Annotation of html5/spec/the-link-element.html, revision 1.183
1.88 mike 1: <!DOCTYPE html>
1.159 sruby 2: <html lang="en-US-x-Hixie"><head><title>4.2.4 The link element — 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; }
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:
1.180 sruby 66: figure.diagrams { border: double black; background: white; padding: 1em; }
67: figure.diagrams img { display: block; margin: 1em auto; }
68:
1.1 mike 69: h2 { page-break-before: always; }
70: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
71: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
72:
73: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
74: li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
75:
76: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
77: div.head p { margin: 0; }
78: div.head h1 { margin: 0; }
79: div.head .logo { float: right; margin: 0 1em; }
80: div.head .logo img { border: none } /* remove border from top image */
81: div.head dl { margin: 1em 0; }
82: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
83:
84: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
85: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
86: body > .toc > li > * { margin-bottom: 0.5em; }
87: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
88: .toc, .toc li { list-style: none; }
89:
90: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
91: .brief li { margin: 0; padding: 0; }
92: .brief li p { margin: 0; padding: 0; }
93:
94: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
95: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
96: .category-list li { display: inline; }
97: .category-list li:not(:last-child)::after { content: ', '; }
98: .category-list li > span, .category-list li > a { text-transform: lowercase; }
99: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
100:
101: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
102: .XXX > :first-child { margin-top: 0; }
103: p .XXX { line-height: 3em; }
104: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
105: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
106: .annotation :link, .annotation :visited { color: inherit; }
107: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
108: .annotation span { border: none ! important; }
109: .note { color: green; background: transparent; font-family: sans-serif; }
110: .warning { color: red; background: transparent; }
111: .note, .warning { font-weight: bolder; font-style: italic; }
112: .note em, .warning em, .note i, .warning i { font-style: normal; }
113: p.note, div.note { padding: 0.5em 2em; }
114: span.note { padding: 0 2em; }
115: .note p:first-child, .warning p:first-child { margin-top: 0; }
116: .note p:last-child, .warning p:last-child { margin-bottom: 0; }
117: .warning:before { font-style: normal; }
118: p.note:before { content: 'Note: '; }
119: p.warning:before { content: '\26A0 Warning! '; }
120:
121: .bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
122: .bookkeeping { font-size: 0.8em; margin: 2em 0; }
123: .bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
124: .bookkeeping dt { margin: 0.5em 2em 0; }
125: .bookkeeping dd { margin: 0 3em 0.5em; }
126:
127: h4 { position: relative; z-index: 3; }
128: h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
129: .element {
130: background: #EEEEFF;
131: color: black;
132: margin: 0 0 1em 0.15em;
133: padding: 0 1em 0.25em 0.75em;
134: border-left: solid #9999FF 0.25em;
135: position: relative;
136: z-index: 1;
137: }
138: .element:before {
139: position: absolute;
140: z-index: 2;
141: top: 0;
142: left: -1.15em;
143: height: 2em;
144: width: 0.9em;
145: background: #EEEEFF;
146: content: ' ';
147: border-style: none none solid solid;
148: border-color: #9999FF;
149: border-width: 0.25em;
150: }
151:
152: .example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
153: td > .example:only-child { margin: 0 0 0 0.1em; }
154:
155: ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
156: ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
157: ul.domTree li li { list-style: none; }
158: 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; }
159: 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; }
160: ul.domTree span { font-style: italic; font-family: serif; }
161: ul.domTree .t1 code { color: purple; font-weight: bold; }
162: ul.domTree .t2 { font-style: normal; font-family: monospace; }
163: ul.domTree .t2 .name { color: black; font-weight: bold; }
164: ul.domTree .t2 .value { color: blue; font-weight: normal; }
165: ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
166: ul.domTree .t7 code, .domTree .t8 code { color: green; }
167: ul.domTree .t10 code { color: teal; }
168:
169: body.dfnEnabled dfn { cursor: pointer; }
170: .dfnPanel {
171: display: inline;
172: position: absolute;
173: z-index: 10;
174: height: auto;
175: width: auto;
176: padding: 0.5em 0.75em;
177: font: small sans-serif, Droid Sans Fallback;
178: background: #DDDDDD;
179: color: black;
180: border: outset 0.2em;
181: }
182: .dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
183: .dfnPanel :link, .dfnPanel :visited { color: black; }
184: .dfnPanel p { font-weight: bolder; }
185: .dfnPanel * + p { margin-top: 0.25em; }
186: .dfnPanel li { list-style-position: inside; }
187:
188: #configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
189: #configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
190: #configUI p label { display: block; }
191: #configUI #updateUI, #configUI .loginUI { text-align: center; }
192: #configUI input[type=button] { display: block; margin: auto; }
193:
194: fieldset { margin: 1em; padding: 0.5em 1em; }
195: fieldset > legend + * { margin-top: 0; }
196: fieldset > :last-child { margin-bottom: 0; }
197: fieldset p { margin: 0.5em 0; }
198:
1.159 sruby 199: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><style type="text/css">
1.1 mike 200:
201: .applies thead th > * { display: block; }
202: .applies thead code { display: block; }
203: .applies tbody th { whitespace: nowrap; }
204: .applies td { text-align: center; }
205: .applies .yes { background: yellow; }
206:
207: .matrix, .matrix td { border: hidden; text-align: right; }
208: .matrix { margin-left: 2em; }
209:
210: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
211: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
212: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
213:
214: td.eg { border-width: thin; text-align: center; }
215:
216: #table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
217: #table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
218: #table-example-1 caption { padding-bottom: 0.5em; }
219: #table-example-1 thead, #table-example-1 tbody { border: none; }
220: #table-example-1 th, #table-example-1 td { border: solid thin; }
221: #table-example-1 th { font-weight: normal; }
222: #table-example-1 td { border-style: none solid; vertical-align: top; }
223: #table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
224: #table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
225: #table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
226: #table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
227: #table-example-1 tbody td:first-child::after { content: leader(". "); }
228: #table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
229: #table-example-1 tbody td:first-child + td { width: 10em; }
230: #table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
231: #table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
232:
233: .apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
234: .apple-table-examples * { font-family: "Times", serif; }
235: .apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
236: .apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
237: .apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
238: .apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
239: .apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
240: .apple-table-examples td { text-align: right; vertical-align: top; }
241: .apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
242: .apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
243: .apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
244: .apple-table-examples sup { line-height: 0; }
245:
246: .details-example img { vertical-align: top; }
247:
248: #base64-table {
249: white-space: nowrap;
250: font-size: 0.6em;
251: column-width: 6em;
252: column-count: 5;
253: column-gap: 1em;
254: -moz-column-width: 6em;
255: -moz-column-count: 5;
256: -moz-column-gap: 1em;
257: -webkit-column-width: 6em;
258: -webkit-column-count: 5;
259: -webkit-column-gap: 1em;
260: }
261: #base64-table thead { display: none; }
262: #base64-table * { border: none; }
263: #base64-table tbody td:first-child:after { content: ':'; }
264: #base64-table tbody td:last-child { text-align: right; }
265:
266: #named-character-references-table {
267: white-space: nowrap;
268: font-size: 0.6em;
269: column-width: 30em;
270: column-gap: 1em;
271: -moz-column-width: 30em;
272: -moz-column-gap: 1em;
273: -webkit-column-width: 30em;
274: -webkit-column-gap: 1em;
275: }
276: #named-character-references-table > table > tbody > tr > td:first-child + td,
277: #named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
278: #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; }
279: #named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
280:
281: .glyph.control { color: red; }
282:
283: @font-face {
284: font-family: 'Essays1743';
1.178 sruby 285: src: url('../fonts/Essays1743.ttf');
1.1 mike 286: }
287: @font-face {
288: font-family: 'Essays1743';
289: font-weight: bold;
1.178 sruby 290: src: url('../fonts/Essays1743-Bold.ttf');
1.1 mike 291: }
292: @font-face {
293: font-family: 'Essays1743';
294: font-style: italic;
1.178 sruby 295: src: url('../fonts/Essays1743-Italic.ttf');
1.1 mike 296: }
297: @font-face {
298: font-family: 'Essays1743';
299: font-style: italic;
300: font-weight: bold;
1.178 sruby 301: src: url('../fonts/Essays1743-BoldItalic.ttf');
1.1 mike 302: }
303:
1.159 sruby 304: </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>
1.1 mike 305: function getCookie(name) {
306: var params = location.search.substr(1).split("&");
307: for (var index = 0; index < params.length; index++) {
308: if (params[index] == name)
309: return "1";
310: var data = params[index].split("=");
311: if (data[0] == name)
312: return unescape(data[1]);
313: }
314: var cookies = document.cookie.split("; ");
315: for (var index = 0; index < cookies.length; index++) {
316: var data = cookies[index].split("=");
317: if (data[0] == name)
318: return unescape(data[1]);
319: }
320: return null;
321: }
1.159 sruby 322: </script><link href="the-base-element.html" title="4.2.3 The base element" rel="prev">
1.161 sruby 323: <link href="spec.html#contents" title="Table of contents" rel="contents">
1.1 mike 324: <link href="the-meta-element.html" title="4.2.5 The meta element" rel="next">
1.22 mike 325: </head><body onload="fixBrokenLink();" class="split chapter"><div class="head" id="head">
1.1 mike 326: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
327:
328: <h1>HTML5</h1>
1.159 sruby 329: <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>
1.182 sruby 330: <h2 class="no-num no-toc" id="editor's-draft-date-1-january-1970">Editor's Draft 21 September 2012</h2>
1.85 mike 331: </div>
1.174 sruby 332: <div class="prev_next">
1.1 mike 333: <a href="the-base-element.html">← 4.2.3 The base element</a> –
1.161 sruby 334: <a href="spec.html#contents">Table of contents</a> –
1.1 mike 335: <a href="the-meta-element.html">4.2.5 The meta element →</a>
1.159 sruby 336: </div>
1.1 mike 337:
1.85 mike 338: <h4 id="the-link-element"><span class="secno">4.2.4 </span>The <dfn><code>link</code></dfn> element</h4>
339:
340: <dl class="element"><dt><a href="element-definitions.html#element-dfn-categories" title="element-dfn-categories">Categories</a>:</dt>
1.159 sruby 341: <dd><a href="content-models.html#metadata-content-0">Metadata content</a>.</dd>
342: <!--MD-->
1.25 mike 343: <dt><a href="element-definitions.html#element-dfn-contexts" title="element-dfn-contexts">Contexts in which this element can be used</a>:</dt>
1.159 sruby 344: <dd>Where <a href="content-models.html#metadata-content-0">metadata content</a> is expected.</dd>
1.1 mike 345: <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>
1.159 sruby 346: <!--MD-->
1.25 mike 347: <dt><a href="element-definitions.html#element-dfn-content-model" title="element-dfn-content-model">Content model</a>:</dt>
1.1 mike 348: <dd>Empty.</dd>
1.25 mike 349: <dt><a href="element-definitions.html#element-dfn-attributes" title="element-dfn-attributes">Content attributes</a>:</dt>
1.1 mike 350: <dd><a href="global-attributes.html#global-attributes">Global attributes</a></dd>
351: <dd><code title="attr-link-href"><a href="#attr-link-href">href</a></code></dd>
352: <dd><code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code></dd>
353: <dd><code title="attr-link-media"><a href="#attr-link-media">media</a></code></dd>
354: <dd><code title="attr-link-hreflang"><a href="#attr-link-hreflang">hreflang</a></code></dd>
355: <dd><code title="attr-link-type"><a href="#attr-link-type">type</a></code></dd>
356: <dd><code title="attr-link-sizes"><a href="links.html#attr-link-sizes">sizes</a></code></dd>
357: <dd>Also, the <code title="attr-link-title"><a href="#attr-link-title">title</a></code> attribute has special semantics on this element.</dd>
1.159 sruby 358: <dt><a href="element-definitions.html#element-dfn-dom" title="element-dfn-dom">DOM interface</a>:</dt><!--TOPIC:DOM APIs-->
1.1 mike 359: <dd>
360: <pre class="idl">interface <dfn id="htmllinkelement">HTMLLinkElement</dfn> : <a href="elements.html#htmlelement">HTMLElement</a> {
361: attribute boolean <a href="#dom-link-disabled" title="dom-link-disabled">disabled</a>;
362: attribute DOMString <a href="#dom-link-href" title="dom-link-href">href</a>;
363: attribute DOMString <a href="#dom-link-rel" title="dom-link-rel">rel</a>;
364: readonly attribute <a href="infrastructure.html#domtokenlist">DOMTokenList</a> <a href="#dom-link-rellist" title="dom-link-relList">relList</a>;
365: attribute DOMString <a href="#dom-link-media" title="dom-link-media">media</a>;
366: attribute DOMString <a href="#dom-link-hreflang" title="dom-link-hreflang">hreflang</a>;
367: attribute DOMString <a href="#dom-link-type" title="dom-link-type">type</a>;
368: [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>;
369: };
370: <a href="#htmllinkelement">HTMLLinkElement</a> implements <a href="infrastructure.html#linkstyle">LinkStyle</a>;</pre>
371: </dd>
1.159 sruby 372: </dl><!--TOPIC:HTML--><p>The <code><a href="#the-link-element">link</a></code> element allows authors to link their
1.85 mike 373: document to other resources.</p>
374:
375: <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 376: be present and must contain a <a href="urls.html#valid-non-empty-url-potentially-surrounded-by-spaces">valid non-empty URL potentially
377: 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 378: element does not define a link.</span></p>
379:
1.159 sruby 380: <!--MD--><!--MD-->
1.85 mike 381: <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>
1.159 sruby 382: <!--MD-->
1.85 mike 383:
384: <p>The types of link indicated (the relationships) are given by the
1.1 mike 385: value of the <dfn id="attr-link-rel" title="attr-link-rel"><code>rel</code></dfn>
386: attribute, which, if present, must have a value that is a <a href="common-microsyntaxes.html#set-of-space-separated-tokens">set
387: of space-separated tokens</a>. The <a href="links.html#linkTypes">allowed
388: keywords and their meanings</a> are defined in a later
389: section. <span class="impl">If the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute is absent, has no
390: keywords, or if none of the keywords used are allowed according to
391: the definitions in this specification, then the element does not
1.85 mike 392: create any links.</span></p>
393:
394: <p>Two categories of links can be created using the
1.1 mike 395: <code><a href="#the-link-element">link</a></code> element: <a href="links.html#external-resource-link" title="external resource
396: link">Links to external resources</a> and <a href="links.html#hyperlink" title="hyperlink">hyperlinks</a>. The <a href="links.html#linkTypes">link
397: types section</a> defines whether a particular link type is an
398: external resource or a hyperlink. One <code><a href="#the-link-element">link</a></code> element can
399: create multiple links (of which some might be external resource
400: links and some might be hyperlinks); exactly which and how many
401: 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 402: the links on a per-link basis, not a per-element basis.</p>
403:
404: <p class="note">Each link created for a <code><a href="#the-link-element">link</a></code> element is
1.1 mike 405: handled separately. For instance, if there are two <code><a href="#the-link-element">link</a></code>
406: elements with <code title="">rel="stylesheet"</code>, they each
407: count as a separate external resource, and each is affected by its
408: own attributes independently. Similarly, if a single
409: <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
410: <a href="links.html#hyperlink">hyperlink</a> (for the <code title="rel-next"><a href="links.html#link-type-next">next</a></code>
411: 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 412: 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>
413:
414: <div class="example">
1.1 mike 415:
416: <p>For example, the following <code><a href="#the-link-element">link</a></code> element creates two
417: hyperlinks (to the same page):</p>
418:
419: <pre><link rel="author license" href="/about"></pre>
420:
421: <p>The two links created by this element are one whose semantic is
422: that the target page has information about the current page's
423: author, and one whose semantic is that the target page has
424: information regarding the license under which the current page is
425: provided.</p>
426:
1.85 mike 427: </div>
428:
429: <p>The exact behavior for links to external resources depends on the
1.1 mike 430: exact relationship, as defined for the relevant link type. Some of
431: the attributes control whether or not the external resource is to be
1.85 mike 432: applied (as defined below).</p>
433:
434: <div class="impl">
1.1 mike 435:
436: <p>For external resources that are represented in the
437: DOM (for example, style sheets), the DOM representation must be made
438: available even if the resource is not applied. To <dfn id="concept-link-obtain" title="concept-link-obtain">obtain the resource</dfn>, the user
439: agent must run the following steps:</p>
440:
441: <ol><li><p>If the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute's
442: value is the empty string, then abort these steps.</p></li>
443:
444: <li><p><a href="urls.html#resolve-a-url" title="resolve a url">Resolve</a> the
445: <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
446: element.</p></li>
447:
448: <li><p>If the previous step fails, then abort these steps.</p></li>
449:
450: <li><p><a href="urls.html#fetch">Fetch</a> the resulting <a href="urls.html#absolute-url">absolute
1.159 sruby 451: URL</a>.</p></li> <!-- http-origin privacy sensitive -->
1.1 mike 452:
453: </ol><p>User agents may opt to only try to obtain such resources when
454: they are needed, instead of pro-actively <a href="urls.html#fetch" title="fetch">fetching</a> all the external resources that are
455: not applied.</p>
456:
457: <p>The semantics of the protocol used (e.g. HTTP) must be followed
458: when fetching external resources. (For example, redirects will be
459: followed and 404 responses will cause the external resource to not
460: be applied.)</p>
461:
1.159 sruby 462: <!-- the next few paragraph are similar to text in the <style> section -->
1.1 mike 463: <p>Once the attempts to obtain the resource and its <a href="infrastructure.html#critical-subresources">critical
464: subresources</a> are complete, the user agent must, if the loads
465: 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
466: event</a> named <code title="event-load">load</code> at the
467: <code><a href="#the-link-element">link</a></code> element, or, if the resource or one of its
468: <a href="infrastructure.html#critical-subresources">critical subresources</a> failed to completely load for any
469: reason (e.g. DNS error, HTTP 404 response, a connection being
470: prematurely closed, unsupported Content-Type), <a href="webappapis.html#queue-a-task">queue a
471: 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>
472: element. Non-network errors in processing the resource or its
473: subresources (e.g. CSS parse errors, PNG decoding errors) are not
474: failures for the purposes of this paragraph.</p>
475:
476: <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
477: source</a>.</p>
478:
479: <p>The element must <a href="the-end.html#delay-the-load-event">delay the load event</a> of the
480: element's document until all the attempts to obtain the resource and
481: its <a href="infrastructure.html#critical-subresources">critical subresources</a> are complete. (Resources that
482: the user agent has not yet attempted to obtain, e.g. because it is
483: waiting for the resource to be needed, do not <a href="the-end.html#delay-the-load-event">delay the load
484: event</a>.)</p>
485:
486: <hr><p id="linkui">Interactive user agents may provide users with a
1.159 sruby 487: means to <a href="links.html#following-hyperlinks-0" title="following hyperlinks">follow the
1.1 mike 488: hyperlinks</a> created using the <code><a href="#the-link-element">link</a></code> element,
489: somewhere within their user interface. The exact interface is not
490: defined by this specification, but it could include the following
491: information (obtained from the element's attributes, again as
492: defined below), in some form or another (possibly simplified), for
493: each hyperlink created with each <code><a href="#the-link-element">link</a></code> element in the
494: document:</p>
495:
1.159 sruby 496: <ul><!-- the order here is the order that makes most sense for a UI --><li>The relationship between this document and the resource (given
1.1 mike 497: by the <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute)</li>
498:
499: <li>The title of the resource (given by the <code title="attr-link-title"><a href="#attr-link-title">title</a></code> attribute).</li>
500:
501: <li>The address of the resource (given by the <code title="attr-link-href"><a href="#attr-link-href">href</a></code> attribute).</li>
502:
503: <li>The language of the resource (given by the <code title="attr-link-hreflang"><a href="#attr-link-hreflang">hreflang</a></code> attribute).</li>
504:
505: <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>
506:
507: </ul><p>User agents could also include other information, such as the
508: type of the resource (as given by the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute).</p>
509:
1.85 mike 510: </div>
511:
512: <p class="note">Hyperlinks created with the <code><a href="#the-link-element">link</a></code>
1.1 mike 513: element and its <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute
514: 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>
515: and <code><a href="the-area-element.html#the-area-element">area</a></code> elements, which indicates the type of a link
516: whose context is given by the link's location within the
1.85 mike 517: document.</p>
518:
519: <p>The <dfn id="attr-link-media" title="attr-link-media"><code>media</code></dfn>
1.1 mike 520: attribute says which media the resource applies to. The value must
1.85 mike 521: be a <a href="common-microsyntaxes.html#valid-media-query">valid media query</a>.</p>
522:
523: <div class="impl">
1.1 mike 524:
525: <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,
526: and describes for which media the document in question was
527: designed.</p>
528:
529: <p>However, if the link is an <a href="links.html#external-resource-link">external resource link</a>,
530: then the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute is
531: prescriptive. The user agent must apply the external resource when
532: the <code title="attr-link-media"><a href="#attr-link-media">media</a></code> attribute's value
533: <a href="common-microsyntaxes.html#matches-the-environment">matches the environment</a> and the other relevant
1.159 sruby 534: conditions apply, and must not apply it otherwise.</p><!-- note
535: similar text in <style> section -->
1.4 mike 536:
1.1 mike 537: <p class="note">The external resource might have further
538: restrictions defined within that limit its applicability. For
539: example, a CSS style sheet might have some <code title="">@media</code> blocks. This specification does not override
1.159 sruby 540: such further restrictions or requirements.</p><!-- note similar text
541: in <style> section -->
1.4 mike 542:
1.85 mike 543: </div>
544:
545: <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
546: media.</p>
547:
548: <p>The <dfn id="attr-link-hreflang" title="attr-link-hreflang"><code>hreflang</code></dfn>
1.1 mike 549: attribute on the <code><a href="#the-link-element">link</a></code> element has the same semantics as
550: the <a href="links.html#attr-hyperlink-hreflang" title="attr-hyperlink-hreflang"><code>hreflang</code>
551: attribute on <code>a</code> and <code>area</code>
1.85 mike 552: elements</a>.</p>
553:
554: <p>The <dfn id="attr-link-type" title="attr-link-type"><code>type</code></dfn> attribute
1.1 mike 555: gives the <a href="infrastructure.html#mime-type">MIME type</a> of the linked resource. It is
556: purely advisory. The value must be a <a href="infrastructure.html#valid-mime-type">valid MIME
1.85 mike 557: type</a>.</p>
558:
559: <p>For <a href="links.html#external-resource-link" title="external resource link">external resource
1.1 mike 560: links</a>, the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute
561: is used as a hint to user agents so that they can avoid fetching
562: resources they do not support. <span class="impl">If the attribute
563: is present, then the user agent must assume that the resource is of
564: the given type (even if that is not a <a href="infrastructure.html#valid-mime-type">valid MIME type</a>,
565: e.g. the empty string). If the attribute is omitted, but the
566: external resource link type has a default type defined, then the
567: user agent must assume that the resource is of that type. If the UA
568: does not support the given <a href="infrastructure.html#mime-type">MIME type</a> for the given link
569: relationship, then the UA should not <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource; if the UA
570: does support the given <a href="infrastructure.html#mime-type">MIME type</a> for the given link
571: relationship, then the UA should <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource at the
572: appropriate time as specified for the <a href="links.html#external-resource-link">external resource
573: link</a>'s particular type. If the attribute is omitted, and the
574: external resource link type does not have a default type defined,
575: but the user agent would <a href="#concept-link-obtain" title="concept-link-obtain">obtain</a> the resource if the type
576: 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 577: assumption that it will be supported.</span></p>
578:
579: <div class="impl">
1.1 mike 580:
581: <p>User agents must not consider the <code title="attr-link-type"><a href="#attr-link-type">type</a></code> attribute authoritative —
582: 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
583: type. Only the actual type (as defined in the next paragraph) is
584: used to determine whether to <em>apply</em> the resource, not the
585: aforementioned assumed type.</p>
586:
587: <p id="concept-link-type-sniffing">If the external resource link
588: type defines rules for processing the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a>, then those rules
589: apply. Otherwise, if the resource is expected to be an image, user
590: agents may apply the <a href="urls.html#content-type-sniffing:-image" title="Content-Type sniffing:
591: image">image sniffing rules</a>, with the <var title="">official
592: 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
593: resulting sniffed type of the resource as if it was the actual
594: type. Otherwise, if neither of these conditions apply or if the user
595: agent opts not to apply the image sniffing rules, then the user
596: agent must use the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a> to determine the
597: type of the resource. If there is no type metadata, but the external
598: resource link type has a default type defined, then the user agent
599: must assume that the resource is of that type.</p>
600:
601: <p class="note">The <code title="rel-stylesheet"><a href="links.html#link-type-stylesheet">stylesheet</a></code>
602: link type defines rules for processing the resource's <a href="urls.html#content-type" title="Content-Type">Content-Type metadata</a>.</p>
603:
604: <p>Once the user agent has established the type of the resource, the
605: user agent must apply the resource if it is of a supported type and
606: the other relevant conditions apply, and must ignore the resource
607: otherwise.</p>
608:
609: <div class="example">
610:
611: <p>If a document contains style sheet links labeled as follows:</p>
612:
613: <pre><link rel="stylesheet" href="A" type="text/plain">
614: <link rel="stylesheet" href="B" type="text/css">
615: <link rel="stylesheet" href="C"></pre>
616:
617: <p>...then a compliant UA that supported only CSS style sheets
618: would fetch the B and C files, and skip the A file (since
619: <code>text/plain</code> is not the <a href="infrastructure.html#mime-type">MIME type</a> for CSS style
620: sheets).</p>
621:
622: <p>For files B and C, it would then check the actual types returned
623: by the server. For those that are sent as <code>text/css</code>, it
624: would apply the styles, but for those labeled as
625: <code>text/plain</code>, or any other type, it would not.</p>
626:
627: <p>If one of the two files was returned without a
628: <a href="urls.html#content-type">Content-Type</a> metadata, or with a syntactically
629: incorrect type like <code title="">Content-Type: "null"</code>, then the default type
630: for <code title="rel-stylesheet"><a href="links.html#link-type-stylesheet">stylesheet</a></code> links would kick
631: in. Since that default type is <code title="">text/css</code>, the
632: style sheet <em>would</em> nonetheless be applied.</p>
633:
634: </div>
635:
1.85 mike 636: </div>
637:
638: <p>The <dfn id="attr-link-title" title="attr-link-title"><code>title</code></dfn>
1.1 mike 639: attribute gives the title of the link. With one exception, it is
640: purely advisory. The value is text. The exception is for style sheet
641: links, where the <code title="attr-link-title"><a href="#attr-link-title">title</a></code>
1.85 mike 642: attribute defines <a href="infrastructure.html#alternative-style-sheet-sets">alternative style sheet sets</a>.</p>
643:
644: <p class="note">The <code title="attr-link-title"><a href="#attr-link-title">title</a></code>
1.1 mike 645: attribute on <code><a href="#the-link-element">link</a></code> elements differs from the global
1.183 ! sruby 646: <code title="attr-title"><a href="global-attributes.html#attr-title">title</a></code> attribute of most other
1.1 mike 647: elements in that a link without a title does not inherit the title
1.85 mike 648: of the parent element: it merely has no title.</p>
649:
650: <p>The <code title="attr-link-sizes"><a href="links.html#attr-link-sizes">sizes</a></code> attribute is used
1.1 mike 651: with the <code title="rel-icon"><a href="links.html#rel-icon">icon</a></code> link type. The attribute
652: must not be specified on <code><a href="#the-link-element">link</a></code> elements that do not have
653: a <code title="attr-link-rel"><a href="#attr-link-rel">rel</a></code> attribute that specifies
1.85 mike 654: the <code title="rel-icon"><a href="links.html#rel-icon">icon</a></code> keyword.</p>
655:
656: <div class="impl">
1.1 mike 657:
1.159 sruby 658: <!--!--><!-- s/header fields/headers/ for consistency with the rest of the spec -->
1.50 mike 659:
660: <p>HTTP <code title="http-link">Link:</code> header fields, if
661: supported, must be assumed to come before any links in the document,
662: in the order that they were given in the HTTP message. These header
663: fields are to be processed according to the rules given in the
1.159 sruby 664: relevant specifications. <a href="references.html#refsHTTP">[HTTP]</a> <a href="references.html#refsWEBLINK">[WEBLINK]</a></p> <!-- WEBLINK is ref for Link:
665: header -->
1.50 mike 666:
667: <p class="note">Registration of relation types in HTTP Link: header
668: fields is distinct from <a href="links.html#linkTypes">HTML link types</a>,
669: and thus their semantics can be different from same-named HTML
670: types.</p>
1.4 mike 671:
1.1 mike 672: <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
673: <a href="common-dom-interfaces.html#reflect">reflect</a> the respective content attributes of the same
674: name.</p>
675:
676: <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>
677:
1.85 mike 678: </div>
679:
680: <p>The IDL attribute <dfn id="dom-link-disabled" title="dom-link-disabled"><code>disabled</code></dfn> only applies
1.1 mike 681: to style sheet links. When the <code><a href="#the-link-element">link</a></code> element defines a
682: style sheet link, then the <code title="dom-link-disabled"><a href="#dom-link-disabled">disabled</a></code> attribute behaves as
683: defined <a href="styling.html#dom-linkstyle-disabled" title="dom-linkstyle-disabled">for the alternative
684: style sheets DOM</a>. For all other <code><a href="#the-link-element">link</a></code> elements it
1.159 sruby 685: always return false and does nothing on setting.</p> <!-- that is
686: normatively required in the definition of dom-linkstyle-disabled -->
1.85 mike 687:
688: <p>The <code><a href="infrastructure.html#linkstyle">LinkStyle</a></code> interface is also implemented by
1.1 mike 689: this element; the <a href="styling.html#styling">styling processing model</a> defines
1.85 mike 690: how. <a href="references.html#refsCSSOM">[CSSOM]</a></p>
691:
692: <div class="example">
1.1 mike 693:
694: <p>Here, a set of <code><a href="#the-link-element">link</a></code> elements provide some style
695: sheets:</p>
696:
697: <pre><!-- a persistent style sheet -->
698: <link rel="stylesheet" href="default.css">
699:
700: <!-- the preferred alternate style sheet -->
701: <link rel="stylesheet" href="green.css" title="Green styles">
702:
703: <!-- some alternate style sheets -->
704: <link rel="alternate stylesheet" href="contrast.css" title="High contrast">
705: <link rel="alternate stylesheet" href="big.css" title="Big fonts">
706: <link rel="alternate stylesheet" href="wide.css" title="Wide screen"></pre>
707:
1.85 mike 708: </div>
709:
710: <div class="example">
1.1 mike 711:
712: <p>The following example shows how you can specify versions of the
713: page that use alternative formats, are aimed at other languages,
714: and that are intended for other media:</p>
715:
716: <pre><link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
717: <link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
718: <link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
719: <link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
720: <link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
721: <link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF"></pre>
722:
1.85 mike 723: </div>
724:
725:
726:
727:
728:
729: </body></html>
Webmaster
![[BACK]](/https/dev.w3.org/cvsweb/icons/back.gif){kind=icon}
Return to the-link-element.html CVS log ![[TXT]](/https/dev.w3.org/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/https/dev.w3.org/cvsweb/icons/dir.gif){kind=icon}
Up to [Public] / html5 / spec