Annotation of html5/spec/syntax.html, revision 1.1144
1.1139 mike 1: <!DOCTYPE html>
1.1144 ! mike 2: <html lang="en-US-x-Hixie"><head><title>8 The HTML syntax — HTML5</title><style type="text/css">
1.1 mike 3: pre { margin-left: 2em; white-space: pre-wrap; }
4: h2 { margin: 3em 0 1em 0; }
5: h3 { margin: 2.5em 0 1em 0; }
6: h4 { margin: 2.5em 0 0.75em 0; }
7: h5, h6 { margin: 2.5em 0 1em; }
8: h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
9: h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
10: p { margin: 1em 0; }
11: hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
12: dl, dd { margin-top: 0; margin-bottom: 0; }
13: dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
14: dt + dt { margin-top: 0; }
15: dd dt { margin-top: 0.25em; margin-bottom: 0; }
16: dd p { margin-top: 0; }
17: dd dl + p { margin-top: 1em; }
18: dd table + p { margin-top: 1em; }
19: p + * > li, dd li { margin: 1em 0; }
20: dt, dfn { font-weight: bold; font-style: normal; }
1.1045 mike 21: i, em { font-style: italic; }
1.1 mike 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; }
1.1048 mike 43: img.extra, p.overview { float: right; }
1.1047 mike 44: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; position: relative; }
1.1 mike 45: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
1.1047 mike 46: pre.idl::before { content: "IDL"; font: bold small sans-serif; padding: 0.5em; background: white; position: absolute; top: 0; margin: -1px 0 0 -4em; width: 1.5em; border: thin solid; border-radius: 0 0 0 0.5em }
1.1 mike 47: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
48: pre.css:first-line { color: #AAAA50; }
1.840 mike 49: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
1.1 mike 50: hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
51: dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
52: dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
53: dl.domintro dd p { margin: 0.5em 0; }
1.1050 mike 54: dl.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; }
1.1 mike 55: dl.switch { padding-left: 2em; }
56: dl.switch > dt { text-indent: -1.5em; }
57: dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
58: dl.triple { padding: 0 0 0 1em; }
59: dl.triple dt, dl.triple dd { margin: 0; display: inline }
60: dl.triple dt:after { content: ':'; }
61: dl.triple dd:after { content: '\A'; white-space: pre; }
62: .diff-old { text-decoration: line-through; color: silver; background: transparent; }
63: .diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
64: a .diff-new { border-bottom: 1px blue solid; }
65:
66: h2 { page-break-before: always; }
67: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
68: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
69:
1.1016 mike 70: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
71: li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
1.1 mike 72:
73: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
74: div.head p { margin: 0; }
75: div.head h1 { margin: 0; }
76: div.head .logo { float: right; margin: 0 1em; }
77: div.head .logo img { border: none } /* remove border from top image */
78: div.head dl { margin: 1em 0; }
1.671 mike 79: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
1.1 mike 80:
81: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
82: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
83: body > .toc > li > * { margin-bottom: 0.5em; }
84: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
85: .toc, .toc li { list-style: none; }
86:
87: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
88: .brief li { margin: 0; padding: 0; }
89: .brief li p { margin: 0; padding: 0; }
90:
91: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
92: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
93: .category-list li { display: inline; }
94: .category-list li:not(:last-child)::after { content: ', '; }
95: .category-list li > span, .category-list li > a { text-transform: lowercase; }
96: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
97:
98: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
99: .XXX > :first-child { margin-top: 0; }
100: p .XXX { line-height: 3em; }
1.159 mike 101: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
102: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
103: .annotation :link, .annotation :visited { color: inherit; }
104: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
105: .annotation span { border: none ! important; }
1.1 mike 106: .note { color: green; background: transparent; font-family: sans-serif; }
107: .warning { color: red; background: transparent; }
108: .note, .warning { font-weight: bolder; font-style: italic; }
1.1045 mike 109: .note em, .warning em, .note i, .warning i { font-style: normal; }
1.1 mike 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:
1.1136 mike 196: .stability {
197: position: fixed;
198: bottom: 0;
199: left: 0; right: 0;
200: margin: 0 auto 0 auto;
201: width: 50%;
202: background: maroon; color: yellow;
203: -webkit-border-radius: 1em 1em 0 0;
204: -moz-border-radius: 1em 1em 0 0;
205: border-radius: 1em 1em 0 0;
206: -moz-box-shadow: 0 0 1em #500;
207: -webkit-box-shadow: 0 0 1em #500;
208: box-shadow: 0 0 1em red;
209: padding: 0.5em 1em;
210: text-align: center;
211: }
212: .stability strong {
213: display: block;
214: }
215: .stability input {
216: appearance: none; margin: 0; border: 0; padding: 0.25em 0.5em; background: transparent; color: black;
217: position: absolute; top: -0.5em; right: 0; font: 1.25em sans-serif; text-align: center;
218: }
219: .stability input:hover {
220: color: white;
221: text-shadow: 0 0 2px black;
222: }
223: .stability input:active {
224: padding: 0.3em 0.45em 0.2em 0.55em;
225: }
226: .stability :link, .stability :visited,
227: .stability :link:hover, .stability :visited:hover {
228: background: transparent;
229: color: white;
230: }
231:
232: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css"><meta content="noindex" name="robots"><style type="text/css">
1.267 mike 233:
1.292 mike 234: .applies thead th > * { display: block; }
235: .applies thead code { display: block; }
236: .applies tbody th { whitespace: nowrap; }
237: .applies td { text-align: center; }
238: .applies .yes { background: yellow; }
239:
1.1007 mike 240: .matrix, .matrix td { border: hidden; text-align: right; }
1.267 mike 241: .matrix { margin-left: 2em; }
242:
243: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
244: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
245: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
246:
1.1009 mike 247: td.eg { border-width: thin; text-align: center; }
248:
1.267 mike 249: #table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
250: #table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
251: #table-example-1 caption { padding-bottom: 0.5em; }
252: #table-example-1 thead, #table-example-1 tbody { border: none; }
253: #table-example-1 th, #table-example-1 td { border: solid thin; }
254: #table-example-1 th { font-weight: normal; }
255: #table-example-1 td { border-style: none solid; vertical-align: top; }
256: #table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
257: #table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
258: #table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
259: #table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
260: #table-example-1 tbody td:first-child::after { content: leader(". "); }
261: #table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
262: #table-example-1 tbody td:first-child + td { width: 10em; }
263: #table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
264: #table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
265:
266: .apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
267: .apple-table-examples * { font-family: "Times", serif; }
268: .apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
269: .apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
270: .apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
271: .apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
272: .apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
273: .apple-table-examples td { text-align: right; vertical-align: top; }
274: .apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
275: .apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
276: .apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
277: .apple-table-examples sup { line-height: 0; }
278:
1.724 mike 279: .details-example img { vertical-align: top; }
280:
1.1028 mike 281: #base64-table {
282: white-space: nowrap;
283: font-size: 0.6em;
284: column-width: 6em;
285: column-count: 5;
286: column-gap: 1em;
287: -moz-column-width: 6em;
288: -moz-column-count: 5;
289: -moz-column-gap: 1em;
290: -webkit-column-width: 6em;
291: -webkit-column-count: 5;
292: -webkit-column-gap: 1em;
293: }
294: #base64-table thead { display: none; }
295: #base64-table * { border: none; }
296: #base64-table tbody td:first-child:after { content: ':'; }
297: #base64-table tbody td:last-child { text-align: right; }
298:
1.882 mike 299: #named-character-references-table {
1.1010 mike 300: white-space: nowrap;
1.882 mike 301: font-size: 0.6em;
1.1010 mike 302: column-width: 30em;
1.882 mike 303: column-gap: 1em;
1.1010 mike 304: -moz-column-width: 30em;
1.882 mike 305: -moz-column-gap: 1em;
1.1010 mike 306: -webkit-column-width: 30em;
1.882 mike 307: -webkit-column-gap: 1em;
308: }
1.1010 mike 309: #named-character-references-table > table > tbody > tr > td:first-child + td,
1.882 mike 310: #named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
311: #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 312: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
1.882 mike 313:
1.997 mike 314: .glyph.control { color: red; }
315:
1.999 mike 316: @font-face {
317: font-family: 'Essays1743';
318: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743.ttf');
319: }
320: @font-face {
321: font-family: 'Essays1743';
322: font-weight: bold;
323: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Bold.ttf');
324: }
325: @font-face {
326: font-family: 'Essays1743';
327: font-style: italic;
328: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Italic.ttf');
329: }
330: @font-face {
331: font-family: 'Essays1743';
332: font-style: italic;
333: font-weight: bold;
334: src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-BoldItalic.ttf');
335: }
336:
1.1042 mike 337: </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">
1.1033 mike 338: function getCookie(name) {
339: var params = location.search.substr(1).split("&");
340: for (var index = 0; index < params.length; index++) {
341: if (params[index] == name)
342: return "1";
343: var data = params[index].split("=");
344: if (data[0] == name)
345: return unescape(data[1]);
346: }
347: var cookies = document.cookie.split("; ");
348: for (var index = 0; index < cookies.length; index++) {
349: var data = cookies[index].split("=");
350: if (data[0] == name)
351: return unescape(data[1]);
352: }
353: return null;
354: }
1.1142 mike 355: </script><script src="load-timeout.js"></script>
1.996 mike 356: <script src="link-fixup.js"></script>
1.1052 mike 357: <link href="dnd.html" title="7.6 Drag and drop" rel="prev">
358: <link href="index.html#contents" title="Table of contents" rel="contents">
1.996 mike 359: <link href="parsing.html" title="8.2 Parsing HTML documents" rel="next">
1.1073 mike 360: </head><body onload="fixBrokenLink();" class="split chapter"><div class="head" id="head">
1.1 mike 361: <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 362:
1.183 mike 363: <h1>HTML5</h1>
1.1141 mike 364: <h2 class="no-num no-toc" id="a-vocabulary-and-associated-apis-for-html-and-xhtml">A vocabulary and associated APIs for HTML and XHTML</h2><p>This is revision 1.5610.</p>
1.1136 mike 365:
1.1141 mike 366: <h2 class="no-num no-toc" id="w3c-working-draft-20-april-2012">W3C Working Draft 20 April 2012</h2>
1.1136 mike 367: </div>
1.1052 mike 368:
1.1136 mike 369: <nav class="prev_next">
1.1052 mike 370: <a href="dnd.html">← 7.6 Drag and drop</a> –
371: <a href="index.html#contents">Table of contents</a> –
372: <a href="parsing.html">8.2 Parsing HTML documents →</a>
1.996 mike 373: <ol class="toc"><li><a href="syntax.html#syntax"><span class="secno">8 </span>The HTML syntax</a>
374: <ol><li><a href="syntax.html#writing"><span class="secno">8.1 </span>Writing HTML documents</a>
375: <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>
376: <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>
1.1052 mike 377: <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></nav>
1.1 mike 378:
1.1136 mike 379: <h2 id="syntax"><span class="secno">8 </span><dfn>The HTML syntax</dfn></h2>
380:
381: <p class="note">This section only describes the rules for resources
1.725 mike 382: labeled with an <a href="infrastructure.html#html-mime-type">HTML MIME type</a>. Rules for XML resources
383: are discussed in the section below entitled "<a href="the-xhtml-syntax.html#the-xhtml-syntax">The XHTML
1.1136 mike 384: syntax</a>".</p>
385:
386:
387: <h3 id="writing"><span class="secno">8.1 </span>Writing HTML documents</h3>
388:
389: <div class="impl">
1.1 mike 390:
391: <p><i>This section only applies to documents, authoring tools, and
392: markup generators. In particular, it does not apply to conformance
393: checkers; conformance checkers must use the requirements given in
394: the next section ("parsing HTML documents").</i></p>
395:
1.1136 mike 396: </div>
397:
398: <p>Documents must consist of the following parts, in the given
399: order:</p>
400:
401: <ol><li>Optionally, a single "BOM" (U+FEFF) character.</li>
1.1 mike 402:
403: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 404: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 405:
406: <li>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a>.
407:
408: </li><li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 409: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 410:
1.1052 mike 411: <li>The root element, in the form of an <code><a href="the-html-element.html#the-html-element">html</a></code> <a href="#syntax-elements" title="syntax-elements">element</a>.</li>
1.1 mike 412:
413: <li>Any number of <a href="#syntax-comments" title="syntax-comments">comments</a> and
1.996 mike 414: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 415:
416: </ol><p>The various types of content mentioned above are described in the
1.1136 mike 417: next few sections.</p>
418:
419: <p>In addition, there are some restrictions on how <a href="the-meta-element.html#character-encoding-declaration" title="character encoding declaration">character encoding
1.1 mike 420: declarations</a> are to be serialized, as discussed in the
1.1136 mike 421: section on that topic.</p>
422:
423: <div class="note">
1.1 mike 424:
1.1052 mike 425: <p>Space characters before the root <code><a href="the-html-element.html#the-html-element">html</a></code> element, and
426: space characters at the start of the <code><a href="the-html-element.html#the-html-element">html</a></code> element and
427: before the <code><a href="the-head-element.html#the-head-element">head</a></code> element, will be dropped when the
1.1 mike 428: document is parsed; space characters <em>after</em> the root
1.1052 mike 429: <code><a href="the-html-element.html#the-html-element">html</a></code> element will be parsed as if they were at the end
430: of the <code><a href="the-body-element.html#the-body-element">body</a></code> element. Thus, space characters around the
1.1 mike 431: root element do not round-trip.</p>
432:
433: <p>It is suggested that newlines be inserted after the DOCTYPE,
434: after any comments that are before the root element, after the
1.1052 mike 435: <code><a href="the-html-element.html#the-html-element">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
436: that are inside the <code><a href="the-html-element.html#the-html-element">html</a></code> element but before the
437: <code><a href="the-head-element.html#the-head-element">head</a></code> element.</p>
1.1 mike 438:
1.1136 mike 439: </div>
440:
441: <p>Many strings in the HTML syntax (e.g. the names of elements and
1.1 mike 442: their attributes) are case-insensitive, but only for characters in
1.547 mike 443: the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL
444: LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL
1.1 mike 445: LETTER Z). For convenience, in this section this is just referred to
1.1136 mike 446: as "case-insensitive".</p>
447:
448:
449: <h4 id="the-doctype"><span class="secno">8.1.1 </span>The DOCTYPE</h4>
450:
451: <p>A <dfn id="syntax-doctype" title="syntax-doctype">DOCTYPE</dfn> is a required preamble.</p>
452:
453: <p class="note">DOCTYPEs are required for legacy reasons. When
1.1 mike 454: omitted, browsers tend to use a different rendering mode that is
455: incompatible with some specifications. Including the DOCTYPE in a
456: document ensures that the browser makes a best-effort attempt at
1.1136 mike 457: following the relevant specifications.</p>
458:
459: <p>A DOCTYPE must consist of the following components, in this
460: order:</p>
461:
462: <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 463: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1011 mike 464: <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 465: <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 466: <li>Zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.588 mike 467: <li>A U+003E GREATER-THAN SIGN character (>).</li>
1.1011 mike 468: </ol><p class="note">In other words, <code><!DOCTYPE html></code>,
1.1136 mike 469: case-insensitively.</p>
470:
471: <hr><p>For the purposes of HTML generators that cannot output HTML
1.1 mike 472: markup with the short DOCTYPE "<code title=""><!DOCTYPE
1.1011 mike 473: html></code>", a <dfn id="doctype-legacy-string">DOCTYPE legacy string</dfn> may be inserted
1.1 mike 474: into the DOCTYPE (in the position defined above). This string must
1.1136 mike 475: consist of:</p>
476:
477: <ol class="brief"><li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 478: <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 479: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 480: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>quote mark</i>).</li>
1.1047 mike 481: <li>The literal string "<code><a href="urls.html#about:legacy-compat">about:legacy-compat</a></code>".</li>
1.856 mike 482: <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 483: </ol><p class="note">In other words, <code><!DOCTYPE html SYSTEM
484: "about:legacy-compat"></code> or <code><!DOCTYPE html SYSTEM
1.1004 mike 485: 'about:legacy-compat'></code>, case-insensitively except for the
1.1136 mike 486: part in single or double quotes.</p>
487:
488: <p>The <a href="#doctype-legacy-string">DOCTYPE legacy string</a> should not be used unless
1.1 mike 489: the document is generated from a system that cannot output the
1.1136 mike 490: shorter string.</p>
491:
492: <hr><p>To help authors transition from HTML4 and XHTML1, an
1.861 mike 493: <dfn id="obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</dfn> can be inserted into
494: the DOCTYPE (in the position defined above). This string must
1.1136 mike 495: consist of:</p>
496:
497: <ol class="brief"><li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 498: <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 499: <li>One or more <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.861 mike 500: <li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>first quote mark</i>).</li>
501: <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>
502: <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 503: <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 504: <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>
505: <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>
506: <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>
507: </ol><table><caption>
508: Allowed values for public and system identifiers in an <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a>.
509: </caption>
510: <thead><tr><th> Public identifier
511: </th><th> System identifier
512: </th></tr></thead><tbody><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
513: </td><td>
514: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.0//EN</code>
515: </td><td> <code title="">http://www.w3.org/TR/REC-html40/strict.dtd</code>
516: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
517: </td><td>
518: </td></tr><tr><td> <code title="">-//W3C//DTD HTML 4.01//EN</code>
519: </td><td> <code title="">http://www.w3.org/TR/html4/strict.dtd</code>
520: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.0 Strict//EN</code>
521: </td><td> <code title="">http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</code>
522: </td></tr><tr><td> <code title="">-//W3C//DTD XHTML 1.1//EN</code>
523: </td><td> <code title="">http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd</code>
524: </td></tr></tbody></table><p>A <a href="#syntax-doctype" title="syntax-doctype">DOCTYPE</a> containing an
525: <a href="#obsolete-permitted-doctype-string">obsolete permitted DOCTYPE string</a> is an <dfn id="obsolete-permitted-doctype">obsolete
526: permitted DOCTYPE</dfn>. Authors should not use <a href="#obsolete-permitted-doctype" title="obsolete permitted DOCTYPE">obsolete permitted
1.1136 mike 527: DOCTYPEs</a>, as they are unnecessarily long.</p>
528:
529:
530:
531:
532: <h4 id="elements-0"><span class="secno">8.1.2 </span>Elements</h4>
533:
534: <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 535: <a href="#raw-text-elements">raw text elements</a>, <a href="#rcdata-elements">RCDATA elements</a>,
1.1136 mike 536: <a href="#foreign-elements">foreign elements</a>, and <a href="#normal-elements">normal elements</a>.</p>
537:
538: <dl><dt><dfn id="void-elements">Void elements</dfn></dt>
1.1 mike 539:
1.1052 mike 540: <dd><code><a href="the-area-element.html#the-area-element">area</a></code>, <code><a href="the-base-element.html#the-base-element">base</a></code>, <code><a href="the-br-element.html#the-br-element">br</a></code>,
541: <code><a href="the-col-element.html#the-col-element">col</a></code>, <code><a href="the-command-element.html#the-command-element">command</a></code>, <code><a href="the-embed-element.html#the-embed-element">embed</a></code>,
542: <code><a href="the-hr-element.html#the-hr-element">hr</a></code>, <code><a href="the-img-element.html#the-img-element">img</a></code>, <code><a href="the-input-element.html#the-input-element">input</a></code>,
543: <code><a href="the-keygen-element.html#the-keygen-element">keygen</a></code>, <code><a href="the-link-element.html#the-link-element">link</a></code>, <code><a href="the-meta-element.html#the-meta-element">meta</a></code>,
544: <code><a href="the-param-element.html#the-param-element">param</a></code>, <code><a href="the-source-element.html#the-source-element">source</a></code>, <code><a href="the-track-element.html#the-track-element">track</a></code>,
545: <code><a href="the-wbr-element.html#the-wbr-element">wbr</a></code></dd>
1.1034 mike 546:
1.1 mike 547:
1.373 mike 548: <dt><dfn id="raw-text-elements">Raw text elements</dfn></dt>
1.1 mike 549:
1.1052 mike 550: <dd><code><a href="the-script-element.html#the-script-element">script</a></code>, <code><a href="the-style-element.html#the-style-element">style</a></code></dd>
1.1055 mike 551:
1.373 mike 552: <dt><dfn id="rcdata-elements">RCDATA elements</dfn></dt>
1.1 mike 553:
1.1052 mike 554: <dd><code><a href="the-textarea-element.html#the-textarea-element">textarea</a></code>, <code><a href="the-title-element.html#the-title-element">title</a></code></dd>
1.1 mike 555:
1.373 mike 556: <dt><dfn id="foreign-elements">Foreign elements</dfn></dt>
1.1 mike 557:
1.1047 mike 558: <dd>Elements from the <a href="namespaces.html#mathml-namespace">MathML namespace</a>
559: and the <a href="namespaces.html#svg-namespace">SVG namespace</a>.</dd>
1.1 mike 560:
1.373 mike 561: <dt><dfn id="normal-elements">Normal elements</dfn></dt>
1.1 mike 562:
563: <dd>All other allowed <a href="infrastructure.html#html-elements">HTML elements</a> are normal
564: elements.</dd>
565:
566: </dl><p><dfn id="syntax-tags" title="syntax-tags">Tags</dfn> are used to delimit the start
1.373 mike 567: and end of elements in the markup. <a href="#raw-text-elements" title="raw text
568: elements">Raw text</a>, <a href="#rcdata-elements" title="RCDATA
569: elements">RCDATA</a>, and <a href="#normal-elements" title="normal
570: elements">normal</a> elements have a <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> to indicate where they
571: begin, and an <a href="#syntax-end-tag" title="syntax-end-tag">end tag</a> to
572: indicate where they end. The start and end tags of certain
573: <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 574: later. Those that cannot be omitted must not be omitted. <a href="#void-elements">Void
575: elements</a> only have a start tag; end tags must not be
1.373 mike 576: specified for <a href="#void-elements">void elements</a>. <a href="#foreign-elements">Foreign
577: elements</a> must either have a start tag and an end tag, or a
578: start tag that is marked as self-closing, in which case they must
1.1136 mike 579: not have an end tag.</p>
580:
581: <p>The contents of the element must be placed between just after the
1.1 mike 582: start tag (which <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied,
583: in certain cases</a>) and just before the end tag (which again,
584: <a href="#syntax-tag-omission" title="syntax-tag-omission">might be implied in certain
585: cases</a>). The exact allowed contents of each individual element
1.1004 mike 586: depend on the content model of that element, as described earlier in
587: this specification. Elements must not contain content that their
1.1 mike 588: content model disallows. In addition to the restrictions placed on
589: the contents by those content models, however, the five types of
1.1136 mike 590: elements have additional <em>syntactic</em> requirements.</p>
591:
592: <p><a href="#void-elements">Void elements</a> can't have any contents (since there's
1.1 mike 593: no end tag, no content can be put between the start tag and the end
1.1136 mike 594: tag).</p>
595:
596: <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
597: below.</p>
598:
599: <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
1.373 mike 600: must not contain an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.
1.1 mike 601: There are also <a href="#cdata-rcdata-restrictions">further
1.1136 mike 602: restrictions</a> described below.</p>
603:
604: <p><a href="#foreign-elements">Foreign elements</a> whose start tag is marked as
1.373 mike 605: self-closing can't have any contents (since, again, as there's no
606: end tag, no content can be put between the start tag and the end
607: tag). <a href="#foreign-elements">Foreign elements</a> whose start tag is <em>not</em>
608: 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
1.1136 mike 609: contain the character U+003C LESS-THAN SIGN (<) or an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.</p>
610:
611: <div class="note">
1.374 mike 612:
613: <p>The HTML syntax does not support namespace
614: declarations, even in <a href="#foreign-elements">foreign elements</a>.</p>
615:
616: <p>For instance, consider the following HTML fragment:</p>
617:
618: <pre><p>
619: <svg>
620: <metadata>
621: <!-- this is invalid -->
622: <cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/>
623: </metadata>
624: </svg>
625: </p></pre>
626:
627: <p>The innermost element, <code title="">cdr:license</code>, is
628: actually in the SVG namespace, as the "<code title="">xmlns:cdr</code>" attribute has no effect (unlike in
629: XML). In fact, as the comment in the fragment above says, the
630: fragment is actually non-conforming. This is because the SVG
631: specification does not define any elements called "<code title="">cdr:license</code>" in the SVG namespace.</p>
632:
1.1136 mike 633: </div>
634:
635: <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 636: contain the character U+003C LESS-THAN SIGN (<) or an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>. Some
637: <a href="#normal-elements">normal elements</a> also have <a href="#element-restrictions">yet more restrictions</a> on what
1.1 mike 638: content they are allowed to hold, beyond the restrictions imposed by
639: the content model and those described in this paragraph. Those
1.1136 mike 640: restrictions are described below.</p>
641:
642: <p>Tags contain a <dfn id="syntax-tag-name" title="syntax-tag-name">tag name</dfn>,
1.1 mike 643: giving the element's name. HTML elements all have names that only
1.1136 mike 644: use characters in the range <a href="common-microsyntaxes.html#ascii-digits">ASCII digits</a>, <a href="common-microsyntaxes.html#lowercase-ascii-letters">lowercase ASCII letters</a>, and <a href="common-microsyntaxes.html#uppercase-ascii-letters">uppercase ASCII letters</a>. In the HTML syntax, tag names, even those for <a href="#foreign-elements">foreign
1.462 mike 645: elements</a>, may be written with any mix of lower- and uppercase
646: letters that, when converted to all-lowercase, matches the element's
1.1136 mike 647: tag name; tag names are case-insensitive.</p>
648:
649:
650: <h5 id="start-tags"><span class="secno">8.1.2.1 </span>Start tags</h5>
651:
652: <p><dfn id="syntax-start-tag" title="syntax-start-tag">Start tags</dfn> must have the
653: following format:</p>
654:
655: <ol><li>The first character of a start tag must be a U+003C LESS-THAN
1.588 mike 656: SIGN character (<).</li>
1.1 mike 657:
658: <li>The next few characters of a start tag must be the element's
659: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
660:
661: <li>If there are to be any attributes in the next step, there must
1.996 mike 662: first be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 663: characters</a>.</li>
664:
665: <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 666: below. Attributes must be separated from each other by one or more
1.996 mike 667: <a href="common-microsyntaxes.html#space-character" title="space character">space characters</a>.</li>
1.1 mike 668:
1.766 mike 669: <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 670: there may be one or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.766 mike 671: characters</a>. (Some attributes are required to be followed by
672: a space. See the <a href="#syntax-attributes" title="syntax-attributes">attributes
673: section</a> below.)</li>
1.1 mike 674:
675: <li>Then, if the element is one of the <a href="#void-elements">void elements</a>,
1.373 mike 676: or if the element is a <a href="#foreign-elements" title="foreign elements">foreign
1.588 mike 677: element</a>, then there may be a single U+002F SOLIDUS character
678: (/). This character has no effect on <a href="#void-elements">void elements</a>,
679: but on <a href="#foreign-elements">foreign elements</a> it marks the start tag as
680: self-closing.</li>
1.1 mike 681:
682: <li>Finally, start tags must be closed by a U+003E GREATER-THAN
1.588 mike 683: SIGN character (>).</li>
1.1 mike 684:
1.1136 mike 685: </ol><h5 id="end-tags"><span class="secno">8.1.2.2 </span>End tags</h5>
686:
687: <p><dfn id="syntax-end-tag" title="syntax-end-tag">End tags</dfn> must have the
688: following format:</p>
689:
690: <ol><li>The first character of an end tag must be a U+003C LESS-THAN
1.588 mike 691: SIGN character (<).</li>
1.1 mike 692:
1.1136 mike 693: <li>The second character of an end tag must be a "/" (U+002F) character.</li>
1.1 mike 694:
695: <li>The next few characters of an end tag must be the element's
696: <a href="#syntax-tag-name" title="syntax-tag-name">tag name</a>.</li>
697:
1.996 mike 698: <li>After the tag name, there may be one or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 699: character">space characters</a>.</li>
700:
1.588 mike 701: <li>Finally, end tags must be closed by a U+003E GREATER-THAN SIGN
702: character (>).</li>
1.1 mike 703:
1.1136 mike 704: </ol><h5 id="attributes-0"><span class="secno">8.1.2.3 </span>Attributes</h5>
705:
706: <p><dfn id="syntax-attributes" title="syntax-attributes">Attributes</dfn> for an element
707: are expressed inside the element's start tag.</p>
708:
709: <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 710: one or more characters other than the <a href="common-microsyntaxes.html#space-character" title="space
1.1136 mike 711: character">space characters</a>, U+0000 NULL, """ (U+0022), "'" (U+0027), U+003E GREATER-THAN SIGN
712: (>), "/" (U+002F), and "=" (U+003D) characters,
1.1 mike 713: the control characters, and any characters that are not defined by
1.462 mike 714: Unicode. In the HTML syntax, attribute names, even those for
715: <a href="#foreign-elements">foreign elements</a>, may be written with any mix of lower-
716: and uppercase letters that are an <a href="infrastructure.html#ascii-case-insensitive">ASCII
1.1136 mike 717: case-insensitive</a> match for the attribute's name.</p>
718:
719: <p><dfn id="syntax-attribute-value" title="syntax-attribute-value">Attribute values</dfn> are a
1.1 mike 720: 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
1.1136 mike 721: additional restriction that the text cannot contain an <a href="#syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous ampersand</a>.</p>
722:
723: <p>Attributes can be specified in four different ways:</p>
724:
725: <dl><dt>Empty attribute syntax</dt>
1.1 mike 726:
727: <dd>
728:
729: <p>Just the <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute
1.837 mike 730: name</a>. The value is implicitly the empty string.</p>
1.1 mike 731:
732: <div class="example">
733:
1.1052 mike 734: <p>In the following example, the <code title="attr-fe-disabled"><a href="attributes-common-to-form-controls.html#attr-fe-disabled">disabled</a></code> attribute is given with
1.1 mike 735: the empty attribute syntax:</p>
736:
737: <pre><input <em>disabled</em>></pre>
738:
739: </div>
740:
741: <p>If an attribute using the empty attribute syntax is to be
1.996 mike 742: followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 743: character</a> separating the two.</p>
744:
745: </dd>
746:
1.2 mike 747: <dt id="unquoted">Unquoted attribute value syntax</dt>
1.1 mike 748:
749: <dd>
750:
751: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 752: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 753: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 754: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1 mike 755: character">space characters</a>, followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
756: addition to the requirements given above for attribute values,
1.996 mike 757: must not contain any literal <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1136 mike 758: characters</a>, any """ (U+0022) characters,
759: "'" (U+0027) characters, "=" (U+003D) characters, U+003C LESS-THAN SIGN characters (<), U+003E
760: GREATER-THAN SIGN characters (>), or "`" (U+0060) characters, and must not be the empty string.</p>
1.463 mike 761:
1.1034 mike 762:
1.1 mike 763:
1.1055 mike 764:
1.1 mike 765: <div class="example">
766:
1.1047 mike 767: <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 768: with the unquoted attribute value syntax:</p>
769:
770: <pre><input <em>value=yes</em>></pre>
771:
772: </div>
773:
774: <p>If an attribute using the unquoted attribute syntax is to be
1.1136 mike 775: followed by another attribute or by the optional "/" (U+002F) 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 776: must be a <a href="common-microsyntaxes.html#space-character">space character</a> separating the two.</p>
1.1 mike 777:
778: </dd>
779:
780: <dt>Single-quoted attribute value syntax</dt>
781:
782: <dd>
783:
784: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 785: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 786: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 787: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1136 mike 788: character">space characters</a>, followed by a single "'" (U+0027) character, followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 789: addition to the requirements given above for attribute values,
1.1136 mike 790: must not contain any literal "'" (U+0027) characters, and
1.588 mike 791: finally followed by a second single U+0027 APOSTROPHE character
792: (').</p>
1.1 mike 793:
794: <div class="example">
795:
1.1047 mike 796: <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 797: single-quoted attribute value syntax:</p>
798:
799: <pre><input <em>type='checkbox'</em>></pre>
800:
801: </div>
802:
803: <p>If an attribute using the single-quoted attribute syntax is to
1.996 mike 804: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 805: character</a> separating the two.</p>
806:
807: </dd>
808:
809: <dt>Double-quoted attribute value syntax</dt>
810:
811: <dd>
812:
813: <p>The <a href="#syntax-attribute-name" title="syntax-attribute-name">attribute name</a>,
1.996 mike 814: followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1 mike 815: characters</a>, followed by a single U+003D EQUALS SIGN
1.996 mike 816: character, followed by zero or more <a href="common-microsyntaxes.html#space-character" title="space
1.1136 mike 817: character">space characters</a>, followed by a single """ (U+0022) character, followed by the <a href="#syntax-attribute-value" title="syntax-attribute-value">attribute value</a>, which, in
1.1 mike 818: addition to the requirements given above for attribute values,
1.1136 mike 819: must not contain any literal """ (U+0022) characters,
820: and finally followed by a second single """ (U+0022) character.</p>
1.1 mike 821:
822: <div class="example">
823:
1.1052 mike 824: <p>In the following example, the <code title="attr-fe-name"><a href="attributes-common-to-form-controls.html#attr-fe-name">name</a></code> attribute is given with the
1.1 mike 825: double-quoted attribute value syntax:</p>
826:
827: <pre><input <em>name="be evil"</em>></pre>
828:
829: </div>
830:
831: <p>If an attribute using the double-quoted attribute syntax is to
1.996 mike 832: be followed by another attribute, then there must be a <a href="common-microsyntaxes.html#space-character">space
1.1 mike 833: character</a> separating the two.</p>
834:
835: </dd>
836:
837: </dl><p>There must never be two or more attributes on the same start tag
838: whose names are an <a href="infrastructure.html#ascii-case-insensitive">ASCII case-insensitive</a> match for
1.1136 mike 839: each other.</p>
840:
841: <hr><p>When a <a href="#foreign-elements" title="foreign elements">foreign element</a> has
1.462 mike 842: one of the namespaced attributes given by the local name and
843: namespace of the first and second cells of a row from the following
844: table, it must be written using the name given by the third cell
1.1136 mike 845: from the same row.</p>
846:
847: <table><thead><tr><th> Local name </th><th> Namespace </th><th> Attribute name
1.1047 mike 848: </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>
849: </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>
850: </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>
851: </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>
852: </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>
853: </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>
854: </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>
855: </td></tr><tr><td> <code title="">base</code> </td><td> <a href="namespaces.html#xml-namespace">XML namespace</a> </td><td> <code title="">xml:base</code>
856: </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>
857: </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>
858: </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>
859: </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 860: </td></tr></tbody></table><p>No other namespaced attribute can be expressed in <a href="#syntax">the
1.1136 mike 861: HTML syntax</a>.</p>
862:
863:
864: <h5 id="optional-tags"><span class="secno">8.1.2.4 </span>Optional tags</h5>
865:
866: <p>Certain tags can be <dfn id="syntax-tag-omission" title="syntax-tag-omission">omitted</dfn>.</p>
867:
868: <p class="note">Omitting an element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> in the situations
1.1045 mike 869: described below does not mean the element is not present; it is
870: implied, but it is still there. For example, an HTML document always
1.1136 mike 871: has a root <code><a href="the-html-element.html#the-html-element">html</a></code> element, even if the string <code title=""><html></code> doesn't appear anywhere in the markup.</p>
872:
873:
874: <p>An <code><a href="the-html-element.html#the-html-element">html</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
875: first thing inside the <code><a href="the-html-element.html#the-html-element">html</a></code> element is not a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p>
876:
877:
878: <p>An <code><a href="the-html-element.html#the-html-element">html</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 879: tag</a> may be omitted if the <code><a href="the-html-element.html#the-html-element">html</a></code> element is not
1.1136 mike 880: immediately followed by a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p>
881:
882:
883: <p>A <code><a href="the-head-element.html#the-head-element">head</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
1.821 mike 884: element is empty, or if the first thing inside the
1.1136 mike 885: <code><a href="the-head-element.html#the-head-element">head</a></code> element is an element.</p>
886:
887:
888: <p>A <code><a href="the-head-element.html#the-head-element">head</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 889: tag</a> may be omitted if the <code><a href="the-head-element.html#the-head-element">head</a></code> element is not
1.1136 mike 890: 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>
891:
892:
893: <p>A <code><a href="the-body-element.html#the-body-element">body</a></code> element's <a href="#syntax-start-tag" title="syntax-start-tag">start tag</a> may be omitted if the
1.1052 mike 894: element is empty, or if the first thing inside the <code><a href="the-body-element.html#the-body-element">body</a></code>
1.996 mike 895: 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
1.1052 mike 896: inside the <code><a href="the-body-element.html#the-body-element">body</a></code> element is a <code><a href="the-script-element.html#the-script-element">script</a></code> or
1.1136 mike 897: <code><a href="the-style-element.html#the-style-element">style</a></code> element. </p>
898:
899:
900: <p>A <code><a href="the-body-element.html#the-body-element">body</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 901: tag</a> may be omitted if the <code><a href="the-body-element.html#the-body-element">body</a></code> element is not
1.1136 mike 902: immediately followed by a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p>
903:
904:
905: <p>An <code><a href="the-li-element.html#the-li-element">li</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 906: tag</a> may be omitted if the <code><a href="the-li-element.html#the-li-element">li</a></code> element is
907: immediately followed by another <code><a href="the-li-element.html#the-li-element">li</a></code> element or if there
1.1136 mike 908: is no more content in the parent element.</p>
909:
910:
911: <p>A <code><a href="the-dt-element.html#the-dt-element">dt</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 912: tag</a> may be omitted if the <code><a href="the-dt-element.html#the-dt-element">dt</a></code> element is
913: immediately followed by another <code><a href="the-dt-element.html#the-dt-element">dt</a></code> element or a
1.1136 mike 914: <code><a href="the-dd-element.html#the-dd-element">dd</a></code> element.</p>
915:
916:
917: <p>A <code><a href="the-dd-element.html#the-dd-element">dd</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 918: tag</a> may be omitted if the <code><a href="the-dd-element.html#the-dd-element">dd</a></code> element is
919: immediately followed by another <code><a href="the-dd-element.html#the-dd-element">dd</a></code> element or a
920: <code><a href="the-dt-element.html#the-dt-element">dt</a></code> element, or if there is no more content in the
1.1136 mike 921: parent element.</p>
922:
923:
924: <p>A <code><a href="the-p-element.html#the-p-element">p</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 925: tag</a> may be omitted if the <code><a href="the-p-element.html#the-p-element">p</a></code> element is
926: immediately followed by an <code><a href="the-address-element.html#the-address-element">address</a></code>,
927: <code><a href="the-article-element.html#the-article-element">article</a></code>, <code><a href="the-aside-element.html#the-aside-element">aside</a></code>, <code><a href="the-blockquote-element.html#the-blockquote-element">blockquote</a></code>,
928: <code><a href="obsolete.html#dir">dir</a></code>, <code><a href="the-div-element.html#the-div-element">div</a></code>, <code><a href="the-dl-element.html#the-dl-element">dl</a></code>,
929: <code><a href="the-fieldset-element.html#the-fieldset-element">fieldset</a></code>, <code><a href="the-footer-element.html#the-footer-element">footer</a></code>, <code><a href="the-form-element.html#the-form-element">form</a></code>,
930: <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h1</a></code>, <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h2</a></code>, <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h3</a></code>, <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h4</a></code>,
931: <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h5</a></code>, <code><a href="the-h1-h2-h3-h4-h5-and-h6-elements.html#the-h1-h2-h3-h4-h5-and-h6-elements">h6</a></code>, <code><a href="the-header-element.html#the-header-element">header</a></code>,
932: <code><a href="the-hgroup-element.html#the-hgroup-element">hgroup</a></code>, <code><a href="the-hr-element.html#the-hr-element">hr</a></code>, <code><a href="the-menu-element.html#the-menu-element">menu</a></code>,
933: <code><a href="the-nav-element.html#the-nav-element">nav</a></code>, <code><a href="the-ol-element.html#the-ol-element">ol</a></code>, <code><a href="the-p-element.html#the-p-element">p</a></code>, <code><a href="the-pre-element.html#the-pre-element">pre</a></code>,
934: <code><a href="the-section-element.html#the-section-element">section</a></code>, <code><a href="the-table-element.html#the-table-element">table</a></code>, or <code><a href="the-ul-element.html#the-ul-element">ul</a></code>,
1.1 mike 935: element, or if there is no more content in the parent element and
1.1136 mike 936: the parent element is not an <code><a href="the-a-element.html#the-a-element">a</a></code> element.</p>
937:
938:
939: <p>An <code><a href="the-rt-element.html#the-rt-element">rt</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 940: tag</a> may be omitted if the <code><a href="the-rt-element.html#the-rt-element">rt</a></code> element is
941: immediately followed by an <code><a href="the-rt-element.html#the-rt-element">rt</a></code> or <code><a href="the-rp-element.html#the-rp-element">rp</a></code>
1.1136 mike 942: element, or if there is no more content in the parent element.</p>
943:
944:
945: <p>An <code><a href="the-rp-element.html#the-rp-element">rp</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 946: tag</a> may be omitted if the <code><a href="the-rp-element.html#the-rp-element">rp</a></code> element is
947: immediately followed by an <code><a href="the-rt-element.html#the-rt-element">rt</a></code> or <code><a href="the-rp-element.html#the-rp-element">rp</a></code>
1.1136 mike 948: element, or if there is no more content in the parent element.</p>
949:
950:
951: <p>An <code><a href="the-optgroup-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
1.1052 mike 952: <code><a href="the-optgroup-element.html#the-optgroup-element">optgroup</a></code> element is immediately followed by
953: another <code><a href="the-optgroup-element.html#the-optgroup-element">optgroup</a></code> element, or if there is no
1.1136 mike 954: more content in the parent element.</p>
955:
956:
957:
958: <p>An <code><a href="the-option-element.html#the-option-element">option</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 959: tag</a> may be omitted if the <code><a href="the-option-element.html#the-option-element">option</a></code> element is
960: immediately followed by another <code><a href="the-option-element.html#the-option-element">option</a></code> element, or if
961: it is immediately followed by an <code><a href="the-optgroup-element.html#the-optgroup-element">optgroup</a></code> element, or
1.1136 mike 962: if there is no more content in the parent element.</p>
963:
964:
965: <p>A <code><a href="the-colgroup-element.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
1.1052 mike 966: first thing inside the <code><a href="the-colgroup-element.html#the-colgroup-element">colgroup</a></code> element is a
967: <code><a href="the-col-element.html#the-col-element">col</a></code> element, and if the element is not immediately
968: preceded by another <code><a href="the-colgroup-element.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
1.1136 mike 969: omitted if the element is empty.)</p>
970:
971:
972: <p>A <code><a href="the-colgroup-element.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
1.1052 mike 973: <code><a href="the-colgroup-element.html#the-colgroup-element">colgroup</a></code> element is not immediately followed by a
1.1136 mike 974: <a href="common-microsyntaxes.html#space-character">space character</a> or a <a href="#syntax-comments" title="syntax-comments">comment</a>.</p>
975:
976:
977: <p>A <code><a href="the-thead-element.html#the-thead-element">thead</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 978: tag</a> may be omitted if the <code><a href="the-thead-element.html#the-thead-element">thead</a></code> element is
979: immediately followed by a <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> or <code><a href="the-tfoot-element.html#the-tfoot-element">tfoot</a></code>
1.1136 mike 980: element.</p>
981:
982:
983: <p>A <code><a href="the-tbody-element.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
1.1052 mike 984: first thing inside the <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> element is a
985: <code><a href="the-tr-element.html#the-tr-element">tr</a></code> element, and if the element is not immediately
986: preceded by a <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code>, <code><a href="the-thead-element.html#the-thead-element">thead</a></code>, or
987: <code><a href="the-tfoot-element.html#the-tfoot-element">tfoot</a></code> element whose <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1 mike 988: tag</a> has been omitted. (It can't be omitted if the element is
1.1136 mike 989: empty.)</p>
990:
991:
992: <p>A <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 993: tag</a> may be omitted if the <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> element is
994: immediately followed by a <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> or <code><a href="the-tfoot-element.html#the-tfoot-element">tfoot</a></code>
1.1136 mike 995: element, or if there is no more content in the parent element.</p>
996:
997:
998: <p>A <code><a href="the-tfoot-element.html#the-tfoot-element">tfoot</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 999: tag</a> may be omitted if the <code><a href="the-tfoot-element.html#the-tfoot-element">tfoot</a></code> element is
1000: immediately followed by a <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> element, or if there is
1.1136 mike 1001: no more content in the parent element.</p>
1002:
1003:
1004: <p>A <code><a href="the-tr-element.html#the-tr-element">tr</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 1005: tag</a> may be omitted if the <code><a href="the-tr-element.html#the-tr-element">tr</a></code> element is
1006: immediately followed by another <code><a href="the-tr-element.html#the-tr-element">tr</a></code> element, or if there
1.1136 mike 1007: is no more content in the parent element.</p>
1008:
1009:
1010: <p>A <code><a href="the-td-element.html#the-td-element">td</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 1011: tag</a> may be omitted if the <code><a href="the-td-element.html#the-td-element">td</a></code> element is
1012: immediately followed by a <code><a href="the-td-element.html#the-td-element">td</a></code> or <code><a href="the-th-element.html#the-th-element">th</a></code>
1.1136 mike 1013: element, or if there is no more content in the parent element.</p>
1014:
1015:
1016: <p>A <code><a href="the-th-element.html#the-th-element">th</a></code> element's <a href="#syntax-end-tag" title="syntax-end-tag">end
1.1052 mike 1017: tag</a> may be omitted if the <code><a href="the-th-element.html#the-th-element">th</a></code> element is
1018: immediately followed by a <code><a href="the-td-element.html#the-td-element">td</a></code> or <code><a href="the-th-element.html#the-th-element">th</a></code>
1.1136 mike 1019: element, or if there is no more content in the parent element.</p>
1020:
1021: <p><strong>However</strong>, a <a href="#syntax-start-tag" title="syntax-start-tag">start
1022: tag</a> must never be omitted if it has any attributes.</p>
1023:
1024:
1025: <h5 id="element-restrictions"><span class="secno">8.1.2.5 </span>Restrictions on content models</h5>
1026:
1027: <p>For historical reasons, certain elements have extra restrictions
1028: beyond even the restrictions given by their content model.</p>
1029:
1030: <p>A <code><a href="the-table-element.html#the-table-element">table</a></code> element must not contain <code><a href="the-tr-element.html#the-tr-element">tr</a></code>
1.1 mike 1031: elements, even though these elements are technically allowed inside
1.1052 mike 1032: <code><a href="the-table-element.html#the-table-element">table</a></code> elements according to the content models
1033: described in this specification. (If a <code><a href="the-tr-element.html#the-tr-element">tr</a></code> element is
1034: put inside a <code><a href="the-table-element.html#the-table-element">table</a></code> in the markup, it will in fact imply
1.1136 mike 1035: a <code><a href="the-tbody-element.html#the-tbody-element">tbody</a></code> start tag before it.)</p>
1036:
1037: <p>A single <a href="#syntax-newlines" title="syntax-newlines">newline</a> may be
1.304 mike 1038: placed immediately after the <a href="#syntax-start-tag" title="syntax-start-tag">start
1.1052 mike 1039: tag</a> of <code><a href="the-pre-element.html#the-pre-element">pre</a></code> and <code><a href="the-textarea-element.html#the-textarea-element">textarea</a></code>
1.1 mike 1040: elements. This does not affect the processing of the element. The
1.304 mike 1041: otherwise optional <a href="#syntax-newlines" title="syntax-newlines">newline</a>
1.381 mike 1042: <em>must</em> be included if the element's contents themselves start
1043: with a <a href="#syntax-newlines" title="syntax-newlines">newline</a> (because
1044: otherwise the leading newline in the contents would be treated like
1.1136 mike 1045: the optional newline, and ignored).</p>
1046:
1047: <div class="example">
1.1052 mike 1048: <p>The following two <code><a href="the-pre-element.html#the-pre-element">pre</a></code> blocks are equivalent:</p>
1.1 mike 1049: <pre><pre>Hello</pre></pre>
1050: <pre><pre><br>Hello</pre></pre>
1.1136 mike 1051: </div>
1052:
1053:
1054: <h5 id="cdata-rcdata-restrictions"><span class="secno">8.1.2.6 </span>Restrictions on the contents of raw text and RCDATA elements</h5>
1055:
1056: <p>The text in <a href="#raw-text-elements" title="raw text elements">raw text</a> and
1.889 mike 1057: <a href="#rcdata-elements">RCDATA elements</a> must not contain any occurrences of the
1058: string "<code title=""></</code>" (U+003C LESS-THAN SIGN, U+002F
1059: SOLIDUS) followed by characters that case-insensitively match the
1.1136 mike 1060: tag name of the element followed by one of "tab" (U+0009), "LF" (U+000A), "FF" (U+000C), "CR" (U+000D), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or
1061: "/" (U+002F).</p>
1062:
1063:
1064: <h4 id="text-0"><span class="secno">8.1.3 </span>Text</h4>
1065:
1066: <p><dfn id="syntax-text" title="syntax-text">Text</dfn> is allowed inside elements,
1.1108 mike 1067: attribute values, and comments. Extra constraints are placed on what
1068: is and what is not allowed in text based on where the text is to be
1.1136 mike 1069: put, as described in the other sections.</p>
1070:
1071:
1072: <h5 id="newlines"><span class="secno">8.1.3.1 </span>Newlines</h5>
1073:
1074: <p><dfn id="syntax-newlines" title="syntax-newlines">Newlines</dfn> in HTML may be
1075: represented either as "CR" (U+000D) characters, "LF" (U+000A) characters, or pairs of "CR" (U+000D),
1076: "LF" (U+000A) characters in that order.</p>
1077:
1078: <p>Where <a href="#syntax-charref" title="syntax-charref">character references</a>
1079: are allowed, a character reference of a "LF" (U+000A)
1080: character (but not a "CR" (U+000D) character) also
1081: represents a <a href="#syntax-newlines" title="syntax-newlines">newline</a>.</p>
1082:
1083:
1084: <h4 id="character-references"><span class="secno">8.1.4 </span>Character references</h4>
1085:
1086: <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 1087: to escape characters that couldn't otherwise legally be included in
1.1136 mike 1088: <a href="#syntax-text" title="syntax-text">text</a>.</p>
1089:
1090: <p>Character references must start with a U+0026 AMPERSAND character
1.588 mike 1091: (&). Following this, there are three possible kinds of character
1.1136 mike 1092: references:</p>
1093:
1094: <dl><dt>Named character references</dt>
1.1 mike 1095:
1096: <dd>The ampersand must be followed by one of the names given in the
1097: <a href="named-character-references.html#named-character-references">named character references</a> section, using the same
1.677 mike 1098: case. <span class="impl">The name must be one that is terminated by
1.1136 mike 1099: a ";" (U+003B) character.</span></dd>
1.1 mike 1100:
1101:
1102: <dt>Decimal numeric character reference</dt>
1103:
1.1136 mike 1104: <dd>The ampersand must be followed by a "#" (U+0023) character, followed by one or more digits in the range <a href="common-microsyntaxes.html#ascii-digits">ASCII digits</a>, representing a base-ten
1.588 mike 1105: integer that corresponds to a Unicode code point that is allowed
1106: according to the definition below. The digits must then be followed
1.1136 mike 1107: by a ";" (U+003B) character.</dd>
1.1 mike 1108:
1109:
1110: <dt>Hexadecimal numeric character reference</dt>
1111:
1.1136 mike 1112: <dd>The ampersand must be followed by a "#" (U+0023) character, which must be followed by either a "x" (U+0078) character or a "X" (U+0058) character, which must then be followed by one or more digits in
1113: the range <a href="common-microsyntaxes.html#ascii-digits">ASCII digits</a>, U+0061
1.588 mike 1114: LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041
1115: LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F,
1.464 mike 1116: representing a base-sixteen integer that corresponds to a Unicode
1117: code point that is allowed according to the definition below. The
1118: digits must then be followed by a U+003B SEMICOLON character
1119: (;).</dd>
1.378 mike 1120:
1121: </dl><p>The numeric character reference forms described above are allowed
1.882 mike 1122: to reference any Unicode code point other than U+0000, U+000D,
1123: permanently undefined Unicode characters (noncharacters), and
1.996 mike 1124: control characters other than <a href="common-microsyntaxes.html#space-character" title="space character">space
1.1136 mike 1125: characters</a>.</p>
1126:
1127: <p>An <dfn id="syntax-ambiguous-ampersand" title="syntax-ambiguous-ampersand">ambiguous
1.464 mike 1128: ampersand</dfn> is a U+0026 AMPERSAND character (&) that is
1.1136 mike 1129: followed by one or more characters in the range <a href="common-microsyntaxes.html#ascii-digits">ASCII digits</a>, <a href="common-microsyntaxes.html#lowercase-ascii-letters">lowercase ASCII letters</a>, and <a href="common-microsyntaxes.html#uppercase-ascii-letters">uppercase ASCII letters</a>, followed by a U+003B SEMICOLON character
1.897 mike 1130: (;), where these characters do not match any of the names given in
1.1136 mike 1131: the <a href="named-character-references.html#named-character-references">named character references</a> section.</p>
1132:
1133:
1134: <h4 id="cdata-sections"><span class="secno">8.1.5 </span>CDATA sections</h4>
1135:
1136: <p><dfn id="syntax-cdata" title="syntax-cdata">CDATA sections</dfn> must consist of
1137: the following components, in this order:</p>
1138:
1139: <ol><li>The string "<code title=""><![CDATA[</code>".</li>
1.1029 mike 1140:
1141: <li>Optionally, <a href="#syntax-text" title="syntax-text">text</a>, with the
1142: additional restriction that the text must not contain the string
1143: "<code title="">]]></code>".</li>
1144:
1145: <li>The string "<code title="">]]></code>".</li>
1146:
1147: </ol><div class="example">
1.724 mike 1148:
1149: <p>CDATA sections can only be used in foreign content (MathML or
1150: SVG). In this example, a CDATA section is used to escape the
1151: contents of an <code>ms</code> element:</p>
1152:
1153: <pre><p>You can add a string to a number, but this stringifies the number:</p>
1154: <math>
1155: <ms><![CDATA[x<y]]></ms>
1156: <mo>+</mo>
1157: <mn>3</mn>
1158: <mo>=</mo>
1159: <ms><![CDATA[x<y3]]></ms>
1160: </math></pre>
1161:
1.1136 mike 1162: </div>
1163:
1164:
1165: <h4 id="comments"><span class="secno">8.1.6 </span>Comments</h4>
1166:
1167: <p><dfn id="syntax-comments" title="syntax-comments">Comments</dfn> must start with the
1.1 mike 1168: four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
1169: MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<code title=""><!--</code>). Following this sequence, the comment may
1170: have <a href="#syntax-text" title="syntax-text">text</a>, with the additional
1171: restriction that the text must not start with a single U+003E
1.1136 mike 1172: GREATER-THAN SIGN character (>), nor start with a "-" (U+002D) character followed by a U+003E GREATER-THAN SIGN
1.588 mike 1173: (>) character, nor contain two consecutive U+002D HYPHEN-MINUS
1.1136 mike 1174: characters (<code title="">--</code>), nor end with a "-" (U+002D) character. Finally, the comment must be ended by
1.1 mike 1175: the three character sequence U+002D HYPHEN-MINUS, U+002D
1.1136 mike 1176: HYPHEN-MINUS, U+003E GREATER-THAN SIGN (<code title="">--></code>).</p>
1177:
1178:
1179: </body></html>
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