether to loop the media resource
+      Boolean attribute
+    
 low
+      meter
+      High limit of low range
+      Valid floating point number*
+    
 manifest
+      html
+      Application cache manifest
+      Valid non-empty URL potentially surrounded by spaces
+    
 max
+      input
+      Maximum value
+      varies*
+    
 max
+      meter;
+          progress
+      Upper bound of range
+      Valid floating point number*
+    
 maxlength
+      input;
+          textarea
+      Maximum length of value
+      Valid non-negative integer
+    
 media
+      a;
+          area;
+          link;
+          source;
+          style
+      Applicable media
+      Valid media query
+    
 method
+      form
+      HTTP method to use for form submission
+      "GET"; "POST"; "PUT"; "DELETE"
+    
 min
+      input
+      Minimum value
+      varies*
+    
 min
+      meter
+      Lower bound of range
+      Valid floating point number*
+    
 multiple
+      input;
+          select
+      Whether to allow multiple values
+      Boolean attribute
+    
 name
+      button;
+          fieldset;
+          input;
+          keygen;
+          output;
+          select;
+          textarea
+      Name of form control to use for form submission and in the form.elements API
+      Text*
+    
 name
+      form
+      Name of form to use in the document.forms API
+      Text*
+    
 name
+      iframe;
+          object
+      Name of nested browsing context
+      Valid browsing context name or keyword
+    
 name
+      map
+      Name of image map to reference from the usemap attribute
+      Text*
+    
 name
+      meta
+      Metadata name
+      Text*
+    
 name
+      param
+      Name of parameter
+      Text
+    
 novalidate
+      form
+      Bypass form control validation for form submission
+      Boolean attribute
+    
 open
+      details
+      Whether the details are visible
+      Boolean attribute
+    
 optimum
+      meter
+      Optimum value in gauge
+      Valid floating point number*
+    
 pattern
+      input
+      Pattern to be matched by the form control's value
+      Regular expression matching the JavaScript Pattern production
+
+    
 ping
+      a;
+          area
+      URLs to ping
+      Set of space-separated tokens consisting of valid non-empty URLs
+
+    
 placeholder
+      input;
+          textarea
+      User-visible label to be placed within the form control
+      Text*
+    
 poster
+      video
+      Poster frame to show prior to video playback
+      Valid non-empty URL potentially surrounded by spaces
+    
 preload
+      audio;
+          video
+      Hints how much buffering the media resource will likely need
+      "none";
+          "metadata";
+          "auto"
+    
 pubdate
+      time
+      Whether the element's value represents a publication time for the nearest article or body
+      Boolean attribute
+    
 radiogroup
+      command
+      Name of group of commands to treat as a radio button group
+      Text
+    
 readonly
+      input;
+          textarea
+      Whether to allow the value to be edited by the user
+      Boolean attribute
+    
 rel
+      a;
+          area;
+          link
+      Relationship between the document containing the hyperlink and the destination resource
+      Set of space-separated tokens*
+    
 required
+      input;
+          textarea
+      Whether the control is required for form submission
+      Boolean attribute
+    
 reversed
+      ol
+      Number the list backwards
+      Boolean attribute
+    
 rows
+      textarea
+      Number of lines to show
+      Valid non-negative integer greater than zero
+    
 rowspan
+      td;
+          th
+      Number of rows that the cell is to span
+      Valid non-negative integer
+    
 sandbox
+      iframe
+      Security rules for nested content
+      Unordered set of unique space-separated tokens consisting of
+          "allow-same-origin",
+          "allow-forms", and
+          "allow-scripts"
+    
 spellcheck
+      HTML elements
+      Whether the element is to have its spelling and grammar checked
+      "true"; "false"
+    
 scope
+      th
+      Specifies which cells the header cell applies to
+      "row";
+          "col";
+          "rowgroup";
+          "colgroup"
+    
 scoped
+      style
+      Whether the styles apply to the entire document or just the parent subtree
+      Boolean attribute
+    
 seamless
+      iframe
+      Whether to apply the document's styles to the nested content
+      Boolean attribute
+    
 selected
+      option
+      Whether the option is selected by default
+      Boolean attribute
+    
 shape
+      area
+      The kind of shape to be created in an image map
+      "circle";
+          "default";
+          "poly";
+          "rect"
+    
 size
+      input;
+          select
+      Size of the control
+      Valid non-negative integer greater than zero
+    
 sizes
+      link
+      Sizes of the icons (for rel="icon")
+      Unordered set of unique space-separated tokens consisting of sizes*
+    
 span
+      col;
+          colgroup
+      Number of columns spanned by the element
+      Valid non-negative integer greater than zero
+    
 src
+      audio;
+          embed;
+          iframe;
+          img;
+          input;
+          script;
+          source;
+
+          track;
+
+          video
+      Address of the resource
+      Valid non-empty URL potentially surrounded by spaces
+    
 srcdoc
+      iframe
+      A document to render in the iframe
+      The source of an iframe srcdoc document*
+
+    
 srclang
+      track
+      Language of the timed track
+      Valid BCP 47 language tag
+
+    
 start
+      ol
+      Ordinal value of the first item
+      Valid integer
+    
 step
+      input
+      Granularity to be matched by the form control's value
+      Valid floating point number greater than zero, or "any"
+    
 style
+      HTML elements
+      Presentational and formatting instructions
+      CSS declarations*
+    
 summary
+      table
+      Explanatory text for complex tables for users of screen readers
+      Text*
+    
 tabindex
+      HTML elements
+      Whether the element is focusable, and the relative order of the element for the purposes of sequential focus navigation
+      Valid integer
+    
 target
+      a;
+          area
+      Browsing context for hyperlink navigation
+      Valid browsing context name or keyword
+    
 target
+      base
+      Default browsing context for hyperlink navigation and form submission
+      Valid browsing context name or keyword
+    
 target
+      form
+      Browsing context for form submission
+      Valid browsing context name or keyword
+    
 title
+      HTML elements
+      Advisory information for the element
+      Text
+    
 title
+      abbr;
+          dfn
+      Full term or expansion of abbreviation
+      Text
+    
 title
+      command
+      Hint describing the command
+      Text
+    
 title
+      link
+      Title of the link
+      Text
+    
 title
+      link;
+          style
+      Alternative style sheet set name
+      Text
+    
 type
+      a;
+          area;
+          link
+      Hint for the type of the referenced resource
+      Valid MIME type
+    
 type
+      button
+      Type of button
+      "submit";
+          "reset";
+          "button"
+    
 type
+      button;
+          input
+      Type of form control
+      input type keyword
+    
 type
+      command
+      Type of command
+      "command";
+          "checkbox";
+          "radio"
+    
 type
+      embed;
+          object;
+          script;
+          source;
+          style
+      Type of embedded resource
+      Valid MIME type
+    
 type
+      menu
+      Type of menu
+      "context"; "toolbar"
+    
 usemap
+      img;
+          object
+      Name of image map to use
+      Valid hash-name reference*
+    
 value
+      button;
+          option
+      Value to be used for form submission
+      Text
+    
 value
+      input
+      Value of the form control
+      varies*
+    
 value
+      li
+      Ordinal value of the list item
+      Valid integer
+    
 value
+      meter;
+          progress
+      Current value of the element
+      Valid floating point number
+    
 value
+      param
+      Value of parameter
+      Text
+    
 width
+      canvas;
+          embed;
+          iframe;
+          img;
+          input;
+          object;
+          video
+      Horizontal dimension
+      Valid non-negative integer
+    
 wrap
+      textarea
+      How the value of the form control is to be wrapped for form submission
+      "soft";
+          "hard"
+  
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.

+
+  

+   
List of event handler content attributes
 Attribute
+      Element(s)
+      Description
+      Value
+   
 onabort
+      HTML elements
+      abort event handler
+      Event handler content attribute
+
+    
 onafterprint
+      body
+      afterprint event handler for Window object
+      Event handler content attribute
+
+    
 onbeforeprint
+      body
+      beforeprint event handler for Window object
+      Event handler content attribute
+
+    
 onbeforeunload
+      body
+      beforeunload event handler for Window object
+      Event handler content attribute
+
+    
 onblur
+      body
+      blur event handler for Window object
+      Event handler content attribute
+
+    
 onblur
+      HTML elements
+      blur event handler
+      Event handler content attribute
+
+    
 oncanplay
+      HTML elements
+      canplay event handler
+      Event handler content attribute
+
+    
 oncanplaythrough
+      HTML elements
+      canplaythrough event handler
+      Event handler content attribute
+
+    
 onchange
+      HTML elements
+      change event handler
+      Event handler content attribute
+
+    
 onclick
+      HTML elements
+      click event handler
+      Event handler content attribute
+
+    
 oncontextmenu
+      HTML elements
+      contextmenu event handler
+      Event handler content attribute
+
+    
 ondblclick
+      HTML elements
+      dblclick event handler
+      Event handler content attribute
+
+    
 ondrag
+      HTML elements
+      drag event handler
+      Event handler content attribute
+
+    
 ondragend
+      HTML elements
+      dragend event handler
+      Event handler content attribute
+
+    
 ondragenter
+      HTML elements
+      dragenter event handler
+      Event handler content attribute
+
+    
 ondragleave
+      HTML elements
+      dragleave event handler
+      Event handler content attribute
+
+    
 ondragover
+      HTML elements
+      dragover event handler
+      Event handler content attribute
+
+    
 ondragstart
+      HTML elements
+      dragstart event handler
+      Event handler content attribute
+
+    
 ondrop
+      HTML elements
+      drop event handler
+      Event handler content attribute
+
+    
 ondurationchange
+      HTML elements
+      durationchange event handler
+      Event handler content attribute
+
+    
 onemptied
+      HTML elements
+      emptied event handler
+      Event handler content attribute
+
+    
 onended
+      HTML elements
+      ended event handler
+      Event handler content attribute
+
+    
 onerror
+      body
+      error event handler for Window object, and handler for script error notifications
+      Event handler content attribute
+
+    
 onerror
+      HTML elements
+      error event handler
+      Event handler content attribute
+
+    
 onfocus
+      body
+      focus event handler for Window object
+      Event handler content attribute
+
+    
 onfocus
+      HTML elements
+      focus event handler
+      Event handler content attribute
+
+    
 onformchange
+      HTML elements
+      formchange event handler
+      Event handler content attribute
+
+    
 onforminput
+      HTML elements
+      forminput event handler
+      Event handler content attribute
+
+    
 onhashchange
+      body
+      hashchange event handler for Window object
+      Event handler content attribute
+
+    
 oninput
+      HTML elements
+      input event handler
+      Event handler content attribute
+
+    
 oninvalid
+      HTML elements
+      invalid event handler
+      Event handler content attribute
+
+    
 onkeydown
+      HTML elements
+      keydown event handler
+      Event handler content attribute
+
+    
 onkeypress
+      HTML elements
+      keypress event handler
+      Event handler content attribute
+
+    
 onkeyup
+      HTML elements
+      keyup event handler
+      Event handler content attribute
+
+    
 onload
+      body
+      load event handler for Window object
+      Event handler content attribute
+
+    
 onload
+      HTML elements
+      load event handler
+      Event handler content attribute
+
+    
 onloadeddata
+      HTML elements
+      loadeddata event handler
+      Event handler content attribute
+
+    
 onloadedmetadata
+      HTML elements
+      loadedmetadata event handler
+      Event handler content attribute
+
+    
 onloadstart
+      HTML elements
+      loadstart event handler
+      Event handler content attribute
+
+    
 onmessage
+      body
+      message event handler for Window object
+      Event handler content attribute
+
+    
 onmousedown
+      HTML elements
+      mousedown event handler
+      Event handler content attribute
+
+    
 onmousemove
+      HTML elements
+      mousemove event handler
+      Event handler content attribute
+
+    
 onmouseout
+      HTML elements
+      mouseout event handler
+      Event handler content attribute
+
+    
 onmouseover
+      HTML elements
+      mouseover event handler
+      Event handler content attribute
+
+    
 onmouseup
+      HTML elements
+      mouseup event handler
+      Event handler content attribute
+
+    
 onmousewheel
+      HTML elements
+      mousewheel event handler
+      Event handler content attribute
+
+    
 onoffline
+      body
+      offline event handler for Window object
+      Event handler content attribute
+
+    
 ononline
+      body
+      online event handler for Window object
+      Event handler content attribute
+
+    
 onpause
+      HTML elements
+      pause event handler
+      Event handler content attribute
+
+    
 onplay
+      HTML elements
+      play event handler
+      Event handler content attribute
+
+    
 onplaying
+      HTML elements
+      playing event handler
+      Event handler content attribute
+
+    
 onpagehide
+      body
+      pagehide event handler for Window object
+      Event handler content attribute
+
+    
 onpageshow
+      body
+      pageshow event handler for Window object
+      Event handler content attribute
+
+    
 onpopstate
+      body
+      popstate event handler for Window object
+      Event handler content attribute
+
+    
 onprogress
+      HTML elements
+      progress event handler
+      Event handler content attribute
+
+    
 onratechange
+      HTML elements
+      ratechange event handler
+      Event handler content attribute
+
+    
 onreadystatechange
+      HTML elements
+      readystatechange event handler
+      Event handler content attribute
+
+    
 onredo
+      body
+      redo event handler for Window object
+      Event handler content attribute
+
+    
 onresize
+      body
+      resize event handler for Window object
+      Event handler content attribute
+
+    
 onscroll
+      HTML elements
+      scroll event handler
+      Event handler content attribute
+
+    
 onseeked
+      HTML elements
+      seeked event handler
+      Event handler content attribute
+
+    
 onseeking
+      HTML elements
+      seeking event handler
+      Event handler content attribute
+
+    
 onselect
+      HTML elements
+      select event handler
+      Event handler content attribute
+
+    
 onshow
+      HTML elements
+      show event handler
+      Event handler content attribute
+
+    
 onstalled
+      HTML elements
+      stalled event handler
+      Event handler content attribute
+
+    
 onstorage
+      body
+      storage event handler for Window object
+      Event handler content attribute
+
+    
 onsubmit
+      HTML elements
+      submit event handler
+      Event handler content attribute
+
+    
 onsuspend
+      HTML elements
+      suspend event handler
+      Event handler content attribute
+
+    
 ontimeupdate
+      HTML elements
+      timeupdate event handler
+      Event handler content attribute
+
+    
 onundo
+      body
+      undo event handler for Window object
+      Event handler content attribute
+
+    
 onunload
+      body
+      unload event handler for Window object
+      Event handler content attribute
+
+    
 onvolumechange
+      HTML elements
+      volumechange event handler
+      Event handler content attribute
+
+    
 onwaiting
+      HTML elements
+      waiting event handler
+      Event handler content attribute
+
+  
Interfaces

+
+  
This section is non-normative.

+
+  
+   
List of interfaces for elements
 Element(s)
+      Interface(s)
+   
 a
+      HTMLAnchorElement : HTMLElement
+
+    
 abbr
+      HTMLElement
+
+    
 address
+      HTMLElement
+
+    
 area
+      HTMLAreaElement : HTMLElement
+
+    
 article
+      HTMLElement
+
+    
 aside
+      HTMLElement
+
+    
 audio
+      HTMLAudioElement : HTMLMediaElement : HTMLElement
+
+    
 b
+      HTMLElement
+
+    
 base
+      HTMLBaseElement : HTMLElement
+
+    
 bdo
+      HTMLElement
+
+    
 blockquote
+      HTMLQuoteElement : HTMLElement
+
+    
 body
+      HTMLBodyElement : HTMLElement
+
+    
 br
+      HTMLBRElement : HTMLElement
+
+    
 button
+      HTMLButtonElement : HTMLElement
+
+    
 canvas
+      HTMLCanvasElement : HTMLElement
+
+    
 caption
+      HTMLTableCaptionElement : HTMLElement
+
+    
 cite
+      HTMLElement
+
+    
 code
+      HTMLElement
+
+    
 col
+      HTMLTableSectionElement : HTMLElement
+
+    
 colgroup
+      HTMLTableColElement : HTMLElement
+
+    
 command
+      HTMLCommandElement : HTMLElement
+
+    
 datalist
+      HTMLDataListElement : HTMLElement
+
+    
 dd
+      HTMLElement
+
+    
 del
+      HTMLModElement : HTMLElement
+
+    
 details
+      HTMLDetailsElement : HTMLElement
+
+    
 div
+      HTMLDivElement : HTMLElement
+
+    
 dl
+      HTMLDListElement : HTMLElement
+
+    
 dt
+      HTMLElement
+
+    
 em
+      HTMLElement
+
+    
 embed
+      HTMLEmbedElement : HTMLElement
+
+    
 fieldset
+      HTMLFieldSetElement : HTMLElement
+
+    
 figcaption
+      HTMLElement
+
+    
 figure
+      HTMLElement
+
+    
 footer
+      HTMLElement
+
+    
 form
+      HTMLFormElement : HTMLElement
+
+    
 head
+      HTMLHeadElement : HTMLElement
+
+    
 h1
+      HTMLHeadingElement : HTMLElement
+
+    
 h2
+      HTMLHeadingElement : HTMLElement
+
+    
 h3
+      HTMLHeadingElement : HTMLElement
+
+    
 h4
+      HTMLHeadingElement : HTMLElement
+
+    
 h5
+      HTMLHeadingElement : HTMLElement
+
+    
 h6
+      HTMLHeadingElement : HTMLElement
+
+    
 header
+      HTMLElement
+
+    
 hgroup
+      HTMLElement
+
+    
 hr
+      HTMLHRElement : HTMLElement
+
+    
 html
+      HTMLHtmlElement : HTMLElement
+
+    
 i
+      HTMLElement
+
+    
 iframe
+      HTMLIFrameElement : HTMLElement
+
+    
 img
+      HTMLImageElement : HTMLElement
+
+    
 input
+      HTMLInputElement : HTMLElement
+
+    
 ins
+      HTMLModElement : HTMLElement
+
+    
 kbd
+      HTMLElement
+
+    
 keygen
+      HTMLKeygenElement : HTMLElement
+
+    
 label
+      HTMLLabelElement : HTMLElement
+
+    
 legend
+      HTMLLegendElement : HTMLElement
+
+    
 li
+      HTMLLIElement : HTMLElement
+
+    
 link
+      HTMLLinkElement : HTMLElement
+
+    
 map
+      HTMLMapElement : HTMLElement
+
+    
 mark
+      HTMLElement
+
+    
 meter
+      HTMLMeterElement : HTMLElement
+
+    
 nav
+      HTMLElement
+
+    
 noscript
+      HTMLElement
+
+    
 object
+      HTMLObjectElement : HTMLElement
+
+    
 ol
+      HTMLOListElement : HTMLElement
+
+    
 optgroup
+      HTMLOptGroupElement : HTMLElement
+
+    
 option
+      HTMLOptionElement : HTMLElement
+
+    
 output
+      HTMLOutputElement : HTMLElement
+
+    
 p
+      HTMLParagraphElement : HTMLElement
+
+    
 param
+      HTMLParamElement : HTMLElement
+
+    
 pre
+      HTMLPreElement : HTMLElement
+
+    
 progress
+      HTMLProgressElement : HTMLElement
+
+    
 q
+      HTMLElement
+
+    
 rp
+      HTMLElement
+
+    
 rt
+      HTMLElement
+
+    
 ruby
+      HTMLElement
+
+    
 samp
+      HTMLElement
+
+    
 section
+      HTMLElement
+
+    
 select
+      HTMLSelectElement : HTMLElement
+
+    
 small
+      HTMLElement
+
+    
 source
+      HTMLSourceElement : HTMLElement
+
+    
 span
+      HTMLSpanElement : HTMLElement
+
+    
 strong
+      HTMLElement
+
+    
 style
+      HTMLStyleElement : HTMLElement
+
+    
 sub
+      HTMLElement
+
+    
 summary
+      HTMLElement
+
+    
 sup
+      HTMLElement
+
+    
 table
+      HTMLTableElement : HTMLElement
+
+    
 tbody
+      HTMLTableSectionElement : HTMLElement
+
+    
 td
+      HTMLTableDataCellElement : HTMLTableCellElement : HTMLElement
+
+    
 textarea
+      HTMLTextAreaElement : HTMLElement
+
+    
 tfoot
+      HTMLTableSectionElement : HTMLElement
+
+    
 th
+      HTMLTableHeaderCellElement : HTMLTableCellElement : HTMLElement
+
+    
 thead
+      HTMLTableSectionElement : HTMLElement
+
+    
 time
+      HTMLTimeElement : HTMLElement
+
+    
 title
+      HTMLTitleElement : HTMLElement
+
+    
 tr
+      HTMLTableRowElement : HTMLElement
+
+
+    
 track
+      HTMLTrackElement : HTMLElement
+
+
+    
 ul
+      HTMLUListElement : HTMLElement
+
+    
 var
+      HTMLElement
+
+    
 video
+      HTMLVideoElement : HTMLMediaElement : HTMLElement
+
+    
 wbr
+      HTMLElement
+
+  
Events

+
+  
This section is non-normative.

+
+  
+   
List of events
 Event
+      Interface
+      Description
+   
 DOMActivate
+      Event
+      Fired at an element before its activation behavior is run
+
+    
 DOMContentLoaded
+      Event
+      Fired at the Document once it and its scripts have loaded, without waiting for other subresources
+
+    
 abort
+      Event
+      Fired at the Window when the download was aborted by the user
+
+    
 afterprint
+      Event
+      Fired at the Window after printing
+
+    
 beforeprint
+      Event
+      Fired at the Window before printing
+
+    
 beforeunload
+      BeforeUnloadEvent
+      Fired at the Window when the page is about to be unloaded, in case the page would like to show a warning prompt
+
+    
 blur
+      Event
+      Fired at nodes losing focus
+
+    
 change
+      Event
+      Fired at controls when the user commits a value change
+
+    
 contextmenu
+      Event
+      Fired at elements when the user requests their context menu
+
+    
 error
+      Event
+      Fired at elements when network and script errors occur
+
+    
 focus
+      Event
+      Fired at nodes gaining focus
+
+    
 formchange
+      Event
+      Fired at form controls when the user commits a value change to a control on the form
+
+    
 forminput
+      Event
+      Fired at form controls when the user changes the value of a control on the form
+
+    
 hashchange
+      HashChangeEvent
+      Fired at the Window when the fragment identifier part of the document's current address changes
+
+    
 input
+      Event
+      Fired at controls when the user changes the value
+
+    
 invalid
+      Event
+      Fired at controls during form validation if they do not satisfy their constraints
+
+    
 load
+      Event
+      Fired at the Window when the document has finished loading; fired at an element containing a resource (e.g. img, embed) when its resource has finished loading
+
+    
 message
+      MessageEvent
+      Fired at an object when the object receives a message
+
+    
 offline
+      Event
+      Fired at the Window when the network connections fails
+
+    
 online
+      Event
+      Fired at the Window when the network connections returns
+
+    
 pagehide
+      PageTransitionEvent
+      Fired at the Window when the page's entry in the session history stops being the current entry
+
+    
 pageshow
+      PageTransitionEvent
+      Fired at the Window when the page's entry in the session history becomes the current entry
+
+    
 popstate
+      PopStateEvent
+      Fired at the Window when the user navigates the session history
+
+    
 readystatechange
+      Event
+      Fired at the Document when it finishes parsing and again when all its subresources have finished loading
+
+    
 redo
+      UndoManagerEvent
+      Fired at the Window object when the user goes forward in the undo transaction history
+
+    
 reset
+      Event
+      Fired at a form element when it is reset
+
+    
 show
+      Event
+      Fired at a menu element when it is shown as a context menu
+
+    
 submit
+      Event
+      Fired at a form element when it is submitted
+
+    
 undo
+      UndoManagerEvent
+      Fired at the Window object when the user goes backward in the undo transaction history
+
+    
 unload
+      Event
+      Fired at the Window object when the page is going away
+
+  
See also media element
+  events, application cache events,
+  and drag-and-drop events.

+
+
+
+
+
+
+
+
+
+
+  
References

+
+  
All references are normative unless marked "Non-normative".

+
+  
+
+  
[ABNF]

+   
Augmented
+   BNF for Syntax Specifications: ABNF, D. Crocker,
+   P. Overell. IETF.

+
+   
[ABOUT]

+   
The
+   'about' URI scheme, J. Holsten, L. Hunt. IETF.

+
+   
[ARIA]

+   
Accessible Rich
+   Internet Applications (WAI-ARIA), J. Craig, M. Cooper, L. Pappas,
+   R. Schwerdtfeger, L. Seeman. W3C.

+
+   
[ARIAIMPL]

+   
WAI-ARIA 1.0
+   User Agent Implementation Guide, A. Snow-Weaver,
+   M. Cooper. W3C.

+
+   
[ATAG]

+   
(Non-normative) Authoring Tool Accessibility
+   Guidelines (ATAG) 2.0, J. Richards, J. Spellman,
+   J. Treviranus. W3C.

+
+   
[ATOM]

+   
(Non-normative) The Atom Syndication
+   Format, M. Nottingham, R. Sayre. IETF.

+
+   
[BCP47]

+   
Tags for
+   Identifying Languages; Matching of Language Tags,
+   A. Phillips, M. Davis. IETF.

+
+   
[BECSS]

+   
Behavioral
+   Extensions to CSS, I. Hickson. W3C.

+
+   
[BEZIER]

+   
Courbes à poles, P. de Casteljau. INPI, 1959.

+
+   
[BIDI]

+   
UAX #9: Unicode
+   Bidirectional Algorithm, M. Davis. Unicode Consortium.

+
+   
[BOCU1]

+   
(Non-normative) UTN #6: BOCU-1:
+   MIME-Compatible Unicode Compression, M. Scherer,
+   M. Davis. Unicode Consortium.

+
+   
[CESU8]

+   
(Non-normative) UTR #26: Compatibility
+   Encoding Scheme For UTF-16: 8-BIT (CESU-8),
+   T. Phipps. Unicode Consortium.

+
+   
[CHARMOD]

+   
(Non-normative) Character Model for the World
+   Wide Web 1.0: Fundamentals, M. Dürst, F. Yergeau,
+   R. Ishida, M. Wolf, T. Texin. W3C.

+
+   
[COMPUTABLE]

+   
(Non-normative) On computable
+   numbers, with an application to the
+   Entscheidungsproblem, A. Turing. In Proceedings of
+   the London Mathematical Society, series 2, volume 42, pages
+   230-265. London Mathematical Society, 1937.

+
+   
[COOKIES]

+   
+   
HTTP State
+   Management Mechanism, A. Barth. IETF.

+
+   
[CORS]

+   
+   
Cross-Origin
+   Resource Sharing, A. van Kesteren.  W3C.

+
+   
[CSS]

+   
Cascading Style Sheets Level 2
+   Revision 1, B. Bos, T. Çelik, I.
+   Hickson, H. Lie. W3C.

+
+   
[CSSATTR]

+   
CSS
+   Styling Attribute Syntax, E. Etemad. W3C.

+
+   
[CSSCOLOR]

+   
+   
CSS Color
+   Module Level 3, T. Çelik, C. Lilley, L.
+   Baron. W3C.

+
+   
[CSSFONTS]

+   
CSS Fonts
+   Module Level 3, J. Daggett. W3C.

+
+   
[CSSOM]

+   
Cascading Style Sheets
+   Object Model (CSSOM), A. van Kesteren. W3C.

+
+   
[CSSUI]

+   
CSS3 Basic User
+   Interface Module, T. Çelik. W3C.

+
+   
[DOMCORE]

+   
Document
+   Object Model (DOM) Level 3 Core Specification, A. Le
+   Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
+   S. Byrnes. W3C.

+   
+
+   
[DOMEVENTS]

+   
+   
Document
+   Object Model (DOM) Level 3 Events Specification,
+   D. Schepers. W3C.

+
+   
[DOMRANGE]

+   
Document
+   Object Model (DOM) Level 2 Traversal and Range
+   Specification, J.  Kesselman, J. Robie, M. Champion,
+   P. Sharpe, V. Apparao, L.  Wood. W3C.

+
+   
[E163]

+   
Recommendation E.163 — Numbering Plan for The International
+   Telephone Service, CCITT Blue Book, Fascicle II.2, pp. 128-134, November
+   1988.

+
+   
[ECMA262]

+   
ECMAScript
+   Language Specification. ECMA.

+
+   
[ECMA357]

+   
(Non-normative) ECMAScript
+   for XML (E4X) Specification. ECMA.

+
+   
[EUCKR]

+   
Hangul Unix Environment. Korea Industrial
+   Standards Association. Ref. No. KS C 5861-1992.

+
+   
[EVENTSOURCE]

+   
+   
Server-Sent
+   Events, I. Hickson. W3C.

+
+   
[FILEAPI]

+   
File
+   API, A. Ranganathan. W3C.

+
+   
[GBK]

+   
Chinese Internal Code Specification. Chinese IT
+   Standardization Technical Committee.

+   
+
+   
[GRAPHICS]

+   
(Non-normative) Computer Graphics: Principles and
+   Practice in C, Second Edition, J. Foley, A. van Dam,
+   S. Feiner, J. Hughes. Addison-Wesley. ISBN
+   0-201-84840-6.

+   
+
+   
[GREGORIAN]

+   
(Non-normative) Inter Gravissimas, A. Lilius,
+   C. Clavius. Gregory XIII Papal Bulls, February 1582.

+
+   
[HATOM]

+   
(Non-normative) hAtom, D
+   Janes. Microformats.

+
+   
[HTMLDIFF]

+   
+   
(Non-normative) HTML5
+   differences from HTML4, A. van Kesteren.  W3C.

+
+   
[HTTP]

+   
Hypertext
+   Transfer Protocol — HTTP/1.1, R. Fielding, J. Gettys,
+   J. Mogul, H.  Frystyk, L. Masinter, P. Leach, T. Berners-Lee. IETF.

+
+   
[IANACHARSET]

+   
Character
+   Sets. IANA.

+
+   
[IANAPERMHEADERS]

+   
Permanent
+   Message Header Field Names. IANA.

+
+   
[ISO8601]

+   
ISO8601: Data elements and interchange formats — Information interchange — Representation of dates and times. ISO.

+
+   
[ISO885911]

+   
ISO-8859-11:
+   Information technology — 8-bit single-byte coded graphic
+   character sets — Part 11: Latin/Thai
+   alphabet. ISO.

+
+   
[JSON]

+   
The
+   application/json Media Type for JavaScript Object Notation
+   (JSON), D. Crockford. IETF.

+
+   
[JSURL]

+   
The
+   'javascript' resource identifier scheme,
+   B. Höhrmann. IETF.

+
+   
[MAILTO]

+   
The mailto URL
+   scheme, P. Hoffman, L. Masinter, J. Zawinski.
+   IETF.

+
+   
[MATHML]

+   
Mathematical
+   Markup Language (MathML), D. Carlisle, P. Ion, R. Miner,
+   N. Poppelier. W3C.

+
+   
[MIMESNIFF]

+   
Content-Type
+   Processing Model, A. Barth, I. Hickson. IETF.

+
+   
[MQ]

+   
+   
Media
+   Queries, H. Lie, T.  Çelik, D. Glazman, A. van
+   Kesteren. W3C.

+
+   
[NPAPI]

+   
(Non-normative) Gecko
+   Plugin API Reference. Mozilla.

+
+   
[OPENSEARCH]

+   
Autodiscovery
+   in HTML/XHTML. In OpenSearch 1.1 Draft 4,
+   Section 4.6.2. OpenSearch.org.

+
+   
[ORIGIN]

+   
The HTTP
+   Origin Header, A. Barth, C. Jackson, I. Hickson. IETF.

+
+   
[PINGBACK]

+   
Pingback
+   1.0, S. Langridge, I. Hickson.

+
+   
[PNG]

+   
Portable Network
+   Graphics (PNG) Specification, D. Duce. W3C.

+
+   
[PORTERDUFF]

+   
Compositing
+   Digital Images, T. Porter, T. Duff. In Computer
+   graphics, volume 18, number 3, pp. 253-259. ACM Press, July
+   1984.

+
+   
[PPUTF8]

+   
(Non-normative) The
+   Properties and Promises  of
+   UTF-8, M. Dürst. University of Zürich. In Proceedings of the 11th International
+   Unicode Conference.

+
+   
[PROGRESS]

+   
+   
Progress
+   Events, C. McCathieNevile. W3C.

+
+   
[PSL]

+   
Public Suffix List.
+   Mozilla Foundation.

+
+   
[RFC1034]

+   
Domain
+   Names - Concepts and Facilities, P. Mockapetris. IETF,
+   November 1987.

+
+   
[RFC1345]

+   
Character Mnemonics
+   and Character Sets, K. Simonsen. IETF.

+
+   
[RFC1468]

+   
Japanese Character
+   Encoding for Internet Messages, J. Murai, M. Crispin, E. van der
+   Poel. IETF.

+
+   
[RFC1554]

+   
ISO-2022-JP-2:
+   Multilingual Extension of ISO-2022-JP, M. Ohta, K. Handa. IETF.

+
+   
[RFC1557]

+   
Korean Character
+   Encoding for Internet Messages, U. Choi, K. Chon, H. Park. IETF.

+
+   
[RFC1842]

+
+   
ASCII
+   Printable Characters-Based Chinese Character Encoding for Internet
+   Messages, Y. Wei, Y. Zhang, J. Li, J. Ding, Y. Jiang.
+   IETF.

+
+   
[RFC1922]

+   
Chinese Character
+   Encoding for Internet Messages, HF. Zhu, DY. Hu, ZG. Wang, TC. Kao,
+   WCH. Chang, M. Crispin. IETF.

+
+   
[RFC2045]

+   
Multipurpose Internet
+   Mail Extensions (MIME) Part One: Format of Internet Message Bodies,
+   N. Freed, N. Borenstein. IETF.

+
+   
[RFC2046]

+   
Multipurpose Internet
+   Mail Extensions (MIME) Part Two: Media Types, N. Freed,
+   N.  Borenstein. IETF.
 
+
+   
[RFC2119]

+   
Key words for use in
+   RFCs to Indicate Requirement Levels, S. Bradner. IETF.

+
+   
[RFC2237]

+   
Japanese Character
+   Encoding for Internet Messages, K. Tamaru. IETF.

+
+   
[RFC2313]

+   
PKCS #1:
+   RSA Encryption, B. Kaliski. IETF.

+
+   
[RFC2318]

+   
The
+   text/css Media Type, H. Lie, B. Bos, C. Lilley. IETF.

+
+   
[RFC2388]

+   
Returning Values from
+   Forms: multipart/form-data, L. Masinter. IETF.

+
+   
[RFC2425]

+   
A MIME
+   Content-Type for Directory Information, T. Howes,
+   M. Smith, F. Dawson. IETF.

+
+   
[RFC2426]

+   
vCard MIME Directory
+   Profile, F. Dawson, T. Howes. IETF.

+
+   
[RFC2445]

+   
Internet Calendaring
+   and Scheduling Core Object Specification (iCalendar), F. Dawson, D.
+   Stenerson. IETF.

+
+   
[RFC2483]

+   
URI Resolution
+   Services Necessary for URN Resolution, M. Mealling, R. Daniel.
+   IETF.

+
+   
[RFC2781]

+   
UTF-16, an
+   encoding of ISO 10646, P. Hoffman, F. Yergeau. IETF.

+
+   
[RFC2646]

+   
The Text/Plain Format
+   Parameter, R. Gellens. IETF.

+
+   
[RFC3023]

+   
XML Media
+   Types, M. Murata, S. St. Laurent, D. Kohn. IETF.

+
+   
[RFC3279]

+   
Algorithms
+   and Identifiers for the Internet X.509 Public Key Infrastructure
+   Certificate and Certificate Revocation List (CRL)
+   Profile, W. Polk, R. Housley, L. Bassham. IETF.

+
+   
[RFC3490]

+   
Internationalizing
+   Domain Names in Applications (IDNA), P. Faltstrom, P. Hoffman, A.
+   Costello. IETF.

+
+   
[RFC3548]

+   
The Base16, Base32,
+   and Base64 Data Encodings, S. Josefsson. IETF.

+
+   
[RFC3864]

+   
Registration Procedures
+   for Message Header Fields, G. Klyne, M. Nottingham,
+   J. Mogul. IETF.

+
+   
[RFC3986]

+   
Uniform Resource
+   Identifier (URI): Generic Syntax, T. Berners-Lee, R. Fielding, L.
+   Masinter. IETF.

+
+   
[RFC3987]

+   
Internationalized
+   Resource Identifiers (IRIs), M. Dürst, M. Suignard. IETF.

+
+   
[RFC4281]

+   
The Codecs Parameter
+   for "Bucket" Media Types, R. Gellens, D. Singer, P. Frojdh. IETF.

+
+   
[RFC4329]

+   
(Non-normative) Scripting Media
+   Types, B. Höhrmann. IETF.

+
+   
[RFC4770]

+   
vCard Extensions for
+   Instant Messaging (IM), C. Jennings, J. Reschke. IETF.

+
+   
[RFC5280]

+   
Internet
+   X.509 Public Key Infrastructure Certificate and Certificate
+   Revocation List (CRL) Profile, D. Cooper, S. Santesson,
+   S. Farrell, S. Boeyen, R. Housley, W. Polk. IETF.

+
+   
[RFC5322]

+   
Internet Message
+   Format, P. Resnick. IETF.

+
+   
[RFC5724]

+   
URI Scheme
+   for Global System for Mobile Communications (GSM) Short Message
+   Service (SMS), E. Wilde, A. Vaha-Sipila. IETF.

+
+   
[SCSU]

+   
(Non-normative) UTR #6: A Standard
+   Compression Scheme For Unicode, M. Wolf, K. Whistler,
+   C. Wicksteed, M. Davis, A. Freytag, M. Scherer. Unicode Consortium.

+
+   
[SELECTORS]

+   
Selectors,
+   T. Çelik, E. Etemad, D.  Glazman, I. Hickson, P. Linss,
+   J. Williams. W3C.

+
+   
[SHIFTJIS]

+   
JIS X0208: 7-bit and 8-bit double byte coded KANJI sets
+   for information interchange. Japanese Standards Association.

+
+   
[SRGB]

+   
IEC
+   61966-2-1: Multimedia systems and equipment — Colour measurement
+   and management — Part 2-1: Colour management — Default RGB colour
+   space — sRGB. IEC.

+
+   
[SVG]

+   
Scalable Vector
+   Graphics (SVG) Tiny 1.2 Specification, O. Andersson,
+   R. Berjon, E. Dahlström, A. Emmons, J. Ferraiolo, A. Grasso,
+   V. Hardy, S. Hayman, D. Jackson, C. Lilley, C. McCormack,
+   A. Neumann, C. Northway, A. Quint, N. Ramani, D. Schepers,
+   A. Shellshear. W3C.

+
+   
[TIS620]

+   
UDC
+   681.3.04:003.62. Thai Industrial Standards Institute,
+   Ministry of Industry, Royal Thai Government. ISBN
+   974-606-153-4.

+
+   
[UAAG]

+   
(Non-normative) Web Content Accessibility
+   Guidelines (UAAG) 2.0, J. Allan, K. Ford, J. Richards,
+   J. Spellman. W3C.

+
+   
[UNICODE]

+   
The Unicode Standard. Unicode Consortium.

+
+   
[UNIVCHARDET]

+   
(Non-normative) A
+   composite approach to language/encoding
+   detection, S. Li, K. Momoi. Netscape. In
+   Proceedings of the 19th International Unicode
+   Conference.

+
+   
[UTF7]

+   
UTF-7: A
+   Mail-Safe Transformation Format of Unicode,
+   D. Goldsmith, M. Davis. IETF.

+
+   
[UTF8DET]

+   
(Non-normative) Multilingual
+   form encoding, M. Dürst. W3C.

+
+   
[UTR36]

+   
(Non-normative) UTR #36: Unicode
+   Security Considerations, M. Davis, M. Suignard. Unicode
+   Consortium.

+
+   
[WCAG]

+   
(Non-normative) Web Content Accessibility
+   Guidelines (WCAG) 2.0, B. Caldwell, M. Cooper, L. Reid,
+   G. Vanderheiden. W3C.

+
+   
[WEBIDL]

+   
+   
Web
+   IDL, C. McCormack. W3C.

+
+   
+   
Web
+   Linking, M. Nottingham. IETF.

+
+   
[WEBSOCKET]

+   
+   
The WebSocket
+   API, I. Hickson. W3C.

+
+   
[WEBSQL]

+   
Web SQL
+   Database, I. Hickson. W3C.

+
+   
[WEBSTORAGE]

+   
Web
+   Storage, I. Hickson. W3C.

+
+   
[WEBWORKERS]

+   
+   
Web
+   Workers, I. Hickson. W3C.

+
+   
[WHATWGWIKI]

+   
The WHATWG Wiki. WHATWG.

+
+   
[WIN1252]

+   
Windows 1252. Microsoft.

+
+   
[WIN1254]

+   
Windows 1254. Microsoft.

+
+   
[WIN31J]

+   
Windows Codepage 932. Microsoft.

+
+   
[WIN874]

+   
Windows 874. Microsoft.

+
+   
[WIN949]

+   
Windows Codepage 949. Microsoft.

+
+   
[X121]

+   
Recommendation X.121 — International Numbering Plan for
+   Public Data Networks, CCITT Blue Book, Fascicle VIII.3,
+   pp. 317-332.

+
+   
[X690]

+   
Recommendation
+   X.690 — Information Technology — ASN.1 Encoding Rules —
+   Specification of Basic Encoding Rules (BER), Canonical Encoding
+   Rules (CER), and Distinguished Encoding Rules
+   (DER). International Telecommunication Union.

+
+   
[XHR]

+   
+   
XMLHttpRequest,
+   A. van Kesteren. W3C.

+
+   
[XML]

+   
Extensible Markup
+   Language, T. Bray, J. Paoli, C. Sperberg-McQueen,
+   E. Maler, F. Yergeau. W3C.

+
+   
[XMLBASE]

+   
XML
+   Base, J. Marsh, R. Tobin. W3C.

+
+   
[XMLNS]

+   
Namespaces in
+   XML, T. Bray, D. Hollander, A. Layman, R. Tobin. W3C.

+
+   
[XPATH10]

+   
XML Path
+   Language (XPath) Version 1.0, J. Clark, S. DeRose. W3C.

+
+   
[XSLT10]

+   
XSL
+   Transformations (XSLT) Version 1.0, J. Clark. W3C.

+
+
+
+  
Acknowledgements
 
+
+  
Thanks to
+
+  Aankhen,
+  Aaron Boodman,
+  Aaron Leventhal,
+  Adam Barth,
+  Adam de Boor,
+  Adam Hepton,
+  Adam Roben,
+  Addison Phillips,
+  Adele Peterson,
+  Adrian Bateman,
+  Adrian Sutton,
+  Agustín Fernández,
+  Ajai Tirumali,
+  Akatsuki Kitamura,
+  Alan Plum,
+  Alastair Campbell,
+  Alex Bishop,
+  Alex Nicolaou,
+  Alex Rousskov,
+  Alexander J. Vincent,
+  Alexey Feldgendler,
+  Алексей Проскуряков (Alexey Proskuryakov),
+  Alexis Deveria,
+  Allan Clements,
+  Amos Jeffries,
+  Anders Carlsson,
+  Andreas,
+  Andrei Popescu,
+  André E. Veltstra,
+  Andrew Clover,
+  Andrew Gove,
+  Andrew Grieve,
+  Andrew Oakley,
+  Andrew Sidwell,
+  Andrew Smith,
+  Andrew W. Hagen,
+  Andrey V. Lukyanov,
+  Andy Heydon,
+  Andy Palay,
+  Anne van Kesteren,
+  Anthony Boyd,
+  Anthony Bryan,
+  Anthony Hickson,
+  Anthony Ricaud,
+  Antti Koivisto,
+  Aron Spohr,
+  Arphen Lin,
+  Aryeh Gregor,
+  Asbjørn Ulsberg,
+  Ashley Sheridan,
+  Atsushi Takayama,
+  Aurelien Levy,
+  Ave Wrigley,
+  Ben Boyle,
+  Ben Godfrey,
+  Ben Lerner,
+  Ben Leslie,
+  Ben Meadowcroft,
+  Ben Millard,
+  Benjamin Carl Wiley Sittler,
+  Benjamin Hawkes-Lewis,
+  Bert Bos,
+  Bijan Parsia,
+  Bil Corry,
+  Bill Mason,
+  Bill McCoy,
+  Billy Wong,
+  Bjartur Thorlacius,
+  Björn Höhrmann,
+  Blake Frantz,
+  Boris Zbarsky,
+  Brad Fults,
+  Brad Neuberg,
+  Brady Eidson,
+  Brendan Eich,
+  Brenton Simpson,
+  Brett Wilson,
+  Brett Zamir,
+  Brian Campbell,
+  Brian Korver,
+  Brian Kuhn,
+  Brian Ryner,
+  Brian Smith,
+  Brian Wilson,
+  Bryan Sullivan,
+  Bruce D'Arcus,
+  Bruce Lawson,
+  Bruce Miller,
+  C. Williams,
+  Cameron McCormack,
+  Cao Yipeng,
+  Carlos Gabriel Cardona,
+  Carlos Perelló Marín,
+  Chao Cai,
+  윤석찬 (Channy Yun),
+  Charl van Niekerk,
+  Charles Iliya Krempeaux,
+  Charles McCathieNevile,
+  Chris Apers,
+  Chris Cressman,
+  Chris Evans,
+  Chris Morris,
+  Chris Pearce,
+  Christian Biesinger,
+  Christian Johansen,
+  Christian Schmidt,
+  Christopher Aillon,
+  Chriswa,
+  Cole Robison,
+  Colin Fine,
+  Collin Jackson,
+  Corprew Reed,
+  Craig Cockburn,
+  Csaba Gabor,
+  Csaba Marton,
+  Daniel Barclay,
+  Daniel Bratell,
+  Daniel Brooks,
+  Daniel Brumbaugh Keeney,
+  Daniel Cheng,
+  Daniel Davis,
+  Daniel Glazman,
+  Daniel Peng,
+  Daniel Schattenkirchner,
+  Daniel Spång,
+  Daniel Steinberg,
+  Danny Sullivan,
+  Darin Adler,
+  Darin Fisher,
+  Darxus,
+  Dave Camp,
+  Dave Hodder,
+  Dave Lampton,
+  Dave Singer,
+  Dave Townsend,
+  David Baron,
+  David Bloom,
+  David Bruant,
+  David Carlisle,
+  David E. Cleary,
+  David Egan Evans,
+  David Flanagan,
+  David Gerard,
+  David Håsäther,
+  David Hyatt,
+  David I. Lehn,
+  David Matja,
+  David Remahl,
+  David Smith,
+  David Woolley,
+  DeWitt Clinton,
+  Dean Edridge,
+  Dean Edwards,
+  Debi Orton,
+  Derek Featherstone,
+  Devdatta,
+  Dimitri Glazkov,
+  Dimitry Golubovsky,
+  Divya Manian,
+  dolphinling,
+  Dominique Hazaël-Massieux,
+  Don Brutzman,
+  Doron Rosenberg,
+  Doug Kramer,
+  Drew Wilson,
+  Edmund Lai,
+  Eduard Pascual,
+  Eduardo Vela,
+  Edward O'Connor,
+  Edward Welbourne,
+  Edward Z. Yang,
+  Eira Monstad,
+  Eitan Adler,
+  Eliot Graff,
+  Elizabeth Castro,
+  Elliott Sprehn,
+  Elliotte Harold,
+  Eric Carlson,
+  Eric Law,
+  Eric Rescorla,
+  Erik Arvidsson,
+  Evan Martin,
+  Evan Prodromou,
+  Evert,
+  fantasai,
+  Felix Sasaki,
+  Francesco Schwarz,
+  Francis Brosnan Blazquez,
+  Franck 'Shift' Quélain,
+  Frank Barchard,
+  鵜飼文敏 (Fumitoshi Ukai),
+  Futomi Hatano,
+  Gavin Carothers,
+  Gareth Rees,
+  Garrett Smith,
+  Geoffrey Garen,
+  Geoffrey Sneddon,
+  George Lund,
+  Gianmarco Armellin,
+  Giovanni Campagna,
+  Graham Klyne,
+  Greg Botten,
+  Greg Houston,
+  Greg Wilkins,
+  Gregg Tavares,
+  Grey,
+  Gytis Jakutonis,
+  Håkon Wium Lie,
+  Hallvord Reiar Michaelsen Steen,
+  Hans S. Tømmerhalt,
+  Henri Sivonen,
+  Henrik Lied,
+  Henry Mason,
+  Hugh Winkler,
+  Ian Bicking,
+  Ian Davis,
+  Ignacio Javier,
+  Ivan Enderlin,
+  Ivo Emanuel Gonçalves,
+  J. King,
+  Jacques Distler,
+  James Craig,
+  James Graham,
+  James Justin Harrell,
+  James M Snell,
+  James Perrett,
+  James Robinson,
+  Jan-Klaas Kollhof,
+  Jason Kersey,
+  Jason Lustig,
+  Jason White,
+  Jasper Bryant-Greene,
+  Jatinder Mann,
+  Jed Hartman,
+  Jeff Balogh,
+  Jeff Cutsinger,
+  Jeff Schiller,
+  Jeff Walden,
+  Jeffrey Zeldman,
+  胡慧鋒 (Jennifer Braithwaite),
+  Jens Bannmann,
+  Jens Fendler,
+  Jens Lindström,
+  Jens Meiert,
+  Jeremy Keith,
+  Jeremy Orlow,
+  Jeroen van der Meer,
+  Jian Li,
+  Jim Jewett,
+  Jim Ley,
+  Jim Meehan,
+  Jjgod Jiang,
+  João Eiras,
+  Joe Clark,
+  Joe Gregorio,
+  Joel Spolsky,
+  Johan Herland,
+  John Boyer,
+  John Bussjaeger,
+  John Carpenter,
+  John Fallows,
+  John Foliot,
+  John Harding,
+  John Keiser,
+  John Snyders,
+  John-Mark Bell,
+  Johnny Stenback,
+  Jon Ferraiolo,
+  Jon Gibbins,
+  Jon Perlow,
+  Jonas Sicking,
+  Jonathan Cook,
+  Jonathan Rees,
+  Jonathan Worent,
+  Jonny Axelsson,
+  Jorgen Horstink,
+  Jorunn Danielsen Newth,
+  Joseph Kesselman,
+  Joseph Pecoraro,
+  Josh Aas,
+  Josh Levenberg,
+  Joshua Randall,
+  Jukka K. Korpela,
+  Jules Clément-Ripoche,
+  Julian Reschke,
+  Justin Lebar,
+  Justin Sinclair,
+  Kai Hendry,
+  Kartikaya Gupta,
+  Kathy Walton,
+  Kelly Norton,
+  Kevin Benson,
+  Kornél Pál,
+  Kornel Lesinski,
+  Kristof Zelechovski,
+  黒澤剛志 (Kurosawa Takeshi),
+  Kyle Hofmann,
+  Léonard Bouchet,
+  Lachlan Hunt,
+  Larry Masinter,
+  Larry Page,
+  Lars Gunther,
+  Lars Solberg,
+  Laura Granka,
+  Laura L. Carlson,
+  Laura Wisewell,
+  Laurens Holst,
+  Lee Kowalkowski,
+  Leif Halvard Silli,
+  Lenny Domnitser,
+  Leons Petrazickis,
+  Lobotom Dysmon,
+  Logan,
+  Loune,
+  Luke Kenneth Casson Leighton,
+  Maciej Stachowiak,
+  Magnus Kristiansen,
+  Maik Merten,
+  Malcolm Rowe,
+  Mark Birbeck,
+  Mark Miller,
+  Mark Nottingham,
+  Mark Pilgrim,
+  Mark Rowe,
+  Mark Schenk,
+  Mark Wilton-Jones,
+  Martijn Wargers,
+  Martin Atkins,
+  Martin Dürst,
+  Martin Honnen,
+  Martin Kutschker,
+  Martin Thomson,
+  Masataka Yakura,
+  Mathieu Henri,
+  Matt Schmidt,
+  Matt Wright,
+  Matthew Gregan,
+  Matthew Mastracci,
+  Matthew Raymond,
+  Matthew Thomas,
+  Mattias Waldau,
+  Max Romantschuk,
+  Menno van Slooten,
+  Micah Dubinko,
+  Michael 'Ratt' Iannarelli,
+  Michael A. Nachbaur,
+  Michael A. Puls II,
+  Michael Carter,
+  Michael Daskalov,
+  Michael Enright,
+  Michael Gratton,
+  Michael Nordman,
+  Michael Powers,
+  Michael(tm) Smith,
+  Michal Zalewski,
+  Michel Fortin,
+  Michelangelo De Simone,
+  Michiel van der Blonk,
+  Mihai Şucan,
+  Mike Brown,
+  Mike Dierken,
+  Mike Dixon,
+  Mike Schinkel,
+  Mike Shaver,
+  Mikko Rantalainen,
+  Mohamed Zergaoui,
+  Mounir Lamouri,
+  Ms2ger,
+  NARUSE Yui,
+  Neil Deakin,
+  Neil Rashbrook,
+  Neil Soiffer,
+  Nicholas Shanks,
+  Nicholas Stimpson,
+  Nicholas Zakas,
+  Nicolas Gallagher,
+  Noah Mendelsohn,
+  Noah Slater,
+  Ojan Vafai,
+  Olaf Hoffmann,
+  Olav Junker Kjær,
+  Oldřich Vetešník,
+  Oliver Hunt,
+  Oliver Rigby,
+  Olivier Gendrin,
+  Olli Pettay,
+  Patrick H. Lauke,
+  Paul Norman,
+  Per-Erik Brodin,
+  Perry Smith,
+  Peter Karlsson,
+  Peter Kasting,
+  Peter Stark,
+  Peter-Paul Koch,
+  Phil Pickering,
+  Philip Jägenstedt,
+  Philip Taylor,
+  Philip TAYLOR,
+  Prateek Rungta,
+  Pravir Gupta,
+  Rachid Finge,
+  Rajas Moonka,
+  Ralf Stoltze,
+  Ralph Giles,
+  Raphael Champeimont,
+  Remco,
+  Remy Sharp,
+  Rene Saarsoo,
+  Rene Stach,
+  Ric Hardacre,
+  Rich Doughty,
+  Richard Ishida,
+  Rigo Wenning,
+  Rikkert Koppes,
+  Rimantas Liubertas,
+  Riona Macnamara,
+  Rob Ennals,
+  Rob Jellinghaus,
+  Robert Blaut,
+  Robert Collins,
+  Robert O'Callahan,
+  Robert Sayre,
+  Robin Berjon,
+  Roland Steiner,
+  Roman Ivanov,
+  Roy Fielding,
+  Ryan King,
+  S. Mike Dierken,
+  Salvatore Loreto,
+  Sam Dutton,
+  Sam Kuper,
+  Sam Ruby,
+  Sam Weinig,
+  Sander van Lambalgen,
+  Sarven Capadisli,
+  Scott González,
+  Scott Hess,
+  Sean Fraser,
+  Sean Hogan,
+  Sean Knapp,
+  Sebastian Markbåge,
+  Sebastian Schnitzenbaumer,
+  Seth Call,
+  Shanti Rao,
+  Shaun Inman,
+  Shiki Okasaka,
+  Sierk Bornemann,
+  Sigbjørn Vik,
+  Silvia Pfeiffer,
+  Simon Montagu,
+  Simon Pieters,
+  Simon Spiegel,
+  skeww, 
+  Stefan Haustein,
+  Stefan Santesson,
+  Steffen Meschkat,
+  Stephen Ma,
+  Steve Faulkner,
+  Steve Runyon,
+  Steven Bennett,
+  Steven Garrity,
+  Steven Tate,
+  Stewart Brodie,
+  Stuart Ballard,
+  Stuart Parmenter,
+  Subramanian Peruvemba,
+  Sunava Dutta,
+  Susan Borgrink,
+  Susan  Lesch,
+  Sylvain Pasche,
+  T. J. Crowder,
+  Tantek Çelik,
+  田村健人 (TAMURA Kent),
+  Ted Mielczarek,
+  Terrence Wood,
+  Thomas Broyer,
+  Thomas O'Connor,
+  Tim Altman,
+  Tim Johansson,
+  Toby Inkster,
+  Todd Moody,
+  Tom Pike,
+  Tommy Thorsen,
+  Travis Leithead,
+  Tyler Close,
+  Vladimir Katardjiev,
+  Vladimir Vukićević,
+  voracity,
+  Wakaba,
+  Wayne Pollock,
+  Wellington Fernando de Macedo,
+  Will Levine,
+  William Swanson,
+  Wladimir Palant,
+  Wojciech Mach,
+  Wolfram Kriesing,
+  Yang Chen,
+  Yehuda Katz,
+  Yi-An Huang,
+  Yngve Nysaeter Pettersen,
+  Yuzo Fujishima,
+  Zhenbin Xu,
+  Zoltan Herczeg,
+  and
+  Øistein E. Andersen,
+
+  for their useful comments, both large and small, that have led to
+  changes to this specification over the years.

+
+  
Thanks also to everyone who has ever posted about HTML to their
+  blogs, public mailing lists, or forums, including all the
+  contributors to the various W3C HTML WG
+  lists and the various WHATWG lists.
+
+  
Special thanks to Richard Williamson for creating the first
+  implementation of canvas in Safari, from which the
+  canvas feature was designed.

+
+  
Special thanks also to the Microsoft employees who first
+  implemented the event-based drag-and-drop mechanism, contenteditable, and other
+  features first widely deployed by the Windows Internet Explorer
+  browser.

+
+  
Thanks to the participants of the microdata usability study for
+  allowing us to use their mistakes as a guide for designing the
+  microdata feature.

+
+
+  
Thanks to the SubRip community, including in particular Zuggy and
+  ai4spam, for their work on the SubRip software program whose SRT
+  file format was used as the basis for the WebSRT timed track file
+  format.

+
+
+  

+
+  
Special thanks and $10,000 to David Hyatt who came up with a
+  broken implementation of the adoption
+  agency algorithm that the editor had to reverse engineer and fix
+  before using it in the parsing section.

+
+  

+
+  
Thanks to the many sources that provided inspiration for the
+  examples used in the specification.

+
+
+  
Thanks also to the Microsoft blogging community for some ideas,
+  to the attendees of the W3C Workshop on Web Applications and
+  Compound Documents for inspiration, to the #mrt crew, the #mrt.no
+  crew, and the #whatwg crew, and to Pillar and Hedral for their ideas
+  and support.

+
+  
+
+
+ 
diff --git a/PerformanceTests/Parser/resources/runner.js b/PerformanceTests/Parser/resources/runner.js
new file mode 100644
index 0000000..4baa497
--- /dev/null
+++ b/PerformanceTests/Parser/resources/runner.js
@@ -0,0 +1,95 @@
+function log(text) {
+    document.getElementById("log").innerText += text + "\n";
+    window.scrollTo(document.body.height);
+}
+
+function loadFile(path) {
+    var xhr = new XMLHttpRequest();
+    xhr.open("GET", path, false);
+    xhr.send(null);
+    return xhr.responseText;
+}
+
+var runCount = -1;
+var runFunction = function() {};
+var completedRuns = -1; // Discard the any runs < 0.
+var times = [];
+
+function computeAverage(values) {
+    var sum = 0;
+    for (var i = 0; i < values.length; i++)
+        sum += values[i];
+    return sum / values.length;
+}
+
+function computeMax(values) {
+    var max = values.length ? values[0] : 0;
+    for (var i = 1; i < values.length; i++) {
+        if (max < values[i])
+            max = values[i];
+    }
+    return max;
+}
+
+function computeMedian(values) {
+    values.sort(function(a, b) { return a - b; });
+    var len = values.length;
+    if (len % 2)
+        return values[(len-1)/2];
+    return (values[len/2-1] + values[len/2]) / 2;
+}
+
+function computeMin(values) {
+    var min = values.length ? values[0] : 0;
+    for (var i = 1; i < values.length; i++) {
+        if (min > values[i])
+            min = values[i];
+    }
+    return min;
+}
+
+function computeStdev(values) {
+    var average = computeAverage(values);
+    var sumOfSquaredDeviations = 0;
+    for (var i = 0; i < values.length; ++i) {
+        var deviation = values[i] - average;
+        sumOfSquaredDeviations += deviation * deviation;
+    }
+    return Math.sqrt(sumOfSquaredDeviations / values.length);
+}
+
+function logStatistics(times) {
+    log("");
+    log("avg " + computeAverage(times));
+    log("median " + computeMedian(times));
+    log("stdev " + computeStdev(times));
+    log("min " + computeMin(times));
+    log("max " + computeMax(times));
+}
+
+function run() {
+    var start = new Date();
+    for (var i = 0; i < 10; ++i)
+        window.runFunction();
+    var time = new Date() - start;
+    completedRuns++;
+    if (completedRuns <= 0) {
+        log("Ignoring warm-up run (" + time + ")");
+    } else {
+        times.push(time);
+        log(time);
+    }
+    if (completedRuns < window.runCount) {
+        window.setTimeout(run, 0);
+    } else {
+        logStatistics(times);
+    }
+}
+
+function start(runCount, runFunction) {
+    window.runCount = runCount;
+    window.runFunction = runFunction;
+
+    log("Running " + runCount + " times");
+    run();
+}
diff --git a/PerformanceTests/Parser/xml-parser.html b/PerformanceTests/Parser/xml-parser.html
new file mode 100644
index 0000000..2e507c8
--- /dev/null
+++ b/PerformanceTests/Parser/xml-parser.html
@@ -0,0 +1,19 @@
+
+
+

+
+
+
diff --git a/PerformanceTests/SunSpider/ChangeLog b/PerformanceTests/SunSpider/ChangeLog
new file mode 100644
index 0000000..8241848
--- /dev/null
+++ b/PerformanceTests/SunSpider/ChangeLog
@@ -0,0 +1,1083 @@
+2010-11-29  Geoffrey Garen  
+
+        Reviewed by Gavin Barraclough.
+
+        Improved accuracy of command-line SunSpider.
+
+        * resources/sunspider-standalone-driver.js: Use the returned number of
+        elapsed milliseconds from "run" and "checkSyntax" instead of measuring
+        ourselves, for slightly more accurate numbers.
+
+2010-09-16  Gavin Barraclough  
+
+        Reviewed by Mark Rowe.
+        https://bugs.webkit.org/show_bug.cgi?id=45924
+
+        Modify the SunSpider harness to allow a path to be passed to the --suite
+        argument, supress the normal prepend-"tests/" behaviour for suite names
+        containing a '/'.
+
+        Also wrap the code in an anonymous function to move variables out of global
+        scope (currently the harness cannot handle running tests the overwrite the
+        variable 'j').
+
+        * resources/sunspider-standalone-driver.js:
+        * sunspider:
+
+2010-08-27  Michael Saboff  
+
+        Reviewed by Stephanie Lewis.
+
+        Added version 5 and version 6 of V8 tests with modifications similar
+        to the version 4 tests so they'll work with the SunSpider test harness.
+        Note that these files are external source and therefore don't conform 
+        to WebKit coding standards.
+        https://bugs.webkit.org/show_bug.cgi?id=44638
+
+        * tests/v8-v5: Added.
+        * tests/v8-v5/LIST: Added.
+        * tests/v8-v5/v8-crypto.js: Added.
+        * tests/v8-v5/v8-deltablue.js: Added.
+        * tests/v8-v5/v8-earley-boyer.js: Added.
+        * tests/v8-v5/v8-raytrace.js: Added.
+        * tests/v8-v5/v8-regexp.js: Added.
+        * tests/v8-v5/v8-richards.js: Added.
+        * tests/v8-v5/v8-splay.js: Added.
+        * tests/v8-v6: Added.
+        * tests/v8-v6/LIST: Added.
+        * tests/v8-v6/v8-crypto.js: Added.
+        * tests/v8-v6/v8-deltablue.js: Added.
+        * tests/v8-v6/v8-earley-boyer.js: Added.
+        * tests/v8-v6/v8-raytrace.js: Added.
+        * tests/v8-v6/v8-regexp.js: Added.
+        * tests/v8-v6/v8-richards.js: Added.
+        * tests/v8-v6/v8-splay.js: Added.
+
+2010-07-15  Stephanie Lewis  
+
+        Reviewed by Geoff Garen.
+
+        http://bugs.webkit.org/show_bug.cgi?id=42406
+        Output location of results file.
+
+        * sunspider:
+
+2010-05-17  Maciej Stachowiak  
+
+        Reviewed by Mark Rowe.
+
+        Browser-hosted version of SunSpider runs tests twice as many times as advertised
+        https://bugs.webkit.org/show_bug.cgi?id=39201
+
+        * make-hosted: Make sure to reset test list after every test suite.
+
+2010-05-07  Adam Roben  
+
+        Fix typo in sunspider-compare-results.js that caused incorrect
+        two-sample t statistics to be computed
+
+        Fixes  SunSpider computes incorrect
+        two-sample t statistics
+
+        Reviewed by Darin Adler.
+
+        * resources/sunspider-compare-results.js:
+        (sunspiderCompareResults.resultLine): Fixed the calculation of the t
+        variable to match the definition of a two-sample t statistic. Looks
+        like this was just a simple typo.
+
+2010-04-05  Darin Adler  
+
+        Updated the ignore property for changes to the contents here.
+
+        * .: Modified property svn:ignore.
+
+2010-02-20  Maciej Stachowiak  
+
+        Reviewed by Adam Barth.
+
+        Add sunspider-0.9.1 to the site in preparation for announcing it.
+        https://bugs.webkit.org/show_bug.cgi?id=35206
+
+        * hosted/sunspider.css: Remove tabs, which I noticed where present while
+        copying to the WebKitSite directory.
+
+2010-01-11  Oliver Hunt  
+
+        Reviewed by Darin Adler.
+
+        Sunspider parse-only tests don't run
+        https://bugs.webkit.org/show_bug.cgi?id=33489
+
+        Fix parse-only test list
+
+        * tests/parse-only/LIST:
+
+2009-12-15  Maciej Stachowiak  
+
+        Reviewed by Adele Peterson.
+
+        Make SunSpider version more prominent in the title
+        https://bugs.webkit.org/show_bug.cgi?id=32574
+
+        * hosted/sunspider.html:
+        * hosted/versions.html:
+        * resources/driver-TEMPLATE.html:
+        * resources/results-TEMPLATE.html:
+
+2009-12-15  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        Make SunSpider refuse to compare results across content versions
+        https://bugs.webkit.org/show_bug.cgi?id=32573
+        
+        The results URL now includes a version indicator, and compare mode
+        will refuse to compare between versions.
+
+        * resources/driver-TEMPLATE.html:
+        * resources/results-TEMPLATE.html:
+
+2009-12-14  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        Some Browser-hosted SunSpider files are not valid HTML5
+        https://bugs.webkit.org/show_bug.cgi?id=32536
+        
+        Made various fixes to validate as HTML5 with no warnings (mainly removing bogus
+        close tags and adding a meta charset declaration).
+
+        * hosted/sunspider.html:
+        * hosted/versions.html:
+        * resources/TEMPLATE.html:
+        * resources/driver-TEMPLATE.html:
+        * resources/results-TEMPLATE.html:
+
+2009-12-14  Maciej Stachowiak  
+
+        Reviewed by Eric Seidel.
+
+        Make sunspider-0.9.1 the default content set (both command-line and hosted)
+        https://bugs.webkit.org/show_bug.cgi?id=32537
+
+        * hosted/sunspider.html: Change default suite link.
+        * sunspider: Change default suite.
+        * sunspider-compare-results: Likewise.
+
+2009-12-14  Maciej Stachowiak  
+
+        Reviewed by Sam Weinig.
+
+        in-browser SunSpider suffers excessive penalty under power management
+        https://bugs.webkit.org/show_bug.cgi?id=32505
+        
+        I have made a few changes to address this:
+        
+        1) Change how browser-hosted SunSpider loads tests - preload the content and write it in with
+        document.write to reduce triggering of progress UI.
+        2) Reduce time between tests to 10ms from 500ms, so that power management doesn't keep the CPU
+        stepped all the way down the whole time.
+        3) Run the test cycle an extra time for warmup before the runs that count.
+
+        * hosted/sunspider-record-result.js: Removed.
+        * make-hosted:
+        * resources/TEMPLATE.html:
+        * resources/driver-TEMPLATE.html:
+
+2009-12-13  Maciej Stachowiak  
+
+        Reviewed by Gavin Barraclough.
+
+        SunSpider/tests/string-base64.js does not compute a valid base64 encoded string
+        https://bugs.webkit.org/show_bug.cgi?id=16806
+
+        Based on a patch by Eric Seidel.
+        
+        Fix the base64 computation to actually compute correct results. The impact on runtime of
+        the test is pretty small, but noticeable for some browsers. But at least it's not
+        doing a wrong and meaningless computation any more.
+        
+        * tests/sunspider-0.9.1/string-base64.js:
+        ():
+        (base64ToString):
+
+2009-12-13  Maciej Stachowiak  
+
+        Fixing commit error...
+        
+        I accidentally committed my last patch in a form that broke Web-hosted SunSpider. Fixing.
+
+        * resources/driver-TEMPLATE.html:
+
+2009-12-13  Maciej Stachowiak  
+
+        Reviewed by Sam Weinig.
+
+        Use JSON.parse instead of eval for Web-hosted SunSpider results processing
+        https://bugs.webkit.org/show_bug.cgi?id=32490
+
+        * hosted/json2.js: Added. Incorporated from json.org
+        * resources/driver-TEMPLATE.html: Fix an HTML validation bug I noticed.
+        * resources/results-TEMPLATE.html: Use JSON.parse instead of eval to process
+        results.
+
+2009-12-12  Maciej Stachowiak  
+
+        Reviewed by Oliver Hunt.
+
+        Enable Web-hosted version of SunSpider to handle multiple versions
+        https://bugs.webkit.org/show_bug.cgi?id=32478
+
+        * make-hosted: Now generate the hosted version to be able to run both the
+        0.9 and the 0.9.1 test suites.
+        * hosted: Modified property svn:ignore.
+        * hosted/sunspider-driver.html: Removed.
+        * hosted/sunspider-results.html: Removed.
+        * hosted/sunspider.html:
+        * hosted/versions.html: Added.
+        * resources/TEMPLATE.html:
+        * resources/driver-TEMPLATE.html: Copied from hosted/sunspider-driver.html.
+        * resources/driver-TEMPLATE.html: Copied from hosted/sunspider-results.html.
+
+2009-12-12  Maciej Stachowiak  
+
+        Reviewed by Oliver Hunt.
+
+        Give command-line sunspider the ability to handle multiple suites and versions
+        https://bugs.webkit.org/show_bug.cgi?id=32477
+        
+        Each suite/version's set of tests are now in a separate subdirectory of tests/, with a file named LIST
+        enumerating the tests. Current suites are:
+        
+        sunspider-0.9 - riginal SunSpider content 
+        sunspider-0.9.1 - SunSpider suite with a few tests fixed (and a few more to come)
+        ubench - "ubench" microbenchmark suite
+        v8-v4 - version 4 of the v8 benchmark
+        parse-only - some parser tests
+        
+        Sunspider can now be run with the --suite= parameter to select a
+        suite. The default is --suite=sunspider-0.9.
+
+        * .: Modified property svn:ignore to ignore new results directories.
+        * make-hosted: Generate based on sunspider-0.9 suite.
+        * resources/TEMPLATE.html: Fix an HTML compliance problem.
+        * resources/sunspider-standalone-driver.js: Become aware of suite names.
+        * sunspider: Modified to handle multiple suites as described above.
+        * sunspider-compare-results: ditto
+        * tests/LIST: Moved to tests/sunspider-0.9/ and tests/sunspider-0.9.1/
+        * tests/LIST-PARSE-ONLY: Moved to parse-only/LIST
+        * tests/LIST-UBENCH: Removed.
+        * tests/LIST-V8: Removed.
+        * tests/3d-cube.js: Moved to tests/sunspider-0.9 and tests/sunspider-0.9.1
+        * tests/3d-morph.js: ditto
+        * tests/3d-raytrace.js: ditto
+        * tests/access-binary-trees.js: ditto
+        * tests/access-fannkuch.js: ditto
+        * tests/access-nbody.js: ditto
+        * tests/access-nsieve.js: ditto
+        * tests/bitops-3bit-bits-in-byte.js: ditto
+        * tests/bitops-bits-in-byte.js: ditto
+        * tests/bitops-bitwise-and.js: ditto
+        * tests/bitops-nsieve-bits.js: ditto
+        * tests/controlflow-recursive.js: ditto
+        * tests/crypto-aes.js: ditto
+        * tests/crypto-md5.js: ditto
+        * tests/crypto-sha1.js: ditto
+        * tests/date-format-tofte.js: ditto
+        * tests/date-format-xparb.js: ditto
+        * tests/math-cordic.js: ditto
+        * tests/math-partial-sums.js: ditto
+        * tests/math-spectral-norm.js: ditto
+        * tests/regexp-dna.js: ditto
+        * tests/string-base64.js: ditto
+        * tests/string-fasta.js: ditto
+        * tests/string-tagcloud.js: ditto
+        * tests/string-unpack-code.js: ditto
+        * tests/string-validate-input.js: ditto
+        * tests/sunspider-0.9/: Added
+        * tests/sunspider-0.9/*.js: Moved from one level up
+        * tests/sunspider-0.9.1: Added.
+        * tests/sunspider-0.9.1/*.js: Moved from one level up.
+        * tests/v8-crypto.js: Moved to v8-v4/ directory.
+        * tests/v8-deltablue.js: ditto
+        * tests/v8-earley-boyer.js: ditto
+        * tests/v8-raytrace.js: ditto
+        * tests/v8-regexp.js: ditto
+        * tests/v8-richards.js: ditto
+        * tests/v8-splay.js: ditto
+        * tests/v8-v4: Added.
+
+2009-09-30  Csaba Osztrogonac  
+
+        Reviewed by Darin Adler.
+
+        Platform specific null device replaced with a platform independent.
+        https://bugs.webkit.org/show_bug.cgi?id=29544
+
+        * sunspider: Using File::Spec->devnull() instead of /dev/null and NUL.
+
+2009-09-21  Csaba Osztrogonac  
+
+        Reviewed by Maciej Stachowiak.
+
+        [Qt] Make sunspider script work on Windows platform.
+        https://bugs.webkit.org/show_bug.cgi?id=29544
+
+        * sunspider:
+        Using platform specific null device instead of /dev/null.
+
+2009-06-19  Adam Treat  
+
+        Reviewed by Oliver Hunt.
+
+        https://bugs.webkit.org/show_bug.cgi?id=26540
+        Currently the SunSpider test driver lacks an option to run a test suite that
+        will test JavaScriptCore parsing performance only.  This patch adds just such
+        a test suite and option to SunSpider as well as the jsc test shell.  I've included
+        three large javascript source files found in the wild: jquery, mootools and prototype.
+        Combined with the concatenation of all three, these form a new testsuite to measure
+        and test pure JavaScriptCore parsing performance.
+
+        * resources/sunspider-standalone-driver.js:
+          Load the js with parse-only flag if it is part of the parse-only suite.
+        * sunspider:
+          Add the parse-only suite to the list of options.
+        * sunspider-compare-results:
+          Add the parse-only suite to the list of options.
+        * tests/LIST-PARSE-ONLY: Added.
+        * tests/parse-only/concat-jquery-mootools-prototype.js: Added.
+          A very large concatenation of the scripts found below.  This js takes ~30ms to parse on my machine.
+        * tests/parse-only/jquery-1.3.2.js: Added.
+          Latest version from jquery.com.
+        * tests/parse-only/mootools-1.2.2-core-nc.js: Added.
+          Latest version from mootools.net.
+        * tests/parse-only/prototype-1.6.0.3.js: Added.
+          Latest version from prototypejs.org.
+
+2009-06-13  Steve Falkenburg  
+
+        Update V8 benchmark to version 4.
+        
+        Reviewed by Cameron Zwarich.
+
+        * tests/LIST-V8:
+        * tests/v8-crypto.js:
+        * tests/v8-deltablue.js:
+        * tests/v8-earley-boyer.js:
+        * tests/v8-raytrace.js:
+        * tests/v8-regexp.js: Added.
+        * tests/v8-richards.js:
+        * tests/v8-splay.js: Added.
+
+2009-05-26  Olivier DOLE  
+
+        Reviewed by Maciej.
+
+        Store sunspider test suite results in a specific directory for each
+        different type of benchmark (sunspider, V8 or ubench).
+
+        * sunspider:
+        * sunspider-compare-results:
+
+2009-05-12  Steve Falkenburg  
+
+        Build fix.
+
+        * SunSpider.make:
+
+2009-05-11  Steve Falkenburg  
+
+        Include SunSpider tests in production builds.
+        
+        Reviewed by Adam Roben.
+
+        * SunSpider.make: Added.
+        * xcopy.excludes: Added.
+
+2009-03-04  Oliver Hunt  
+
+        Added a few more tests to ubench
+
+        RS=Gavin Barraclough
+
+        Adding a couple of test to cover too few and too many arguments.  This
+        is needed to prevent regressions in all call paths from my current refactoring.
+
+        * tests/LIST-UBENCH:
+        * tests/ubench/function-correct-args.js: Added.
+        (f):
+        * tests/ubench/function-excess-args.js: Added.
+        (f):
+
+2008-10-30  Zoltan Horvath  
+
+        Fix a bug where when V8's or UBENCH's test suite list file is missing
+        the error message is suggesting that SunSpider's list file is missing.
+
+        Reviewed by Sam Weinig.
+
+        * sunspider:
+        (loadTestsList): Fix the error message to use the right list name.
+
+2008-10-07  David Hyatt  
+
+        https://bugs.webkit.org/show_bug.cgi?id=18989
+
+        Remove global substitution from SunSpider regexp test, since only Firefox was honoring it and
+        we want all browsers to be doing the same thing on the test.
+
+        Reviewed by Maciej
+
+        * tests/regexp-dna.js:
+
+2008-09-09  Cameron Zwarich  
+
+        Rubber-stamped by Maciej Stachowiak.
+
+        The bleeding edge branch of V8 now supports passing fileanmes after
+        '-f', so the SunSpider script should be changed to do this again.
+        This allows all 3 major JavaScript engines to be used with the
+        unmodified SunSpider script.
+
+        * sunspider:
+
+2008-09-04  Cameron Zwarich  
+
+        Reviewed by Maciej Stachowiak.
+
+        Add a '--args' option to SunSpider, so that we can pass '-j' to TraceMonkey
+        and '--expose-gc' to V8. Also, rename the '--v8' option to '--v8-suite' and
+        correct the punctuation in its documentation.
+
+        * sunspider:
+
+2008-09-04  Cameron Zwarich  
+
+        Reviewed by Oliver Hunt.
+
+        Bug 20616: Incorporate V8 benchmarks in testing
+        
+
+        This is a first attempt at running the V8 benchmarks within SunSpider,
+        with the --v8 option. The number of iterations is fixed for each
+        benchmark, and was chosen to make each of the benchmarks run between
+        500 ms and 600 ms in V8 on my machine, a 2.16 GHz MacBook Pro.
+
+        * sunspider:
+        * tests/LIST-V8: Added.
+        * tests/v8-crypto.js: Added.
+        * tests/v8-deltablue.js: Added.
+        * tests/v8-earley-boyer.js: Added.
+        * tests/v8-raytrace.js: Added.
+        * tests/v8-richards.js: Added.
+
+2008-09-02  Cameron Zwarich  
+
+        Not reviewed.
+
+        Remove a local change that was accidentally committed in r36034.
+
+        * resources/sunspider-standalone-driver.js:
+
+2008-09-02  Cameron Zwarich  
+
+        Rubber-stamped by Oliver Hunt.
+
+        Make SunSpider work with JavaScript shells that don't take filenames
+        after a '-f' argument.
+
+        * sunspider:
+
+2008-06-07  Cameron Zwarich  
+
+        Reviewed by Timothy.
+
+        Remove the --squirrelfish option from SunSpider, as it is no longer needed.
+
+        * sunspider:
+        * tests/LIST-SQUIRRELFISH: Removed.
+
+2008-06-03  Alexey Proskuryakov  
+
+        Rubber-stamped by Mark Rowe.
+
+        Roll out r31215 - with Mac OS X 10.5.3, there is no need to pause update daemon any more.
+
+        * sunspider:
+
+2008-04-15  Maciej Stachowiak  
+
+        Rubber stamped by Oliver.
+        
+        - add newly working tests to squirrelfish list
+
+        * tests/LIST-SQUIRRELFISH: Add 3d-raytrace and string-unpack-code
+
+2008-04-14  Maciej Stachowiak  
+
+        Rubber stamped by Oliver.
+        
+        - move ubench tests properly.
+
+        * tests/ubench: Added.
+        * tests/ubench/function-closure.js: Added.
+        * tests/ubench/function-empty.js: Added.
+        * tests/ubench/function-missing-args.js: Added.
+        * tests/ubench/function-sum.js: Added.
+        * tests/ubench/loop-empty-resolve.js: Added.
+        * tests/ubench/loop-empty.js: Added.
+        * tests/ubench/loop-sum.js: Added.
+
+2008-04-14  Maciej Stachowiak  
+
+        Rubber stamped by Oliver.
+
+        * sunspider: Don't force --runs=1 in squirrelfish mode any more.
+
+2008-04-14  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+
+        - make --squirrelfish mode use the real harness, but a reduced set of tests
+
+        Also add a new ubench mode which runs the older squirrelfish microbenchmarks.
+
+        * sunspider:
+        * tests/LIST-SQUIRRELFISH:
+        * tests/LIST-UBENCH: Added.
+        * tests/squirrelfish: Moved to tests/ubench
+
+2008-04-14  Geoffrey Garen  
+
+        Reviewed by Maciej Stachowiak.
+        
+        Removed an unused test.
+
+        * tests/squirrelfish/loop-resolve.js: Removed.
+
+2008-04-10  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        Add newly runnable tests to --squirrelfish mode.
+
+        * tests/LIST-SQUIRRELFISH:
+
+2008-04-06  Geoffrey Garen  
+
+        Reviewed by Maciej Stachowiak.
+        
+        A little more love for --squirrelfish mode:
+        
+        Fixed a misplaced sort. Results properly sort now.
+        
+        Added a test list just for squirrelfish, and updated it to include
+        all currently passing SunSpider tests.
+        
+        Fixed the pruning regexp to match 3d-morph.js.
+
+        * sunspider:
+
+2008-03-26  Geoffrey Garen  
+
+        Reviewed by Oliver Hunt.
+        
+        --squirrelfish mode: pared down tests for squirrelfish to chew on.
+
+        * sunspider:
+        * tests/LIST:
+        * tests/squirrelfish: Added.
+        * tests/squirrelfish/function-closure.js: Added.
+        * tests/squirrelfish/function-empty.js: Added.
+        * tests/squirrelfish/function-missing-args.js: Added.
+        * tests/squirrelfish/function-sum.js: Added.
+        * tests/squirrelfish/loop-empty-resolve.js: Added.
+        * tests/squirrelfish/loop-empty.js: Added.
+        * tests/squirrelfish/loop-resolve.js: Added.
+        * tests/squirrelfish/loop-sum.js: Added.
+
+2008-03-21  Alexey Proskuryakov  
+
+        Reviewed by Geoff.
+
+        * sunspider: Pause update daemon on Darwin to make results reliable
+        again (workaround for ).
+
+2008-02-07  Eric Seidel  
+
+        Reviewed by Sam.
+
+        * sunspider: add an error message when ./tests/LIST is not found
+
+2007-12-29  Alp Toker  
+
+        Fix typo.
+
+        * hosted/sunspider.html:
+
+2007-12-29  Alp Toker  
+
+        Reviewed by Maciej.
+
+        Provide the current URL in the SunSpider results page. Useful for
+        copying benchmark results out of browsers without a location bar or
+        where the location bar can't handle long URLs.
+
+        * hosted/sunspider-results.html:
+
+2007-12-20  Eric Seidel  
+
+        Reviewed by mjs.
+
+        * sunspider: increase default number of runs for more accurate numbers
+
+2007-12-18  Mark Rowe  
+
+        Fix typo.
+
+        * hosted/sunspider.html:
+
+2007-12-18  Maciej Stachowiak  
+
+        Reviewed by Eric.
+        
+        - give an extra digit of precision for small differences.
+
+        * resources/sunspider-compare-results.js:
+
+2007-12-17  Maciej Stachowiak  
+
+        Reviewed by Eric.
+        
+        - work around IE layout bugs
+
+        * hosted/sunspider.css:
+
+2007-12-17  Maciej Stachowiak  
+
+        Reviewed by Mark.
+        
+        - fix compare feature
+
+        * hosted/sunspider-results.html:
+
+2007-12-17  Maciej Stachowiak  
+
+        Reviewed by Mark.
+        
+        - Change the format of the output URL to be shorter, to meet IE constraints
+
+        * hosted/sunspider-driver.html:
+        * hosted/sunspider-results.html:
+
+2007-12-13  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        - Add some explanatory test and a dumb logo to SunSpider web hosted version
+
+        * hosted/sunspider-driver.html:
+        * hosted/sunspider-results.html:
+        * hosted/sunspider.css:
+        * hosted/sunspider.html:
+
+2007-12-13  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        - Make the web-hosted version of SunSpider look a little bit less drab.
+
+        * hosted/sunspider-driver.html:
+        * hosted/sunspider-results.html:
+        * hosted/sunspider.css: Added.
+        * hosted/sunspider.html:
+        * resources/TEMPLATE.html:
+
+2007-12-12  Maciej Stachowiak  
+
+        Reviewed by Sam.
+        
+        - Change sunspider-compare-results output from showing "% faster" values to "x as fast" values.
+        
+        A sample of what new-style results would look like:
+        
+        TEST                   COMPARISON            FROM                 TO             DETAILS
+        ...
+        ** TOTAL **:           1.41x as fast     6613.6ms +/- 0.1%   4703.0ms +/- 0.1%     significant
+        ...
+            3bit-bits-in-byte: *1.36x as slow*     88.8ms +/- 0.6%    121.1ms +/- 0.6%     significant
+        
+        * resources/sunspider-compare-results.js:
+
+2007-11-14  Eric Seidel  
+
+        Reviewed by Sam.
+
+        * sunspider: add --shark-cache for L2 Cache Miss profiling
+
+2007-11-09  Alexey Proskuryakov  
+
+        Reviewed by Darin Adler.
+
+        http://bugs.webkit.org/show_bug.cgi?id=15925
+        SunSpider should check for Shark being installed
+
+        * sunspider: Explicitly test that shark command line tool is installed.
+
+2007-11-04  Darin Adler  
+
+        * hosted/sunspider.html: Tweaked formatting a bit.
+
+2007-11-03  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        - Add compare mode and a description of the benchmark to the hosted version.
+
+        * hosted/sunspider-results.html: Add compare mode - you can just paste in another results URL.
+        * hosted/sunspider.html: Added intro text.
+        * make-hosted: Copy new file.
+        * resources/sunspider-compare-results.js: Made more reusable by putting the implementation in
+        a function.
+        * resources/sunspider-standalone-compare.js: Added. Calls the function in the way standalone mode
+        expects.
+        * sunspider-compare-results: Use sunspider-standalone-compare.js.
+
+2007-11-02  Darin Adler  
+
+        * sunspider: Changed "--base" to "--set-baseline".
+
+2007-11-02  Darin Adler  
+
+        Reviewed by Maciej.
+
+        * sunspider: Added a "--base" option that records the current test as a baseline.
+        Moved the code to find the newest .mshark file into a function (since I needed to use
+        it in the other script and I prefer to copy/paste a function).
+
+        * sunspider-compare-results: Added logic to compare the baseline with the last
+        run when you don't pass any parameters.
+
+2007-10-29  Maciej Stachowiak  
+
+        Reviewed by Eric.
+        
+        - Added list of ECMAScript3 features that SunSpider does not cover currently.
+
+        * UNCOVERED: Added.
+
+2007-10-29  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        - Give better error messages when sunspider-compare-results fails
+
+        * sunspider-compare-results:
+
+2007-10-29  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+        
+        - fix Date tests to work in command-line SpiderMonkey
+
+        * tests/date-format-tofte.js:
+        * tests/date-format-xparb.js:
+
+2007-10-29  Darin Adler  
+
+        Reviewed by Maciej.
+
+        * sunspider: Added --shark20 option, to run Shark at its highest sample
+        resolution instead of its default.
+
+2007-10-28  Adam Roben  
+
+        Fix SunSpider on Windows
+
+        Reviewed by Eric.
+
+        * sunspider: Don't use colons in filenames.
+
+2007-10-28  Darin Adler  
+
+        Reviewed by Adam.
+
+        * resources/sunspider-analyze-results.js: Tweak the output format a little.
+        Change so that when there's only one run we don't write out confidence
+        intervals at all rather than writing "NaN" over and over again.
+
+        * sunspider: Use the time and date as a suffix on the results file, that way
+        all the results are left behind in the tmp directory. This will make it easy
+        for us to add features that compare past results in the future. Also rename
+        the .mshark files using the same scheme.
+
+        * sunspider-compare-results: Relax the parsing rules so we can parse the
+        results file exactly as it's emitted from sunspider.
+
+2007-10-25  Adam Roben  
+
+        Strip carriage returns from results
+
+        Carriage returns were screwing up sunspider-compare-results on
+        Windows.
+
+        Rubberstamped by Oliver.
+
+        * sunspider:
+
+2007-10-24  Darin Adler  
+
+        Reviewed by Eric.
+
+        * sunspider: Open the profile in shark after completing a run.
+        * sunspider-compare-results: Tiny perl tweaks.
+
+2007-10-23  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        - Don't hardcode my path to testkjs
+        
+        * sunspider-compare-results:
+
+2007-10-23  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+        
+        - Add a compare script to compare results, and improve formatting of standard results a bit.
+
+        * resources/sunspider-analyze-results.js:
+        * resources/sunspider-compare-results.js: Added.
+        * sunspider-compare-results: Added.
+
+2007-10-23  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        * resources/sunspider-analyze-results.js: Do the error range
+        properly, using the t-distribution instead of 1.96 (which was
+        based on the normal distribution).
+        
+        * sunspider: Print results in a way that will be friendlier to the
+        soon-to-come compare mode.
+
+2007-10-22  Maciej Stachowiak  
+
+        Reviewed by Review.
+        
+        - add more tests (probably the final set for now)
+        
+        Already balanced. Added date, regexp, control flow, and a few
+        more string and object/array access tests.
+        
+        * tests/LIST:
+        * tests/access-fannkuch.js: Added.
+        * tests/access-nbody.js: Added.
+        * tests/controlflow-recursive.js: Added.
+        * tests/date-format-tofte.js: Added.
+        * tests/date-format-xparb.js: Added.
+        * tests/regexp-dna.js: Added.
+        * tests/string-validate-input.js: Added.
+
+2007-10-21  Eric Seidel  
+
+        Reviewed by mjs.
+
+        * sunspider: make --shark only sample from testkjs
+
+2007-10-21  Maciej Stachowiak  
+
+        Rubber stamped by Eric.
+        
+        - added crypto tests (already balanced)
+
+        * tests/LIST:
+        * tests/crypto-aes.js: Added.
+        * tests/crypto-md5.js: Added.
+        * tests/crypto-sha1.js: Added.
+
+2007-10-21  Maciej Stachowiak  
+
+        Reviewed by Adam.
+        
+        - rebalance new tests
+        
+        Scaled the new tests so they take 400-600ms on a reasonably normal user setup:
+        
+        Internet Explorer 7, Window XP, Dell Latitude D810 with a 2.13GHz Pentium M
+
+        This balances them with the existing tests.
+
+        * tests/access-binary-trees.js:
+        * tests/access-nsieve.js:
+        * tests/bitops-nsieve-bits.js:
+        * tests/math-partial-sums.js:
+        * tests/math-spectral-norm.js:
+        * tests/string-fasta.js:
+
+2007-10-20  Eric Seidel  
+
+        Reviewed by darin.
+        
+        Add improved argument handling to sunspider, including
+        --runs=, --tests=
+
+        Reviewed by Mark.
+
+        - Add more new tests, mostly from the computer language shootout. Not normalized yet.
+        
+        * TODO:
+        * tests/LIST:
+        * tests/access-binary-trees.js: Added.
+        * tests/access-nsieve.js: Added.
+        * tests/bitops-nsieve-bits.js: Added.
+        * tests/math-partial-sums.js: Added.
+        * tests/math-spectral-norm.js: Added.
+        * tests/string-fasta.js: Added.
+
+2007-10-20  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        * TODO: Updated to note areas that are now well-covered.
+        
+        - Change the tests and the driver to avoid leaving large object
+        graphs hanging around, since that throws off the subsequent tests.
+        
+        * resources/sunspider-standalone-driver.js:
+        * tests/3d-cube.js:
+        * tests/3d-morph.js:
+        * tests/3d-raytrace.js:
+        * tests/bitops-bitwise-and.js:
+        * tests/string-base64.js:
+        * tests/string-tagcloud.js:
+
+2007-10-20  Maciej Stachowiak  
+
+        Reviewed by Nikolas.
+        
+        - Rebalance test complexity.
+        
+        Scaled all the tests so they take 400-600ms on a reasonably normal user setup:
+        
+        Internet Explorer 7, Window XP, Dell Latitude D810 with a 2.13GHz Pentium M
+
+        However, for some tests, IE7 was a huge outlier compared to other
+        major browsers. For those tests, I used Firefox 2.0.0.8 on the
+        same OS and hardware as a normalization basis.
+        
+        * tests/3d-morph.js:
+        * tests/3d-raytrace.js:
+        * tests/bitops-3bit-bits-in-byte.js:
+        * tests/bitops-bits-in-byte.js:
+        * tests/bitops-bitwise-and.js:
+        * tests/math-cordic.js:
+        * tests/string-base64.js:
+        * tests/string-tagcloud.js:
+        * tests/string-unpack-code.js:
+
+2007-10-20  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        - Fix the browser-hosted driver to be compatible with Safari 2
+
+        * hosted/sunspider-driver.html:
+
+2007-10-20  Maciej Stachowiak  
+
+        Rubber stamped by Hyatt.
+        
+        - Add BSD license notice to cordic test, the original author said to do so.
+
+        * tests/math-cordic.js:
+
+2007-10-18  Maciej Stachowiak  
+
+        Reviewed by Eric.
+        
+        - Support Windows and Windows browsers.
+
+        * hosted/sunspider-results.html: Display results correctly in IE.
+        * sunspider: tweaks to work on Windows, and with spaces in the path.
+
+2007-10-18  Maciej Stachowiak  
+
+        Rubber stamped by Oliver.
+
+        * tests/string-tagcloud.js: Remove stray print()
+
+2007-10-17  Maciej Stachowiak  
+
+        Reviewed by Oliver.
+        
+        Add some string test cases.
+
+        * tests/string-base64.js: Added. Does base64 encoding and decoding.
+        * tests/string-tagcloud.js: Added. Parses a JSON string and
+        generates tagcloud HTML markup based on the data.        
+        * tests/string-unpack-code.js: Added. Unpack compressed versions of
+        four of the most popular JavaScript libraries.
+        * tests/LIST: Added the new tests.
+
+2007-10-16  Maciej Stachowiak  
+
+        Reviewed by Anders.
+
+        * TODO: Updated with info on how to do the stats properly.
+
+        * hosted/sunspider-driver.html: Reduce timeout from 500 to 200 to
+        avoid overly slowing down the benchmark.
+
+        Added some 3D-related test cases.
+        
+        * tests/3d-cube.js: Added.
+        * tests/3d-morph.js: Added.
+        * tests/3d-raytrace.js: Added.
+        * tests/LIST:
+
+2007-10-14  Maciej Stachowiak  
+
+        Reviewed by Darin Adler.
+
+        - New JavaScript benchmark
+        http://bugs.webkit.org/show_bug.cgi?id=15515
+        
+        A start on a new JavaScript benchmark, with standalone and
+        browser-hosted drivers.
+        
+        The test content is still incomplete and the drivers could use
+        some more features but there is enough here to make a good start.
+        
+        The drivers compute a 95% confidence interval on the mean for the
+        whole test, each category, and each individual test to make it
+        easier to tell whether differences are statistically
+        significant. The confidence interval can be narrowed by running
+        the test more times.
+        
+        * TODO: Added. Remaining things that need to be done.
+        * sunspider: Added. Perl script that acts as the standalone test driver.
+        * resources/sunspider-standalone-driver.js: Added. JavaScript part
+        of standalone test driver.
+        * resources/sunspider-analyze-results.js: Added. JavaScript statistical
+        analysis code.
+        * resources/TEMPLATE.html: Added. Template for browser-hosted tests.
+        * make-hosted: Added. Script to generate browser-hosted tests.
+        * hosted/sunspider.html: Added. Start page for browser-hosted test.
+        * hosted/sunspider-driver.html: Added. Driver for browser-hosted tests.
+        * hosted/sunspider-results.html: Added. Results page for browser-hosted
+        tests.
+        * hosted/sunspider-record-result.js: Added. Helper file for browser-hosted
+        tests.
+        * tests/LIST: Added. List of tests to use.
+        * tests/bitops-3bit-bits-in-byte.js: Added. Some initial test content.
+        * tests/bitops-bits-in-byte.js: Added. Ditto.
+        * tests/bitops-bitwise-and.js: Added. Ditto.
+        * tests/math-cordic.js: Added. Ditto.
+
diff --git a/PerformanceTests/SunSpider/SunSpider.make b/PerformanceTests/SunSpider/SunSpider.make
new file mode 100644
index 0000000..46b1468
--- /dev/null
+++ b/PerformanceTests/SunSpider/SunSpider.make
@@ -0,0 +1,4 @@
+install:
+    xcopy /exclude:$(SRCROOT)\xcopy.excludes "$(SRCROOT)\tests" "$(DSTROOT)\AppleInternal\tests\SunSpider\tests" /e/v/i/h/y
+    xcopy /exclude:$(SRCROOT)\xcopy.excludes "$(SRCROOT)\resources" "$(DSTROOT)\AppleInternal\tests\SunSpider\resources" /e/v/i/h/y
+    xcopy /exclude:$(SRCROOT)\xcopy.excludes "$(SRCROOT)\sunspider" "$(DSTROOT)\AppleInternal\tests\SunSpider" /v/i/h/y
diff --git a/PerformanceTests/SunSpider/TODO b/PerformanceTests/SunSpider/TODO
new file mode 100644
index 0000000..fee4bc0
--- /dev/null
+++ b/PerformanceTests/SunSpider/TODO
@@ -0,0 +1,70 @@
+
+* Add more test cases. Categories we'd like to cover (with reasonably
+  real-world tests, preferably not microbenchmarks) include:
+
+  (X marks the ones that are fairly well covered now).
+
+    X math (general)
+    X bitops
+    X 3-d (the math bits)
+    - crypto / encoding
+    X string processing
+    - regexps
+    - date processing
+    - array processing
+    - control flow
+    - function calls / recursion
+    - object access (unclear if it is possible to make a realistic 
+      benchmark that isolates this)
+
+  I'd specifically like to add all the computer language shootout
+  tests that Mozilla is using.
+
+* Normalize tests. Most of the test cases available have a repeat
+  count of some sort, so the time they take can be tuned. The tests
+  should be tuned so that each category contributes about the same
+  total, and so each test in each category contributes about the same
+  amount. The question is, what implementation should be the baseline?
+  My current thought is to either pick some specific browser on a
+  specific platform (IE 7 or Firefox 2 perhaps), or try to target the
+  average that some set of same-generation release browsers get on
+  each test. The latter is more work. IE7 is probably a reasonable
+  normalization target since it is the latest version of the most
+  popular browser, so results on this benchmark will tell you how much
+  you have to gain or lose by using a different browser.
+
+* Instead of using the standard error, the correct way to calculate
+  a 95% confidence interval for a small sample is the t-test. 
+  . Basically this involves
+  using values from a 2-tailed t-distribution table instead of 1.96 to
+  multiply by the error function, a table is available at
+  
+
+* Add support to compare two different engines (or two builds of the
+  same engine) interleaved.
+
+* Add support to compare two existing sets of saved results.
+
+* Allow repeat count to be controlled from the browser-hosted version
+  and the WebKitTools wrapper script.
+
+* Add support to run only a subset of the tests (both command-line and
+  web versions).
+
+* Add a profile mode for the command-line version that runs the tests
+  repeatedly in the same command-line interpreter instance, for ease
+  of profiling.
+
+* Make the browser-hosted version prettier, both in general design and
+  maybe using bar graphs for the output.
+
+* Make it possible to track change over time and generate a graph per
+  result showing result and error bar for each version.
+
+* Hook up to automated testing / buildbot infrastructure.
+
+* Possibly... add the ability to download iBench from its original
+  server, pull out the JS test content, preprocess it, and add it as a
+  category to the benchmark.
+
+* Profit.
diff --git a/PerformanceTests/SunSpider/UNCOVERED b/PerformanceTests/SunSpider/UNCOVERED
new file mode 100644
index 0000000..2a34572
--- /dev/null
+++ b/PerformanceTests/SunSpider/UNCOVERED
@@ -0,0 +1,99 @@
+
+The following language features are not covered:
+
+Operators:
+
+>>>=
+^=
+%=
+in
+prefix --
+>>=
+delete
+void
+instanceof
+
+
+statements:
+
+with
+switch
+
+
+core language feaures:
+
+getters / setters
+closure data access
+heavy use of first-class functions
+
+Builtins:
+
+String.search
+
+Number.toFixed
+Number.toExponential
+Number.toPrecision
+
+RegExp.exec
+RegExp custom properties
+
+Function.apply
+Function.call
+
+parseInt
+parseFloat
+escape
+unescape
+decodeURI
+encodeURI
+
+
+Date.toDateString
+Date.toTimeString
+Date.getUTCFullYear
+Date.getUTCMonth
+Date.getUTCDate
+Date.getUTCDay
+Date.getUTCSeconds
+Date.getMilliseconds
+Date.getUTCMilliseconds
+Date.set*
+
+
+Math.E
+Math.LN2
+Math.LN10
+Math.LOG2E
+Math.LOG10E
+Math.SQRT1_2
+Math.SQRT2
+Math.acos
+Math.asin
+Math.atan
+Math.atan2
+Math.exp
+Math.min
+Math.tan
+
+Object.hasOwnProperty
+Object.propertyIsEnumerable
+Object.isPrototypeOf
+
+
+Array.concat
+Array.join
+Array.pop 
+Array.push
+Array.reverse
+Array.shift
+Array.slice
+Array.sort
+Array.splice
+Array.unshift
+Array.every
+Array.forEach
+Array.some
+Array.indexOf
+Array.lastIndexOf
+Array.filter
+Array.map
diff --git a/PerformanceTests/SunSpider/hosted/json2.js b/PerformanceTests/SunSpider/hosted/json2.js
new file mode 100644
index 0000000..39d8f37
--- /dev/null
+++ b/PerformanceTests/SunSpider/hosted/json2.js
@@ -0,0 +1,481 @@
+/*
+    http://www.JSON.org/json2.js
+    2009-09-29
+
+    Public Domain.
+
+    NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
+
+    See http://www.JSON.org/js.html
+
+
+    This code should be minified before deployment.
+    See http://javascript.crockford.com/jsmin.html
+
+    USE YOUR OWN COPY. IT IS EXTREMELY UNWISE TO LOAD CODE FROM SERVERS YOU DO
+    NOT CONTROL.
+
+
+    This file creates a global JSON object containing two methods: stringify
+    and parse.
+
+        JSON.stringify(value, replacer, space)
+            value       any JavaScript value, usually an object or array.
+
+            replacer    an optional parameter that determines how object
+                        values are stringified for objects. It can be a
+                        function or an array of strings.
+
+            space       an optional parameter that specifies the indentation
+                        of nested structures. If it is omitted, the text will
+                        be packed without extra whitespace. If it is a number,
+                        it will specify the number of spaces to indent at each
+                        level. If it is a string (such as '\t' or ' '),
+                        it contains the characters used to indent at each level.
+
+            This method produces a JSON text from a JavaScript value.
+
+            When an object value is found, if the object contains a toJSON
+            method, its toJSON method will be called and the result will be
+            stringified. A toJSON method does not serialize: it returns the
+            value represented by the name/value pair that should be serialized,
+            or undefined if nothing should be serialized. The toJSON method
+            will be passed the key associated with the value, and this will be
+            bound to the value
+
+            For example, this would serialize Dates as ISO strings.
+
+                Date.prototype.toJSON = function (key) {
+                    function f(n) {
+                        // Format integers to have at least two digits.
+                        return n < 10 ? '0' + n : n;
+                    }
+
+                    return this.getUTCFullYear()   + '-' +
+                         f(this.getUTCMonth() + 1) + '-' +
+                         f(this.getUTCDate())      + 'T' +
+                         f(this.getUTCHours())     + ':' +
+                         f(this.getUTCMinutes())   + ':' +
+                         f(this.getUTCSeconds())   + 'Z';
+                };
+
+            You can provide an optional replacer method. It will be passed the
+            key and value of each member, with this bound to the containing
+            object. The value that is returned from your method will be
+            serialized. If your method returns undefined, then the member will
+            be excluded from the serialization.
+
+            If the replacer parameter is an array of strings, then it will be
+            used to select the members to be serialized. It filters the results
+            such that only members with keys listed in the replacer array are
+            stringified.
+
+            Values that do not have JSON representations, such as undefined or
+            functions, will not be serialized. Such values in objects will be
+            dropped; in arrays they will be replaced with null. You can use
+            a replacer function to replace those with JSON values.
+            JSON.stringify(undefined) returns undefined.
+
+            The optional space parameter produces a stringification of the
+            value that is filled with line breaks and indentation to make it
+            easier to read.
+
+            If the space parameter is a non-empty string, then that string will
+            be used for indentation. If the space parameter is a number, then
+            the indentation will be that many spaces.
+
+            Example:
+
+            text = JSON.stringify(['e', {pluribus: 'unum'}]);
+            // text is '["e",{"pluribus":"unum"}]'
+
+
+            text = JSON.stringify(['e', {pluribus: 'unum'}], null, '\t');
+            // text is '[\n\t"e",\n\t{\n\t\t"pluribus": "unum"\n\t}\n]'
+
+            text = JSON.stringify([new Date()], function (key, value) {
+                return this[key] instanceof Date ?
+                    'Date(' + this[key] + ')' : value;
+            });
+            // text is '["Date(---current time---)"]'
+
+
+        JSON.parse(text, reviver)
+            This method parses a JSON text to produce an object or array.
+            It can throw a SyntaxError exception.
+
+            The optional reviver parameter is a function that can filter and
+            transform the results. It receives each of the keys and values,
+            and its return value is used instead of the original value.
+            If it returns what it received, then the structure is not modified.
+            If it returns undefined then the member is deleted.
+
+            Example:
+
+            // Parse the text. Values that look like ISO date strings will
+            // be converted to Date objects.
+
+            myData = JSON.parse(text, function (key, value) {
+                var a;
+                if (typeof value === 'string') {
+                    a =
+/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*)?)Z$/.exec(value);
+                    if (a) {
+                        return new Date(Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4],
+                            +a[5], +a[6]));
+                    }
+                }
+                return value;
+            });
+
+            myData = JSON.parse('["Date(09/09/2001)"]', function (key, value) {
+                var d;
+                if (typeof value === 'string' &&
+                        value.slice(0, 5) === 'Date(' &&
+                        value.slice(-1) === ')') {
+                    d = new Date(value.slice(5, -1));
+                    if (d) {
+                        return d;
+                    }
+                }
+                return value;
+            });
+
+
+    This is a reference implementation. You are free to copy, modify, or
+    redistribute.
+*/
+
+/*jslint evil: true, strict: false */
+
+/*members "", "\b", "\t", "\n", "\f", "\r", "\"", JSON, "\\", apply,
+    call, charCodeAt, getUTCDate, getUTCFullYear, getUTCHours,
+    getUTCMinutes, getUTCMonth, getUTCSeconds, hasOwnProperty, join,
+    lastIndex, length, parse, prototype, push, replace, slice, stringify,
+    test, toJSON, toString, valueOf
+*/
+
+
+// Create a JSON object only if one does not already exist. We create the
+// methods in a closure to avoid creating global variables.
+
+if (!this.JSON) {
+    this.JSON = {};
+}
+
+(function () {
+
+    function f(n) {
+        // Format integers to have at least two digits.
+        return n < 10 ? '0' + n : n;
+    }
+
+    if (typeof Date.prototype.toJSON !== 'function') {
+
+        Date.prototype.toJSON = function (key) {
+
+            return isFinite(this.valueOf()) ?
+                   this.getUTCFullYear()   + '-' +
+                 f(this.getUTCMonth() + 1) + '-' +
+                 f(this.getUTCDate())      + 'T' +
+                 f(this.getUTCHours())     + ':' +
+                 f(this.getUTCMinutes())   + ':' +
+                 f(this.getUTCSeconds())   + 'Z' : null;
+        };
+
+        String.prototype.toJSON =
+        Number.prototype.toJSON =
+        Boolean.prototype.toJSON = function (key) {
+            return this.valueOf();
+        };
+    }
+
+    var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+        escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+        gap,
+        indent,
+        meta = {    // table of character substitutions
+            '\b': '\\b',
+            '\t': '\\t',
+            '\n': '\\n',
+            '\f': '\\f',
+            '\r': '\\r',
+            '"' : '\\"',
+            '\\': '\\\\'
+        },
+        rep;
+
+
+    function quote(string) {
+
+// If the string contains no control characters, no quote characters, and no
+// backslash characters, then we can safely slap some quotes around it.
+// Otherwise we must also replace the offending characters with safe escape
+// sequences.
+
+        escapable.lastIndex = 0;
+        return escapable.test(string) ?
+            '"' + string.replace(escapable, function (a) {
+                var c = meta[a];
+                return typeof c === 'string' ? c :
+                    '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
+            }) + '"' :
+            '"' + string + '"';
+    }
+
+
+    function str(key, holder) {
+
+// Produce a string from holder[key].
+
+        var i,          // The loop counter.
+            k,          // The member key.
+            v,          // The member value.
+            length,
+            mind = gap,
+            partial,
+            value = holder[key];
+
+// If the value has a toJSON method, call it to obtain a replacement value.
+
+        if (value && typeof value === 'object' &&
+                typeof value.toJSON === 'function') {
+            value = value.toJSON(key);
+        }
+
+// If we were called with a replacer function, then call the replacer to
+// obtain a replacement value.
+
+        if (typeof rep === 'function') {
+            value = rep.call(holder, key, value);
+        }
+
+// What happens next depends on the value's type.
+
+        switch (typeof value) {
+        case 'string':
+            return quote(value);
+
+        case 'number':
+
+// JSON numbers must be finite. Encode non-finite numbers as null.
+
+            return isFinite(value) ? String(value) : 'null';
+
+        case 'boolean':
+        case 'null':
+
+// If the value is a boolean or null, convert it to a string. Note:
+// typeof null does not produce 'null'. The case is included here in
+// the remote chance that this gets fixed someday.
+
+            return String(value);
+
+// If the type is 'object', we might be dealing with an object or an array or
+// null.
+
+        case 'object':
+
+// Due to a specification blunder in ECMAScript, typeof null is 'object',
+// so watch out for that case.
+
+            if (!value) {
+                return 'null';
+            }
+
+// Make an array to hold the partial results of stringifying this object value.
+
+            gap += indent;
+            partial = [];
+
+// Is the value an array?
+
+            if (Object.prototype.toString.apply(value) === '[object Array]') {
+
+// The value is an array. Stringify every element. Use null as a placeholder
+// for non-JSON values.
+
+                length = value.length;
+                for (i = 0; i < length; i += 1) {
+                    partial[i] = str(i, value) || 'null';
+                }
+
+// Join all of the elements together, separated with commas, and wrap them in
+// brackets.
+
+                v = partial.length === 0 ? '[]' :
+                    gap ? '[\n' + gap +
+                            partial.join(',\n' + gap) + '\n' +
+                                mind + ']' :
+                          '[' + partial.join(',') + ']';
+                gap = mind;
+                return v;
+            }
+
+// If the replacer is an array, use it to select the members to be stringified.
+
+            if (rep && typeof rep === 'object') {
+                length = rep.length;
+                for (i = 0; i < length; i += 1) {
+                    k = rep[i];
+                    if (typeof k === 'string') {
+                        v = str(k, value);
+                        if (v) {
+                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
+                        }
+                    }
+                }
+            } else {
+
+// Otherwise, iterate through all of the keys in the object.
+
+                for (k in value) {
+                    if (Object.hasOwnProperty.call(value, k)) {
+                        v = str(k, value);
+                        if (v) {
+                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
+                        }
+                    }
+                }
+            }
+
+// Join all of the member texts together, separated with commas,
+// and wrap them in braces.
+
+            v = partial.length === 0 ? '{}' :
+                gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' +
+                        mind + '}' : '{' + partial.join(',') + '}';
+            gap = mind;
+            return v;
+        }
+    }
+
+// If the JSON object does not yet have a stringify method, give it one.
+
+    if (typeof JSON.stringify !== 'function') {
+        JSON.stringify = function (value, replacer, space) {
+
+// The stringify method takes a value and an optional replacer, and an optional
+// space parameter, and returns a JSON text. The replacer can be a function
+// that can replace values, or an array of strings that will select the keys.
+// A default replacer method can be provided. Use of the space parameter can
+// produce text that is more easily readable.
+
+            var i;
+            gap = '';
+            indent = '';
+
+// If the space parameter is a number, make an indent string containing that
+// many spaces.
+
+            if (typeof space === 'number') {
+                for (i = 0; i < space; i += 1) {
+                    indent += ' ';
+                }
+
+// If the space parameter is a string, it will be used as the indent string.
+
+            } else if (typeof space === 'string') {
+                indent = space;
+            }
+
+// If there is a replacer, it must be a function or an array.
+// Otherwise, throw an error.
+
+            rep = replacer;
+            if (replacer && typeof replacer !== 'function' &&
+                    (typeof replacer !== 'object' ||
+                     typeof replacer.length !== 'number')) {
+                throw new Error('JSON.stringify');
+            }
+
+// Make a fake root object containing our value under the key of ''.
+// Return the result of stringifying the value.
+
+            return str('', {'': value});
+        };
+    }
+
+
+// If the JSON object does not yet have a parse method, give it one.
+
+    if (typeof JSON.parse !== 'function') {
+        JSON.parse = function (text, reviver) {
+
+// The parse method takes a text and an optional reviver function, and returns
+// a JavaScript value if the text is a valid JSON text.
+
+            var j;
+
+            function walk(holder, key) {
+
+// The walk method is used to recursively walk the resulting structure so
+// that modifications can be made.
+
+                var k, v, value = holder[key];
+                if (value && typeof value === 'object') {
+                    for (k in value) {
+                        if (Object.hasOwnProperty.call(value, k)) {
+                            v = walk(value, k);
+                            if (v !== undefined) {
+                                value[k] = v;
+                            } else {
+                                delete value[k];
+                            }
+                        }
+                    }
+                }
+                return reviver.call(holder, key, value);
+            }
+
+
+// Parsing happens in four stages. In the first stage, we replace certain
+// Unicode characters with escape sequences. JavaScript handles many characters
+// incorrectly, either silently deleting them, or treating them as line endings.
+
+            cx.lastIndex = 0;
+            if (cx.test(text)) {
+                text = text.replace(cx, function (a) {
+                    return '\\u' +
+                        ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
+                });
+            }
+
+// In the second stage, we run the text against regular expressions that look
+// for non-JSON patterns. We are especially concerned with '()' and 'new'
+// because they can cause invocation, and '=' because it can cause mutation.
+// But just to be safe, we want to reject all unexpected forms.
+
+// We split the second stage into 4 regexp operations in order to work around
+// crippling inefficiencies in IE's and Safari's regexp engines. First we
+// replace the JSON backslash pairs with '@' (a non-JSON character). Second, we
+// replace all simple value tokens with ']' characters. Third, we delete all
+// open brackets that follow a colon or comma or that begin the text. Finally,
+// we look to see that the remaining characters are only whitespace or ']' or
+// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
+
+            if (/^[\],:{}\s]*$/.
+test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
+replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
+replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {
+
+// In the third stage we use the eval function to compile the text into a
+// JavaScript structure. The '{' operator is subject to a syntactic ambiguity
+// in JavaScript: it can begin a block or an object literal. We wrap the text
+// in parens to eliminate the ambiguity.
+
+                j = eval('(' + text + ')');
+
+// In the optional fourth stage, we recursively walk the new structure, passing
+// each name/value pair to a reviver function for possible transformation.
+
+                return typeof reviver === 'function' ?
+                    walk({'': j}, '') : j;
+            }
+
+// If the text is not JSON parseable, then a SyntaxError is thrown.
+
+            throw new SyntaxError('JSON.parse');
+        };
+    }
+}());
diff --git a/PerformanceTests/SunSpider/hosted/sunspider.css b/PerformanceTests/SunSpider/hosted/sunspider.css
new file mode 100644
index 0000000..c91a103
--- /dev/null
+++ b/PerformanceTests/SunSpider/hosted/sunspider.css
@@ -0,0 +1,31 @@
+
+body { font-family: sans-serif;
+       margin: 20px; 
+       background-color: #D9D5A1; 
+       color: #1B0636 }
+
+h2 { background-color: #4E8AB9; 
+     margin: -20px -20px 0px -20px; 
+     padding: 30px 20px 30px 20px; 
+     color: yellow;
+     border-bottom: 2px solid #360D6B;
+     zoom: 1.0 /* I CAN HAS LAYOUT? (ie hack) */ }
+
+dt { font-weight: bold }
+
+dd { margin-bottom: 1em; margin-top: 0.5em }
+
+:link { color: #1363A1 }
+:visited { color: #5113A1 }
+
+#testframe { margin-top: 20px;
+             width: 80%;
+             height: 500px;
+             border: 2px solid #360D6B }
+
+#logo { float: left;
+        position: relative; 
+        bottom: 0.33em;
+        padding-right: 20px;
+        margin-bottom: -40px; 
+        font-size: 3em }
diff --git a/PerformanceTests/SunSpider/hosted/sunspider.html b/PerformanceTests/SunSpider/hosted/sunspider.html
new file mode 100644
index 0000000..ac65970
--- /dev/null
+++ b/PerformanceTests/SunSpider/hosted/sunspider.html
@@ -0,0 +1,81 @@
+
+
+
+
+
+
+
+SunSpider 0.9.1 JavaScript Benchmark
+
+
+
+
+
+
SunSpider 0.9.1 JavaScript Benchmark

+
+
This is SunSpider, a JavaScript benchmark. This benchmark tests the
+core JavaScript language only, not the DOM or other browser APIs. It
+is designed to compare different versions of the same browser, and
+different browsers to each other. Unlike many widely available
+JavaScript benchmarks, this test is:

+
+

+
Real World

+
This test mostly avoids microbenchmarks, and tries to focus on
+the kinds of actual problems developers solve with JavaScript today,
+and the problems they may want to tackle in the future as the language
+gets faster. This includes tests to generate a tagcloud from JSON
+input, a 3D raytracer, cryptography tests, code decompression, and
+many more examples. There are a few microbenchmarkish things, but they
+mostly represent real performance problems that developers have
+encountered.

+
+
Balanced

+
This test is balanced between different areas of the language and
+different types of code. It's not all math, all string processing, or
+all timing simple loops. In addition to having tests in many
+categories, the individual tests were balanced to take similar amounts
+of time on currently shipping versions of popular browsers.

+
+
Statistically Sound

+
One of the challenges of benchmarking is knowing how much noise
+you have in your measurements. This benchmark runs each test multiple
+times and determines an error range (technically, a 95% confidence
+interval). In addition, in comparison mode it tells you if you have
+enough data to determine if the difference is statistically
+significant.

+
+

+
+
Current version - sunspider-0.9.1: Start Now!

+(When you run the benchmark, be patient - it loops through all of the
+test cases five times and can take a minute or longer to complete.)

+
+All versions.
+
+
+
+
diff --git a/PerformanceTests/SunSpider/hosted/versions.html b/PerformanceTests/SunSpider/hosted/versions.html
new file mode 100644
index 0000000..47741ce
--- /dev/null
+++ b/PerformanceTests/SunSpider/hosted/versions.html
@@ -0,0 +1,54 @@
+
+
+
+
+
+
+
+
+SunSpider 0.9.1 JavaScript Benchmark
+
+
+
+
+
+
SunSpider 0.9.1 JavaScript Benchmark

+
+
This is SunSpider, a JavaScript benchmark. This benchmark tests the
+core JavaScript language only, not the DOM or other browser APIs. It
+is designed to compare different versions of the same browser, and
+different browsers to each other.

+
+
This version of the harness is 0.9.1. This page lists all versions
+of the test content:

+
+
+
+
+
diff --git a/PerformanceTests/SunSpider/make-hosted b/PerformanceTests/SunSpider/make-hosted
new file mode 100755
index 0000000..65b30c1
--- /dev/null
+++ b/PerformanceTests/SunSpider/make-hosted
@@ -0,0 +1,112 @@
+#!/usr/bin/perl -w
+
+# Copyright (C) 2007 Apple Inc.  All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+
+use strict;
+
+open TEMPLATE, " };
+close TEMPLATE;
+
+open DRIVER_TEMPLATE, " };
+close DRIVER_TEMPLATE;
+
+open RESULTS_TEMPLATE, " };
+close RESULTS_TEMPLATE;
+
+my @suites = ("sunspider-0.9", "sunspider-0.9.1");
+
+foreach my $suite (@suites) {
+
+    my @tests = ();
+    my @categories = ();
+    my %uniqueCategories = ();
+
+    mkdir "hosted/${suite}";
+
+    open TESTLIST, "<./tests/${suite}/LIST";
+    while () {
+	chomp;
+	next unless $_;
+	push @tests, $_;
+	my $category = $_;
+	$category =~ s/-.*//;
+	if (!$uniqueCategories{$category}) {
+	    push @categories, $category;
+	    $uniqueCategories{$category} = $category;
+	}
+    }
+    close TESTLIST;
+
+    my @testContents = ();
+    for my $test (@tests) {
+	my $name = "${test}";
+
+	open SCRIPT, " };
+	close SCRIPT;
+
+	my $output = $template;
+	$output =~ s/\@NAME\@/${name}/g;
+	$output =~ s/\@SCRIPT\@/${script}/g;
+	$output =~ s/\\/\\\\/g;
+	$output =~ s/"/\\"/g;
+	$output =~ s/\n/\\n\\\n/g;
+	$output = $output;
+	push @testContents, $output;
+    }
+
+    my $output = $driverTemplate;
+    $output =~ s/\@SUITE\@/${suite}/g;
+
+    open OUTPUT, ">hosted/${suite}/driver.html";
+    print OUTPUT $output;
+    close OUTPUT;
+
+    $output = $resultsTemplate;
+    $output =~ s/\@SUITE\@/${suite}/g;
+
+    open OUTPUT, ">hosted/${suite}/results.html";
+    print OUTPUT $output;
+    close OUTPUT;
+
+    my $prefix = "var tests = [ " . join(", ", map { '"' . $_ . '"' } @tests) . " ];\n";
+    $prefix .= "var categories = [ " . join(", ", map { '"' . $_ . '"' } @categories) . " ];\n";
+
+    open PREFIX, ">hosted/${suite}/sunspider-test-prefix.js";
+    print PREFIX $prefix;
+    close PREFIX;
+
+    my $contents = "var testContents = [ " . join(", ", map { '"' . $_ . '"' } @testContents) . " ];\n";
+
+    open CONTENTS, ">hosted/${suite}/sunspider-test-contents.js";
+    print CONTENTS $contents;
+    close CONTENTS;    
+}
+
+system("cp resources/sunspider-analyze-results.js hosted");
+system("cp resources/sunspider-compare-results.js hosted");
+print "hosted/sunspider.html is ready to use.\n";
diff --git a/PerformanceTests/SunSpider/resources/TEMPLATE.html b/PerformanceTests/SunSpider/resources/TEMPLATE.html
new file mode 100644
index 0000000..3dc3f2f
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/TEMPLATE.html
@@ -0,0 +1,58 @@
+
+
+
+
+
+
+
+SunSpider @NAME@
+
+
+
+
+
@NAME@

+

+

+
+
+
+
+
diff --git a/PerformanceTests/SunSpider/resources/driver-TEMPLATE.html b/PerformanceTests/SunSpider/resources/driver-TEMPLATE.html
new file mode 100644
index 0000000..12d0952
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/driver-TEMPLATE.html
@@ -0,0 +1,115 @@
+
+
+
+
+
+
+
+
+SunSpider 0.9.1 JavaScript Benchmark (@SUITE@ test suite - In Progress...)
+
+
+
+
+
+
SunSpider JavaScript Benchmark (In Progress...)

+
Content Version: @SUITE@

+
+
+
+
+
+

+

+
+
+
diff --git a/PerformanceTests/SunSpider/resources/results-TEMPLATE.html b/PerformanceTests/SunSpider/resources/results-TEMPLATE.html
new file mode 100644
index 0000000..d5007fd
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/results-TEMPLATE.html
@@ -0,0 +1,108 @@
+
+
+
+
+
+
+
+
+SunSpider 0.9.1 JavaScript Benchmark Results (@SUITE@ test suite)
+
+
+
+
+
SunSpider 0.9.1 JavaScript Benchmark Results

+
+
Content Version: @SUITE@

+
+
Run Again

+
+


+(You can bookmark this results URL for later comparison.)

+
+
To compare to another run, paste a saved result URL in the text field below and press enter:

+

+

+
+
+

+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/PerformanceTests/SunSpider/resources/sunspider-analyze-results.js b/PerformanceTests/SunSpider/resources/sunspider-analyze-results.js
new file mode 100644
index 0000000..d849f59
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/sunspider-analyze-results.js
@@ -0,0 +1,268 @@
+/*
+ * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+var count = output.length;
+
+var itemTotals = {};
+itemTotals.length = count;
+
+var total = 0;
+var categoryTotals = {};
+var testTotalsByCategory = {};
+
+var mean = 0;
+var categoryMeans = {};
+var testMeansByCategory = {};
+
+var stdDev = 0;
+var categoryStdDevs = {};
+var testStdDevsByCategory = {};
+
+var stdErr = 0;
+var categoryStdErrs = {};
+var testStdErrsByCategory = {};
+
+function initialize()
+{
+    itemTotals = {total: []};
+
+    for (var i = 0; i < categories.length; i++) {
+        var category = categories[i];
+        itemTotals[category] = [];
+        categoryTotals[category] = 0;
+        testTotalsByCategory[category] = {};
+        categoryMeans[category] = 0;
+        testMeansByCategory[category] = {};
+        categoryStdDevs[category] = 0;
+        testStdDevsByCategory[category] = {};
+        categoryStdErrs[category] = 0;
+        testStdErrsByCategory[category] = {};
+    }
+
+    for (var i = 0; i < tests.length; i++) {
+        var test = tests[i];
+        itemTotals[test] = [];
+        var category = test.replace(/-.*/, "");
+        testTotalsByCategory[category][test] = 0;
+        testMeansByCategory[category][test] = 0;
+        testStdDevsByCategory[category][test] = 0;
+        testStdErrsByCategory[category][test] = 0;
+    }
+
+    for (var i = 0; i < count; i++) {
+        itemTotals["total"][i] = 0;
+        for (var category in categoryTotals) {
+            itemTotals[category][i] = 0;
+            for (var test in testTotalsByCategory[category]) {
+                itemTotals[test][i] = 0;
+            }
+        }
+    }
+}
+
+function computeItemTotals()
+{
+    for (var i = 0; i < output.length; i++) {
+        var result = output[i];
+        for (var test in result) {
+            var time = result[test];
+            var category = test.replace(/-.*/, "");
+            itemTotals["total"][i] += time;
+            itemTotals[category][i] += time;
+            itemTotals[test][i] += time;
+        }
+    }
+}
+
+function computeTotals()
+{
+    for (var i = 0; i < output.length; i++) {
+        var result = output[i];
+        for (var test in result) {
+            var time = result[test];
+            var category = test.replace(/-.*/, "");
+            total += time;
+            categoryTotals[category] += time;
+            testTotalsByCategory[category][test] += time;
+        }
+    }
+}
+
+function computeMeans()
+{
+    mean = total / count;
+    for (var category in categoryTotals) {
+        categoryMeans[category] = categoryTotals[category] / count;
+        for (var test in testTotalsByCategory[category]) {
+            testMeansByCategory[category][test] = testTotalsByCategory[category][test] / count;
+        }
+    }
+}
+
+function standardDeviation(mean, items)
+{
+    var deltaSquaredSum = 0;
+    for (var i = 0; i < items.length; i++) {
+        var delta = items[i] - mean;
+        deltaSquaredSum += delta * delta;
+    }
+    variance = deltaSquaredSum / (items.length - 1);
+    return Math.sqrt(variance);
+}
+
+function computeStdDevs()
+{
+    stdDev = standardDeviation(mean, itemTotals["total"]);
+    for (var category in categoryStdDevs) {
+        categoryStdDevs[category] = standardDeviation(categoryMeans[category], itemTotals[category]);
+    }
+    for (var category in categoryStdDevs) {
+        for (var test in testStdDevsByCategory[category]) {
+            testStdDevsByCategory[category][test] = standardDeviation(testMeansByCategory[category][test], itemTotals[test]);
+        }
+    }
+}
+
+function computeStdErrors()
+{
+    var sqrtCount = Math.sqrt(count);
+
+    stdErr = stdDev / sqrtCount;
+    for (var category in categoryStdErrs) {
+        categoryStdErrs[category] = categoryStdDevs[category] / sqrtCount;
+    }
+    for (var category in categoryStdDevs) {
+        for (var test in testStdErrsByCategory[category]) {
+            testStdErrsByCategory[category][test] = testStdDevsByCategory[category][test] / sqrtCount;
+        }
+    }
+
+}
+
+var tDistribution = [NaN, NaN, 12.71, 4.30, 3.18, 2.78, 2.57, 2.45, 2.36, 2.31, 2.26, 2.23, 2.20, 2.18, 2.16, 2.14, 2.13, 2.12, 2.11, 2.10, 2.09, 2.09, 2.08, 2.07, 2.07, 2.06, 2.06, 2.06, 2.05, 2.05, 2.05, 2.04, 2.04, 2.04, 2.03, 2.03, 2.03, 2.03, 2.03, 2.02, 2.02, 2.02, 2.02, 2.02, 2.02, 2.02, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.96];
+var tMax = tDistribution.length;
+var tLimit = 1.96;
+
+function tDist(n)
+{
+    if (n > tMax)
+        return tLimit;
+    return tDistribution[n];
+}
+
+
+function formatResult(meanWidth, mean, stdErr, n)
+{
+    var meanString = mean.toFixed(1).toString();
+    while (meanString.length < meanWidth) {
+        meanString = " " + meanString;
+    }
+
+    if (n == 1)
+        return meanString + "ms";
+
+    return meanString + "ms +/- " + ((tDist(n) * stdErr / mean) * 100).toFixed(1) + "%";
+}
+
+function computeLabelWidth()
+{
+    var width = "Total".length;
+    for (var category in categoryMeans) {
+        if (category.length + 2 > width)
+            width = category.length + 2;
+    }
+    for (var i = 0; i < tests.length; i++) {
+        var shortName = tests[i].replace(/^[^-]*-/, "");
+        if (shortName.length + 4 > width)
+            width = shortName.length + 4;
+    }
+
+    return width;
+}
+
+function computeMeanWidth()
+{
+    var width = mean.toFixed(1).toString().length;
+    for (var category in categoryMeans) {
+        var candidate = categoryMeans[category].toFixed(2).toString().length;
+        if (candidate > width)
+            width = candidate;
+        for (var test in testMeansByCategory[category]) {
+            var candidate = testMeansByCategory[category][test].toFixed(2).toString().length;
+            if (candidate > width)
+                width = candidate;
+        }
+    }
+
+    return width;
+}
+
+function resultLine(labelWidth, indent, label, meanWidth, mean, stdErr)
+{
+    var result = "";
+    for (i = 0; i < indent; i++) {
+        result += " ";
+    }
+    
+    result += label + ": ";
+
+    for (i = 0; i < (labelWidth - (label.length + indent)); i++) {
+        result += " ";
+    }
+    
+    return result + formatResult(meanWidth, mean, stdErr, count);
+}
+
+function printOutput()
+{
+    var labelWidth = computeLabelWidth();
+    var meanWidth = computeMeanWidth();
+
+    print("\n");
+    print("============================================");
+    if (count == 1)
+        print("RESULTS");
+    else
+        print("RESULTS (means and 95% confidence intervals)");
+    print("--------------------------------------------");
+    print(resultLine(labelWidth, 0, "Total", meanWidth, mean, stdErr));
+    print("--------------------------------------------");
+    for (var category in categoryMeans) {
+        print("");
+        print(resultLine(labelWidth, 2, category, meanWidth, categoryMeans[category], categoryStdErrs[category]));
+        for (var test in testMeansByCategory[category]) {
+            var shortName = test.replace(/^[^-]*-/, "");
+            print(resultLine(labelWidth, 4, shortName, meanWidth, testMeansByCategory[category][test], testStdErrsByCategory[category][test]));
+        }
+    }
+}
+
+initialize();
+computeItemTotals();
+computeTotals();
+computeMeans();
+computeStdDevs();
+computeStdErrors();
+printOutput();
diff --git a/PerformanceTests/SunSpider/resources/sunspider-compare-results.js b/PerformanceTests/SunSpider/resources/sunspider-compare-results.js
new file mode 100644
index 0000000..24671ea
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/sunspider-compare-results.js
@@ -0,0 +1,380 @@
+/*
+ * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+function sunspiderCompareResults(output1, output2)
+{
+    var count1 = output1.length;
+    var count2 = output2.length;
+
+    var itemTotals1 = {};
+    itemTotals1.length = count1;
+    
+    var total1 = 0;
+    var categoryTotals1 = {};
+    var testTotalsByCategory1 = {};
+    
+    var mean1 = 0;
+    var categoryMeans1 = {};
+    var testMeansByCategory1 = {};
+    
+    var stdDev1 = 0;
+    var categoryStdDevs1 = {};
+    var testStdDevsByCategory1 = {};
+    
+    var stdErr1 = 0;
+    var categoryStdErrs1 = {};
+    var testStdErrsByCategory1 = {};
+    
+    var itemTotals2 = {};
+    itemTotals2.length = count2;
+    
+    var total2 = 0;
+    var categoryTotals2 = {};
+    var testTotalsByCategory2 = {};
+    
+    var mean2 = 0;
+    var categoryMeans2 = {};
+    var testMeansByCategory2 = {};
+    
+    var stdDev2 = 0;
+    var categoryStdDevs2 = {};
+    var testStdDevsByCategory2 = {};
+    
+    var stdErr2 = 0;
+    var categoryStdErrs2 = {};
+    var testStdErrsByCategory2 = {};
+    
+    function initialize()
+    {
+        itemTotals1 = {total: []};
+        
+        for (var i = 0; i < categories.length; i++) {
+            var category = categories[i];
+            itemTotals1[category] = [];
+            categoryTotals1[category] = 0;
+            testTotalsByCategory1[category] = {};
+            categoryMeans1[category] = 0;
+            testMeansByCategory1[category] = {};
+            categoryStdDevs1[category] = 0;
+            testStdDevsByCategory1[category] = {};
+            categoryStdErrs1[category] = 0;
+            testStdErrsByCategory1[category] = {};
+        }
+        
+        for (var i = 0; i < tests.length; i++) {
+            var test = tests[i];
+            itemTotals1[test] = [];
+            var category = test.replace(/-.*/, "");
+            testTotalsByCategory1[category][test] = 0;
+            testMeansByCategory1[category][test] = 0;
+            testStdDevsByCategory1[category][test] = 0;
+            testStdErrsByCategory1[category][test] = 0;
+        }
+        
+        for (var i = 0; i < count1; i++) {
+            itemTotals1["total"][i] = 0;
+            for (var category in categoryTotals1) {
+                itemTotals1[category][i] = 0;
+                for (var test in testTotalsByCategory1[category]) {
+                    itemTotals1[test][i] = 0;
+                }
+            }
+        }
+        
+        itemTotals2 = {total: []};
+        
+        for (var i = 0; i < categories.length; i++) {
+            var category = categories[i];
+            itemTotals2[category] = [];
+            categoryTotals2[category] = 0;
+            testTotalsByCategory2[category] = {};
+            categoryMeans2[category] = 0;
+            testMeansByCategory2[category] = {};
+            categoryStdDevs2[category] = 0;
+            testStdDevsByCategory2[category] = {};
+            categoryStdErrs2[category] = 0;
+            testStdErrsByCategory2[category] = {};
+        }
+        
+        for (var i = 0; i < tests.length; i++) {
+            var test = tests[i];
+            itemTotals2[test] = [];
+            var category = test.replace(/-.*/, "");
+            testTotalsByCategory2[category][test] = 0;
+            testMeansByCategory2[category][test] = 0;
+            testStdDevsByCategory2[category][test] = 0;
+            testStdErrsByCategory2[category][test] = 0;
+        }
+        
+        for (var i = 0; i < count2; i++) {
+            itemTotals2["total"][i] = 0;
+            for (var category in categoryTotals2) {
+                itemTotals2[category][i] = 0;
+                for (var test in testTotalsByCategory2[category]) {
+                    itemTotals2[test][i] = 0;
+                }
+            }
+        }
+        
+    }
+    
+    function computeItemTotals(output, itemTotals)
+    {
+        for (var i = 0; i < output.length; i++) {
+            var result = output[i];
+            for (var test in result) {
+                var time = result[test];
+                var category = test.replace(/-.*/, "");
+                itemTotals["total"][i] += time;
+                itemTotals[category][i] += time;
+                itemTotals[test][i] += time;
+            }
+        }
+    }
+    
+    function computeTotals(output, categoryTotals, testTotalsByCategory)
+    {
+        var total = 0;
+        
+        for (var i = 0; i < output.length; i++) {
+            var result = output[i];
+            for (var test in result) {
+                var time = result[test];
+                var category = test.replace(/-.*/, "");
+                total += time;
+                categoryTotals[category] += time;
+                testTotalsByCategory[category][test] += time;
+            }
+        }
+        
+        return total;
+    }
+    
+    function computeMeans(count, total, categoryTotals, categoryMeans, testTotalsByCategory, testMeansByCategory)
+    {
+        var mean = total / count;
+        for (var category in categoryTotals) {
+            categoryMeans[category] = categoryTotals[category] / count;
+            for (var test in testTotalsByCategory[category]) {
+                testMeansByCategory[category][test] = testTotalsByCategory[category][test] / count;
+            }
+        }
+        return mean;
+    }
+    
+    function standardDeviation(mean, items)
+    {
+        var deltaSquaredSum = 0;
+        for (var i = 0; i < items.length; i++) {
+            var delta = items[i] - mean;
+            deltaSquaredSum += delta * delta;
+        }
+        variance = deltaSquaredSum / (items.length - 1);
+        return Math.sqrt(variance);
+    }
+    
+    function computeStdDevs(mean, itemTotals, categoryStdDevs, categoryMeans, testStdDevsByCategory, testMeansByCategory)
+    {
+        var stdDev = standardDeviation(mean, itemTotals["total"]);
+        for (var category in categoryStdDevs) {
+            categoryStdDevs[category] = standardDeviation(categoryMeans[category], itemTotals[category]);
+        }
+        for (var category in categoryStdDevs) {
+            for (var test in testStdDevsByCategory[category]) {
+                testStdDevsByCategory[category][test] = standardDeviation(testMeansByCategory[category][test], itemTotals[test]);
+            }
+        }
+        return stdDev;
+    }
+    
+    function computeStdErrors(count, stdDev, categoryStdErrs, categoryStdDevs, testStdErrsByCategory, testStdDevsByCategory)
+    {
+        var sqrtCount = Math.sqrt(count);
+        
+        var stdErr = stdDev / sqrtCount;
+        for (var category in categoryStdErrs) {
+            categoryStdErrs[category] = categoryStdDevs[category] / sqrtCount;
+        }
+        for (var category in categoryStdDevs) {
+            for (var test in testStdErrsByCategory[category]) {
+                testStdErrsByCategory[category][test] = testStdDevsByCategory[category][test] / sqrtCount;
+            }
+        }
+        
+        return stdErr;
+    }
+    
+    var tDistribution = [NaN, NaN, 12.71, 4.30, 3.18, 2.78, 2.57, 2.45, 2.36, 2.31, 2.26, 2.23, 2.20, 2.18, 2.16, 2.14, 2.13, 2.12, 2.11, 2.10, 2.09, 2.09, 2.08, 2.07, 2.07, 2.06, 2.06, 2.06, 2.05, 2.05, 2.05, 2.04, 2.04, 2.04, 2.03, 2.03, 2.03, 2.03, 2.03, 2.02, 2.02, 2.02, 2.02, 2.02, 2.02, 2.02, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.01, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.99, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.98, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.97, 1.96];
+    var tMax = tDistribution.length;
+    var tLimit = 1.96;
+    
+    function tDist(n)
+    {
+        if (n > tMax)
+            return tLimit;
+        return tDistribution[n];
+    }
+    
+    
+    function formatMean(meanWidth, mean, stdErr, count)
+    {
+        var meanString = mean.toFixed(1).toString();
+        while (meanString.length < meanWidth) {
+            meanString = " " + meanString;
+        }
+        
+        var error = "+/- " + ((tDist(count) * stdErr / mean) * 100).toFixed(1) + "% ";
+        
+        return meanString + "ms " + error;
+    }
+    
+    function computeLabelWidth()
+    {
+        var width = "Total".length;
+        for (var category in categoryMeans1) {
+            if (category.length + 2 > width)
+                width = category.length + 2;
+        }
+        for (var i = 0; i < tests.length; i++) {
+            var shortName = tests[i].replace(/^[^-]*-/, "");
+            if (shortName.length + 4 > width)
+                width = shortName.length + 4;
+        }
+        
+        return width;
+    }
+    
+    function computeMeanWidth(mean, categoryMeans, testMeansByCategory)
+    {
+        var width = mean.toFixed(1).toString().length;
+        for (var category in categoryMeans) {
+            var candidate = categoryMeans[category].toFixed(1).toString().length;
+            if (candidate > width)
+                width = candidate;
+            for (var test in testMeansByCategory[category]) {
+                var candidate = testMeansByCategory[category][test].toFixed(1).toString().length;
+                if (candidate > width)
+                    width = candidate;
+            }
+        }
+        
+        return width;
+    }
+    
+    function pad(str, n)
+    {
+        while (str.length < n) {
+            str += " ";
+        }
+        return str;
+    }
+    
+    function resultLine(labelWidth, indent, label, meanWidth1, mean1, stdErr1, meanWidth2, mean2, stdErr2)
+    {
+        result = pad("", indent);    
+        result += label + ": ";
+        result = pad(result, labelWidth + 2);
+        
+        var t = (mean1 - mean2) / (Math.sqrt((stdErr1 * stdErr1) + (stdErr2 * stdErr2)));
+        var df = count1 + count2 - 2;
+        
+        var statisticallySignificant = (Math.abs(t) > tDist(df+1));
+        var diff = mean2 - mean1;
+        var percentage = 100 * diff / mean1;
+        var isFaster = diff < 0;
+        var probablySame = (percentage < 0.1) && !statisticallySignificant;
+        var ratio = isFaster ? (mean1 / mean2) : (mean2 / mean1);
+        var fixedRatio = (ratio < 1.2) ? ratio.toFixed(3).toString() : ((ratio < 10) ? ratio.toFixed(2).toString() : ratio.toFixed(1).toString());
+        var formattedRatio = isFaster ? fixedRatio + "x as fast" : "*" + fixedRatio + "x as slow*";
+
+        var diffSummary;
+        var diffDetail;
+        
+        if (probablySame) {
+            diffSummary = "-";
+            diffDetail = "";
+        } else if (!statisticallySignificant) {
+            diffSummary = "??";
+            diffDetail =  "    not conclusive: might be " + formattedRatio;
+        } else {
+            diffSummary = formattedRatio;
+            diffDetail = "    significant"; 
+        }
+        
+        return result + pad(diffSummary, 18) + formatMean(meanWidth1, mean1, stdErr1, count1) + "  " + formatMean(meanWidth2, mean2, stdErr2, count2) + diffDetail;
+    }
+    
+    function printOutput()
+    {
+        var labelWidth = computeLabelWidth();
+        var meanWidth1 = computeMeanWidth(mean1, categoryMeans1, testMeansByCategory1);
+        var meanWidth2 = computeMeanWidth(mean2, categoryMeans2, testMeansByCategory2);
+        
+        print("\n");
+        var header = "TEST";
+        while (header.length < labelWidth)
+            header += " ";
+        header += "  COMPARISON            FROM                 TO             DETAILS";
+        print(header);
+        print("");
+        print("=============================================================================");
+        print("");
+        print(resultLine(labelWidth, 0, "** TOTAL **", meanWidth1, mean1, stdErr1, meanWidth2, mean2, stdErr2));
+        print("");
+        print("=============================================================================");
+        
+        for (var category in categoryMeans1) {
+            print("");
+            print(resultLine(labelWidth, 2, category,
+                             meanWidth1, categoryMeans1[category], categoryStdErrs1[category],
+                             meanWidth2, categoryMeans2[category], categoryStdErrs2[category]));
+            for (var test in testMeansByCategory1[category]) {
+                var shortName = test.replace(/^[^-]*-/, "");
+                print(resultLine(labelWidth, 4, shortName, 
+                                 meanWidth1, testMeansByCategory1[category][test], testStdErrsByCategory1[category][test],
+                                 meanWidth2, testMeansByCategory2[category][test], testStdErrsByCategory2[category][test]));
+            }
+        }
+    }
+    
+    initialize();
+    
+    computeItemTotals(output1, itemTotals1);
+    computeItemTotals(output2, itemTotals2);
+
+    total1 = computeTotals(output1, categoryTotals1, testTotalsByCategory1);
+    total2 = computeTotals(output2, categoryTotals2, testTotalsByCategory2);
+
+    mean1 = computeMeans(count1, total1, categoryTotals1, categoryMeans1, testTotalsByCategory1, testMeansByCategory1);
+    mean2 = computeMeans(count2, total2, categoryTotals2, categoryMeans2, testTotalsByCategory2, testMeansByCategory2);
+
+    stdDev1 = computeStdDevs(mean1, itemTotals1, categoryStdDevs1, categoryMeans1, testStdDevsByCategory1, testMeansByCategory1);
+    stdDev2 = computeStdDevs(mean2, itemTotals2, categoryStdDevs2, categoryMeans2, testStdDevsByCategory2, testMeansByCategory2);
+
+    stdErr1 = computeStdErrors(count1, stdDev1, categoryStdErrs1, categoryStdDevs1, testStdErrsByCategory1, testStdDevsByCategory1);
+    stdErr2 = computeStdErrors(count2, stdDev2, categoryStdErrs2, categoryStdDevs2, testStdErrsByCategory2, testStdDevsByCategory2);
+
+    printOutput();
+}
diff --git a/PerformanceTests/SunSpider/resources/sunspider-standalone-compare.js b/PerformanceTests/SunSpider/resources/sunspider-standalone-compare.js
new file mode 100644
index 0000000..e82c155
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/sunspider-standalone-compare.js
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+sunspiderCompareResults(output1, output2);
diff --git a/PerformanceTests/SunSpider/resources/sunspider-standalone-driver.js b/PerformanceTests/SunSpider/resources/sunspider-standalone-driver.js
new file mode 100644
index 0000000..136e6b7
--- /dev/null
+++ b/PerformanceTests/SunSpider/resources/sunspider-standalone-driver.js
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+var results = new Array();
+
+(function(){
+
+var time = 0;
+var times = [];
+times.length = tests.length;
+
+for (var j = 0; j < tests.length; j++) {
+    var testName = suitePath + "/" + tests[j] + ".js";
+    var startTime = new Date;
+    if (testName.indexOf('parse-only') >= 0)
+        times[j] = checkSyntax(testName);
+    else
+        times[j] = run(testName);
+    gc();
+}
+
+function recordResults(tests, times)
+{
+    var output = "{\n";
+
+    for (j = 0; j < tests.length; j++) {
+        output += '    "' + tests[j] + '": ' + times[j] + ',\n'; 
+    }
+    output = output.substring(0, output.length - 2) + "\n";
+
+    output += "}";
+    print(output);
+}
+
+recordResults(tests, times);
+
+})();
+
diff --git a/PerformanceTests/SunSpider/sunspider b/PerformanceTests/SunSpider/sunspider
new file mode 100755
index 0000000..dbe26cd
--- /dev/null
+++ b/PerformanceTests/SunSpider/sunspider
@@ -0,0 +1,244 @@
+#!/usr/bin/perl -w
+
+# Copyright (C) 2007 Apple Inc. All rights reserved.
+# Copyright (C) 2007 Eric Seidel 
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+
+use strict;
+use Getopt::Long;
+use File::Basename;
+use File::Spec;
+use Cwd;
+use POSIX qw(strftime);
+use Time::HiRes qw(gettimeofday tv_interval);
+
+my $showHelp = 0;
+my $runShark = 0;
+my $runShark20 = 0;
+my $runSharkCache = 0;
+my $ubench = 0;
+my $v8suite = 0;
+my $suite = "";
+my $parseOnly = 0;
+my $jsShellPath;
+my $jsShellArgs = "";
+my $setBaseline = 0;
+my $testsPattern;
+my $testRuns = 10;
+
+my $programName = basename($0);
+my $usage = < \$testRuns,
+           'set-baseline' => \$setBaseline,
+           'shell=s' => \$jsShellPath,
+           'args=s' => \$jsShellArgs,
+           'shark' => \$runShark,
+           'shark20' => \$runShark20,
+           'shark-cache' => \$runSharkCache,
+           'suite=s' => \$suite,
+           'ubench' => \$ubench,
+           'v8-suite' => \$v8suite,
+           'parse-only' => \$parseOnly,
+           'tests=s' => \$testsPattern,
+           'help' => \$showHelp);
+
+
+$suite = "ubench" if ($ubench);
+$suite = "v8-v4" if ($v8suite);
+$suite = "parse-only" if ($parseOnly);
+$suite = "sunspider-0.9.1" if (!$suite);
+
+my $resultDirectory = "${suite}-results";
+
+my $suitePath = $suite;
+$suitePath = "tests/" . $suitePath unless ($suite =~ /\//);
+
+$runShark = 1 if $runSharkCache;
+$runShark = 20 if $runShark20;
+$testRuns = 1 if $runShark;
+if ($runShark && ! -x "/usr/bin/shark") {
+    die "Please install CHUD tools from http://developer.apple.com/tools/download/\n";
+}
+
+my $sharkCacheProfileIndex = 0;
+if ($runSharkCache) {
+    my $sharkProfileList = `shark -l 2>&1`;
+    for my $profile (split(/\n/, $sharkProfileList)) {
+        $profile =~ /(\d+) - (.+)/;
+        next  unless (defined $1);
+        my $profileIndex = $1;
+        my $profileName = $2;
+        if ($profileName =~ /L2 Cache/) {
+            $sharkCacheProfileIndex = $profileIndex;
+            print "Using Shark L2 Cache Miss Profile: " . $profile . "\n";
+            last;
+        }
+    }
+    die "Failed to find L2 Cache Miss Profile for --shark-cache\n"  unless ($sharkCacheProfileIndex);
+}
+
+if (!$jsShellPath || $showHelp) {
+   print STDERR $usage;
+   exit 1;
+}
+
+sub dumpToFile($$)
+{
+    my ($contents, $path) = @_;
+    open FILE, ">", $path or die "Failed to open $path";
+    print FILE $contents;
+    close FILE;
+}
+
+my @tests = ();
+my @categories = ();
+my %uniqueCategories = ();
+
+sub loadTestsList()
+{
+    open TESTLIST, "<", "${suitePath}/LIST" or die "Can't find ${suitePath}/LIST";
+    while () {
+        chomp;
+        next unless !$testsPattern || /$testsPattern/;
+        
+        push @tests, $_;
+        my $category = $_;
+        $category =~ s/-.*//;
+        if (!$uniqueCategories{$category}) {
+            push @categories, $category;
+            $uniqueCategories{$category} = $category;
+        }
+    }
+    close TESTLIST;
+}
+
+my $timeString = strftime "%Y-%m-%d-%H.%M.%S", localtime $^T;
+my $prefixFile = "$resultDirectory/sunspider-test-prefix.js";
+my $resultsFile = "$resultDirectory/sunspider-results-$timeString.js";
+
+sub writePrefixFile()
+{
+    my $prefix = "var suitePath = " . '"' . $suitePath . '"' . ";\n";
+    $prefix .= "var tests = [ " . join(", ", map { '"' . $_ . '"' } @tests) . " ];\n";
+    $prefix .= "var categories = [ " . join(", ", map { '"' . $_ . '"' } @categories) . " ];\n";
+
+    mkdir "$resultDirectory";
+    dumpToFile($prefix, $prefixFile);
+}
+
+sub runTestsOnce($)
+{
+    my ($useShark) = @_;
+    my $shellArgs = $jsShellArgs . " -f $prefixFile -f resources/sunspider-standalone-driver.js 2> " . File::Spec->devnull();
+    my $output;
+    if ($useShark) {
+        my $intervalArg = $useShark == 20 ? "-I 20u" : "";
+        my $cacheArg = $runSharkCache ? "-c $sharkCacheProfileIndex" : "";
+        $output = `shark $intervalArg $cacheArg -i -1-q "$jsShellPath" $shellArgs`;
+    } else {
+        $output = `"$jsShellPath" $shellArgs | grep -v break`;
+    }
+    return $output;
+}
+
+sub newestFile($$)
+{
+    my ($dir, $pattern) = @_;
+
+    my $newestAge;
+    my $newestFile = "";
+    opendir DIR, $dir or die;
+    for my $file (readdir DIR) {
+        if ($file =~ $pattern) {
+            my $age = -M "$dir/$file";
+            if (!defined $newestAge || $age < $newestAge) {
+                $newestFile = $file;
+                $newestAge = $age;
+            }
+        }
+    }
+    closedir DIR;
+
+    return "$dir/$newestFile";
+}
+
+loadTestsList();
+if ($testsPattern) {
+    print STDERR "Found " . scalar(@tests) . " tests matching '" . $testsPattern . "'\n";
+} else {
+    print STDERR "Found " . scalar(@tests) . " tests\n";
+}
+die "No tests to run"  unless scalar(@tests);
+print STDERR "Running SunSpider once for warmup, then " . ($runShark ? "under Shark" : "$testRuns time" . ($testRuns == 1 ? "" : "s")) . "\n";
+writePrefixFile();
+
+runTestsOnce(0);
+print "Discarded first run.\n";
+
+my $result;
+my $count = 0;
+my @results = ();
+my $total = 0;
+print "[";
+while ($count++ < $testRuns) {
+    $result = runTestsOnce($runShark);
+    $result =~ s/\r\n/\n/g;
+    chomp $result;
+    push @results, $result;
+    print $result;
+    print ",\n" unless ($count == $testRuns);
+}
+print "]\n";
+
+my $output = "var output = [\n" . join(",\n", @results) . "\n];\n";
+dumpToFile($output, $resultsFile);
+dumpToFile(File::Spec->rel2abs($resultsFile), "$resultDirectory/baseline-filename.txt") if $setBaseline;
+
+system("$jsShellPath", "-f", $prefixFile, "-f", $resultsFile, "-f", "resources/sunspider-analyze-results.js");
+
+print("\nResults are located at $resultsFile\n");
+
+if ($runShark) {
+    my $newestMShark = newestFile(".", qr/\.mshark$/);
+    if ($newestMShark) {
+        my $profileFile = "$resultDirectory/sunspider-profile-$timeString.mshark";
+        rename $newestMShark, $profileFile or die;
+        exec "/usr/bin/open", $profileFile;
+    }
+}
diff --git a/PerformanceTests/SunSpider/sunspider-compare-results b/PerformanceTests/SunSpider/sunspider-compare-results
new file mode 100755
index 0000000..09b7052
--- /dev/null
+++ b/PerformanceTests/SunSpider/sunspider-compare-results
@@ -0,0 +1,161 @@
+#!/usr/bin/perl -w
+
+# Copyright (C) 2007 Apple Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+
+use strict;
+use Getopt::Long;
+use File::Basename;
+
+my $showHelp = 0;
+my $jsShellPath;
+my $suite = "";
+my $ubench = 0;
+my $v8suite = 0;
+my $parseOnly = 0;
+
+my $programName = basename($0);
+my $usage = < \$jsShellPath,
+           'suite=s' => \$suite,
+           'ubench' => \$ubench,
+           'v8-suite' => \$v8suite,
+           'parse-only' => \$parseOnly,
+           'help' => \$showHelp);
+
+$suite = "ubench" if ($ubench);
+$suite = "v8-v4" if ($v8suite);
+$suite = "parse-only" if ($parseOnly);
+$suite = "sunspider-0.9.1" if (!$suite);
+
+my $resultDirectory = "${suite}-results";
+
+if ((scalar @ARGV != 0 && scalar @ARGV != 2) || !$jsShellPath || $showHelp) {
+   print STDERR $usage;
+   exit 1;
+}
+
+sub readResultsFile($)
+{
+    my ($filename) = @_;
+    open FILE, "<", $filename or die;
+    my $foundStart = 0;
+    my $foundOutput = 0;
+    my $foundEnd = 0;
+    my $result = "";
+    while () {
+        if (!$foundStart) {
+            if (/^\[\{$/) {
+                $foundStart = 1;
+                $result .= $_;
+            } elsif (/^var \w+ = \[$/) {
+                $foundOutput = 1;
+            } elsif ($foundOutput && /^\{$/) {
+                $foundOutput = 0;
+                $foundStart = 1;
+                $result = "[{\n";
+            }
+        } else {
+            if (/\];?$/) {
+                $foundEnd = 1;
+                chomp;
+                s/;$//;
+                $result .= $_;
+                last;
+            } else {
+                $result .= $_;
+            }
+        } 
+    }
+    close FILE;
+
+    die "Cound not find data in ${filename} - needs to start with [{" unless $foundStart;
+    die "Cound not find data in ${filename} - needs to end with }]" unless $foundEnd;
+
+    return $result;
+}
+
+sub dumpToFile($$)
+{
+    my ($contents, $path) = @_;
+    open FILE, ">", $path or die;
+    print FILE $contents;
+    close FILE;
+}
+
+sub readFile($)
+{
+    my ($path) = @_;
+    open FILE, "<", $path or die;
+    my $result = ;
+    close FILE;
+    return $result;
+}
+
+sub newestFile($$)
+{
+    my ($dir, $pattern) = @_;
+
+    my $newestAge;
+    my $newestFile = "";
+    opendir DIR, $dir or die;
+    for my $file (readdir DIR) {
+        if ($file =~ $pattern) {
+            my $age = -M "$dir/$file";
+            if (!defined $newestAge || $age < $newestAge) {
+                $newestFile = $file;
+                $newestAge = $age;
+            }
+        }
+    }
+    closedir DIR;
+
+    return "$dir/$newestFile";
+}
+
+my $file1;
+my $file2;
+
+if (scalar @ARGV == 2) {
+    $file1 = $ARGV[0];
+    $file2 = $ARGV[1];
+} else {
+    $file1 = readFile("$resultDirectory/baseline-filename.txt");
+    $file2 = newestFile("$resultDirectory", qr/sunspider-results-.+\.js$/);
+}
+
+my $output = "var output1 = " . readResultsFile($file1) . ";\n";
+$output .= "var output2 = " . readResultsFile($file2) . ";\n";
+
+dumpToFile($output, "$resultDirectory/sunspider-comparison-data.js");
+
+system($jsShellPath, "-f", "$resultDirectory/sunspider-test-prefix.js", "-f", "$resultDirectory/sunspider-comparison-data.js", "-f", "resources/sunspider-compare-results.js", "-f", "resources/sunspider-standalone-compare.js");
diff --git a/PerformanceTests/SunSpider/tests/parse-only/LIST b/PerformanceTests/SunSpider/tests/parse-only/LIST
new file mode 100644
index 0000000..7ad5006
--- /dev/null
+++ b/PerformanceTests/SunSpider/tests/parse-only/LIST
@@ -0,0 +1,4 @@
+jquery-1.3.2
+mootools-1.2.2-core-nc
+prototype-1.6.0.3
+concat-jquery-mootools-prototype
diff --git a/PerformanceTests/SunSpider/tests/parse-only/concat-jquery-mootools-prototype.js b/PerformanceTests/SunSpider/tests/parse-only/concat-jquery-mootools-prototype.js
new file mode 100644
index 0000000..af4a11b
--- /dev/null
+++ b/PerformanceTests/SunSpider/tests/parse-only/concat-jquery-mootools-prototype.js
@@ -0,0 +1,12699 @@
+/*!
+ * jQuery JavaScript Library v1.3.2
+ * http://jquery.com/
+ *
+ * Copyright (c) 2009 John Resig
+ * Dual licensed under the MIT and GPL licenses.
+ * http://docs.jquery.com/License
+ *
+ * Date: 2009-02-19 17:34:21 -0500 (Thu, 19 Feb 2009)
+ * Revision: 6246
+ */
+(function(){
+
+var 
+	// Will speed up references to window, and allows munging its name.
+	window = this,
+	// Will speed up references to undefined, and allows munging its name.
+	undefined,
+	// Map over jQuery in case of overwrite
+	_jQuery = window.jQuery,
+	// Map over the $ in case of overwrite
+	_$ = window.$,
+
+	jQuery = window.jQuery = window.$ = function( selector, context ) {
+		// The jQuery object is actually just the init constructor 'enhanced'
+		return new jQuery.fn.init( selector, context );
+	},
+
+	// A simple way to check for HTML strings or ID strings
+	// (both of which we optimize for)
+	quickExpr = /^[^<]*(<(.|\s)+>)[^>]*$|^#([\w-]+)$/,
+	// Is it a simple selector
+	isSimple = /^.[^:#\[\.,]*$/;
+
+jQuery.fn = jQuery.prototype = {
+	init: function( selector, context ) {
+		// Make sure that a selection was provided
+		selector = selector || document;
+
+		// Handle $(DOMElement)
+		if ( selector.nodeType ) {
+			this[0] = selector;
+			this.length = 1;
+			this.context = selector;
+			return this;
+		}
+		// Handle HTML strings
+		if ( typeof selector === "string" ) {
+			// Are we dealing with HTML string or an ID?
+			var match = quickExpr.exec( selector );
+
+			// Verify a match, and that no context was specified for #id
+			if ( match && (match[1] || !context) ) {
+
+				// HANDLE: $(html) -> $(array)
+				if ( match[1] )
+					selector = jQuery.clean( [ match[1] ], context );
+
+				// HANDLE: $("#id")
+				else {
+					var elem = document.getElementById( match[3] );
+
+					// Handle the case where IE and Opera return items
+					// by name instead of ID
+					if ( elem && elem.id != match[3] )
+						return jQuery().find( selector );
+
+					// Otherwise, we inject the element directly into the jQuery object
+					var ret = jQuery( elem || [] );
+					ret.context = document;
+					ret.selector = selector;
+					return ret;
+				}
+
+			// HANDLE: $(expr, [context])
+			// (which is just equivalent to: $(content).find(expr)
+			} else
+				return jQuery( context ).find( selector );
+
+		// HANDLE: $(function)
+		// Shortcut for document ready
+		} else if ( jQuery.isFunction( selector ) )
+			return jQuery( document ).ready( selector );
+
+		// Make sure that old selector state is passed along
+		if ( selector.selector && selector.context ) {
+			this.selector = selector.selector;
+			this.context = selector.context;
+		}
+
+		return this.setArray(jQuery.isArray( selector ) ?
+			selector :
+			jQuery.makeArray(selector));
+	},
+
+	// Start with an empty selector
+	selector: "",
+
+	// The current version of jQuery being used
+	jquery: "1.3.2",
+
+	// The number of elements contained in the matched element set
+	size: function() {
+		return this.length;
+	},
+
+	// Get the Nth element in the matched element set OR
+	// Get the whole matched element set as a clean array
+	get: function( num ) {
+		return num === undefined ?
+
+			// Return a 'clean' array
+			Array.prototype.slice.call( this ) :
+
+			// Return just the object
+			this[ num ];
+	},
+
+	// Take an array of elements and push it onto the stack
+	// (returning the new matched element set)
+	pushStack: function( elems, name, selector ) {
+		// Build a new jQuery matched element set
+		var ret = jQuery( elems );
+
+		// Add the old object onto the stack (as a reference)
+		ret.prevObject = this;
+
+		ret.context = this.context;
+
+		if ( name === "find" )
+			ret.selector = this.selector + (this.selector ? " " : "") + selector;
+		else if ( name )
+			ret.selector = this.selector + "." + name + "(" + selector + ")";
+
+		// Return the newly-formed element set
+		return ret;
+	},
+
+	// Force the current matched set of elements to become
+	// the specified array of elements (destroying the stack in the process)
+	// You should use pushStack() in order to do this, but maintain the stack
+	setArray: function( elems ) {
+		// Resetting the length to 0, then using the native Array push
+		// is a super-fast way to populate an object with array-like properties
+		this.length = 0;
+		Array.prototype.push.apply( this, elems );
+
+		return this;
+	},
+
+	// Execute a callback for every element in the matched set.
+	// (You can seed the arguments with an array of args, but this is
+	// only used internally.)
+	each: function( callback, args ) {
+		return jQuery.each( this, callback, args );
+	},
+
+	// Determine the position of an element within
+	// the matched set of elements
+	index: function( elem ) {
+		// Locate the position of the desired element
+		return jQuery.inArray(
+			// If it receives a jQuery object, the first element is used
+			elem && elem.jquery ? elem[0] : elem
+		, this );
+	},
+
+	attr: function( name, value, type ) {
+		var options = name;
+
+		// Look for the case where we're accessing a style value
+		if ( typeof name === "string" )
+			if ( value === undefined )
+				return this[0] && jQuery[ type || "attr" ]( this[0], name );
+
+			else {
+				options = {};
+				options[ name ] = value;
+			}
+
+		// Check to see if we're setting style values
+		return this.each(function(i){
+			// Set all the styles
+			for ( name in options )
+				jQuery.attr(
+					type ?
+						this.style :
+						this,
+					name, jQuery.prop( this, options[ name ], type, i, name )
+				);
+		});
+	},
+
+	css: function( key, value ) {
+		// ignore negative width and height values
+		if ( (key == 'width' || key == 'height') && parseFloat(value) < 0 )
+			value = undefined;
+		return this.attr( key, value, "curCSS" );
+	},
+
+	text: function( text ) {
+		if ( typeof text !== "object" && text != null )
+			return this.empty().append( (this[0] && this[0].ownerDocument || document).createTextNode( text ) );
+
+		var ret = "";
+
+		jQuery.each( text || this, function(){
+			jQuery.each( this.childNodes, function(){
+				if ( this.nodeType != 8 )
+					ret += this.nodeType != 1 ?
+						this.nodeValue :
+						jQuery.fn.text( [ this ] );
+			});
+		});
+
+		return ret;
+	},
+
+	wrapAll: function( html ) {
+		if ( this[0] ) {
+			// The elements to wrap the target around
+			var wrap = jQuery( html, this[0].ownerDocument ).clone();
+
+			if ( this[0].parentNode )
+				wrap.insertBefore( this[0] );
+
+			wrap.map(function(){
+				var elem = this;
+
+				while ( elem.firstChild )
+					elem = elem.firstChild;
+
+				return elem;
+			}).append(this);
+		}
+
+		return this;
+	},
+
+	wrapInner: function( html ) {
+		return this.each(function(){
+			jQuery( this ).contents().wrapAll( html );
+		});
+	},
+
+	wrap: function( html ) {
+		return this.each(function(){
+			jQuery( this ).wrapAll( html );
+		});
+	},
+
+	append: function() {
+		return this.domManip(arguments, true, function(elem){
+			if (this.nodeType == 1)
+				this.appendChild( elem );
+		});
+	},
+
+	prepend: function() {
+		return this.domManip(arguments, true, function(elem){
+			if (this.nodeType == 1)
+				this.insertBefore( elem, this.firstChild );
+		});
+	},
+
+	before: function() {
+		return this.domManip(arguments, false, function(elem){
+			this.parentNode.insertBefore( elem, this );
+		});
+	},
+
+	after: function() {
+		return this.domManip(arguments, false, function(elem){
+			this.parentNode.insertBefore( elem, this.nextSibling );
+		});
+	},
+
+	end: function() {
+		return this.prevObject || jQuery( [] );
+	},
+
+	// For internal use only.
+	// Behaves like an Array's method, not like a jQuery method.
+	push: [].push,
+	sort: [].sort,
+	splice: [].splice,
+
+	find: function( selector ) {
+		if ( this.length === 1 ) {
+			var ret = this.pushStack( [], "find", selector );
+			ret.length = 0;
+			jQuery.find( selector, this[0], ret );
+			return ret;
+		} else {
+			return this.pushStack( jQuery.unique(jQuery.map(this, function(elem){
+				return jQuery.find( selector, elem );
+			})), "find", selector );
+		}
+	},
+
+	clone: function( events ) {
+		// Do the clone
+		var ret = this.map(function(){
+			if ( !jQuery.support.noCloneEvent && !jQuery.isXMLDoc(this) ) {
+				// IE copies events bound via attachEvent when
+				// using cloneNode. Calling detachEvent on the
+				// clone will also remove the events from the orignal
+				// In order to get around this, we use innerHTML.
+				// Unfortunately, this means some modifications to
+				// attributes in IE that are actually only stored
+				// as properties will not be copied (such as the
+				// the name attribute on an input).
+				var html = this.outerHTML;
+				if ( !html ) {
+					var div = this.ownerDocument.createElement("div");
+					div.appendChild( this.cloneNode(true) );
+					html = div.innerHTML;
+				}
+
+				return jQuery.clean([html.replace(/ jQuery\d+="(?:\d+|null)"/g, "").replace(/^\s*/, "")])[0];
+			} else
+				return this.cloneNode(true);
+		});
+
+		// Copy the events from the original to the clone
+		if ( events === true ) {
+			var orig = this.find("*").andSelf(), i = 0;
+
+			ret.find("*").andSelf().each(function(){
+				if ( this.nodeName !== orig[i].nodeName )
+					return;
+
+				var events = jQuery.data( orig[i], "events" );
+
+				for ( var type in events ) {
+					for ( var handler in events[ type ] ) {
+						jQuery.event.add( this, type, events[ type ][ handler ], events[ type ][ handler ].data );
+					}
+				}
+
+				i++;
+			});
+		}
+
+		// Return the cloned set
+		return ret;
+	},
+
+	filter: function( selector ) {
+		return this.pushStack(
+			jQuery.isFunction( selector ) &&
+			jQuery.grep(this, function(elem, i){
+				return selector.call( elem, i );
+			}) ||
+
+			jQuery.multiFilter( selector, jQuery.grep(this, function(elem){
+				return elem.nodeType === 1;
+			}) ), "filter", selector );
+	},
+
+	closest: function( selector ) {
+		var pos = jQuery.expr.match.POS.test( selector ) ? jQuery(selector) : null,
+			closer = 0;
+
+		return this.map(function(){
+			var cur = this;
+			while ( cur && cur.ownerDocument ) {
+				if ( pos ? pos.index(cur) > -1 : jQuery(cur).is(selector) ) {
+					jQuery.data(cur, "closest", closer);
+					return cur;
+				}
+				cur = cur.parentNode;
+				closer++;
+			}
+		});
+	},
+
+	not: function( selector ) {
+		if ( typeof selector === "string" )
+			// test special case where just one selector is passed in
+			if ( isSimple.test( selector ) )
+				return this.pushStack( jQuery.multiFilter( selector, this, true ), "not", selector );
+			else
+				selector = jQuery.multiFilter( selector, this );
+
+		var isArrayLike = selector.length && selector[selector.length - 1] !== undefined && !selector.nodeType;
+		return this.filter(function() {
+			return isArrayLike ? jQuery.inArray( this, selector ) < 0 : this != selector;
+		});
+	},
+
+	add: function( selector ) {
+		return this.pushStack( jQuery.unique( jQuery.merge(
+			this.get(),
+			typeof selector === "string" ?
+				jQuery( selector ) :
+				jQuery.makeArray( selector )
+		)));
+	},
+
+	is: function( selector ) {
+		return !!selector && jQuery.multiFilter( selector, this ).length > 0;
+	},
+
+	hasClass: function( selector ) {
+		return !!selector && this.is( "." + selector );
+	},
+
+	val: function( value ) {
+		if ( value === undefined ) {			
+			var elem = this[0];
+
+			if ( elem ) {
+				if( jQuery.nodeName( elem, 'option' ) )
+					return (elem.attributes.value || {}).specified ? elem.value : elem.text;
+				
+				// We need to handle select boxes special
+				if ( jQuery.nodeName( elem, "select" ) ) {
+					var index = elem.selectedIndex,
+						values = [],
+						options = elem.options,
+						one = elem.type == "select-one";
+
+					// Nothing was selected
+					if ( index < 0 )
+						return null;
+
+					// Loop through all the selected options
+					for ( var i = one ? index : 0, max = one ? index + 1 : options.length; i < max; i++ ) {
+						var option = options[ i ];
+
+						if ( option.selected ) {
+							// Get the specifc value for the option
+							value = jQuery(option).val();
+
+							// We don't need an array for one selects
+							if ( one )
+								return value;
+
+							// Multi-Selects return an array
+							values.push( value );
+						}
+					}
+
+					return values;				
+				}
+
+				// Everything else, we just grab the value
+				return (elem.value || "").replace(/\r/g, "");
+
+			}
+
+			return undefined;
+		}
+
+		if ( typeof value === "number" )
+			value += '';
+
+		return this.each(function(){
+			if ( this.nodeType != 1 )
+				return;
+
+			if ( jQuery.isArray(value) && /radio|checkbox/.test( this.type ) )
+				this.checked = (jQuery.inArray(this.value, value) >= 0 ||
+					jQuery.inArray(this.name, value) >= 0);
+
+			else if ( jQuery.nodeName( this, "select" ) ) {
+				var values = jQuery.makeArray(value);
+
+				jQuery( "option", this ).each(function(){
+					this.selected = (jQuery.inArray( this.value, values ) >= 0 ||
+						jQuery.inArray( this.text, values ) >= 0);
+				});
+
+				if ( !values.length )
+					this.selectedIndex = -1;
+
+			} else
+				this.value = value;
+		});
+	},
+
+	html: function( value ) {
+		return value === undefined ?
+			(this[0] ?
+				this[0].innerHTML.replace(/ jQuery\d+="(?:\d+|null)"/g, "") :
+				null) :
+			this.empty().append( value );
+	},
+
+	replaceWith: function( value ) {
+		return this.after( value ).remove();
+	},
+
+	eq: function( i ) {
+		return this.slice( i, +i + 1 );
+	},
+
+	slice: function() {
+		return this.pushStack( Array.prototype.slice.apply( this, arguments ),
+			"slice", Array.prototype.slice.call(arguments).join(",") );
+	},
+
+	map: function( callback ) {
+		return this.pushStack( jQuery.map(this, function(elem, i){
+			return callback.call( elem, i, elem );
+		}));
+	},
+
+	andSelf: function() {
+		return this.add( this.prevObject );
+	},
+
+	domManip: function( args, table, callback ) {
+		if ( this[0] ) {
+			var fragment = (this[0].ownerDocument || this[0]).createDocumentFragment(),
+				scripts = jQuery.clean( args, (this[0].ownerDocument || this[0]), fragment ),
+				first = fragment.firstChild;
+
+			if ( first )
+				for ( var i = 0, l = this.length; i < l; i++ )
+					callback.call( root(this[i], first), this.length > 1 || i > 0 ?
+							fragment.cloneNode(true) : fragment );
+		
+			if ( scripts )
+				jQuery.each( scripts, evalScript );
+		}
+
+		return this;
+		
+		function root( elem, cur ) {
+			return table && jQuery.nodeName(elem, "table") && jQuery.nodeName(cur, "tr") ?
+				(elem.getElementsByTagName("tbody")[0] ||
+				elem.appendChild(elem.ownerDocument.createElement("tbody"))) :
+				elem;
+		}
+	}
+};
+
+// Give the init function the jQuery prototype for later instantiation
+jQuery.fn.init.prototype = jQuery.fn;
+
+function evalScript( i, elem ) {
+	if ( elem.src )
+		jQuery.ajax({
+			url: elem.src,
+			async: false,
+			dataType: "script"
+		});
+
+	else
+		jQuery.globalEval( elem.text || elem.textContent || elem.innerHTML || "" );
+
+	if ( elem.parentNode )
+		elem.parentNode.removeChild( elem );
+}
+
+function now(){
+	return +new Date;
+}
+
+jQuery.extend = jQuery.fn.extend = function() {
+	// copy reference to target object
+	var target = arguments[0] || {}, i = 1, length = arguments.length, deep = false, options;
+
+	// Handle a deep copy situation
+	if ( typeof target === "boolean" ) {
+		deep = target;
+		target = arguments[1] || {};
+		// skip the boolean and the target
+		i = 2;
+	}
+
+	// Handle case when target is a string or something (possible in deep copy)
+	if ( typeof target !== "object" && !jQuery.isFunction(target) )
+		target = {};
+
+	// extend jQuery itself if only one argument is passed
+	if ( length == i ) {
+		target = this;
+		--i;
+	}
+
+	for ( ; i < length; i++ )
+		// Only deal with non-null/undefined values
+		if ( (options = arguments[ i ]) != null )
+			// Extend the base object
+			for ( var name in options ) {
+				var src = target[ name ], copy = options[ name ];
+
+				// Prevent never-ending loop
+				if ( target === copy )
+					continue;
+
+				// Recurse if we're merging object values
+				if ( deep && copy && typeof copy === "object" && !copy.nodeType )
+					target[ name ] = jQuery.extend( deep, 
+						// Never move original objects, clone them
+						src || ( copy.length != null ? [ ] : { } )
+					, copy );
+
+				// Don't bring in undefined values
+				else if ( copy !== undefined )
+					target[ name ] = copy;
+
+			}
+
+	// Return the modified object
+	return target;
+};
+
+// exclude the following css properties to add px
+var	exclude = /z-?index|font-?weight|opacity|zoom|line-?height/i,
+	// cache defaultView
+	defaultView = document.defaultView || {},
+	toString = Object.prototype.toString;
+
+jQuery.extend({
+	noConflict: function( deep ) {
+		window.$ = _$;
+
+		if ( deep )
+			window.jQuery = _jQuery;
+
+		return jQuery;
+	},
+
+	// See test/unit/core.js for details concerning isFunction.
+	// Since version 1.3, DOM methods and functions like alert
+	// aren't supported. They return false on IE (#2968).
+	isFunction: function( obj ) {
+		return toString.call(obj) === "[object Function]";
+	},
+
+	isArray: function( obj ) {
+		return toString.call(obj) === "[object Array]";
+	},
+
+	// check if an element is in a (or is an) XML document
+	isXMLDoc: function( elem ) {
+		return elem.nodeType === 9 && elem.documentElement.nodeName !== "HTML" ||
+			!!elem.ownerDocument && jQuery.isXMLDoc( elem.ownerDocument );
+	},
+
+	// Evalulates a script in a global context
+	globalEval: function( data ) {
+		if ( data && /\S/.test(data) ) {
+			// Inspired by code by Andrea Giammarchi
+			// http://webreflection.blogspot.com/2007/08/global-scope-evaluation-and-dom.html
+			var head = document.getElementsByTagName("head")[0] || document.documentElement,
+				script = document.createElement("script");
+
+			script.type = "text/javascript";
+			if ( jQuery.support.scriptEval )
+				script.appendChild( document.createTextNode( data ) );
+			else
+				script.text = data;
+
+			// Use insertBefore instead of appendChild  to circumvent an IE6 bug.
+			// This arises when a base node is used (#2709).
+			head.insertBefore( script, head.firstChild );
+			head.removeChild( script );
+		}
+	},
+
+	nodeName: function( elem, name ) {
+		return elem.nodeName && elem.nodeName.toUpperCase() == name.toUpperCase();
+	},
+
+	// args is for internal usage only
+	each: function( object, callback, args ) {
+		var name, i = 0, length = object.length;
+
+		if ( args ) {
+			if ( length === undefined ) {
+				for ( name in object )
+					if ( callback.apply( object[ name ], args ) === false )
+						break;
+			} else
+				for ( ; i < length; )
+					if ( callback.apply( object[ i++ ], args ) === false )
+						break;
+
+		// A special, fast, case for the most common use of each
+		} else {
+			if ( length === undefined ) {
+				for ( name in object )
+					if ( callback.call( object[ name ], name, object[ name ] ) === false )
+						break;
+			} else
+				for ( var value = object[0];
+					i < length && callback.call( value, i, value ) !== false; value = object[++i] ){}
+		}
+
+		return object;
+	},
+
+	prop: function( elem, value, type, i, name ) {
+		// Handle executable functions
+		if ( jQuery.isFunction( value ) )
+			value = value.call( elem, i );
+
+		// Handle passing in a number to a CSS property
+		return typeof value === "number" && type == "curCSS" && !exclude.test( name ) ?
+			value + "px" :
+			value;
+	},
+
+	className: {
+		// internal only, use addClass("class")
+		add: function( elem, classNames ) {
+			jQuery.each((classNames || "").split(/\s+/), function(i, className){
+				if ( elem.nodeType == 1 && !jQuery.className.has( elem.className, className ) )
+					elem.className += (elem.className ? " " : "") + className;
+			});
+		},
+
+		// internal only, use removeClass("class")
+		remove: function( elem, classNames ) {
+			if (elem.nodeType == 1)
+				elem.className = classNames !== undefined ?
+					jQuery.grep(elem.className.split(/\s+/), function(className){
+						return !jQuery.className.has( classNames, className );
+					}).join(" ") :
+					"";
+		},
+
+		// internal only, use hasClass("class")
+		has: function( elem, className ) {
+			return elem && jQuery.inArray( className, (elem.className || elem).toString().split(/\s+/) ) > -1;
+		}
+	},
+
+	// A method for quickly swapping in/out CSS properties to get correct calculations
+	swap: function( elem, options, callback ) {
+		var old = {};
+		// Remember the old values, and insert the new ones
+		for ( var name in options ) {
+			old[ name ] = elem.style[ name ];
+			elem.style[ name ] = options[ name ];
+		}
+
+		callback.call( elem );
+
+		// Revert the old values
+		for ( var name in options )
+			elem.style[ name ] = old[ name ];
+	},
+
+	css: function( elem, name, force, extra ) {
+		if ( name == "width" || name == "height" ) {
+			var val, props = { position: "absolute", visibility: "hidden", display:"block" }, which = name == "width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ];
+
+			function getWH() {
+				val = name == "width" ? elem.offsetWidth : elem.offsetHeight;
+
+				if ( extra === "border" )
+					return;
+
+				jQuery.each( which, function() {
+					if ( !extra )
+						val -= parseFloat(jQuery.curCSS( elem, "padding" + this, true)) || 0;
+					if ( extra === "margin" )
+						val += parseFloat(jQuery.curCSS( elem, "margin" + this, true)) || 0;
+					else
+						val -= parseFloat(jQuery.curCSS( elem, "border" + this + "Width", true)) || 0;
+				});
+			}
+
+			if ( elem.offsetWidth !== 0 )
+				getWH();
+			else
+				jQuery.swap( elem, props, getWH );
+
+			return Math.max(0, Math.round(val));
+		}
+
+		return jQuery.curCSS( elem, name, force );
+	},
+
+	curCSS: function( elem, name, force ) {
+		var ret, style = elem.style;
+
+		// We need to handle opacity special in IE
+		if ( name == "opacity" && !jQuery.support.opacity ) {
+			ret = jQuery.attr( style, "opacity" );
+
+			return ret == "" ?
+				"1" :
+				ret;
+		}
+
+		// Make sure we're using the right name for getting the float value
+		if ( name.match( /float/i ) )
+			name = styleFloat;
+
+		if ( !force && style && style[ name ] )
+			ret = style[ name ];
+
+		else if ( defaultView.getComputedStyle ) {
+
+			// Only "float" is needed here
+			if ( name.match( /float/i ) )
+				name = "float";
+
+			name = name.replace( /([A-Z])/g, "-$1" ).toLowerCase();
+
+			var computedStyle = defaultView.getComputedStyle( elem, null );
+
+			if ( computedStyle )
+				ret = computedStyle.getPropertyValue( name );
+
+			// We should always get a number back from opacity
+			if ( name == "opacity" && ret == "" )
+				ret = "1";
+
+		} else if ( elem.currentStyle ) {
+			var camelCase = name.replace(/\-(\w)/g, function(all, letter){
+				return letter.toUpperCase();
+			});
+
+			ret = elem.currentStyle[ name ] || elem.currentStyle[ camelCase ];
+
+			// From the awesome hack by Dean Edwards
+			// http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291
+
+			// If we're not dealing with a regular pixel number
+			// but a number that has a weird ending, we need to convert it to pixels
+			if ( !/^\d+(px)?$/i.test( ret ) && /^\d/.test( ret ) ) {
+				// Remember the original values
+				var left = style.left, rsLeft = elem.runtimeStyle.left;
+
+				// Put in the new values to get a computed value out
+				elem.runtimeStyle.left = elem.currentStyle.left;
+				style.left = ret || 0;
+				ret = style.pixelLeft + "px";
+
+				// Revert the changed values
+				style.left = left;
+				elem.runtimeStyle.left = rsLeft;
+			}
+		}
+
+		return ret;
+	},
+
+	clean: function( elems, context, fragment ) {
+		context = context || document;
+
+		// !context.createElement fails in IE with an error but returns typeof 'object'
+		if ( typeof context.createElement === "undefined" )
+			context = context.ownerDocument || context[0] && context[0].ownerDocument || document;
+
+		// If a single string is passed in and it's a single tag
+		// just do a createElement and skip the rest
+		if ( !fragment && elems.length === 1 && typeof elems[0] === "string" ) {
+			var match = /^<(\w+)\s*\/?>$/.exec(elems[0]);
+			if ( match )
+				return [ context.createElement( match[1] ) ];
+		}
+
+		var ret = [], scripts = [], div = context.createElement("div");
+
+		jQuery.each(elems, function(i, elem){
+			if ( typeof elem === "number" )
+				elem += '';
+
+			if ( !elem )
+				return;
+
+			// Convert html string into DOM nodes
+			if ( typeof elem === "string" ) {
+				// Fix "XHTML"-style tags in all browsers
+				elem = elem.replace(/(<(\w+)[^>]*?)\/>/g, function(all, front, tag){
+					return tag.match(/^(abbr|br|col|img|input|link|meta|param|hr|area|embed)$/i) ?
+						all :
+						front + ">";
+				});
+
+				// Trim whitespace, otherwise indexOf won't work as expected
+				var tags = elem.replace(/^\s+/, "").substring(0, 10).toLowerCase();
+
+				var wrap =
+					// option or optgroup
+					!tags.indexOf("", "" ] ||
+
+					!tags.indexOf("", "" ] ||
+
+					tags.match(/^<(thead|tbody|tfoot|colg|cap)/) &&
+					[ 1, "", "
" ] ||
+
+					!tags.indexOf("", "" ] ||
+
+				 	//  matched above
+					(!tags.indexOf("", "" ] ||
+
+					!tags.indexOf("", "" ] ||
+
+					// IE can't serialize  and