Annotation of html5/spec/syntax.html, revision 1.1033
1.872 mike 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
1.894 mike 2: <!DOCTYPE html>
1.1025 mike 3: <!-- when publishing, change bits marked ZZZ
4: ZZZ: Set PUB to 1 for TR/ drafts, 0 for dev drafts; PUB-Y lines are used if it's 1 and PUB-N lines if it's 0.
5: ZZZ: Set YEAR, SHORTDAY (month/day), and LONGDAY accordingly. They are used by the INSERT FOO bits below.
6: --><html lang="en-US-x-Hixie" class="split chapter"><head><title>8 The HTML syntax — HTML5 </title><style type="text/css">
1.1 mike 7: pre { margin-left: 2em; white-space: pre-wrap; }
8: h2 { margin: 3em 0 1em 0; }
9: h3 { margin: 2.5em 0 1em 0; }
10: h4 { margin: 2.5em 0 0.75em 0; }
11: h5, h6 { margin: 2.5em 0 1em; }
12: h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
13: h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
14: p { margin: 1em 0; }
15: hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
16: dl, dd { margin-top: 0; margin-bottom: 0; }
17: dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
18: dt + dt { margin-top: 0; }
19: dd dt { margin-top: 0.25em; margin-bottom: 0; }
20: dd p { margin-top: 0; }
21: dd dl + p { margin-top: 1em; }
22: dd table + p { margin-top: 1em; }
23: p + * > li, dd li { margin: 1em 0; }
24: dt, dfn { font-weight: bold; font-style: normal; }
25: dt dfn { font-style: italic; }
26: pre, code { font-size: inherit; font-family: monospace; font-variant: normal; }
27: pre strong { color: black; font: inherit; font-weight: bold; background: yellow; }
28: pre em { font-weight: bolder; font-style: normal; }
29: @media screen { code { color: orangered; } code :link, code :visited { color: inherit; } }
30: var sub { vertical-align: bottom; font-size: smaller; position: relative; top: 0.1em; }
31: table { border-collapse: collapse; border-style: hidden hidden none hidden; }
1.983 mike 32: table thead, table tbody { border-bottom: solid; }
1.1 mike 33: table tbody th:first-child { border-left: solid; }
1.475 mike 34: table tbody th { text-align: left; }
1.1 mike 35: table td, table th { border-left: solid; border-right: solid; border-bottom: solid thin; vertical-align: top; padding: 0.2em; }
36: blockquote { margin: 0 0 0 2em; border: 0; padding: 0; font-style: italic; }
37:
38: .bad, .bad *:not(.XXX) { color: gray; border-color: gray; background: transparent; }
39: .matrix, .matrix td { border: none; text-align: right; }
40: .matrix { margin-left: 2em; }
41: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
42: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
43: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
44:
45: .toc dfn, h1 dfn, h2 dfn, h3 dfn, h4 dfn, h5 dfn, h6 dfn { font: inherit; }
46: img.extra { float: right; }
47: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; }
48: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
49: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
50: pre.css:first-line { color: #AAAA50; }
1.840 mike 51: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
1.1 mike 52: hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
53: dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
54: dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
55: dl.domintro dd p { margin: 0.5em 0; }
56: dl.switch { padding-left: 2em; }
57: dl.switch > dt { text-indent: -1.5em; }
58: dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
59: dl.triple { padding: 0 0 0 1em; }
60: dl.triple dt, dl.triple dd { margin: 0; display: inline }
61: dl.triple dt:after { content: ':'; }
62: dl.triple dd:after { content: '\A'; white-space: pre; }
63: .diff-old { text-decoration: line-through; color: silver; background: transparent; }
64: .diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
65: a .diff-new { border-bottom: 1px blue solid; }
66:
67: h2 { page-break-before: always; }
68: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
69: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
70:
1.1016 mike 71: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
72: li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
1.1 mike 73:
74: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
75: div.head p { margin: 0; }
76: div.head h1 { margin: 0; }
77: div.head .logo { float: right; margin: 0 1em; }
78: div.head .logo img { border: none } /* remove border from top image */
79: div.head dl { margin: 1em 0; }
1.671 mike 80: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
1.1 mike 81:
82: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
83: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
84: body > .toc > li > * { margin-bottom: 0.5em; }
85: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
86: .toc, .toc li { list-style: none; }
87:
88: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
89: .brief li { margin: 0; padding: 0; }
90: .brief li p { margin: 0; padding: 0; }
91:
92: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
93: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
94: .category-list li { display: inline; }
95: .category-list li:not(:last-child)::after { content: ', '; }
96: .category-list li > span, .category-list li > a { text-transform: lowercase; }
97: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
98:
99: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
100: .XXX > :first-child { margin-top: 0; }
101: p .XXX { line-height: 3em; }
1.159 mike 102: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
103: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
104: .annotation :link, .annotation :visited { color: inherit; }
105: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
106: .annotation span { border: none ! important; }
1.1 mike 107: .note { color: green; background: transparent; font-family: sans-serif; }
108: .warning { color: red; background: transparent; }
109: .note, .warning { font-weight: bolder; font-style: italic; }
110: p.note, div.note { padding: 0.5em 2em; }
111: span.note { padding: 0 2em; }
112: .note p:first-child, .warning p:first-child { margin-top: 0; }
113: .note p:last-child, .warning p:last-child { margin-bottom: 0; }
114: .warning:before { font-style: normal; }
115: p.note:before { content: 'Note: '; }
116: p.warning:before { content: '\26A0 Warning! '; }
117:
118: .bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
119: .bookkeeping { font-size: 0.8em; margin: 2em 0; }
120: .bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
1.1006 mike 121: .bookkeeping dt { margin: 0.5em 2em 0; }
122: .bookkeeping dd { margin: 0 3em 0.5em; }
1.1 mike 123:
124: h4 { position: relative; z-index: 3; }
125: h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
126: .element {
127: background: #EEEEFF;
128: color: black;
129: margin: 0 0 1em 0.15em;
130: padding: 0 1em 0.25em 0.75em;
131: border-left: solid #9999FF 0.25em;
132: position: relative;
133: z-index: 1;
134: }
135: .element:before {
136: position: absolute;
137: z-index: 2;
138: top: 0;
139: left: -1.15em;
140: height: 2em;
141: width: 0.9em;
142: background: #EEEEFF;
143: content: ' ';
144: border-style: none none solid solid;
145: border-color: #9999FF;
146: border-width: 0.25em;
147: }
148:
1.149 mike 149: .example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
150: td > .example:only-child { margin: 0 0 0 0.1em; }
1.1 mike 151:
152: ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
153: ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
154: ul.domTree li li { list-style: none; }
155: ul.domTree li:first-child::before { position: absolute; top: 0; height: 0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
156: ul.domTree li:not(:last-child)::after { position: absolute; top: 0; bottom: -0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
157: ul.domTree span { font-style: italic; font-family: serif; }
158: ul.domTree .t1 code { color: purple; font-weight: bold; }
159: ul.domTree .t2 { font-style: normal; font-family: monospace; }
160: ul.domTree .t2 .name { color: black; font-weight: bold; }
161: ul.domTree .t2 .value { color: blue; font-weight: normal; }
162: ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
163: ul.domTree .t7 code, .domTree .t8 code { color: green; }
164: ul.domTree .t10 code { color: teal; }
165:
1.736 mike 166: body.dfnEnabled dfn { cursor: pointer; }
167: .dfnPanel {
168: display: inline;
169: position: absolute;
170: z-index: 10;
171: height: auto;
172: width: auto;
173: padding: 0.5em 0.75em;
174: font: small sans-serif, Droid Sans Fallback;
175: background: #DDDDDD;
176: color: black;
177: border: outset 0.2em;
178: }
179: .dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
180: .dfnPanel :link, .dfnPanel :visited { color: black; }
181: .dfnPanel p { font-weight: bolder; }
182: .dfnPanel * + p { margin-top: 0.25em; }
183: .dfnPanel li { list-style-position: inside; }
184:
1.671 mike 185: #configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
186: #configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
187: #configUI p label { display: block; }
188: #configUI #updateUI, #configUI .loginUI { text-align: center; }
189: #configUI input[type=button] { display: block; margin: auto; }
1.1002 mike 190:
1.1021 mike 191: fieldset { margin: 1em; padding: 0.5em 1em; }
192: fieldset > legend + * { margin-top: 0; }
1.1013 mike 193: fieldset > :last-child { margin-bottom: 0; }
1.1021 mike 194: fieldset p { margin: 0.5em 0; }
195:
1.1033 ! mike 196: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><style type="text/css">
1.267 mike 197:
1.292 mike 198: .applies thead th > * { display: block; }
199: .applies thead code { display: block; }
200: .applies tbody th { whitespace: nowrap; }
201: .applies td { text-align: center; }
202: .applies .yes { background: yellow; }
203:
1.1007 mike 204: .matrix, .matrix td { border: hidden; text-align: right; }
1.267 mike 205: .matrix { margin-left: 2em; }
206:
207: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
208: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
209: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
210:
1.1009 mike 211: td.eg { border-width: thin; text-align: center; }
212:
1.267 mike 213: #table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
214: #table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
215: #table-example-1 caption { padding-bottom: 0.5em; }
216: #table-example-1 thead, #table-example-1 tbody { border: none; }
217: #table-example-1 th, #table-example-1 td { border: solid thin; }
218: #table-example-1 th { font-weight: normal; }
219: #table-example-1 td { border-style: none solid; vertical-align: top; }
220: #table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
221: #table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
222: #table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
223: #table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
224: #table-example-1 tbody td:first-child::after { content: leader(". "); }
225: #table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
226: #table-example-1 tbody td:first-child + td { width: 10em; }
227: #table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
228: #table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
229:
230: .apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
231: .apple-table-examples * { font-family: "Times", serif; }
232: .apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
233: .apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
234: .apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
235: .apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
236: .apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
237: .apple-table-examples td { text-align: right; vertical-align: top; }
238: .apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
239: .apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
240: .apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
241: .apple-table-examples sup { line-height: 0; }
242:
1.724 mike 243: .details-example img { vertical-align: top; }
244:
1.1028 mike 245: #base64-table {
246: white-space: nowrap;
247: font-size: 0.6em;
248: column-width: 6em;
249: column-count: 5;
250: column-gap: 1em;
251: -moz-column-width: 6em;
252: -moz-column-count: 5;
253: -moz-column-gap: 1em;
254: -webkit-column-width: 6em;
255: -webkit-column-count: 5;
256: -webkit-column-gap: 1em;
257: }
258: #base64-table thead { display: none; }
259: #base64-table * { border: none; }
260: #base64-table tbody td:first-child:after { content: ':'; }
261: #base64-table tbody td:last-child { text-align: right; }
262:
1.882 mike 263: #named-character-references-table {
1.1010 mike 264: white-space: nowrap;
1.882 mike 265: font-size: 0.6em;
1.1010 mike 266: column-width: 30em;
1.882 mike 267: column-gap: 1em;
1.1010 mike 268: -moz-column-width: 30em;
1.882 mike 269: -moz-column-gap: 1em;
1.1010 mike 270: -webkit-column-width: 30em;
1.882 mike 271: -webkit-column-gap: 1em;
272: }
1.1010 mike 273: #named-character-references-table > table > tbody > tr > td:first-child + td,
1.882 mike 274: #named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
275: #named-character-references-table > table > tbody > tr > td:last-child:hover > span { position: absolute; top: auto; left: auto; margin-left: 0.5em; line-height: 1.2; font-size: 5em; border: outset; padding: 0.25em 0.5em; background: white; width: 1.25em; height: auto; text-align: center; }
1.1010 mike 276: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
1.882 mike 277:
1.997 mike 278: .glyph.control { color: red; }
279:
1.999 mike 280: @font-face {
281: font-family: 'Essays1743';
282: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743.ttf');
283: }
284: @font-face {
285: font-family: 'Essays1743';
286: font-weight: bold;
287: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Bold.ttf');
288: }
289: @font-face {
290: font-family: 'Essays1743';
291: font-style: italic;
292: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Italic.ttf');
293: }
294: @font-face {
295: font-family: 'Essays1743';
296: font-style: italic;
297: font-weight: bold;
298: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-BoldItalic.ttf');
299: }
300:
1.872 mike 301: </style><style type="text/css">
1.881 mike 302: .domintro:before { display: table; margin: -1em -0.5em -0.5em auto; width: auto; content: 'This box is non-normative. Implementation requirements are given below this box.'; color: black; font-style: italic; border: solid 2px; background: white; padding: 0 0.25em; }
1.1033 ! mike 303: </style><link href="data:text/css," id="complete" rel="stylesheet" title="Complete specification"><link href="data:text/css,.impl%20%7B%20display:%20none;%20%7D%0Ahtml%20%7B%20border:%20solid%20yellow;%20%7D%20.domintro:before%20%7B%20display:%20none;%20%7D" id="author" rel="alternate stylesheet" title="Author documentation only"><link href="data:text/css,.impl%20%7B%20background:%20%23FFEEEE;%20%7D%20.domintro:before%20%7B%20background:%20%23FFEEEE;%20%7D" id="highlight" rel="alternate stylesheet" title="Highlight implementation requirements"><script type="text/javascript">
! 304: function getCookie(name) {
! 305: var params = location.search.substr(1).split("&");
! 306: for (var index = 0; index < params.length; index++) {
! 307: if (params[index] == name)
! 308: return "1";
! 309: var data = params[index].split("=");
! 310: if (data[0] == name)
! 311: return unescape(data[1]);
! 312: }
! 313: var cookies = document.cookie.split("; ");
! 314: for (var index = 0; index < cookies.length; index++) {
! 315: var data = cookies[index].split("=");
! 316: if (data[0] == name)
! 317: return unescape(data[1]);
! 318: }
! 319: return null;
! 320: }
! 321: function load(script) {
! 322: var e = document.createElement('script');
! 323: e.setAttribute('src', 'http://www.whatwg.org/specs/web-apps/current-work/' + script + '?' + encodeURIComponent(location) + '&' + encodeURIComponent(document.referrer));
! 324: document.body.appendChild(e);
! 325: }
! 326: function init() {
! 327: if (location.search == '?slow-browser')
! 328: return;
! 329: var configUI = document.createElement('div');
! 330: configUI.id = 'configUI';
! 331: document.body.appendChild(configUI);
! 332: // load('reviewer.js'); // would need cross-site XHR
! 333: if (document.getElementById('head'))
! 334: load('toc.js');
! 335: load('styler.js');
! 336: // load('updater.js'); // would need cross-site XHR
! 337: load('dfn.js'); // doesn't support split-out specs, but, oh well.
! 338: // load('status.js'); // would need cross-site XHR
! 339: if (getCookie('profile') == '1')
! 340: document.getElementsByTagName('h2')[0].textContent += '; load: ' + (new Date() - loadTimer) + 'ms';
! 341: fixBrokenLink();
! 342: }
! 343: </script>
1.996 mike 344: <script src="link-fixup.js"></script>
1.1023 mike 345: <link href="style.css" rel="stylesheet"><link href="dnd.html" title="7.7 Drag and drop" rel="prev">
1.2 mike 346: <link href="spec.html#contents" title="Table of contents" rel="index">
1.996 mike 347: <link href="parsing.html" title="8.2 Parsing HTML documents" rel="next">
1.1033 ! mike 348: </head><body onload="fixBrokenLink(); init()"><div class="head" id="head">
1.1 mike 349: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.998 mike 350:
1.183 mike 351: <h1>HTML5</h1>
1.874 mike 352: </div><div>
1.1023 mike 353: <a href="dnd.html" class="prev">7.7 Drag and drop</a> –
1.2 mike 354: <a href="spec.html#contents">Table of contents</a> –
1.1023 mike 355: <a href="parsing.html" class="next">8.2 Parsing HTML documents</a>
1.996 mike 356: <ol class="toc"><li><a href="syntax.html#syntax"><span class="secno">8 </span>The HTML syntax</a>
357: <ol><li><a href="syntax.html#writing"><span class="secno">8.1 </span>Writing HTML documents</a>
358: <ol><li><a href="syntax.html#the-doctype"><span class="secno">8.1.1 </span>The DOCTYPE</a></li><li><a href="syntax.html#elements-0"><span class="secno">8.1.2 </span>Elements</a>
359: <ol><li><a href="syntax.html#start-tags"><span class="secno">8.1.2.1 </span>Start tags</a></li><li><a href="syntax.html#end-tags"><span class="secno">8.1.2.2 </span>End tags</a></li><li><a href="syntax.html#attributes-0"><span class="secno">8.1.2.3 </span>Attributes</a></li><li><a href="syntax.html#optional-tags"><span class="secno">8.1.2.4 </span>Optional tags</a></li><li><a href="syntax.html#element-restrictions"><span class="secno">8.1.2.5 </span>Restrictions on content models</a></li><li><a href="syntax.html#cdata-rcdata-restrictions"><span class="secno">8.1.2.6 </span>Restrictions on the contents of raw text and RCDATA elements</a></li></ol></li><li><a href="syntax.html#text-0"><span class="secno">8.1.3 </span>Text</a>
360: <ol><li><a href="syntax.html#newlines"><span class="secno">8.1.3.1 </span>Newlines</a></li></ol></li><li><a href="syntax.html#character-references"><span class="secno">8.1.4 </span>Character references</a></li><li><a href="syntax.html#cdata-sections"><span class="secno">8.1.5 </span>CDATA sections</a></li><li><a href="syntax.html#comments"><span class="secno">8.1.6 </span>Comments</a></li></ol></li></ol></li></ol></div>
1.1 mike 361:
1.755 mike 362: <h2 id="syntax"><span class="secno">8 </span><dfn>The HTML syntax</dfn></h2><p class="note">This section only describes the rules for resources
1.725 mike 363: labeled with an <a href="infrastructure.html#html-mime-type">HTML MIME type</a>. Rules for XML resources
364: are discussed in the section below entitled "<a href="the-xhtml-syntax.html#the-xhtml-syntax">The XHTML
1.1008 mike 365: syntax</a>".</p><h3 id="writing"><span class="secno">8.1 </span>Writing HTML documents</h3><div class="impl">
1.1 mike 366:
367: <p><i>This section only applies to documents, authoring tools, and
368: markup generators. In particular, it does not apply to conformance
369: checkers; conformance checkers must use the requirements given in
370: the next section ("parsing HTML documents").</i></p>
371:
1.123 mike 372: </div><p>Documents must consist of the following parts, in the given
373: order:</p><ol><li>Optionally, a single U+FEFF BYTE ORDER MARK (BOM) character.</li>
1.1 mike 374:
375: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 376: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 377:
378: <li>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a>.
379:
380: </li><li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 381: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 382:
1.159 mike 383: <li>The root element, in the form of an <code><a href="semantics.html#the-html-element-0">html</a></code> <a href="#syntax-elements" title="syntax-elements">element</a>.</li>
1.1 mike 384:
385: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 386: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 387:
388: </ol><p>The various types of content mentioned above are described in the
1.123 mike 389: next few sections.</p><p>In addition, there are some restrictions on how <a href="semantics.html#character-encoding-declaration" title="character encoding declaration">character encoding
1.1 mike 390: declarations</a> are to be serialized, as discussed in the
1.123 mike 391: section on that topic.</p><div class="note">
1.1 mike 392:
1.159 mike 393: <p>Space characters before the root <code><a href="semantics.html#the-html-element-0">html</a></code> element, and
394: space characters at the start of the <code><a href="semantics.html#the-html-element-0">html</a></code> element and
395: before the <code><a href="semantics.html#the-head-element-0">head</a></code> element, will be dropped when the
1.1 mike 396: document is parsed; space characters <em>after</em> the root
1.159 mike 397: <code><a href="semantics.html#the-html-element-0">html</a></code> element will be parsed as if they were at the end
1.996 mike 398: of the <code><a href="sections.html#the-body-element-0">body</a></code> element. Thus, space characters around the
1.1 mike 399: root element do not round-trip.</p>
400:
401: <p>It is suggested that newlines be inserted after the DOCTYPE,
402: after any comments that are before the root element, after the
1.159 mike 403: <code><a href="semantics.html#the-html-element-0">html</a></code> element's start tag (if it is not <a href="#syntax-tag-omission" title="syntax-tag-omission">omitted</a>), and after any comments
404: that are inside the <code><a href="semantics.html#the-html-element-0">html</a></code> element but before the
405: <code><a href="semantics.html#the-head-element-0">head</a></code> element.</p>
1.1 mike 406:
1.123 mike 407: </div><p>Many strings in the HTML syntax (e.g. the names of elements and
1.1 mike 408: their attributes) are case-insensitive, but only for characters in
1.547 mike 409: the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL
410: LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL
1.1 mike 411: LETTER Z). For convenience, in this section this is just referred to
1.1026 mike 412: as "case-insensitive".</p><h4 id="the-doctype"><span class="secno">8.1.1 </span>The DOCTYPE</h4><p>A <dfn id="syntax-doctype" title="syntax-doctype">DOCTYPE</dfn> is a <!-- mostly
1.884 mike 413: useless but nonetheless --> required preamble.</p><p class="note">DOCTYPEs are required for legacy reasons. When
1.1 mike 414: omitted, browsers tend to use a different rendering mode that is
415: incompatible with some specifications. Including the DOCTYPE in a
416: document ensures that the browser makes a best-effort attempt at
1.1029 mike 417: following the relevant specifications.</p><p>A DOCTYPE must consist of the following components, in this
1.882 mike 418: order:</p><ol class="brief"><li>A string that is an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for the string "<code title=""><!DOCTYPE</code>".</li>
1.996 mike 419: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1011 mike 420: <li>A string that is an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for the string "<code title="">html</code>".</li>
1.861 mike 421: <li>Optionally, a <a href="#doctype-legacy-string">DOCTYPE legacy string</a> or an <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a> (defined below).</li>
1.996 mike 422: <li>Zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.588 mike 423: <li>A U+003E GREATER-THAN SIGN character (>).</li>
1.1011 mike 424: </ol><p class="note">In other words, <code><!DOCTYPE html></code>,
1.861 mike 425: case-insensitively.</p><hr><p>For the purposes of HTML generators that cannot output HTML
1.1 mike 426: markup with the short DOCTYPE "<code title=""><!DOCTYPE
1.1011 mike 427: html></code>", a <dfn id="doctype-legacy-string">DOCTYPE legacy string</dfn> may be inserted
1.1 mike 428: into the DOCTYPE (in the position defined above). This string must
1.996 mike 429: consist of:</p><ol class="brief"><li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 430: <li>A string that is an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for the string "<code title="">SYSTEM</code>".</li>
1.996 mike 431: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 432: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>quote mark</i>).</li>
1.996 mike 433: <li>The literal string "<code><a href="urls.html#about:legacy-compat">about:legacy-compat</a></code>".</li>
1.856 mike 434: <li>A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step labeled <i>quote mark</i>).</li>
1.1011 mike 435: </ol><p class="note">In other words, <code><!DOCTYPE html SYSTEM
436: "about:legacy-compat"></code> or <code><!DOCTYPE html SYSTEM
1.1004 mike 437: 'about:legacy-compat'></code>, case-insensitively except for the
438: part in single or double quotes.</p><p>The <a href="#doctype-legacy-string">DOCTYPE legacy string</a> should not be used unless
1.1 mike 439: the document is generated from a system that cannot output the
1.861 mike 440: shorter string.</p><hr><!-- see the parser section before changing this bit --><p>To help authors transition from HTML4 and XHTML1, an
441: <dfn id="obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</dfn> can be inserted into
442: the DOCTYPE (in the position defined above). This string must
1.996 mike 443: consist of:</p><ol class="brief"><li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 444: <li>A string that is an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for the string "<code title="">PUBLIC</code>".</li>
1.996 mike 445: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 446: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>first quote mark</i>).</li>
447: <li>The string from one of the cells in the first column of the table below. The row to which this cell belongs is the <i>selected row</i>.</li>
448: <li>A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step labeled <i>first quote mark</i>).</li>
1.996 mike 449: <li>If the cell in the second column of the <i>selected row</i> is not blank, one or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 450: <li>If the cell in the second column of the <i>selected row</i> is not blank, a U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>third quote mark</i>).</li>
451: <li>If the cell in the second column of the <i>selected row</i> is not blank, the string from the cell in the second column of the <i>selected row</i>.</li>
452: <li>If the cell in the second column of the <i>selected row</i> 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 <i>third quote mark</i>).</li>
453: </ol><table><caption>
454: Allowed values for public and system identifiers in an <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a>.
455: </caption>
456: <thead><tr><th> Public identifier
457: </th><th> System identifier
458: </th></tr></thead><tbody><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
459: </td><td>
460: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
461: </td><td> <code title="">http://www.w3.org/TR/REC-html40/strict.dtd</code>
462: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
463: </td><td>
464: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
465: </td><td> <code title="">http://www.w3.org/TR/html4/strict.dtd</code>
466: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.0 Strict//EN</code>
467: </td><td> <code title="">http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</code>
468: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.1//EN</code>
469: </td><td> <code title="">http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd</code>
470: </td></tr></tbody></table><p>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a> containing an
471: <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a> is an <dfn id="obsolete-permitted-doctype">obsolete
472: permitted DOCTYPE</dfn>. Authors should not use <a href="#obsolete-permitted-doctype" title="obsolete permitted DOCTYPE">obsolete permitted
1.1008 mike 473: DOCTYPEs</a>, as they are unnecessarily long.</p><h4 id="elements-0"><span class="secno">8.1.2 </span>Elements</h4><p>There are five different kinds of <dfn id="syntax-elements" title="syntax-elements">elements</dfn>: <a href="#void-elements">void elements</a>,
1.373 mike 474: <a href="#raw-text-elements">raw text elements</a>, <a href="#rcdata-elements">RCDATA elements</a>,
475: <a href="#foreign-elements">foreign elements</a>, and <a href="#normal-elements">normal elements</a>.</p><dl><dt><dfn id="void-elements">Void elements</dfn></dt>
1.1 mike 476:
1.996 mike 477: <dd><code><a href="the-map-element.html#the-area-element">area</a></code>, <code><a href="semantics.html#the-base-element">base</a></code>, <code><a href="text-level-semantics.html#the-br-element">br</a></code>,
478: <code><a href="tabular-data.html#the-col-element">col</a></code>, <code><a href="interactive-elements.html#the-command">command</a></code>, <code><a href="the-iframe-element.html#the-embed-element">embed</a></code>,
479: <code><a href="grouping-content.html#the-hr-element">hr</a></code>, <code><a href="embedded-content-1.html#the-img-element">img</a></code>, <code><a href="the-input-element.html#the-input-element">input</a></code>,
480: <code><a href="the-button-element.html#the-keygen-element">keygen</a></code>, <code><a href="semantics.html#the-link-element">link</a></code>, <code><a href="semantics.html#meta">meta</a></code>,
1.1015 mike 481: <code><a href="the-iframe-element.html#the-param-element">param</a></code>, <code><a href="video.html#the-source-element">source</a></code>, <code><a href="video.html#the-track-element">track</a></code>,
1.973 mike 482: <code><a href="text-level-semantics.html#the-wbr-element">wbr</a></code></dd>
1.1024 mike 483: <!-- see also other places that say VOIDLIST -->
1.1 mike 484:
1.373 mike 485: <dt><dfn id="raw-text-elements">Raw text elements</dfn></dt>
1.1 mike 486:
1.996 mike 487: <dd><code><a href="scripting-1.html#script">script</a></code>, <code><a href="semantics.html#the-style-element">style</a></code></dd> <!-- iframe and
1.91 mike 488: noscript don't count as raw text for syntax purposes -->
1.1 mike 489:
1.373 mike 490: <dt><dfn id="rcdata-elements">RCDATA elements</dfn></dt>
1.1 mike 491:
1.996 mike 492: <dd><code><a href="the-button-element.html#the-textarea-element">textarea</a></code>, <code><a href="semantics.html#the-title-element-0">title</a></code></dd>
1.1 mike 493:
1.373 mike 494: <dt><dfn id="foreign-elements">Foreign elements</dfn></dt>
1.1 mike 495:
1.996 mike 496: <dd>Elements from the <a href="namespaces.html#mathml-namespace">MathML namespace</a>
497: and the <a href="namespaces.html#svg-namespace">SVG namespace</a>.</dd>
1.1 mike 498:
1.373 mike 499: <dt><dfn id="normal-elements">Normal elements</dfn></dt>
1.1 mike 500:
501: <dd>All other allowed <a href="infrastructure.html#html-elements">HTML elements</a> are normal
502: elements.</dd>
503:
504: </dl><p><dfn id="syntax-tags" title="syntax-tags">Tags</dfn> are used to delimit the start
1.373 mike 505: and end of elements in the markup. <a href="#raw-text-elements" title="raw text
506: elements">Raw text</a>, <a href="#rcdata-elements" title="RCDATA
507: elements">RCDATA</a>, and <a href="#normal-elements" title="normal
508: elements">normal</a> elements have a <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> to indicate where they
509: begin, and an <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> to
510: indicate where they end. The start and end tags of certain
511: <a href="#normal-elements">normal elements</a> can be <a href="#syntax-tag-omission" title="syntax-tag-omission">omitted</a>, as described
1.1 mike 512: later. Those that cannot be omitted must not be omitted. <a href="#void-elements">Void
513: elements</a> only have a start tag; end tags must not be
1.373 mike 514: specified for <a href="#void-elements">void elements</a>. <a href="#foreign-elements">Foreign
515: elements</a> must either have a start tag and an end tag, or a
516: start tag that is marked as self-closing, in which case they must
517: not have an end tag.</p><p>The contents of the element must be placed between just after the
1.1 mike 518: start tag (which <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied,
519: in certain cases</a>) and just before the end tag (which again,
520: <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied in certain
521: cases</a>). The exact allowed contents of each individual element
1.1004 mike 522: depend on the content model of that element, as described earlier in
523: this specification. Elements must not contain content that their
1.1 mike 524: content model disallows. In addition to the restrictions placed on
525: the contents by those content models, however, the five types of
1.123 mike 526: elements have additional <em>syntactic</em> requirements.</p><p><a href="#void-elements">Void elements</a> can't have any contents (since there's
1.1 mike 527: no end tag, no content can be put between the start tag and the end
1.373 mike 528: tag).</p><p><a href="#raw-text-elements">Raw text elements</a> can have <a href="#syntax-text" title="syntax-text">text</a>, though it has <a href="#cdata-rcdata-restrictions">restrictions</a> described
529: below.</p><p><a href="#rcdata-elements">RCDATA elements</a> can have <a href="#syntax-text" title="syntax-text">text</a> and <a href="#syntax-charref" title="syntax-charref">character references</a>, but the text
530: must not contain an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.
1.1 mike 531: There are also <a href="#cdata-rcdata-restrictions">further
1.373 mike 532: restrictions</a> described below.</p><p><a href="#foreign-elements">Foreign elements</a> whose start tag is marked as
533: self-closing can't have any contents (since, again, as there's no
534: end tag, no content can be put between the start tag and the end
535: tag). <a href="#foreign-elements">Foreign elements</a> whose start tag is <em>not</em>
536: marked as self-closing can have <a href="#syntax-text" title="syntax-text">text</a>, <a href="#syntax-charref" title="syntax-charref">character references</a>, <a href="#syntax-cdata" title="syntax-cdata">CDATA sections</a>, other <a href="#syntax-elements" title="syntax-elements">elements</a>, and <a href="#syntax-comments" title="syntax-comments">comments</a>, but the text must not
1.588 mike 537: contain the character U+003C LESS-THAN SIGN (<) or an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.</p><div class="note">
1.374 mike 538:
539: <p>The HTML syntax does not support namespace
540: declarations, even in <a href="#foreign-elements">foreign elements</a>.</p>
541:
542: <p>For instance, consider the following HTML fragment:</p>
543:
544: <pre><p>
545: <svg>
546: <metadata>
547: <!-- this is invalid -->
548: <cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/>
549: </metadata>
550: </svg>
551: </p></pre>
552:
553: <p>The innermost element, <code title="">cdr:license</code>, is
554: actually in the SVG namespace, as the "<code title="">xmlns:cdr</code>" attribute has no effect (unlike in
555: XML). In fact, as the comment in the fragment above says, the
556: fragment is actually non-conforming. This is because the SVG
557: specification does not define any elements called "<code title="">cdr:license</code>" in the SVG namespace.</p>
558:
559: </div><p><a href="#normal-elements">Normal elements</a> can have <a href="#syntax-text" title="syntax-text">text</a>, <a href="#syntax-charref" title="syntax-charref">character references</a>, other <a href="#syntax-elements" title="syntax-elements">elements</a>, and <a href="#syntax-comments" title="syntax-comments">comments</a>, but the text must not
1.588 mike 560: contain the character U+003C LESS-THAN SIGN (<) or an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>. Some
561: <a href="#normal-elements">normal elements</a> also have <a href="#element-restrictions">yet more restrictions</a> on what
1.1 mike 562: content they are allowed to hold, beyond the restrictions imposed by
563: the content model and those described in this paragraph. Those
1.123 mike 564: restrictions are described below.</p><p>Tags contain a <dfn id="syntax-tag-name" title="syntax-tag-name">tag name</dfn>,
1.1 mike 565: giving the element's name. HTML elements all have names that only
1.464 mike 566: use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
567: NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
568: Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER
569: Z. In the HTML syntax, tag names, even those for <a href="#foreign-elements">foreign
1.462 mike 570: elements</a>, may be written with any mix of lower- and uppercase
571: letters that, when converted to all-lowercase, matches the element's
1.1008 mike 572: tag name; tag names are case-insensitive.</p><h5 id="start-tags"><span class="secno">8.1.2.1 </span>Start tags</h5><p><dfn id="syntax-start-tag" title="syntax-start-tag">Start tags</dfn> must have the
1.123 mike 573: following format:</p><ol><li>The first character of a start tag must be a U+003C LESS-THAN
1.588 mike 574: SIGN character (<).</li>
1.1 mike 575:
576: <li>The next few characters of a start tag must be the element's
577: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
578:
579: <li>If there are to be any attributes in the next step, there must
1.996 mike 580: first be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 581: characters</a>.</li>
582:
583: <li>Then, the start tag may have a number of attributes, the <a href="#syntax-attributes" title="syntax-attributes">syntax for which</a> is described
1.1004 mike 584: below. Attributes must be separated from each other by one or more
1.996 mike 585: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 586:
1.766 mike 587: <li>After the attributes, or after the <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a> if there are no attributes,
1.996 mike 588: there may be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.766 mike 589: characters</a>. (Some attributes are required to be followed by
590: a space. See the <a href="#syntax-attributes" title="syntax-attributes">attributes
591: section</a> below.)</li>
1.1 mike 592:
593: <li>Then, if the element is one of the <a href="#void-elements">void elements</a>,
1.373 mike 594: or if the element is a <a href="#foreign-elements" title="foreign elements">foreign
1.588 mike 595: element</a>, then there may be a single U+002F SOLIDUS character
596: (/). This character has no effect on <a href="#void-elements">void elements</a>,
597: but on <a href="#foreign-elements">foreign elements</a> it marks the start tag as
598: self-closing.</li>
1.1 mike 599:
600: <li>Finally, start tags must be closed by a U+003E GREATER-THAN
1.588 mike 601: SIGN character (>).</li>
1.1 mike 602:
1.1008 mike 603: </ol><h5 id="end-tags"><span class="secno">8.1.2.2 </span>End tags</h5><p><dfn id="syntax-end-tag" title="syntax-end-tag">End tags</dfn> must have the
1.123 mike 604: following format:</p><ol><li>The first character of an end tag must be a U+003C LESS-THAN
1.588 mike 605: SIGN character (<).</li>
1.1 mike 606:
607: <li>The second character of an end tag must be a U+002F SOLIDUS
1.588 mike 608: character (/).</li>
1.1 mike 609:
610: <li>The next few characters of an end tag must be the element's
611: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
612:
1.996 mike 613: <li>After the tag name, there may be one or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 614: character">space characters</a>.</li>
615:
1.588 mike 616: <li>Finally, end tags must be closed by a U+003E GREATER-THAN SIGN
617: character (>).</li>
1.1 mike 618:
1.1008 mike 619: </ol><h5 id="attributes-0"><span class="secno">8.1.2.3 </span>Attributes</h5><p><dfn id="syntax-attributes" title="syntax-attributes">Attributes</dfn> for an element
1.123 mike 620: are expressed inside the element's start tag.</p><p>Attributes have a name and a value. <dfn id="syntax-attribute-name" title="syntax-attribute-name">Attribute names</dfn> must consist of
1.996 mike 621: one or more characters other than the <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 622: character">space characters</a>, U+0000 NULL, U+0022 QUOTATION
623: MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN
624: (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters,
625: the control characters, and any characters that are not defined by
1.462 mike 626: Unicode. In the HTML syntax, attribute names, even those for
627: <a href="#foreign-elements">foreign elements</a>, may be written with any mix of lower-
628: and uppercase letters that are an <a href="infrastructure.html#ascii-case-insensitive">ASCII
1.123 mike 629: case-insensitive</a> match for the attribute's name.</p><p><dfn id="syntax-attribute-value" title="syntax-attribute-value">Attribute values</dfn> are a
1.1 mike 630: mixture of <a href="#syntax-text" title="syntax-text">text</a> and <a href="#syntax-charref" title="syntax-charref">character references</a>, except with the
1.123 mike 631: additional restriction that the text cannot contain an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.</p><p>Attributes can be specified in four different ways:</p><dl><dt>Empty attribute syntax</dt>
1.1 mike 632:
633: <dd>
634:
635: <p>Just the <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute
1.837 mike 636: name</a>. The value is implicitly the empty string.</p>
1.1 mike 637:
638: <div class="example">
639:
1.996 mike 640: <p>In the following example, the <code title="attr-fe-disabled"><a href="association-of-controls-and-forms.html#attr-fe-disabled">disabled</a></code> attribute is given with
1.1 mike 641: the empty attribute syntax:</p>
642:
643: <pre><input <em>disabled</em>></pre>
644:
645: </div>
646:
647: <p>If an attribute using the empty attribute syntax is to be
1.996 mike 648: followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 649: character</a> separating the two.</p>
650:
651: </dd>
652:
1.2 mike 653: <dt id="unquoted">Unquoted attribute value syntax</dt>
1.1 mike 654:
655: <dd>
656:
657: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 658: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 659: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 660: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 661: character">space characters</a>, followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
662: addition to the requirements given above for attribute values,
1.996 mike 663: must not contain any literal <a href="common-microsyntaxes.html#space-character" title="space character">space
1.588 mike 664: characters</a>, any U+0022 QUOTATION MARK characters ("),
665: U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN
666: characters (=), U+003C LESS-THAN SIGN characters (<), U+003E
667: GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT
668: characters (`), and must not be the empty string.</p>
1.463 mike 669:
670: <!-- The ` character is in this list on a temporary basis, waiting
1.1003 mike 671: for IE to fix its parsing bug whereby it treats ` as an
1.463 mike 672: attribute value delimiter. Otherwise, escaping software that
673: tries to be clever and not use quotes when it doesn't need to
674: could be tricked by an attacker.
675:
676: Posit a site that allows the user to input text that is used
677: verbatim in two attributes, such that the user can set the
678: first attribute's value to:
679:
680: `
681:
682: ...and the second to:
683:
684: ` onload='...payload...' end=x
685:
686: ...with the assumption that the site is going to not quote
687: the first one, and quote the second one with double quotes:
688:
689: <body title=` class="` onload='...payload...' end=x">
690:
691: In IE, this is treated as:
692:
693: <body title=' class="'
694: onload='...payload...'
695: end='x"'>
696:
697: -->
698:
1.1 mike 699:
700: <div class="example">
701:
1.996 mike 702: <p>In the following example, the <code title="attr-input-value"><a href="the-input-element.html#attr-input-value">value</a></code> attribute is given
1.1 mike 703: with the unquoted attribute value syntax:</p>
704:
705: <pre><input <em>value=yes</em>></pre>
706:
707: </div>
708:
709: <p>If an attribute using the unquoted attribute syntax is to be
1.101 mike 710: followed by another attribute or by the optional U+002F SOLIDUS
1.464 mike 711: character (/) allowed in step 6 of the <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> syntax above, then there
1.996 mike 712: must be a <a href="common-microsyntaxes.html#space-character">space character</a> separating the two.</p>
1.1 mike 713:
714: </dd>
715:
716: <dt>Single-quoted attribute value syntax</dt>
717:
718: <dd>
719:
720: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 721: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 722: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 723: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 724: character">space characters</a>, followed by a single U+0027
1.588 mike 725: APOSTROPHE character ('), followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 726: addition to the requirements given above for attribute values,
1.588 mike 727: must not contain any literal U+0027 APOSTROPHE characters ('), and
728: finally followed by a second single U+0027 APOSTROPHE character
729: (').</p>
1.1 mike 730:
731: <div class="example">
732:
1.996 mike 733: <p>In the following example, the <code title="attr-input-type"><a href="the-input-element.html#attr-input-type">type</a></code> attribute is given with the
1.1 mike 734: single-quoted attribute value syntax:</p>
735:
736: <pre><input <em>type='checkbox'</em>></pre>
737:
738: </div>
739:
740: <p>If an attribute using the single-quoted attribute syntax is to
1.996 mike 741: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 742: character</a> separating the two.</p>
743:
744: </dd>
745:
746: <dt>Double-quoted attribute value syntax</dt>
747:
748: <dd>
749:
750: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 751: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 752: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 753: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 754: character">space characters</a>, followed by a single U+0022
1.588 mike 755: QUOTATION MARK character ("), followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 756: addition to the requirements given above for attribute values,
1.588 mike 757: must not contain any literal U+0022 QUOTATION MARK characters ("),
758: and finally followed by a second single U+0022 QUOTATION MARK
759: character (").</p>
1.1 mike 760:
761: <div class="example">
762:
1.996 mike 763: <p>In the following example, the <code title="attr-fe-name"><a href="association-of-controls-and-forms.html#attr-fe-name">name</a></code> attribute is given with the
1.1 mike 764: double-quoted attribute value syntax:</p>
765:
766: <pre><input <em>name="be evil"</em>></pre>
767:
768: </div>
769:
770: <p>If an attribute using the double-quoted attribute syntax is to
1.996 mike 771: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 772: character</a> separating the two.</p>
773:
774: </dd>
775:
776: </dl><p>There must never be two or more attributes on the same start tag
777: whose names are an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for
1.462 mike 778: each other.</p><hr><p>When a <a href="#foreign-elements" title="foreign elements">foreign element</a> has
779: one of the namespaced attributes given by the local name and
780: namespace of the first and second cells of a row from the following
781: table, it must be written using the name given by the third cell
782: from the same row.</p><table><thead><tr><th> Local name </th><th> Namespace </th><th> Attribute name
1.996 mike 783: </th></tr></thead><tbody><tr><td> <code title="">actuate</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:actuate</code>
784: </td></tr><tr><td> <code title="">arcrole</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:arcrole</code>
785: </td></tr><tr><td> <code title="">href</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:href</code>
786: </td></tr><tr><td> <code title="">role</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:role</code>
787: </td></tr><tr><td> <code title="">show</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:show</code>
788: </td></tr><tr><td> <code title="">title</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:title</code>
789: </td></tr><tr><td> <code title="">type</code> </td><td> <a href="namespaces.html#xlink-namespace">XLink namespace</a> </td><td> <code title="">xlink:type</code>
790: </td></tr><tr><td> <code title="">base</code> </td><td> <a href="namespaces.html#xml-namespace">XML namespace</a> <!-- attr-xml-base --> </td><td> <code title="">xml:base</code>
791: </td></tr><tr><td> <code title="">lang</code> </td><td> <a href="namespaces.html#xml-namespace">XML namespace</a> </td><td> <code title="">xml:lang</code>
792: </td></tr><tr><td> <code title="">space</code> </td><td> <a href="namespaces.html#xml-namespace">XML namespace</a> </td><td> <code title="">xml:space</code>
793: </td></tr><tr><td> <code title="">xmlns</code> </td><td> <a href="namespaces.html#xmlns-namespace">XMLNS namespace</a> </td><td> <code title="">xmlns</code>
794: </td></tr><tr><td> <code title="">xlink</code> </td><td> <a href="namespaces.html#xmlns-namespace">XMLNS namespace</a> </td><td> <code title="">xmlns:xlink</code>
1.671 mike 795: </td></tr></tbody></table><p>No other namespaced attribute can be expressed in <a href="#syntax">the
1.1008 mike 796: HTML syntax</a>.</p><h5 id="optional-tags"><span class="secno">8.1.2.4 </span>Optional tags</h5><p>Certain tags can be <dfn id="syntax-tag-omission" title="syntax-tag-omission">omitted</dfn>.</p><p class="note">Omitting an element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> does not mean the element
1.1 mike 797: is not present; it is implied, but it is still there. An HTML
1.159 mike 798: document always has a root <code><a href="semantics.html#the-html-element-0">html</a></code> element, even if the
1.1 mike 799: string <code title=""><html></code> doesn't appear anywhere in
1.159 mike 800: the markup.</p><!-- <html> --><p>An <code><a href="semantics.html#the-html-element-0">html</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
801: first thing inside the <code><a href="semantics.html#the-html-element-0">html</a></code> element is not a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p><!-- </html> --><p>An <code><a href="semantics.html#the-html-element-0">html</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
802: tag</a> may be omitted if the <code><a href="semantics.html#the-html-element-0">html</a></code> element is not
1.821 mike 803: immediately followed by a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p><!-- <head> --><p>A <code><a href="semantics.html#the-head-element-0">head</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
804: element is empty, or if the first thing inside the
1.159 mike 805: <code><a href="semantics.html#the-head-element-0">head</a></code> element is an element.</p><!-- </head> --><p>A <code><a href="semantics.html#the-head-element-0">head</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
806: tag</a> may be omitted if the <code><a href="semantics.html#the-head-element-0">head</a></code> element is not
1.996 mike 807: immediately followed by a <a href="common-microsyntaxes.html#space-character">space character</a> or a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p><!-- <body> --><p>A <code><a href="sections.html#the-body-element-0">body</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
808: element is empty, or if the first thing inside the <code><a href="sections.html#the-body-element-0">body</a></code>
809: element is not a <a href="common-microsyntaxes.html#space-character">space character</a> or a <a href="#syntax-comments" title="syntax-comments">comment</a>, except if the first thing
810: inside the <code><a href="sections.html#the-body-element-0">body</a></code> element is a <code><a href="scripting-1.html#script">script</a></code> or
1.1 mike 811: <code><a href="semantics.html#the-style-element">style</a></code> element. <!-- Note that even if the </head> end
1.872 mike 812: tag is present, the parser makes <style type="text/css"> and <script type="text/javascript"> elements
1.1 mike 813: between </head> and <body> end up in the <head> instead of implying
1.996 mike 814: the <body> --></p><!-- </body> --><p>A <code><a href="sections.html#the-body-element-0">body</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
815: tag</a> may be omitted if the <code><a href="sections.html#the-body-element-0">body</a></code> element is not
816: immediately followed by a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p><!-- </li> --><p>A <code><a href="grouping-content.html#the-li-element">li</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
817: tag</a> may be omitted if the <code><a href="grouping-content.html#the-li-element">li</a></code> element is
818: immediately followed by another <code><a href="grouping-content.html#the-li-element">li</a></code> element or if there
819: is no more content in the parent element.</p><!-- </dt> --><p>A <code><a href="grouping-content.html#the-dt-element">dt</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
820: tag</a> may be omitted if the <code><a href="grouping-content.html#the-dt-element">dt</a></code> element is
821: immediately followed by another <code><a href="grouping-content.html#the-dt-element">dt</a></code> element or a
822: <code><a href="grouping-content.html#the-dd-element">dd</a></code> element.</p><!-- </dd> --><p>A <code><a href="grouping-content.html#the-dd-element">dd</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
823: tag</a> may be omitted if the <code><a href="grouping-content.html#the-dd-element">dd</a></code> element is
824: immediately followed by another <code><a href="grouping-content.html#the-dd-element">dd</a></code> element or a
825: <code><a href="grouping-content.html#the-dt-element">dt</a></code> element, or if there is no more content in the
826: parent element.</p><!-- </p> --><p>A <code><a href="grouping-content.html#the-p-element">p</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
827: tag</a> may be omitted if the <code><a href="grouping-content.html#the-p-element">p</a></code> element is
828: immediately followed by an <code><a href="sections.html#the-address-element">address</a></code>,
829: <code><a href="sections.html#the-article-element">article</a></code>, <code><a href="sections.html#the-aside-element">aside</a></code>, <code><a href="grouping-content.html#the-blockquote-element">blockquote</a></code>,
1.1018 mike 830: <code><a href="obsolete.html#dir">dir</a></code>, <code><a href="grouping-content.html#the-div-element">div</a></code>, <code><a href="grouping-content.html#the-dl-element">dl</a></code>,
831: <code><a href="forms.html#the-fieldset-element">fieldset</a></code>, <code><a href="sections.html#the-footer-element">footer</a></code>, <code><a href="forms.html#the-form-element">form</a></code>,
832: <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h1</a></code>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h2</a></code>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h3</a></code>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h4</a></code>,
833: <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h5</a></code>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h6</a></code>, <code><a href="sections.html#the-header-element">header</a></code>,
834: <code><a href="sections.html#the-hgroup-element">hgroup</a></code>, <code><a href="grouping-content.html#the-hr-element">hr</a></code>, <code><a href="interactive-elements.html#menus">menu</a></code>,
835: <code><a href="sections.html#the-nav-element">nav</a></code>, <code><a href="grouping-content.html#the-ol-element">ol</a></code>, <code><a href="grouping-content.html#the-p-element">p</a></code>, <code><a href="grouping-content.html#the-pre-element">pre</a></code>,
1.996 mike 836: <code><a href="sections.html#the-section-element">section</a></code>, <code><a href="tabular-data.html#the-table-element">table</a></code>, or <code><a href="grouping-content.html#the-ul-element">ul</a></code>,
1.1 mike 837: element, or if there is no more content in the parent element and
1.123 mike 838: the parent element is not an <code><a href="text-level-semantics.html#the-a-element">a</a></code> element.</p><!-- </rt> --><p>An <code><a href="text-level-semantics.html#the-rt-element">rt</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 839: tag</a> may be omitted if the <code><a href="text-level-semantics.html#the-rt-element">rt</a></code> element is
840: immediately followed by an <code><a href="text-level-semantics.html#the-rt-element">rt</a></code> or <code><a href="text-level-semantics.html#the-rp-element">rp</a></code>
1.123 mike 841: element, or if there is no more content in the parent element.</p><!-- </rp> --><p>An <code><a href="text-level-semantics.html#the-rp-element">rp</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 842: tag</a> may be omitted if the <code><a href="text-level-semantics.html#the-rp-element">rp</a></code> element is
843: immediately followed by an <code><a href="text-level-semantics.html#the-rt-element">rt</a></code> or <code><a href="text-level-semantics.html#the-rp-element">rp</a></code>
1.123 mike 844: element, or if there is no more content in the parent element.</p><!-- </optgroup> (the text assumes <optgroup> can only be inside a
1.1 mike 845: <select>; commented out text below can handle the non-<select> case
1.996 mike 846: if we ever allow it) --><p>An <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> may be omitted if the
847: <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element <!--has an ancestor
1.1 mike 848: <code>select</code> element and--> is immediately followed by
1.996 mike 849: another <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element, or if <!--all of the elements
1.1 mike 850: that are ancestors of the <code>optgroup</code> element, up to and
851: including the first ancestor element that is not an
852: <code>optgroup</code> element, have no more content--> there is no
1.123 mike 853: more content in the parent element.</p><!-- so e.g. the max number of </optgroup>s are omitted here:
1.1 mike 854: <select><optgroup></select>
855: <p id=x><optgroup></optgroup>x</p>
856: <p id=x><optgroup><optgroup></optgroup></optgroup>x</p>
857: <p><optgroup id=x><optgroup></optgroup>x</p>
858: <p><optgroup><optgroup id=x>x</p>
1.996 mike 859: --><!-- </option> --><p>An <code><a href="the-button-element.html#the-option-element">option</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
860: tag</a> may be omitted if the <code><a href="the-button-element.html#the-option-element">option</a></code> element is
861: immediately followed by another <code><a href="the-button-element.html#the-option-element">option</a></code> element, or if
862: it is immediately followed by an <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element, or
1.123 mike 863: if there is no more content in the parent element.</p><!-- <colgroup> --><p>A <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
1.1 mike 864: first thing inside the <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element is a
865: <code><a href="tabular-data.html#the-col-element">col</a></code> element, and if the element is not immediately
866: preceded by another <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element whose <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> has been omitted. (It can't be
1.123 mike 867: omitted if the element is empty.)</p><!-- </colgroup> --><p>A <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> may be omitted if the
1.1 mike 868: <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element is not immediately followed by a
1.996 mike 869: <a href="common-microsyntaxes.html#space-character">space character</a> or a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p><!-- </thead> --><p>A <code><a href="tabular-data.html#the-thead-element">thead</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 870: tag</a> may be omitted if the <code><a href="tabular-data.html#the-thead-element">thead</a></code> element is
871: immediately followed by a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> or <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code>
1.123 mike 872: element.</p><!-- <tbody> --><p>A <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
1.1 mike 873: first thing inside the <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element is a
874: <code><a href="tabular-data.html#the-tr-element">tr</a></code> element, and if the element is not immediately
875: preceded by a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code>, <code><a href="tabular-data.html#the-thead-element">thead</a></code>, or
876: <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code> element whose <a href="#syntax-end-tag" title="syntax-end-tag">end
877: tag</a> has been omitted. (It can't be omitted if the element is
1.123 mike 878: empty.)</p><!-- </tbody> --><p>A <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 879: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element is
880: immediately followed by a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> or <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code>
1.123 mike 881: element, or if there is no more content in the parent element.</p><!-- </tfoot> --><p>A <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 882: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code> element is
883: immediately followed by a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element, or if there is
1.123 mike 884: no more content in the parent element.</p><!-- </tr> --><p>A <code><a href="tabular-data.html#the-tr-element">tr</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 885: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tr-element">tr</a></code> element is
886: immediately followed by another <code><a href="tabular-data.html#the-tr-element">tr</a></code> element, or if there
1.123 mike 887: is no more content in the parent element.</p><!-- </td> --><p>A <code><a href="tabular-data.html#the-td-element">td</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 888: tag</a> may be omitted if the <code><a href="tabular-data.html#the-td-element">td</a></code> element is
889: immediately followed by a <code><a href="tabular-data.html#the-td-element">td</a></code> or <code><a href="tabular-data.html#the-th-element">th</a></code>
1.123 mike 890: element, or if there is no more content in the parent element.</p><!-- </th> --><p>A <code><a href="tabular-data.html#the-th-element">th</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 891: tag</a> may be omitted if the <code><a href="tabular-data.html#the-th-element">th</a></code> element is
892: immediately followed by a <code><a href="tabular-data.html#the-td-element">td</a></code> or <code><a href="tabular-data.html#the-th-element">th</a></code>
1.123 mike 893: element, or if there is no more content in the parent element.</p><p><strong>However</strong>, a <a href="#syntax-start-tag" title="syntax-start-tag">start
1.1008 mike 894: tag</a> must never be omitted if it has any attributes.</p><h5 id="element-restrictions"><span class="secno">8.1.2.5 </span>Restrictions on content models</h5><p>For historical reasons, certain elements have extra restrictions
1.123 mike 895: beyond even the restrictions given by their content model.</p><p>A <code><a href="tabular-data.html#the-table-element">table</a></code> element must not contain <code><a href="tabular-data.html#the-tr-element">tr</a></code>
1.1 mike 896: elements, even though these elements are technically allowed inside
897: <code><a href="tabular-data.html#the-table-element">table</a></code> elements according to the content models
898: described in this specification. (If a <code><a href="tabular-data.html#the-tr-element">tr</a></code> element is
899: put inside a <code><a href="tabular-data.html#the-table-element">table</a></code> in the markup, it will in fact imply
1.304 mike 900: a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> start tag before it.)</p><p>A single <a href="#syntax-newlines" title="syntax-newlines">newline</a> may be
901: placed immediately after the <a href="#syntax-start-tag" title="syntax-start-tag">start
1.996 mike 902: tag</a> of <code><a href="grouping-content.html#the-pre-element">pre</a></code> and <code><a href="the-button-element.html#the-textarea-element">textarea</a></code>
1.1 mike 903: elements. This does not affect the processing of the element. The
1.304 mike 904: otherwise optional <a href="#syntax-newlines" title="syntax-newlines">newline</a>
1.381 mike 905: <em>must</em> be included if the element's contents themselves start
906: with a <a href="#syntax-newlines" title="syntax-newlines">newline</a> (because
907: otherwise the leading newline in the contents would be treated like
908: the optional newline, and ignored).</p><div class="example">
1.996 mike 909: <p>The following two <code><a href="grouping-content.html#the-pre-element">pre</a></code> blocks are equivalent:</p>
1.1 mike 910: <pre><pre>Hello</pre></pre>
911: <pre><pre><br>Hello</pre></pre>
1.1008 mike 912: </div><h5 id="cdata-rcdata-restrictions"><span class="secno">8.1.2.6 </span>Restrictions on the contents of raw text and RCDATA elements</h5><p>The text in <a href="#raw-text-elements" title="raw text elements">raw text</a> and
1.889 mike 913: <a href="#rcdata-elements">RCDATA elements</a> must not contain any occurrences of the
914: string "<code title=""></</code>" (U+003C LESS-THAN SIGN, U+002F
915: SOLIDUS) followed by characters that case-insensitively match the
916: tag name of the element followed by one of U+0009 CHARACTER
917: TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D
918: CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or
1.1008 mike 919: U+002F SOLIDUS (/).</p><h4 id="text-0"><span class="secno">8.1.3 </span>Text</h4><p><dfn id="syntax-text" title="syntax-text">Text</dfn> is allowed inside elements,
1.1005 mike 920: attribute values, and comments. Text must consist of Unicode
921: characters. Text must not contain U+0000 characters. Text must not
922: contain permanently undefined Unicode characters (noncharacters).
923: Text must not contain control characters other than <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>. Extra constraints
924: are placed on what is and what is not allowed in text based on where
1.1008 mike 925: the text is to be put, as described in the other sections.</p><h5 id="newlines"><span class="secno">8.1.3.1 </span>Newlines</h5><p><dfn id="syntax-newlines" title="syntax-newlines">Newlines</dfn> in HTML may be
1.1 mike 926: represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A
927: LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR),
1.882 mike 928: U+000A LINE FEED (LF) characters in that order.</p><p>Where <a href="#syntax-charref" title="syntax-charref">character references</a>
929: are allowed, a character reference of a U+000A LINE FEED (LF)
930: character (but not a U+000D CARRIAGE RETURN (CR) character) also
1.1008 mike 931: represents a <a href="#syntax-newlines" title="syntax-newlines">newline</a>.</p><h4 id="character-references"><span class="secno">8.1.4 </span>Character references</h4><p>In certain cases described in other sections, <a href="#syntax-text" title="syntax-text">text</a> may be mixed with <dfn id="syntax-charref" title="syntax-charref">character references</dfn>. These can be used
1.1 mike 932: to escape characters that couldn't otherwise legally be included in
1.588 mike 933: <a href="#syntax-text" title="syntax-text">text</a>.</p><p>Character references must start with a U+0026 AMPERSAND character
934: (&). Following this, there are three possible kinds of character
935: references:</p><dl><dt>Named character references</dt>
1.1 mike 936:
937: <dd>The ampersand must be followed by one of the names given in the
938: <a href="named-character-references.html#named-character-references">named character references</a> section, using the same
1.677 mike 939: case. <span class="impl">The name must be one that is terminated by
940: a U+003B SEMICOLON character (;).</span></dd>
1.1 mike 941:
942:
943: <dt>Decimal numeric character reference</dt>
944:
945: <dd>The ampersand must be followed by a U+0023 NUMBER SIGN
1.588 mike 946: character (#), followed by one or more digits in the range U+0030
947: DIGIT ZERO (0) to U+0039 DIGIT NINE (9), representing a base-ten
948: integer that corresponds to a Unicode code point that is allowed
949: according to the definition below. The digits must then be followed
950: by a U+003B SEMICOLON character (;).</dd>
1.1 mike 951:
952:
953: <dt>Hexadecimal numeric character reference</dt>
954:
955: <dd>The ampersand must be followed by a U+0023 NUMBER SIGN
1.588 mike 956: character (#), which must be followed by either a U+0078 LATIN
957: SMALL LETTER X character (x) or a U+0058 LATIN CAPITAL LETTER X
958: character (X), which must then be followed by one or more digits in
959: the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061
960: LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041
961: LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F,
1.464 mike 962: representing a base-sixteen integer that corresponds to a Unicode
963: code point that is allowed according to the definition below. The
964: digits must then be followed by a U+003B SEMICOLON character
965: (;).</dd>
1.378 mike 966:
967: </dl><p>The numeric character reference forms described above are allowed
1.882 mike 968: to reference any Unicode code point other than U+0000, U+000D,
969: permanently undefined Unicode characters (noncharacters), and
1.996 mike 970: control characters other than <a href="common-microsyntaxes.html#space-character" title="space character">space
1.378 mike 971: characters</a>.</p><p>An <dfn id="syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous
1.464 mike 972: ampersand</dfn> is a U+0026 AMPERSAND character (&) that is
1.897 mike 973: followed by one or more characters in the range U+0030 DIGIT ZERO
974: (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A
975: LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A
976: LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character
977: (;), where these characters do not match any of the names given in
1.1029 mike 978: the <a href="named-character-references.html#named-character-references">named character references</a> section.</p><h4 id="cdata-sections"><span class="secno">8.1.5 </span>CDATA sections</h4><p><dfn id="syntax-cdata" title="syntax-cdata">CDATA sections</dfn> must consist of
979: the following components, in this order:</p><ol><li>The string "<code title=""><![CDATA[</code>".</li>
980:
981: <li>Optionally, <a href="#syntax-text" title="syntax-text">text</a>, with the
982: additional restriction that the text must not contain the string
983: "<code title="">]]></code>".</li>
984:
985: <li>The string "<code title="">]]></code>".</li>
986:
987: </ol><div class="example">
1.724 mike 988:
989: <p>CDATA sections can only be used in foreign content (MathML or
990: SVG). In this example, a CDATA section is used to escape the
991: contents of an <code>ms</code> element:</p>
992:
993: <pre><p>You can add a string to a number, but this stringifies the number:</p>
994: <math>
995: <ms><![CDATA[x<y]]></ms>
996: <mo>+</mo>
997: <mn>3</mn>
998: <mo>=</mo>
999: <ms><![CDATA[x<y3]]></ms>
1000: </math></pre>
1001:
1.1008 mike 1002: </div><h4 id="comments"><span class="secno">8.1.6 </span>Comments</h4><p><dfn id="syntax-comments" title="syntax-comments">Comments</dfn> must start with the
1.1 mike 1003: four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
1004: MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<code title=""><!--</code>). Following this sequence, the comment may
1005: have <a href="#syntax-text" title="syntax-text">text</a>, with the additional
1006: restriction that the text must not start with a single U+003E
1.588 mike 1007: GREATER-THAN SIGN character (>), nor start with a U+002D
1008: HYPHEN-MINUS character (-) followed by a U+003E GREATER-THAN SIGN
1009: (>) character, nor contain two consecutive U+002D HYPHEN-MINUS
1010: characters (<code title="">--</code>), nor end with a U+002D
1011: HYPHEN-MINUS character (-). Finally, the comment must be ended by
1.1 mike 1012: the three character sequence U+002D HYPHEN-MINUS, U+002D
1.996 mike 1013: HYPHEN-MINUS, U+003E GREATER-THAN SIGN (<code title="">--></code>).</p></body></html>
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