Annotation of html5/spec/syntax.html, revision 1.1013
1.872 mike 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
1.894 mike 2: <!DOCTYPE html>
1.996 mike 3: <!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie" class="split chapter"><head><title>8 The HTML syntax — HTML5 </title><style type="text/css">
1.1 mike 4: pre { margin-left: 2em; white-space: pre-wrap; }
5: h2 { margin: 3em 0 1em 0; }
6: h3 { margin: 2.5em 0 1em 0; }
7: h4 { margin: 2.5em 0 0.75em 0; }
8: h5, h6 { margin: 2.5em 0 1em; }
9: h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
10: h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
11: p { margin: 1em 0; }
12: hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
13: dl, dd { margin-top: 0; margin-bottom: 0; }
14: dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
15: dt + dt { margin-top: 0; }
16: dd dt { margin-top: 0.25em; margin-bottom: 0; }
17: dd p { margin-top: 0; }
18: dd dl + p { margin-top: 1em; }
19: dd table + p { margin-top: 1em; }
20: p + * > li, dd li { margin: 1em 0; }
21: dt, dfn { font-weight: bold; font-style: normal; }
22: dt dfn { font-style: italic; }
23: pre, code { font-size: inherit; font-family: monospace; font-variant: normal; }
24: pre strong { color: black; font: inherit; font-weight: bold; background: yellow; }
25: pre em { font-weight: bolder; font-style: normal; }
26: @media screen { code { color: orangered; } code :link, code :visited { color: inherit; } }
27: var sub { vertical-align: bottom; font-size: smaller; position: relative; top: 0.1em; }
28: table { border-collapse: collapse; border-style: hidden hidden none hidden; }
1.983 mike 29: table thead, table tbody { border-bottom: solid; }
1.1 mike 30: table tbody th:first-child { border-left: solid; }
1.475 mike 31: table tbody th { text-align: left; }
1.1 mike 32: table td, table th { border-left: solid; border-right: solid; border-bottom: solid thin; vertical-align: top; padding: 0.2em; }
33: blockquote { margin: 0 0 0 2em; border: 0; padding: 0; font-style: italic; }
34:
35: .bad, .bad *:not(.XXX) { color: gray; border-color: gray; background: transparent; }
36: .matrix, .matrix td { border: none; text-align: right; }
37: .matrix { margin-left: 2em; }
38: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
39: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
40: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
41:
42: .toc dfn, h1 dfn, h2 dfn, h3 dfn, h4 dfn, h5 dfn, h6 dfn { font: inherit; }
43: img.extra { float: right; }
44: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; }
45: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
46: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
47: pre.css:first-line { color: #AAAA50; }
1.840 mike 48: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
1.1 mike 49: hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
50: dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
51: dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
52: dl.domintro dd p { margin: 0.5em 0; }
53: dl.switch { padding-left: 2em; }
54: dl.switch > dt { text-indent: -1.5em; }
55: dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
56: dl.triple { padding: 0 0 0 1em; }
57: dl.triple dt, dl.triple dd { margin: 0; display: inline }
58: dl.triple dt:after { content: ':'; }
59: dl.triple dd:after { content: '\A'; white-space: pre; }
60: .diff-old { text-decoration: line-through; color: silver; background: transparent; }
61: .diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
62: a .diff-new { border-bottom: 1px blue solid; }
63:
64: h2 { page-break-before: always; }
65: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
66: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
67:
68: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]), li > span:not([title=""]):not([class="XXX"]):not([class="impl"]) { border-bottom: solid #9999CC; }
69:
70: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
71: div.head p { margin: 0; }
72: div.head h1 { margin: 0; }
73: div.head .logo { float: right; margin: 0 1em; }
74: div.head .logo img { border: none } /* remove border from top image */
75: div.head dl { margin: 1em 0; }
1.671 mike 76: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
1.1 mike 77:
78: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
79: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
80: body > .toc > li > * { margin-bottom: 0.5em; }
81: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
82: .toc, .toc li { list-style: none; }
83:
84: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
85: .brief li { margin: 0; padding: 0; }
86: .brief li p { margin: 0; padding: 0; }
87:
88: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
89: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
90: .category-list li { display: inline; }
91: .category-list li:not(:last-child)::after { content: ', '; }
92: .category-list li > span, .category-list li > a { text-transform: lowercase; }
93: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
94:
95: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
96: .XXX > :first-child { margin-top: 0; }
97: p .XXX { line-height: 3em; }
1.159 mike 98: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
99: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
100: .annotation :link, .annotation :visited { color: inherit; }
101: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
102: .annotation span { border: none ! important; }
1.1 mike 103: .note { color: green; background: transparent; font-family: sans-serif; }
104: .warning { color: red; background: transparent; }
105: .note, .warning { font-weight: bolder; font-style: italic; }
106: p.note, div.note { padding: 0.5em 2em; }
107: span.note { padding: 0 2em; }
108: .note p:first-child, .warning p:first-child { margin-top: 0; }
109: .note p:last-child, .warning p:last-child { margin-bottom: 0; }
110: .warning:before { font-style: normal; }
111: p.note:before { content: 'Note: '; }
112: p.warning:before { content: '\26A0 Warning! '; }
113:
114: .bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
115: .bookkeeping { font-size: 0.8em; margin: 2em 0; }
116: .bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
1.1006 mike 117: .bookkeeping dt { margin: 0.5em 2em 0; }
118: .bookkeeping dd { margin: 0 3em 0.5em; }
1.1 mike 119:
120: h4 { position: relative; z-index: 3; }
121: h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
122: .element {
123: background: #EEEEFF;
124: color: black;
125: margin: 0 0 1em 0.15em;
126: padding: 0 1em 0.25em 0.75em;
127: border-left: solid #9999FF 0.25em;
128: position: relative;
129: z-index: 1;
130: }
131: .element:before {
132: position: absolute;
133: z-index: 2;
134: top: 0;
135: left: -1.15em;
136: height: 2em;
137: width: 0.9em;
138: background: #EEEEFF;
139: content: ' ';
140: border-style: none none solid solid;
141: border-color: #9999FF;
142: border-width: 0.25em;
143: }
144:
1.149 mike 145: .example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
146: td > .example:only-child { margin: 0 0 0 0.1em; }
1.1 mike 147:
148: ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
149: ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
150: ul.domTree li li { list-style: none; }
151: 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; }
152: 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; }
153: ul.domTree span { font-style: italic; font-family: serif; }
154: ul.domTree .t1 code { color: purple; font-weight: bold; }
155: ul.domTree .t2 { font-style: normal; font-family: monospace; }
156: ul.domTree .t2 .name { color: black; font-weight: bold; }
157: ul.domTree .t2 .value { color: blue; font-weight: normal; }
158: ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
159: ul.domTree .t7 code, .domTree .t8 code { color: green; }
160: ul.domTree .t10 code { color: teal; }
161:
1.736 mike 162: body.dfnEnabled dfn { cursor: pointer; }
163: .dfnPanel {
164: display: inline;
165: position: absolute;
166: z-index: 10;
167: height: auto;
168: width: auto;
169: padding: 0.5em 0.75em;
170: font: small sans-serif, Droid Sans Fallback;
171: background: #DDDDDD;
172: color: black;
173: border: outset 0.2em;
174: }
175: .dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
176: .dfnPanel :link, .dfnPanel :visited { color: black; }
177: .dfnPanel p { font-weight: bolder; }
178: .dfnPanel * + p { margin-top: 0.25em; }
179: .dfnPanel li { list-style-position: inside; }
180:
1.671 mike 181: #configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
182: #configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
183: #configUI p label { display: block; }
184: #configUI #updateUI, #configUI .loginUI { text-align: center; }
185: #configUI input[type=button] { display: block; margin: auto; }
1.1002 mike 186:
1.1013 ! mike 187: fieldset { margin: 1em; }
! 188: fieldset > legend * + { margin-top: 0; }
! 189: fieldset > :last-child { margin-bottom: 0; }
! 190:
! 191: .latest-link::after {
! 192: position: fixed;
! 193: bottom: 0;
! 194: left: 0; right: 0;
! 195: margin: 0 auto 0 auto;
! 196: width: 50%;
! 197: background: maroon; color: yellow;
! 198: -webkit-border-radius: 1em 1em 0 0;
! 199: -moz-border-radius: 1em 1em 0 0;
! 200: border-radius: 1em 1em 0 0;
! 201: -moz-box-shadow: 0 0 1em #500;
! 202: -webkit-box-shadow: 0 0 1em #500;
! 203: box-shadow: 0 0 1em silver;
! 204: padding: 0.5em 1em;
! 205: text-align: center;
! 206: text-decoration: underline;
! 207: white-space: pre-wrap;
! 208: content: 'This is an out-of-date copy of this specification.\A For the up-to-date version, please view the latest editor\'s draft by following this link.';
! 209: }
! 210:
1.267 mike 211: </style><style type="text/css">
212:
1.292 mike 213: .applies thead th > * { display: block; }
214: .applies thead code { display: block; }
215: .applies tbody th { whitespace: nowrap; }
216: .applies td { text-align: center; }
217: .applies .yes { background: yellow; }
218:
1.1007 mike 219: .matrix, .matrix td { border: hidden; text-align: right; }
1.267 mike 220: .matrix { margin-left: 2em; }
221:
222: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
223: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
224: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
225:
1.1009 mike 226: td.eg { border-width: thin; text-align: center; }
227:
1.267 mike 228: #table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
229: #table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
230: #table-example-1 caption { padding-bottom: 0.5em; }
231: #table-example-1 thead, #table-example-1 tbody { border: none; }
232: #table-example-1 th, #table-example-1 td { border: solid thin; }
233: #table-example-1 th { font-weight: normal; }
234: #table-example-1 td { border-style: none solid; vertical-align: top; }
235: #table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
236: #table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
237: #table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
238: #table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
239: #table-example-1 tbody td:first-child::after { content: leader(". "); }
240: #table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
241: #table-example-1 tbody td:first-child + td { width: 10em; }
242: #table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
243: #table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
244:
245: .apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
246: .apple-table-examples * { font-family: "Times", serif; }
247: .apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
248: .apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
249: .apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
250: .apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
251: .apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
252: .apple-table-examples td { text-align: right; vertical-align: top; }
253: .apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
254: .apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
255: .apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
256: .apple-table-examples sup { line-height: 0; }
257:
1.724 mike 258: .details-example img { vertical-align: top; }
259:
1.882 mike 260: #named-character-references-table {
1.1010 mike 261: white-space: nowrap;
1.882 mike 262: font-size: 0.6em;
1.1010 mike 263: column-width: 30em;
1.882 mike 264: column-gap: 1em;
1.1010 mike 265: -moz-column-width: 30em;
1.882 mike 266: -moz-column-gap: 1em;
1.1010 mike 267: -webkit-column-width: 30em;
1.882 mike 268: -webkit-column-gap: 1em;
269: }
1.1010 mike 270: #named-character-references-table > table > tbody > tr > td:first-child + td,
1.882 mike 271: #named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
272: #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 273: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
1.882 mike 274:
1.997 mike 275: .glyph.control { color: red; }
276:
1.999 mike 277: @font-face {
278: font-family: 'Essays1743';
279: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743.ttf');
280: }
281: @font-face {
282: font-family: 'Essays1743';
283: font-weight: bold;
284: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Bold.ttf');
285: }
286: @font-face {
287: font-family: 'Essays1743';
288: font-style: italic;
289: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Italic.ttf');
290: }
291: @font-face {
292: font-family: 'Essays1743';
293: font-style: italic;
294: font-weight: bold;
295: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-BoldItalic.ttf');
296: }
297:
1.872 mike 298: </style><style type="text/css">
1.881 mike 299: .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; }
300: </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">
1.671 mike 301: function getCookie(name) {
302: var params = location.search.substr(1).split("&");
303: for (var index = 0; index < params.length; index++) {
304: if (params[index] == name)
305: return "1";
306: var data = params[index].split("=");
307: if (data[0] == name)
308: return unescape(data[1]);
309: }
310: var cookies = document.cookie.split("; ");
311: for (var index = 0; index < cookies.length; index++) {
312: var data = cookies[index].split("=");
313: if (data[0] == name)
314: return unescape(data[1]);
315: }
316: return null;
317: }
318: function load(script) {
319: var e = document.createElement('script');
1.1013 ! mike 320: e.setAttribute('src', script);
1.671 mike 321: document.body.appendChild(e);
322: }
323: function init() {
324: if (location.search == '?slow-browser')
325: return;
326: var configUI = document.createElement('div');
327: configUI.id = 'configUI';
328: document.body.appendChild(configUI);
329: // load('reviewer.js'); // would need cross-site XHR
330: if (document.getElementById('head'))
331: load('toc.js');
332: load('styler.js');
333: // load('updater.js'); // would need cross-site XHR
1.724 mike 334: load('dfn.js'); // doesn't support split-out specs, but, oh well.
1.671 mike 335: // load('status.js'); // would need cross-site XHR
336: if (getCookie('profile') == '1')
337: document.getElementsByTagName('h2')[0].textContent += '; load: ' + (new Date() - loadTimer) + 'ms';
338: fixBrokenLink();
339: }
1.1013 ! mike 340: </script><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css">
1.996 mike 341: <script src="link-fixup.js"></script>
1.1012 mike 342: <link href="dnd.html" title="7.8 Drag and drop" rel="prev">
1.2 mike 343: <link href="spec.html#contents" title="Table of contents" rel="index">
1.996 mike 344: <link href="parsing.html" title="8.2 Parsing HTML documents" rel="next">
1.671 mike 345: </head><body onload="fixBrokenLink(); init()"><div class="head" id="head">
1.1 mike 346: <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 347:
1.183 mike 348: <h1>HTML5</h1>
1.874 mike 349: </div><div>
1.1012 mike 350: <a href="dnd.html">← 7.8 Drag and drop</a> –
1.2 mike 351: <a href="spec.html#contents">Table of contents</a> –
1.996 mike 352: <a href="parsing.html">8.2 Parsing HTML documents →</a>
353: <ol class="toc"><li><a href="syntax.html#syntax"><span class="secno">8 </span>The HTML syntax</a>
354: <ol><li><a href="syntax.html#writing"><span class="secno">8.1 </span>Writing HTML documents</a>
355: <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>
356: <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>
357: <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 358:
1.755 mike 359: <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 360: labeled with an <a href="infrastructure.html#html-mime-type">HTML MIME type</a>. Rules for XML resources
361: are discussed in the section below entitled "<a href="the-xhtml-syntax.html#the-xhtml-syntax">The XHTML
1.1008 mike 362: syntax</a>".</p><h3 id="writing"><span class="secno">8.1 </span>Writing HTML documents</h3><div class="impl">
1.1 mike 363:
364: <p><i>This section only applies to documents, authoring tools, and
365: markup generators. In particular, it does not apply to conformance
366: checkers; conformance checkers must use the requirements given in
367: the next section ("parsing HTML documents").</i></p>
368:
1.123 mike 369: </div><p>Documents must consist of the following parts, in the given
370: order:</p><ol><li>Optionally, a single U+FEFF BYTE ORDER MARK (BOM) character.</li>
1.1 mike 371:
372: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 373: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 374:
375: <li>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a>.
376:
377: </li><li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 378: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 379:
1.159 mike 380: <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 381:
382: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 383: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 384:
385: </ol><p>The various types of content mentioned above are described in the
1.123 mike 386: 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 387: declarations</a> are to be serialized, as discussed in the
1.123 mike 388: section on that topic.</p><div class="note">
1.1 mike 389:
1.159 mike 390: <p>Space characters before the root <code><a href="semantics.html#the-html-element-0">html</a></code> element, and
391: space characters at the start of the <code><a href="semantics.html#the-html-element-0">html</a></code> element and
392: before the <code><a href="semantics.html#the-head-element-0">head</a></code> element, will be dropped when the
1.1 mike 393: document is parsed; space characters <em>after</em> the root
1.159 mike 394: <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 395: of the <code><a href="sections.html#the-body-element-0">body</a></code> element. Thus, space characters around the
1.1 mike 396: root element do not round-trip.</p>
397:
398: <p>It is suggested that newlines be inserted after the DOCTYPE,
399: after any comments that are before the root element, after the
1.159 mike 400: <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
401: that are inside the <code><a href="semantics.html#the-html-element-0">html</a></code> element but before the
402: <code><a href="semantics.html#the-head-element-0">head</a></code> element.</p>
1.1 mike 403:
1.123 mike 404: </div><p>Many strings in the HTML syntax (e.g. the names of elements and
1.1 mike 405: their attributes) are case-insensitive, but only for characters in
1.547 mike 406: the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL
407: LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL
1.1 mike 408: LETTER Z). For convenience, in this section this is just referred to
1.1008 mike 409: as "case-insensitive".</p><h4 id="the-doctype"><span class="secno">8.1.1 </span>The DOCTYPE</h4><p class="XXX annotation"><span><a href="http://www.w3.org/html/wg/tracker/issues/4">ISSUE-4</a> (html-versioning) and <a href="http://www.w3.org/html/wg/tracker/issues/84">ISSUE-84</a> (legacy-doctypes) block progress to Last Call</span></p><p>A <dfn id="syntax-doctype" title="syntax-doctype">DOCTYPE</dfn> is a <!-- mostly
1.884 mike 410: useless but nonetheless --> required preamble.</p><p class="note">DOCTYPEs are required for legacy reasons. When
1.1 mike 411: omitted, browsers tend to use a different rendering mode that is
412: incompatible with some specifications. Including the DOCTYPE in a
413: document ensures that the browser makes a best-effort attempt at
1.123 mike 414: following the relevant specifications.</p><p>A DOCTYPE must consist of the following characters, in this
1.882 mike 415: 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 416: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1011 mike 417: <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 418: <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 419: <li>Zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.588 mike 420: <li>A U+003E GREATER-THAN SIGN character (>).</li>
1.1011 mike 421: </ol><p class="note">In other words, <code><!DOCTYPE html></code>,
1.861 mike 422: case-insensitively.</p><hr><p>For the purposes of HTML generators that cannot output HTML
1.1 mike 423: markup with the short DOCTYPE "<code title=""><!DOCTYPE
1.1011 mike 424: html></code>", a <dfn id="doctype-legacy-string">DOCTYPE legacy string</dfn> may be inserted
1.1 mike 425: into the DOCTYPE (in the position defined above). This string must
1.996 mike 426: 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 427: <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 428: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 429: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>quote mark</i>).</li>
1.996 mike 430: <li>The literal string "<code><a href="urls.html#about:legacy-compat">about:legacy-compat</a></code>".</li>
1.856 mike 431: <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 432: </ol><p class="note">In other words, <code><!DOCTYPE html SYSTEM
433: "about:legacy-compat"></code> or <code><!DOCTYPE html SYSTEM
1.1004 mike 434: 'about:legacy-compat'></code>, case-insensitively except for the
435: 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 436: the document is generated from a system that cannot output the
1.861 mike 437: shorter string.</p><hr><!-- see the parser section before changing this bit --><p>To help authors transition from HTML4 and XHTML1, an
438: <dfn id="obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</dfn> can be inserted into
439: the DOCTYPE (in the position defined above). This string must
1.996 mike 440: 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 441: <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 442: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 443: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>first quote mark</i>).</li>
444: <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>
445: <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 446: <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 447: <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>
448: <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>
449: <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>
450: </ol><table><caption>
451: Allowed values for public and system identifiers in an <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a>.
452: </caption>
453: <thead><tr><th> Public identifier
454: </th><th> System identifier
455: </th></tr></thead><tbody><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
456: </td><td>
457: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
458: </td><td> <code title="">http://www.w3.org/TR/REC-html40/strict.dtd</code>
459: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
460: </td><td>
461: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
462: </td><td> <code title="">http://www.w3.org/TR/html4/strict.dtd</code>
463: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.0 Strict//EN</code>
464: </td><td> <code title="">http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</code>
465: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.1//EN</code>
466: </td><td> <code title="">http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd</code>
467: </td></tr></tbody></table><p>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a> containing an
468: <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a> is an <dfn id="obsolete-permitted-doctype">obsolete
469: permitted DOCTYPE</dfn>. Authors should not use <a href="#obsolete-permitted-doctype" title="obsolete permitted DOCTYPE">obsolete permitted
1.1008 mike 470: 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 471: <a href="#raw-text-elements">raw text elements</a>, <a href="#rcdata-elements">RCDATA elements</a>,
472: <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 473:
1.996 mike 474: <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>,
475: <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>,
476: <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>,
477: <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>,
478: <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>track</code>,
1.973 mike 479: <code><a href="text-level-semantics.html#the-wbr-element">wbr</a></code></dd>
1.1 mike 480:
1.373 mike 481: <dt><dfn id="raw-text-elements">Raw text elements</dfn></dt>
1.1 mike 482:
1.996 mike 483: <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 484: noscript don't count as raw text for syntax purposes -->
1.1 mike 485:
1.373 mike 486: <dt><dfn id="rcdata-elements">RCDATA elements</dfn></dt>
1.1 mike 487:
1.996 mike 488: <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 489:
1.373 mike 490: <dt><dfn id="foreign-elements">Foreign elements</dfn></dt>
1.1 mike 491:
1.996 mike 492: <dd>Elements from the <a href="namespaces.html#mathml-namespace">MathML namespace</a>
493: and the <a href="namespaces.html#svg-namespace">SVG namespace</a>.</dd>
1.1 mike 494:
1.373 mike 495: <dt><dfn id="normal-elements">Normal elements</dfn></dt>
1.1 mike 496:
497: <dd>All other allowed <a href="infrastructure.html#html-elements">HTML elements</a> are normal
498: elements.</dd>
499:
500: </dl><p><dfn id="syntax-tags" title="syntax-tags">Tags</dfn> are used to delimit the start
1.373 mike 501: and end of elements in the markup. <a href="#raw-text-elements" title="raw text
502: elements">Raw text</a>, <a href="#rcdata-elements" title="RCDATA
503: elements">RCDATA</a>, and <a href="#normal-elements" title="normal
504: elements">normal</a> elements have a <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> to indicate where they
505: begin, and an <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> to
506: indicate where they end. The start and end tags of certain
507: <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 508: later. Those that cannot be omitted must not be omitted. <a href="#void-elements">Void
509: elements</a> only have a start tag; end tags must not be
1.373 mike 510: specified for <a href="#void-elements">void elements</a>. <a href="#foreign-elements">Foreign
511: elements</a> must either have a start tag and an end tag, or a
512: start tag that is marked as self-closing, in which case they must
513: not have an end tag.</p><p>The contents of the element must be placed between just after the
1.1 mike 514: start tag (which <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied,
515: in certain cases</a>) and just before the end tag (which again,
516: <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied in certain
517: cases</a>). The exact allowed contents of each individual element
1.1004 mike 518: depend on the content model of that element, as described earlier in
519: this specification. Elements must not contain content that their
1.1 mike 520: content model disallows. In addition to the restrictions placed on
521: the contents by those content models, however, the five types of
1.123 mike 522: 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 523: no end tag, no content can be put between the start tag and the end
1.373 mike 524: 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
525: 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
526: must not contain an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.
1.1 mike 527: There are also <a href="#cdata-rcdata-restrictions">further
1.373 mike 528: restrictions</a> described below.</p><p><a href="#foreign-elements">Foreign elements</a> whose start tag is marked as
529: self-closing can't have any contents (since, again, as there's no
530: end tag, no content can be put between the start tag and the end
531: tag). <a href="#foreign-elements">Foreign elements</a> whose start tag is <em>not</em>
532: 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 533: 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 534:
535: <p>The HTML syntax does not support namespace
536: declarations, even in <a href="#foreign-elements">foreign elements</a>.</p>
537:
538: <p>For instance, consider the following HTML fragment:</p>
539:
540: <pre><p>
541: <svg>
542: <metadata>
543: <!-- this is invalid -->
544: <cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/>
545: </metadata>
546: </svg>
547: </p></pre>
548:
549: <p>The innermost element, <code title="">cdr:license</code>, is
550: actually in the SVG namespace, as the "<code title="">xmlns:cdr</code>" attribute has no effect (unlike in
551: XML). In fact, as the comment in the fragment above says, the
552: fragment is actually non-conforming. This is because the SVG
553: specification does not define any elements called "<code title="">cdr:license</code>" in the SVG namespace.</p>
554:
555: </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 556: contain the character U+003C LESS-THAN SIGN (<) or an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>. Some
557: <a href="#normal-elements">normal elements</a> also have <a href="#element-restrictions">yet more restrictions</a> on what
1.1 mike 558: content they are allowed to hold, beyond the restrictions imposed by
559: the content model and those described in this paragraph. Those
1.123 mike 560: restrictions are described below.</p><p>Tags contain a <dfn id="syntax-tag-name" title="syntax-tag-name">tag name</dfn>,
1.1 mike 561: giving the element's name. HTML elements all have names that only
1.464 mike 562: use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
563: NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
564: Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER
565: Z. In the HTML syntax, tag names, even those for <a href="#foreign-elements">foreign
1.462 mike 566: elements</a>, may be written with any mix of lower- and uppercase
567: letters that, when converted to all-lowercase, matches the element's
1.1008 mike 568: 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 569: following format:</p><ol><li>The first character of a start tag must be a U+003C LESS-THAN
1.588 mike 570: SIGN character (<).</li>
1.1 mike 571:
572: <li>The next few characters of a start tag must be the element's
573: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
574:
575: <li>If there are to be any attributes in the next step, there must
1.996 mike 576: first be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 577: characters</a>.</li>
578:
579: <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 580: below. Attributes must be separated from each other by one or more
1.996 mike 581: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 582:
1.766 mike 583: <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 584: there may be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.766 mike 585: characters</a>. (Some attributes are required to be followed by
586: a space. See the <a href="#syntax-attributes" title="syntax-attributes">attributes
587: section</a> below.)</li>
1.1 mike 588:
589: <li>Then, if the element is one of the <a href="#void-elements">void elements</a>,
1.373 mike 590: or if the element is a <a href="#foreign-elements" title="foreign elements">foreign
1.588 mike 591: element</a>, then there may be a single U+002F SOLIDUS character
592: (/). This character has no effect on <a href="#void-elements">void elements</a>,
593: but on <a href="#foreign-elements">foreign elements</a> it marks the start tag as
594: self-closing.</li>
1.1 mike 595:
596: <li>Finally, start tags must be closed by a U+003E GREATER-THAN
1.588 mike 597: SIGN character (>).</li>
1.1 mike 598:
1.1008 mike 599: </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 600: following format:</p><ol><li>The first character of an end tag must be a U+003C LESS-THAN
1.588 mike 601: SIGN character (<).</li>
1.1 mike 602:
603: <li>The second character of an end tag must be a U+002F SOLIDUS
1.588 mike 604: character (/).</li>
1.1 mike 605:
606: <li>The next few characters of an end tag must be the element's
607: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
608:
1.996 mike 609: <li>After the tag name, there may be one or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 610: character">space characters</a>.</li>
611:
1.588 mike 612: <li>Finally, end tags must be closed by a U+003E GREATER-THAN SIGN
613: character (>).</li>
1.1 mike 614:
1.1008 mike 615: </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 616: 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 617: one or more characters other than the <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 618: character">space characters</a>, U+0000 NULL, U+0022 QUOTATION
619: MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN
620: (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters,
621: the control characters, and any characters that are not defined by
1.462 mike 622: Unicode. In the HTML syntax, attribute names, even those for
623: <a href="#foreign-elements">foreign elements</a>, may be written with any mix of lower-
624: and uppercase letters that are an <a href="infrastructure.html#ascii-case-insensitive">ASCII
1.123 mike 625: 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 626: 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 627: 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 628:
629: <dd>
630:
631: <p>Just the <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute
1.837 mike 632: name</a>. The value is implicitly the empty string.</p>
1.1 mike 633:
634: <div class="example">
635:
1.996 mike 636: <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 637: the empty attribute syntax:</p>
638:
639: <pre><input <em>disabled</em>></pre>
640:
641: </div>
642:
643: <p>If an attribute using the empty attribute syntax is to be
1.996 mike 644: followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 645: character</a> separating the two.</p>
646:
647: </dd>
648:
1.2 mike 649: <dt id="unquoted">Unquoted attribute value syntax</dt>
1.1 mike 650:
651: <dd>
652:
653: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 654: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 655: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 656: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 657: character">space characters</a>, followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
658: addition to the requirements given above for attribute values,
1.996 mike 659: must not contain any literal <a href="common-microsyntaxes.html#space-character" title="space character">space
1.588 mike 660: characters</a>, any U+0022 QUOTATION MARK characters ("),
661: U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN
662: characters (=), U+003C LESS-THAN SIGN characters (<), U+003E
663: GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT
664: characters (`), and must not be the empty string.</p>
1.463 mike 665:
666: <!-- The ` character is in this list on a temporary basis, waiting
1.1003 mike 667: for IE to fix its parsing bug whereby it treats ` as an
1.463 mike 668: attribute value delimiter. Otherwise, escaping software that
669: tries to be clever and not use quotes when it doesn't need to
670: could be tricked by an attacker.
671:
672: Posit a site that allows the user to input text that is used
673: verbatim in two attributes, such that the user can set the
674: first attribute's value to:
675:
676: `
677:
678: ...and the second to:
679:
680: ` onload='...payload...' end=x
681:
682: ...with the assumption that the site is going to not quote
683: the first one, and quote the second one with double quotes:
684:
685: <body title=` class="` onload='...payload...' end=x">
686:
687: In IE, this is treated as:
688:
689: <body title=' class="'
690: onload='...payload...'
691: end='x"'>
692:
693: -->
694:
1.1 mike 695:
696: <div class="example">
697:
1.996 mike 698: <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 699: with the unquoted attribute value syntax:</p>
700:
701: <pre><input <em>value=yes</em>></pre>
702:
703: </div>
704:
705: <p>If an attribute using the unquoted attribute syntax is to be
1.101 mike 706: followed by another attribute or by the optional U+002F SOLIDUS
1.464 mike 707: 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 708: must be a <a href="common-microsyntaxes.html#space-character">space character</a> separating the two.</p>
1.1 mike 709:
710: </dd>
711:
712: <dt>Single-quoted attribute value syntax</dt>
713:
714: <dd>
715:
716: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 717: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 718: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 719: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 720: character">space characters</a>, followed by a single U+0027
1.588 mike 721: APOSTROPHE character ('), followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 722: addition to the requirements given above for attribute values,
1.588 mike 723: must not contain any literal U+0027 APOSTROPHE characters ('), and
724: finally followed by a second single U+0027 APOSTROPHE character
725: (').</p>
1.1 mike 726:
727: <div class="example">
728:
1.996 mike 729: <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 730: single-quoted attribute value syntax:</p>
731:
732: <pre><input <em>type='checkbox'</em>></pre>
733:
734: </div>
735:
736: <p>If an attribute using the single-quoted attribute syntax is to
1.996 mike 737: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 738: character</a> separating the two.</p>
739:
740: </dd>
741:
742: <dt>Double-quoted attribute value syntax</dt>
743:
744: <dd>
745:
746: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 747: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 748: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 749: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 750: character">space characters</a>, followed by a single U+0022
1.588 mike 751: QUOTATION MARK character ("), followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 752: addition to the requirements given above for attribute values,
1.588 mike 753: must not contain any literal U+0022 QUOTATION MARK characters ("),
754: and finally followed by a second single U+0022 QUOTATION MARK
755: character (").</p>
1.1 mike 756:
757: <div class="example">
758:
1.996 mike 759: <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 760: double-quoted attribute value syntax:</p>
761:
762: <pre><input <em>name="be evil"</em>></pre>
763:
764: </div>
765:
766: <p>If an attribute using the double-quoted attribute syntax is to
1.996 mike 767: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 768: character</a> separating the two.</p>
769:
770: </dd>
771:
772: </dl><p>There must never be two or more attributes on the same start tag
773: whose names are an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for
1.462 mike 774: each other.</p><hr><p>When a <a href="#foreign-elements" title="foreign elements">foreign element</a> has
775: one of the namespaced attributes given by the local name and
776: namespace of the first and second cells of a row from the following
777: table, it must be written using the name given by the third cell
778: from the same row.</p><table><thead><tr><th> Local name </th><th> Namespace </th><th> Attribute name
1.996 mike 779: </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>
780: </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>
781: </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>
782: </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>
783: </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>
784: </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>
785: </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>
786: </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>
787: </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>
788: </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>
789: </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>
790: </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 791: </td></tr></tbody></table><p>No other namespaced attribute can be expressed in <a href="#syntax">the
1.1008 mike 792: 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 793: is not present; it is implied, but it is still there. An HTML
1.159 mike 794: document always has a root <code><a href="semantics.html#the-html-element-0">html</a></code> element, even if the
1.1 mike 795: string <code title=""><html></code> doesn't appear anywhere in
1.159 mike 796: 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
797: 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
798: 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 799: 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
800: element is empty, or if the first thing inside the
1.159 mike 801: <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
802: 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 803: 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
804: element is empty, or if the first thing inside the <code><a href="sections.html#the-body-element-0">body</a></code>
805: 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
806: 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 807: <code><a href="semantics.html#the-style-element">style</a></code> element. <!-- Note that even if the </head> end
1.872 mike 808: tag is present, the parser makes <style type="text/css"> and <script type="text/javascript"> elements
1.1 mike 809: between </head> and <body> end up in the <head> instead of implying
1.996 mike 810: 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
811: tag</a> may be omitted if the <code><a href="sections.html#the-body-element-0">body</a></code> element is not
812: 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
813: tag</a> may be omitted if the <code><a href="grouping-content.html#the-li-element">li</a></code> element is
814: immediately followed by another <code><a href="grouping-content.html#the-li-element">li</a></code> element or if there
815: 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
816: tag</a> may be omitted if the <code><a href="grouping-content.html#the-dt-element">dt</a></code> element is
817: immediately followed by another <code><a href="grouping-content.html#the-dt-element">dt</a></code> element or a
818: <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
819: tag</a> may be omitted if the <code><a href="grouping-content.html#the-dd-element">dd</a></code> element is
820: immediately followed by another <code><a href="grouping-content.html#the-dd-element">dd</a></code> element or a
821: <code><a href="grouping-content.html#the-dt-element">dt</a></code> element, or if there is no more content in the
822: 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
823: tag</a> may be omitted if the <code><a href="grouping-content.html#the-p-element">p</a></code> element is
824: immediately followed by an <code><a href="sections.html#the-address-element">address</a></code>,
825: <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>,
1.305 mike 826: <!--v2DATAGRID <code>datagrid</code>,--> <code><a href="obsolete.html#dir">dir</a></code>,
1.996 mike 827: <code><a href="grouping-content.html#the-div-element">div</a></code>, <code><a href="grouping-content.html#the-dl-element">dl</a></code>, <code><a href="forms.html#the-fieldset-element">fieldset</a></code>,
828: <code><a href="sections.html#the-footer-element">footer</a></code>, <code><a href="forms.html#the-form-element">form</a></code>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h1</a></code>,
829: <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>, <code><a href="sections.html#the-h1-h2-h3-h4-h5-and-h6-elements">h5</a></code>,
830: <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>, <code><a href="sections.html#the-hgroup-element">hgroup</a></code>,
831: <code><a href="grouping-content.html#the-hr-element">hr</a></code>, <code><a href="interactive-elements.html#menus">menu</a></code>, <code><a href="sections.html#the-nav-element">nav</a></code>,
832: <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>,
833: <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 834: element, or if there is no more content in the parent element and
1.123 mike 835: 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 836: tag</a> may be omitted if the <code><a href="text-level-semantics.html#the-rt-element">rt</a></code> element is
837: 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 838: 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 839: tag</a> may be omitted if the <code><a href="text-level-semantics.html#the-rp-element">rp</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><!-- </optgroup> (the text assumes <optgroup> can only be inside a
1.1 mike 842: <select>; commented out text below can handle the non-<select> case
1.996 mike 843: 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
844: <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element <!--has an ancestor
1.1 mike 845: <code>select</code> element and--> is immediately followed by
1.996 mike 846: another <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element, or if <!--all of the elements
1.1 mike 847: that are ancestors of the <code>optgroup</code> element, up to and
848: including the first ancestor element that is not an
849: <code>optgroup</code> element, have no more content--> there is no
1.123 mike 850: more content in the parent element.</p><!-- so e.g. the max number of </optgroup>s are omitted here:
1.1 mike 851: <select><optgroup></select>
852: <p id=x><optgroup></optgroup>x</p>
853: <p id=x><optgroup><optgroup></optgroup></optgroup>x</p>
854: <p><optgroup id=x><optgroup></optgroup>x</p>
855: <p><optgroup><optgroup id=x>x</p>
1.996 mike 856: --><!-- </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
857: tag</a> may be omitted if the <code><a href="the-button-element.html#the-option-element">option</a></code> element is
858: immediately followed by another <code><a href="the-button-element.html#the-option-element">option</a></code> element, or if
859: it is immediately followed by an <code><a href="the-button-element.html#the-optgroup-element">optgroup</a></code> element, or
1.123 mike 860: 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 861: first thing inside the <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element is a
862: <code><a href="tabular-data.html#the-col-element">col</a></code> element, and if the element is not immediately
863: 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 864: 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 865: <code><a href="tabular-data.html#the-colgroup-element">colgroup</a></code> element is not immediately followed by a
1.996 mike 866: <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 867: tag</a> may be omitted if the <code><a href="tabular-data.html#the-thead-element">thead</a></code> element is
868: 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 869: 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 870: first thing inside the <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element is a
871: <code><a href="tabular-data.html#the-tr-element">tr</a></code> element, and if the element is not immediately
872: 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
873: <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code> element whose <a href="#syntax-end-tag" title="syntax-end-tag">end
874: tag</a> has been omitted. (It can't be omitted if the element is
1.123 mike 875: 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 876: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element is
877: 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 878: 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 879: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tfoot-element">tfoot</a></code> element is
880: immediately followed by a <code><a href="tabular-data.html#the-tbody-element">tbody</a></code> element, or if there is
1.123 mike 881: 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 882: tag</a> may be omitted if the <code><a href="tabular-data.html#the-tr-element">tr</a></code> element is
883: immediately followed by another <code><a href="tabular-data.html#the-tr-element">tr</a></code> element, or if there
1.123 mike 884: 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 885: tag</a> may be omitted if the <code><a href="tabular-data.html#the-td-element">td</a></code> element is
886: 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 887: 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 888: tag</a> may be omitted if the <code><a href="tabular-data.html#the-th-element">th</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><p><strong>However</strong>, a <a href="#syntax-start-tag" title="syntax-start-tag">start
1.1008 mike 891: 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 892: 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 893: elements, even though these elements are technically allowed inside
894: <code><a href="tabular-data.html#the-table-element">table</a></code> elements according to the content models
895: described in this specification. (If a <code><a href="tabular-data.html#the-tr-element">tr</a></code> element is
896: 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 897: 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
898: placed immediately after the <a href="#syntax-start-tag" title="syntax-start-tag">start
1.996 mike 899: 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 900: elements. This does not affect the processing of the element. The
1.304 mike 901: otherwise optional <a href="#syntax-newlines" title="syntax-newlines">newline</a>
1.381 mike 902: <em>must</em> be included if the element's contents themselves start
903: with a <a href="#syntax-newlines" title="syntax-newlines">newline</a> (because
904: otherwise the leading newline in the contents would be treated like
905: the optional newline, and ignored).</p><div class="example">
1.996 mike 906: <p>The following two <code><a href="grouping-content.html#the-pre-element">pre</a></code> blocks are equivalent:</p>
1.1 mike 907: <pre><pre>Hello</pre></pre>
908: <pre><pre><br>Hello</pre></pre>
1.1008 mike 909: </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 910: <a href="#rcdata-elements">RCDATA elements</a> must not contain any occurrences of the
911: string "<code title=""></</code>" (U+003C LESS-THAN SIGN, U+002F
912: SOLIDUS) followed by characters that case-insensitively match the
913: tag name of the element followed by one of U+0009 CHARACTER
914: TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D
915: CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or
1.1008 mike 916: 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 917: attribute values, and comments. Text must consist of Unicode
918: characters. Text must not contain U+0000 characters. Text must not
919: contain permanently undefined Unicode characters (noncharacters).
920: Text must not contain control characters other than <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>. Extra constraints
921: are placed on what is and what is not allowed in text based on where
1.1008 mike 922: 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 923: represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A
924: LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR),
1.882 mike 925: U+000A LINE FEED (LF) characters in that order.</p><p>Where <a href="#syntax-charref" title="syntax-charref">character references</a>
926: are allowed, a character reference of a U+000A LINE FEED (LF)
927: character (but not a U+000D CARRIAGE RETURN (CR) character) also
1.1008 mike 928: 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 929: to escape characters that couldn't otherwise legally be included in
1.588 mike 930: <a href="#syntax-text" title="syntax-text">text</a>.</p><p>Character references must start with a U+0026 AMPERSAND character
931: (&). Following this, there are three possible kinds of character
932: references:</p><dl><dt>Named character references</dt>
1.1 mike 933:
934: <dd>The ampersand must be followed by one of the names given in the
935: <a href="named-character-references.html#named-character-references">named character references</a> section, using the same
1.677 mike 936: case. <span class="impl">The name must be one that is terminated by
937: a U+003B SEMICOLON character (;).</span></dd>
1.1 mike 938:
939:
940: <dt>Decimal numeric character reference</dt>
941:
942: <dd>The ampersand must be followed by a U+0023 NUMBER SIGN
1.588 mike 943: character (#), followed by one or more digits in the range U+0030
944: DIGIT ZERO (0) to U+0039 DIGIT NINE (9), representing a base-ten
945: integer that corresponds to a Unicode code point that is allowed
946: according to the definition below. The digits must then be followed
947: by a U+003B SEMICOLON character (;).</dd>
1.1 mike 948:
949:
950: <dt>Hexadecimal numeric character reference</dt>
951:
952: <dd>The ampersand must be followed by a U+0023 NUMBER SIGN
1.588 mike 953: character (#), which must be followed by either a U+0078 LATIN
954: SMALL LETTER X character (x) or a U+0058 LATIN CAPITAL LETTER X
955: character (X), which must then be followed by one or more digits in
956: the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061
957: LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041
958: LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F,
1.464 mike 959: representing a base-sixteen integer that corresponds to a Unicode
960: code point that is allowed according to the definition below. The
961: digits must then be followed by a U+003B SEMICOLON character
962: (;).</dd>
1.378 mike 963:
964: </dl><p>The numeric character reference forms described above are allowed
1.882 mike 965: to reference any Unicode code point other than U+0000, U+000D,
966: permanently undefined Unicode characters (noncharacters), and
1.996 mike 967: control characters other than <a href="common-microsyntaxes.html#space-character" title="space character">space
1.378 mike 968: characters</a>.</p><p>An <dfn id="syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous
1.464 mike 969: ampersand</dfn> is a U+0026 AMPERSAND character (&) that is
1.897 mike 970: followed by one or more characters in the range U+0030 DIGIT ZERO
971: (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A
972: LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A
973: LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character
974: (;), where these characters do not match any of the names given in
1.1008 mike 975: 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 start with
1.1 mike 976: the character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
977: MARK, U+005B LEFT SQUARE BRACKET, U+0043 LATIN CAPITAL LETTER C,
978: U+0044 LATIN CAPITAL LETTER D, U+0041 LATIN CAPITAL LETTER A, U+0054
979: LATIN CAPITAL LETTER T, U+0041 LATIN CAPITAL LETTER A, U+005B LEFT
980: SQUARE BRACKET (<code title=""><![CDATA[</code>). Following this
981: sequence, the CDATA section may have <a href="#syntax-text" title="syntax-text">text</a>, with the additional restriction
982: that the text must not contain the three character sequence U+005D
983: RIGHT SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E
984: GREATER-THAN SIGN (<code title="">]]></code>). Finally, the CDATA
985: section must be ended by the three character sequence U+005D RIGHT
986: SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E GREATER-THAN
1.724 mike 987: SIGN (<code title="">]]></code>).</p><div class="example">
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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