Annotation of html5/spec/the-link-element.html, revision 1.107
1.88 mike 1: <!DOCTYPE html>
1.96 mike 2: <html lang="en-US-x-Hixie"><head><title>4.2.4 The link element — HTML5</title><link rel="stylesheet" href="alert.css"><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; }
21: i, em { font-style: italic; }
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; }
29: table thead, table tbody { border-bottom: solid; }
30: table tbody th:first-child { border-left: solid; }
31: table tbody th { text-align: left; }
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, p.overview { float: right; }
44: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; position: relative; }
45: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
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 }
47: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
48: pre.css:first-line { color: #AAAA50; }
49: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
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; }
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; }
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:
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; }
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; }
79: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
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; }
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; }
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; }
109: .note em, .warning em, .note i, .warning i { font-style: normal; }
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; }
121: .bookkeeping dt { margin: 0.5em 2em 0; }
122: .bookkeeping dd { margin: 0 3em 0.5em; }
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:
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; }
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:
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:
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; }
190:
191: fieldset { margin: 1em; padding: 0.5em 1em; }
192: fieldset > legend + * { margin-top: 0; }
193: fieldset > :last-child { margin-bottom: 0; }
194: fieldset p { margin: 0.5em 0; }
195:
1.85 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">
1.1 mike 233:
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:
240: .matrix, .matrix td { border: hidden; text-align: right; }
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:
247: td.eg { border-width: thin; text-align: center; }
248:
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:
279: .details-example img { vertical-align: top; }
280:
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:
299: #named-character-references-table {
300: white-space: nowrap;
301: font-size: 0.6em;
302: column-width: 30em;
303: column-gap: 1em;
304: -moz-column-width: 30em;
305: -moz-column-gap: 1em;
306: -webkit-column-width: 30em;
307: -webkit-column-gap: 1em;
308: }
309: #named-character-references-table > table > tbody > tr > td:first-child + td,
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; }
312: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
313:
314: .glyph.control { color: red; }
315:
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:
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">
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: }
1.96 mike 355: </script>
1.1 mike 356: <script src="link-fixup.js"></script>
357: <link href="the-base-element.html" title="4.2.3 The base element" rel="prev">
358: <link href="index.html#contents" title="Table of contents" rel="contents">
359: <link href="the-meta-element.html" title="4.2.5 The meta element" rel="next">
1.22 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>
362:
363: <h1>HTML5</h1>
1.107 ! 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 1.5622.</p>
1.1 mike 365:
1.98 mike 366: <h2 class="no-num no-toc" id="w3c-working-draft-29-march-2012">W3C Working Draft 29 March 2012</h2>
1.85 mike 367: </div>
368:
369: <nav class="prev_next">
1.1 mike 370: <a href="the-base-element.html">← 4.2.3 The base element</a> –
371: <a href="index.html#contents">Table of contents</a> –
372: <a href="the-meta-element.html">4.2.5 The meta element →</a>
373: </nav>
374:
1.85 mike 375: <h4 id="the-link-element"><span class="secno">4.2.4 </span>The <dfn><code>link</code></dfn> element</h4>
376:
377: <dl class="element"><dt><a href="element-definitions.html#element-dfn-categories" title="element-dfn-categories">Categories</a>:</dt>
1.1 mike 378: <dd><a href="content-models.html#metadata-content">Metadata content</a>.</dd>
1.25 mike 379: <dt><a href="element-definitions.html#element-dfn-contexts" title="element-dfn-contexts">Contexts in which this element can be used</a>:</dt>
1.1 mike 380: <dd>Where <a href="content-models.html#metadata-content">metadata content</a> is expected.</dd>
381: <dd>In a <code><a href="the-noscript-element.html#the-noscript-element">noscript</a></code> element that is a child of a <code><a href="the-head-element.html#the-head-element">head</a></code> element.</dd>
1.25 mike 382: <dt><a href="element-definitions.html#element-dfn-content-model" title="element-dfn-content-model">Content model</a>:</dt>
1.1 mike 383: <dd>Empty.</dd>
1.25 mike 384: <dt><a href="element-definitions.html#element-dfn-attributes" title="element-dfn-attributes">Content attributes</a>:</dt>
1.1 mike 385: <dd><a href="global-attributes.html#global-attributes">Global attributes</a></dd>
386: <dd><code title="attr-link-href"><a href="#attr-link-href">href</a></code></dd>
387: <dd><code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code></dd>
388: <dd><code title="attr-link-media"><a href="#attr-link-media">media</a></code></dd>
389: <dd><code title="attr-link-hreflang"><a href="#attr-link-hreflang">hreflang</a></code></dd>
390: <dd><code title="attr-link-type"><a href="#attr-link-type">type</a></code></dd>
391: <dd><code title="attr-link-sizes"><a href="links.html#attr-link-sizes">sizes</a></code></dd>
392: <dd>Also, the <code title="attr-link-title"><a href="#attr-link-title">title</a></code> attribute has special semantics on this element.</dd>
1.25 mike 393: <dt><a href="element-definitions.html#element-dfn-dom" title="element-dfn-dom">DOM interface</a>:</dt>
1.1 mike 394: <dd>
395: <pre class="idl">interface <dfn id="htmllinkelement">HTMLLinkElement</dfn> : <a href="elements.html#htmlelement">HTMLElement</a> {
396: attribute boolean <a href="#dom-link-disabled" title="dom-link-disabled">disabled</a>;
397: attribute DOMString <a href="#dom-link-href" title="dom-link-href">href</a>;
398: attribute DOMString <a href="#dom-link-rel" title="dom-link-rel">rel</a>;
399: readonly attribute <a href="infrastructure.html#domtokenlist">DOMTokenList</a> <a href="#dom-link-rellist" title="dom-link-relList">relList</a>;
400: attribute DOMString <a href="#dom-link-media" title="dom-link-media">media</a>;
401: attribute DOMString <a href="#dom-link-hreflang" title="dom-link-hreflang">hreflang</a>;
402: attribute DOMString <a href="#dom-link-type" title="dom-link-type">type</a>;
403: [PutForwards=<span title="dom-DOMSettableTokenList-value">value</span>] readonly attribute <a href="infrastructure.html#domsettabletokenlist">DOMSettableTokenList</a> <a href="#dom-link-sizes" title="dom-link-sizes">sizes</a>;
404: };
405: <a href="#htmllinkelement">HTMLLinkElement</a> implements <a href="infrastructure.html#linkstyle">LinkStyle</a>;</pre>
406: </dd>
407: </dl><p>The <code><a href="#the-link-element">link</a></code> element allows authors to link their
1.85 mike 408: document to other resources.</p>
409:
410: <p>The destination of the link(s) is given by the <dfn id="attr-link-href" title="attr-link-href"><code>href</code></dfn> attribute, which must
1.1 mike 411: be present and must contain a <a href="urls.html#valid-non-empty-url-potentially-surrounded-by-spaces">valid non-empty URL potentially
412: surrounded by spaces</a>. <span class="impl">If the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute is absent, then the
1.85 mike 413: element does not define a link.</span></p>
414:
415: <p>A <code><a href="#the-link-element">link</a></code> element must have <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute.</p>
416:
417:
418: <p>The types of link indicated (the relationships) are given by the
1.1 mike 419: value of the <dfn id="attr-link-rel" title="attr-link-rel"><code>rel</code></dfn>
420: attribute, which, if present, must have a value that is a <a href="common-microsyntaxes.html#set-of-space-separated-tokens">set
421: of space-separated tokens</a>. The <a href="links.html#linkTypes">allowed
422: keywords and their meanings</a> are defined in a later
423: section. <span class="impl">If the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute is absent, has no
424: keywords, or if none of the keywords used are allowed according to
425: the definitions in this specification, then the element does not
1.85 mike 426: create any links.</span></p>
427:
428: <p>Two categories of links can be created using the
1.1 mike 429: <code><a href="#the-link-element">link</a></code> element: <a href="links.html#external-resource-link" title="external resource
430: link">Links to external resources</a> and <a href="links.html#hyperlink" title="hyperlink">hyperlinks</a>. The <a href="links.html#linkTypes">link
431: types section</a> defines whether a particular link type is an
432: external resource or a hyperlink. One <code><a href="#the-link-element">link</a></code> element can
433: create multiple links (of which some might be external resource
434: links and some might be hyperlinks); exactly which and how many
435: links are created depends on the keywords given in the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute. User agents must process
1.85 mike 436: the links on a per-link basis, not a per-element basis.</p>
437:
438: <p class="note">Each link created for a <code><a href="#the-link-element">link</a></code> element is
1.1 mike 439: handled separately. For instance, if there are two <code><a href="#the-link-element">link</a></code>
440: elements with <code title="">rel="stylesheet"</code>, they each
441: count as a separate external resource, and each is affected by its
442: own attributes independently. Similarly, if a single
443: <code><a href="#the-link-element">link</a></code> element has a <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute with the value <code title="">next stylesheet</code>, it creates both a
444: <a href="links.html#hyperlink">hyperlink</a> (for the <code title="rel-next"><a href="links.html#link-type-next">next</a></code>
445: keyword) and an <a href="links.html#external-resource-link">external resource link</a> (for the <code title="rel-stylesheet"><a href="links.html#link-type-stylesheet">stylesheet</a></code> keyword), and they are
1.85 mike 446: affected by other attributes (such as <code title="attr-link-media"><a href="#attr-link-media">media</a></code> or <code title="attr-link-title"><a href="#attr-link-title">title</a></code>) differently.</p>
447:
448: <div class="example">
1.1 mike 449:
450: <p>For example, the following <code><a href="#the-link-element">link</a></code> element creates two
451: hyperlinks (to the same page):</p>
452:
453: <pre><link rel="author license" href="/about"></pre>
454:
455: <p>The two links created by this element are one whose semantic is
456: that the target page has information about the current page's
457: author, and one whose semantic is that the target page has
458: information regarding the license under which the current page is
459: provided.</p>
460:
1.85 mike 461: </div>
462:
463: <p>The exact behavior for links to external resources depends on the
1.1 mike 464: exact relationship, as defined for the relevant link type. Some of
465: the attributes control whether or not the external resource is to be
1.85 mike 466: applied (as defined below).</p>
467:
468: <div class="impl">
1.1 mike 469:
470: <p>For external resources that are represented in the
471: DOM (for example, style sheets), the DOM representation must be made
472: available even if the resource is not applied. To <dfn id="concept-link-obtain" title="concept-link-obtain">obtain the resource</dfn>, the user
473: agent must run the following steps:</p>
474:
475: <ol><li><p>If the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute's
476: value is the empty string, then abort these steps.</p></li>
477:
478: <li><p><a href="urls.html#resolve-a-url" title="resolve a url">Resolve</a> the
479: <a href="urls.html#url">URL</a> given by the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute, relative to the
480: element.</p></li>
481:
482: <li><p>If the previous step fails, then abort these steps.</p></li>
483:
484: <li><p><a href="urls.html#fetch">Fetch</a> the resulting <a href="urls.html#absolute-url">absolute
485: URL</a>.</p></li>
486:
487: </ol><p>User agents may opt to only try to obtain such resources when
488: they are needed, instead of pro-actively <a href="urls.html#fetch" title="fetch">fetching</a> all the external resources that are
489: not applied.</p>
490:
491: <p>The semantics of the protocol used (e.g. HTTP) must be followed
492: when fetching external resources. (For example, redirects will be
493: followed and 404 responses will cause the external resource to not
494: be applied.)</p>
495:
496:
497: <p>Once the attempts to obtain the resource and its <a href="infrastructure.html#critical-subresources">critical
498: subresources</a> are complete, the user agent must, if the loads
499: were successful, <a href="webappapis.html#queue-a-task">queue a task</a> to <a href="webappapis.html#fire-a-simple-event">fire a simple
500: event</a> named <code title="event-load">load</code> at the
501: <code><a href="#the-link-element">link</a></code> element, or, if the resource or one of its
502: <a href="infrastructure.html#critical-subresources">critical subresources</a> failed to completely load for any
503: reason (e.g. DNS error, HTTP 404 response, a connection being
504: prematurely closed, unsupported Content-Type), <a href="webappapis.html#queue-a-task">queue a
505: task</a> to <a href="webappapis.html#fire-a-simple-event">fire a simple event</a> named <code title="event-error">error</code> at the <code><a href="#the-link-element">link</a></code>
506: element. Non-network errors in processing the resource or its
507: subresources (e.g. CSS parse errors, PNG decoding errors) are not
508: failures for the purposes of this paragraph.</p>
509:
510: <p>The <a href="webappapis.html#task-source">task source</a> for these <a href="webappapis.html#concept-task" title="concept-task">tasks</a> is the <a href="webappapis.html#dom-manipulation-task-source">DOM manipulation task
511: source</a>.</p>
512:
513: <p>The element must <a href="the-end.html#delay-the-load-event">delay the load event</a> of the
514: element's document until all the attempts to obtain the resource and
515: its <a href="infrastructure.html#critical-subresources">critical subresources</a> are complete. (Resources that
516: the user agent has not yet attempted to obtain, e.g. because it is
517: waiting for the resource to be needed, do not <a href="the-end.html#delay-the-load-event">delay the load
518: event</a>.)</p>
519:
520: <hr><p id="linkui">Interactive user agents may provide users with a
521: means to <a href="links.html#following-hyperlinks" title="following hyperlinks">follow the
522: hyperlinks</a> created using the <code><a href="#the-link-element">link</a></code> element,
523: somewhere within their user interface. The exact interface is not
524: defined by this specification, but it could include the following
525: information (obtained from the element's attributes, again as
526: defined below), in some form or another (possibly simplified), for
527: each hyperlink created with each <code><a href="#the-link-element">link</a></code> element in the
528: document:</p>
529:
530: <ul><li>The relationship between this document and the resource (given
531: by the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute)</li>
532:
533: <li>The title of the resource (given by the <code title="attr-link-title"><a href="#attr-link-title">title</a></code> attribute).</li>
534:
535: <li>The address of the resource (given by the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute).</li>
536:
537: <li>The language of the resource (given by the <code title="attr-link-hreflang"><a href="#attr-link-hreflang">hreflang</a></code> attribute).</li>
538:
539: <li>The optimum media for the resource (given by the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute).</li>
540:
541: </ul><p>User agents could also include other information, such as the
542: type of the resource (as given by the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute).</p>
543:
1.85 mike 544: </div>
545:
546: <p class="note">Hyperlinks created with the <code><a href="#the-link-element">link</a></code>
1.1 mike 547: element and its <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute
548: apply to the whole page. This contrasts with the <code title="attr-hyperlink-rel"><a href="links.html#attr-hyperlink-rel">rel</a></code> attribute of <code><a href="the-a-element.html#the-a-element">a</a></code>
549: and <code><a href="the-area-element.html#the-area-element">area</a></code> elements, which indicates the type of a link
550: whose context is given by the link's location within the
1.85 mike 551: document.</p>
552:
553: <p>The <dfn id="attr-link-media" title="attr-link-media"><code>media</code></dfn>
1.1 mike 554: attribute says which media the resource applies to. The value must
1.85 mike 555: be a <a href="common-microsyntaxes.html#valid-media-query">valid media query</a>.</p>
556:
557: <div class="impl">
1.1 mike 558:
559: <p>If the link is a <a href="links.html#hyperlink">hyperlink</a> then the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute is purely advisory,
560: and describes for which media the document in question was
561: designed.</p>
562:
563: <p>However, if the link is an <a href="links.html#external-resource-link">external resource link</a>,
564: then the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute is
565: prescriptive. The user agent must apply the external resource when
566: the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute's value
567: <a href="common-microsyntaxes.html#matches-the-environment">matches the environment</a> and the other relevant
568: conditions apply, and must not apply it otherwise.</p>
1.4 mike 569:
1.1 mike 570: <p class="note">The external resource might have further
571: restrictions defined within that limit its applicability. For
572: example, a CSS style sheet might have some <code title="">@media</code> blocks. This specification does not override
573: such further restrictions or requirements.</p>
1.4 mike 574:
1.85 mike 575: </div>
576:
577: <p id="default-media">The default, if the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute is omitted, is "<code title="">all</code>", meaning that by default links apply to all
578: media.</p>
579:
580: <p>The <dfn id="attr-link-hreflang" title="attr-link-hreflang"><code>hreflang</code></dfn>
1.1 mike 581: attribute on the <code><a href="#the-link-element">link</a></code> element has the same semantics as
582: the <a href="links.html#attr-hyperlink-hreflang" title="attr-hyperlink-hreflang"><code>hreflang</code>
583: attribute on <code>a</code> and <code>area</code>
1.85 mike 584: elements</a>.</p>
585:
586: <p>The <dfn id="attr-link-type" title="attr-link-type"><code>type</code></dfn> attribute
1.1 mike 587: gives the <a href="infrastructure.html#mime-type">MIME type</a> of the linked resource. It is
588: purely advisory. The value must be a <a href="infrastructure.html#valid-mime-type">valid MIME
1.85 mike 589: type</a>.</p>
590:
591: <p>For <a href="links.html#external-resource-link" title="external resource link">external resource
1.1 mike 592: links</a>, the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute
593: is used as a hint to user agents so that they can avoid fetching
594: resources they do not support. <span class="impl">If the attribute
595: is present, then the user agent must assume that the resource is of
596: the given type (even if that is not a <a href="infrastructure.html#valid-mime-type">valid MIME type</a>,
597: e.g. the empty string). If the attribute is omitted, but the
598: external resource link type has a default type defined, then the
599: user agent must assume that the resource is of that type. If the UA
600: does not support the given <a href="infrastructure.html#mime-type">MIME type</a> for the given link
601: relationship, then the UA should not <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource; if the UA
602: does support the given <a href="infrastructure.html#mime-type">MIME type</a> for the given link
603: relationship, then the UA should <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource at the
604: appropriate time as specified for the <a href="links.html#external-resource-link">external resource
605: link</a>'s particular type. If the attribute is omitted, and the
606: external resource link type does not have a default type defined,
607: but the user agent would <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource if the type
608: was known and supported, then the user agent should <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource under the
1.85 mike 609: assumption that it will be supported.</span></p>
610:
611: <div class="impl">
1.1 mike 612:
613: <p>User agents must not consider the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute authoritative —
614: upon fetching the resource, user agents must not use the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute to determine its actual
615: type. Only the actual type (as defined in the next paragraph) is
616: used to determine whether to <em>apply</em> the resource, not the
617: aforementioned assumed type.</p>
618:
619: <p id="concept-link-type-sniffing">If the external resource link
620: type defines rules for processing the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a>, then those rules
621: apply. Otherwise, if the resource is expected to be an image, user
622: agents may apply the <a href="urls.html#content-type-sniffing:-image" title="Content-Type sniffing:
623: image">image sniffing rules</a>, with the <var title="">official
624: type</var> being the type determined from the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a>, and use the
625: resulting sniffed type of the resource as if it was the actual
626: type. Otherwise, if neither of these conditions apply or if the user
627: agent opts not to apply the image sniffing rules, then the user
628: agent must use the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a> to determine the
629: type of the resource. If there is no type metadata, but the external
630: resource link type has a default type defined, then the user agent
631: must assume that the resource is of that type.</p>
632:
633: <p class="note">The <code title="rel-stylesheet"><a href="links.html#link-type-stylesheet">stylesheet</a></code>
634: link type defines rules for processing the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a>.</p>
635:
636: <p>Once the user agent has established the type of the resource, the
637: user agent must apply the resource if it is of a supported type and
638: the other relevant conditions apply, and must ignore the resource
639: otherwise.</p>
640:
641: <div class="example">
642:
643: <p>If a document contains style sheet links labeled as follows:</p>
644:
645: <pre><link rel="stylesheet" href="A" type="text/plain">
646: <link rel="stylesheet" href="B" type="text/css">
647: <link rel="stylesheet" href="C"></pre>
648:
649: <p>...then a compliant UA that supported only CSS style sheets
650: would fetch the B and C files, and skip the A file (since
651: <code>text/plain</code> is not the <a href="infrastructure.html#mime-type">MIME type</a> for CSS style
652: sheets).</p>
653:
654: <p>For files B and C, it would then check the actual types returned
655: by the server. For those that are sent as <code>text/css</code>, it
656: would apply the styles, but for those labeled as
657: <code>text/plain</code>, or any other type, it would not.</p>
658:
659: <p>If one of the two files was returned without a
660: <a href="urls.html#content-type">Content-Type</a> metadata, or with a syntactically
661: incorrect type like <code title="">Content-Type: "null"</code>, then the default type
662: for <code title="rel-stylesheet"><a href="links.html#link-type-stylesheet">stylesheet</a></code> links would kick
663: in. Since that default type is <code title="">text/css</code>, the
664: style sheet <em>would</em> nonetheless be applied.</p>
665:
666: </div>
667:
1.85 mike 668: </div>
669:
670: <p>The <dfn id="attr-link-title" title="attr-link-title"><code>title</code></dfn>
1.1 mike 671: attribute gives the title of the link. With one exception, it is
672: purely advisory. The value is text. The exception is for style sheet
673: links, where the <code title="attr-link-title"><a href="#attr-link-title">title</a></code>
1.85 mike 674: attribute defines <a href="infrastructure.html#alternative-style-sheet-sets">alternative style sheet sets</a>.</p>
675:
676: <p class="note">The <code title="attr-link-title"><a href="#attr-link-title">title</a></code>
1.1 mike 677: attribute on <code><a href="#the-link-element">link</a></code> elements differs from the global
678: <code title="attr-title"><a href="global-attributes.html#the-title-attribute">title</a></code> attribute of most other
679: elements in that a link without a title does not inherit the title
1.85 mike 680: of the parent element: it merely has no title.</p>
681:
682: <p>The <code title="attr-link-sizes"><a href="links.html#attr-link-sizes">sizes</a></code> attribute is used
1.1 mike 683: with the <code title="rel-icon"><a href="links.html#rel-icon">icon</a></code> link type. The attribute
684: must not be specified on <code><a href="#the-link-element">link</a></code> elements that do not have
685: a <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute that specifies
1.85 mike 686: the <code title="rel-icon"><a href="links.html#rel-icon">icon</a></code> keyword.</p>
687:
688: <div class="impl">
1.1 mike 689:
1.50 mike 690:
691:
692: <p>HTTP <code title="http-link">Link:</code> header fields, if
693: supported, must be assumed to come before any links in the document,
694: in the order that they were given in the HTTP message. These header
695: fields are to be processed according to the rules given in the
696: relevant specifications. <a href="references.html#refsHTTP">[HTTP]</a> <a href="references.html#refsWEBLINK">[WEBLINK]</a></p>
697:
698: <p class="note">Registration of relation types in HTTP Link: header
699: fields is distinct from <a href="links.html#linkTypes">HTML link types</a>,
700: and thus their semantics can be different from same-named HTML
701: types.</p>
1.4 mike 702:
1.1 mike 703: <p>The IDL attributes <dfn id="dom-link-href" title="dom-link-href"><code>href</code></dfn>, <dfn id="dom-link-rel" title="dom-link-rel"><code>rel</code></dfn>, <dfn id="dom-link-media" title="dom-link-media"><code>media</code></dfn>, <dfn id="dom-link-hreflang" title="dom-link-hreflang"><code>hreflang</code></dfn>, <dfn id="dom-link-type" title="dom-link-type"><code>type</code></dfn>, and <dfn id="dom-link-sizes" title="dom-link-sizes"><code>sizes</code></dfn> each must
704: <a href="common-dom-interfaces.html#reflect">reflect</a> the respective content attributes of the same
705: name.</p>
706:
707: <p>The IDL attribute <dfn id="dom-link-rellist" title="dom-link-rellist"><code>relList</code></dfn> <span class="impl">must</span> <a href="common-dom-interfaces.html#reflect" title="reflect">reflect</a> the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> content attribute.</p>
708:
1.85 mike 709: </div>
710:
711: <p>The IDL attribute <dfn id="dom-link-disabled" title="dom-link-disabled"><code>disabled</code></dfn> only applies
1.1 mike 712: to style sheet links. When the <code><a href="#the-link-element">link</a></code> element defines a
713: style sheet link, then the <code title="dom-link-disabled"><a href="#dom-link-disabled">disabled</a></code> attribute behaves as
714: defined <a href="styling.html#dom-linkstyle-disabled" title="dom-linkstyle-disabled">for the alternative
715: style sheets DOM</a>. For all other <code><a href="#the-link-element">link</a></code> elements it
1.85 mike 716: always return false and does nothing on setting.</p>
717:
718: <p>The <code><a href="infrastructure.html#linkstyle">LinkStyle</a></code> interface is also implemented by
1.1 mike 719: this element; the <a href="styling.html#styling">styling processing model</a> defines
1.85 mike 720: how. <a href="references.html#refsCSSOM">[CSSOM]</a></p>
721:
722: <div class="example">
1.1 mike 723:
724: <p>Here, a set of <code><a href="#the-link-element">link</a></code> elements provide some style
725: sheets:</p>
726:
727: <pre><!-- a persistent style sheet -->
728: <link rel="stylesheet" href="default.css">
729:
730: <!-- the preferred alternate style sheet -->
731: <link rel="stylesheet" href="green.css" title="Green styles">
732:
733: <!-- some alternate style sheets -->
734: <link rel="alternate stylesheet" href="contrast.css" title="High contrast">
735: <link rel="alternate stylesheet" href="big.css" title="Big fonts">
736: <link rel="alternate stylesheet" href="wide.css" title="Wide screen"></pre>
737:
1.85 mike 738: </div>
739:
740: <div class="example">
1.1 mike 741:
742: <p>The following example shows how you can specify versions of the
743: page that use alternative formats, are aimed at other languages,
744: and that are intended for other media:</p>
745:
746: <pre><link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
747: <link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
748: <link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
749: <link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
750: <link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
751: <link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF"></pre>
752:
1.85 mike 753: </div>
754:
755:
756:
757:
758:
759: </body></html>
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