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1 <html>
2 <head>
3 <script src="../htmlrunner.js"></script>
4 <script>
5 window.onload = function(){
6 startTest("dom-query", '');
7
8 // Try to force real results
9 var ret, tmp;
10 var num = 40;
11 var html = document.body.innerHTML;
12
13 prep(function(){
14 html = html.replace(/id="test(\w).*?"/g, 'id="test$1' + num + '" ');
15 html = html.replace(/name="test.*?"/g, 'name="test' + num + '"') ;
16 html = html.replace(/class="foo.*?"/g, 'class="foo test' + num + ' bar"');
17 var div = document.createElement("div");
18 div.innerHTML = html;
19 document.body.appendChild( div );
20 });
21
22 test( "getElementById", function(){
23 for ( var i = 0; i < num * 30; i++ ) {
24 ret = document.getElementById("testA" + num).nodeType;
25 ret = document.getElementById("testB" + num).nodeType;
26 ret = document.getElementById("testC" + num).nodeType;
27 ret = document.getElementById("testD" + num).nodeType;
28 ret = document.getElementById("testE" + num).nodeType;
29 ret = document.getElementById("testF" + num).nodeType;
30 }
31 });
32
33 test( "getElementById (not in document)", function(){
34 for ( var i = 0; i < num * 30; i++ ) {
35 ret = document.getElementById("testA");
36 ret = document.getElementById("testB");
37 ret = document.getElementById("testC");
38 ret = document.getElementById("testD");
39 ret = document.getElementById("testE");
40 ret = document.getElementById("testF");
41 }
42 });
43
44 test( "getElementsByTagName(div)", function(){
45 for ( var i = 0; i < num; i++ ) {
46 var elems = document.getElementsByTagName("div");
47 ret = elems[elems.length-1].nodeType;
48 }
49 });
50
51 test( "getElementsByTagName(p)", function(){
52 for ( var i = 0; i < num; i++ ) {
53 var elems = document.getElementsByTagName("p");
54 ret = elems[elems.length-1].nodeType;
55 }
56 });
57
58 test( "getElementsByTagName(a)", function(){
59 for ( var i = 0; i < num; i++ ) {
60 var elems = document.getElementsByTagName("a");
61 ret = elems[elems.length-1].nodeType;
62 }
63 });
64
65 test( "getElementsByTagName(*)", function(){
66 for ( var i = 0; i < num; i++ ) {
67 var elems = document.getElementsByTagName("*");
68 ret = elems[elems.length-1].nodeType;
69 }
70 });
71
72 test( "getElementsByTagName (not in document)", function(){
73 for ( var i = 0; i < num; i++ ) {
74 var elems = document.getElementsByTagName("strong");
75 ret = elems.length == 0;
76 }
77 });
78
79 test( "getElementsByName", function(){
80 for ( var i = 0; i < num * 20; i++ ) {
81 var elems = document.getElementsByName("test" + num);
82 ret = elems[elems.length-1].nodeType;
83 var elems = document.getElementsByName("test" + num);
84 ret = elems[elems.length-1].nodeType;
85 var elems = document.getElementsByName("test" + num);
86 ret = elems[elems.length-1].nodeType;
87 var elems = document.getElementsByName("test" + num);
88 ret = elems[elems.length-1].nodeType;
89 }
90 });
91
92 test( "getElementsByName (not in document)", function(){
93 for ( var i = 0; i < num * 20; i++ ) {
94 ret = document.getElementsByName("test").length == 0;
95 ret = document.getElementsByName("test").length == 0;
96 ret = document.getElementsByName("test").length == 0;
97 ret = document.getElementsByName("test").length == 0;
98 ret = document.getElementsByName("test").length == 0;
99 }
100 });
101
102 endTest();
103 };
104 </script>
105 </head>
106 <body>
107 <div class="head">
108 <p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org /Icons/w3c_home" width=72></a>
109
110 <h1 id="title">Selectors</h1>
111
112 <h2>W3C Working Draft 15 December 2005</h2>
113
114 <dl>
115
116 <dt>This version:
117
118 <dd><a href="http://www.w3.org/TR/2005/WD-css3-selectors-20051215">
119 http://www.w3.org/TR/2005/WD-css3-selectors-20051215</a>
120
121 <dt>Latest version:
122
123 <dd><a href="http://www.w3.org/TR/css3-selectors">
124 http://www.w3.org/TR/css3-selectors</a>
125
126 <dt>Previous version:
127
128 <dd><a href="http://www.w3.org/TR/2001/CR-css3-selectors-20011113">
129 http://www.w3.org/TR/2001/CR-css3-selectors-20011113</a>
130
131 <dt><a name=editors-list></a>Editors:
132
133 <dd class="vcard"><span class="fn">Daniel Glazman</span> (Invited Expert)</d d>
134
135 <dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/"> Tantek &Ccedil;elik</a> (Invited Expert)
136
137 <dd class="vcard"><a href="mailto:ian@hixie.ch" class="url fn">Ian Hickson</ a> (<span
138 class="company"><a href="http://www.google.com/">Google</a></span>)
139
140 <dd class="vcard"><span class="fn">Peter Linss</span> (former editor, <span class="company"><a
141 href="http://www.netscape.com/">Netscape/AOL</a></span>)
142
143 <dd class="vcard"><span class="fn">John Williams</span> (former editor, <spa n class="company"><a
144 href="http://www.quark.com/">Quark, Inc.</a></span>)
145
146 </dl>
147
148 <p class="copyright"><a
149 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">
150 Copyright</a> &copy; 2005 <a href="http://www.w3.org/"><abbr
151 title="World Wide Web Consortium">W3C</abbr></a><sup>&reg;</sup>
152 (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
153 Institute of Technology">MIT</abbr></a>, <a
154 href="http://www.ercim.org/"><acronym title="European Research
155 Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a
156 href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
157 <a
158 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liabili ty</a>,
159 <a
160 href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark </a>,
161 <a
162 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
163 use</a> rules apply.
164
165 <hr title="Separator for header">
166
167 </div>
168
169 <h2><a name=abstract></a>Abstract</h2>
170
171 <p><em>Selectors</em> are patterns that match against elements in a
172 tree. Selectors have been optimized for use with HTML and XML, and
173 are designed to be usable in performance-critical code.</p>
174
175 <p><acronym title="Cascading Style Sheets">CSS</acronym> (Cascading
176 Style Sheets) is a language for describing the rendering of <acronym
177 title="Hypertext Markup Language">HTML</acronym> and <acronym
178 title="Extensible Markup Language">XML</acronym> documents on
179 screen, on paper, in speech, etc. CSS uses Selectors for binding
180 style properties to elements in the document. This document
181 describes extensions to the selectors defined in CSS level 2. These
182 extended selectors will be used by CSS level 3.
183
184 <p>Selectors define the following function:</p>
185
186 <pre>expression &#x2217; element &rarr; boolean</pre>
187
188 <p>That is, given an element and a selector, this specification
189 defines whether that element matches the selector.</p>
190
191 <p>These expressions can also be used, for instance, to select a set
192 of elements, or a single element from a set of elements, by
193 evaluating the expression across all the elements in a
194 subtree. <acronym title="Simple Tree Transformation
195 Sheets">STTS</acronym> (Simple Tree Transformation Sheets), a
196 language for transforming XML trees, uses this mechanism. <a href="#refsSTTS"> [STTS]</a></p>
197
198 <h2><a name=status></a>Status of this document</h2>
199
200 <p><em>This section describes the status of this document at the
201 time of its publication. Other documents may supersede this
202 document. A list of current W3C publications and the latest revision
203 of this technical report can be found in the <a
204 href="http://www.w3.org/TR/">W3C technical reports index at
205 http://www.w3.org/TR/.</a></em></p>
206
207 <p>This document describes the selectors that already exist in <a
208 href="#refsCSS1"><abbr title="CSS level 1">CSS1</abbr></a> and <a
209 href="#refsCSS21"><abbr title="CSS level 2">CSS2</abbr></a>, and
210 also proposes new selectors for <abbr title="CSS level
211 3">CSS3</abbr> and other languages that may need them.</p>
212
213 <p>The CSS Working Group doesn't expect that all implementations of
214 CSS3 will have to implement all selectors. Instead, there will
215 probably be a small number of variants of CSS3, called profiles. For
216 example, it may be that only a profile for interactive user agents
217 will include all of the selectors.</p>
218
219 <p>This specification is a last call working draft for the the <a
220 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a>
221 (<a href="/Style/">Style Activity</a>). This
222 document is a revision of the <a
223 href="http://www.w3.org/TR/2001/CR-css3-selectors-20011113/">Candidate
224 Recommendation dated 2001 November 13</a>, and has incorporated
225 implementation feedback received in the past few years. It is
226 expected that this last call will proceed straight to Proposed
227 Recommendation stage since it is believed that interoperability will
228 be demonstrable.</p>
229
230 <p>All persons are encouraged to review and implement this
231 specification and return comments to the (<a
232 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>)
233 public mailing list <a
234 href="http://www.w3.org/Mail/Lists.html#www-style">www-style</a>
235 (see <a href="http://www.w3.org/Mail/Request">instructions</a>). W3C
236 Members can also send comments directly to the CSS Working
237 Group.
238 The deadline for comments is 14 January 2006.</p>
239
240 <p>This is still a draft document and may be updated, replaced, or
241 obsoleted by other documents at any time. It is inappropriate to
242 cite a W3C Working Draft as other than &quot;work in progress&quot;.
243
244 <p>This document may be available in <a
245 href="http://www.w3.org/Style/css3-selectors-updates/translations">translation </a>.
246 The English version of this specification is the only normative
247 version.
248
249 <div class="subtoc">
250
251 <h2 id="testF10"><a name=contents>Table of contents</a></h2>
252
253 <ul class="toc">
254 <li class="tocline2"><a href="#context">1. Introduction</a>
255 <ul>
256 <li><a href="#dependencies">1.1. Dependencies</a> </li>
257 <li><a href="#terminology">1.2. Terminology</a> </li>
258 <li><a href="#changesFromCSS2">1.3. Changes from CSS2</a> </li>
259 </ul>
260 <li class="tocline2"><a href="#selectors">2. Selectors</a>
261 <li class="tocline2"><a href="#casesens">3. Case sensitivity</a>
262 <li class="tocline2"><a href="#selector-syntax">4. Selector syntax</a>
263 <li class="tocline2"><a href="#grouping">5. Groups of selectors</a>
264 <li class="tocline2"><a href="#simple-selectors">6. Simple selectors</a>
265 <ul class="toc">
266 <li class="tocline3"><a href="#type-selectors">6.1. Type selectors</a>
267 <ul class="toc">
268 <li class="tocline4"><a href="#typenmsp">6.1.1. Type selectors and names paces</a></li>
269 </ul>
270 <li class="tocline3"><a href="#universal-selector">6.2. Universal selector </a>
271 <ul>
272 <li><a href="#univnmsp">6.2.1. Universal selector and namespaces</a></li >
273 </ul>
274 <li class="tocline3"><a href="#attribute-selectors">6.3. Attribute selecto rs</a>
275 <ul class="toc">
276 <li class="tocline4"><a href="#attribute-representation">6.3.1. Represen tation of attributes and attributes values</a>
277 <li><a href="#attribute-substrings">6.3.2. Substring matching attribute selectors</a>
278 <li class="tocline4"><a href="#attrnmsp">6.3.3. Attribute selectors and namespaces</a>
279 <li class="tocline4"><a href="#def-values">6.3.4. Default attribute valu es in DTDs</a></li>
280 </ul>
281 <li class="tocline3"><a href="#class-html">6.4. Class selectors</a>
282 <li class="tocline3"><a href="#id-selectors">6.5. ID selectors</a>
283 <li class="tocline3"><a href="#pseudo-classes">6.6. Pseudo-classes</a>
284 <ul class="toc">
285 <li class="tocline4"><a href="#dynamic-pseudos">6.6.1. Dynamic pseudo-cl asses</a>
286 <li class="tocline4"><a href="#target-pseudo">6.6.2. The :target pseudo- class</a>
287 <li class="tocline4"><a href="#lang-pseudo">6.6.3. The :lang() pseudo-cl ass</a>
288 <li class="tocline4"><a href="#UIstates">6.6.4. UI element states pseudo -classes</a>
289 <li class="tocline4"><a href="#structural-pseudos">6.6.5. Structural pse udo-classes</a>
290 <ul>
291 <li><a href="#root-pseudo">:root pseudo-class</a>
292 <li><a href="#nth-child-pseudo">:nth-child() pseudo-class</a>
293 <li><a href="#nth-last-child-pseudo">:nth-last-child()</a>
294 <li><a href="#nth-of-type-pseudo">:nth-of-type() pseudo-class</a>
295 <li><a href="#nth-last-of-type-pseudo">:nth-last-of-type()</a>
296 <li><a href="#first-child-pseudo">:first-child pseudo-class</a>
297 <li><a href="#last-child-pseudo">:last-child pseudo-class</a>
298 <li><a href="#first-of-type-pseudo">:first-of-type pseudo-class</a>
299 <li><a href="#last-of-type-pseudo">:last-of-type pseudo-class</a>
300 <li><a href="#only-child-pseudo">:only-child pseudo-class</a>
301 <li><a href="#only-of-type-pseudo">:only-of-type pseudo-class</a>
302 <li><a href="#empty-pseudo">:empty pseudo-class</a></li>
303 </ul>
304 <li class="tocline4"><a href="#negation">6.6.7. The negation pseudo-clas s</a></li>
305 </ul>
306 </li>
307 </ul>
308 <li><a href="#pseudo-elements">7. Pseudo-elements</a>
309 <ul>
310 <li><a href="#first-line">7.1. The ::first-line pseudo-element</a>
311 <li><a href="#first-letter">7.2. The ::first-letter pseudo-element</a>
312 <li><a href="#UIfragments">7.3. The ::selection pseudo-element</a>
313 <li><a href="#gen-content">7.4. The ::before and ::after pseudo-elements</ a></li>
314 </ul>
315 <li class="tocline2"><a href="#combinators">8. Combinators</a>
316 <ul class="toc">
317 <li class="tocline3"><a href="#descendant-combinators">8.1. Descendant com binators</a>
318 <li class="tocline3"><a href="#child-combinators">8.2. Child combinators</ a>
319 <li class="tocline3"><a href="#sibling-combinators">8.3. Sibling combinato rs</a>
320 <ul class="toc">
321 <li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adja cent sibling combinator</a>
322 <li class="tocline4"><a href="#general-sibling-combinators">8.3.2. Gener al sibling combinator</a></li>
323 </ul>
324 </li>
325 </ul>
326 <li class="tocline2"><a href="#specificity">9. Calculating a selector's spec ificity</a>
327 <li class="tocline2"><a href="#w3cselgrammar">10. The grammar of Selectors</ a>
328 <ul class="toc">
329 <li class="tocline3"><a href="#grammar">10.1. Grammar</a>
330 <li class="tocline3"><a href="#lex">10.2. Lexical scanner</a></li>
331 </ul>
332 <li class="tocline2"><a href="#downlevel">11. Namespaces and down-level clie nts</a>
333 <li class="tocline2"><a href="#profiling">12. Profiles</a>
334 <li><a href="#Conformance">13. Conformance and requirements</a>
335 <li><a href="#Tests">14. Tests</a>
336 <li><a href="#ACKS">15. Acknowledgements</a>
337 <li class="tocline2"><a href="#references">16. References</a>
338 </ul>
339
340 </div>
341
342 <h2 id="testA10"><a name=context>1. Introduction</a></h2>
343
344 <h3><a name=dependencies></a>1.1. Dependencies</h3>
345
346 <p>Some features of this specification are specific to CSS, or have
347 particular limitations or rules specific to CSS. In this
348 specification, these have been described in terms of CSS2.1. <a
349 href="#refsCSS21">[CSS21]</a></p>
350
351 <h3><a name=terminology></a>1.2. Terminology</h3>
352
353 <p>All of the text of this specification is normative except
354 examples, notes, and sections explicitly marked as
355 non-normative.</p>
356
357 <h3><a name=changesFromCSS2></a>1.3. Changes from CSS2</h3>
358
359 <p><em>This section is non-normative.</em></p>
360
361 <p>The main differences between the selectors in CSS2 and those in
362 Selectors are:
363
364 <ul>
365
366 <li>the list of basic definitions (selector, group of selectors,
367 simple selector, etc.) has been changed; in particular, what was
368 referred to in CSS2 as a simple selector is now called a sequence
369 of simple selectors, and the term "simple selector" is now used for
370 the components of this sequence</li>
371
372 <li>an optional namespace component is now allowed in type element
373 selectors, the universal selector and attribute selectors</li>
374
375 <li>a <a href="#general-sibling-combinators">new combinator</a> has been intr oduced</li>
376
377 <li>new simple selectors including substring matching attribute
378 selectors, and new pseudo-classes</li>
379
380 <li>new pseudo-elements, and introduction of the "::" convention
381 for pseudo-elements</li>
382
383 <li>the grammar has been rewritten</li>
384
385 <li>profiles to be added to specifications integrating Selectors
386 and defining the set of selectors which is actually supported by
387 each specification</li>
388
389 <li>Selectors are now a CSS3 Module and an independent
390 specification; other specifications can now refer to this document
391 independently of CSS</li>
392
393 <li>the specification now has its own test suite</li>
394
395 </ul>
396
397 <h2 id="testB10"><a name=selectors></a>2. Selectors</h2>
398
399 <p><em>This section is non-normative, as it merely summarizes the
400 following sections.</em></p>
401
402 <p>A Selector represents a structure. This structure can be used as a
403 condition (e.g. in a CSS rule) that determines which elements a
404 selector matches in the document tree, or as a flat description of the
405 HTML or XML fragment corresponding to that structure.</p>
406
407 <p>Selectors may range from simple element names to rich contextual
408 representations.</p>
409
410 <p>The following table summarizes the Selector syntax:</p>
411
412 <table class="selectorsReview">
413 <thead>
414 <tr>
415 <th class="pattern">Pattern</th>
416 <th class="meaning">Meaning</th>
417 <th class="described">Described in section</th>
418 <th class="origin">First defined in CSS level</th></tr>
419 <tbody>
420 <tr>
421 <td class="pattern">*</td>
422 <td class="meaning">any element</td>
423 <td class="described"><a
424 href="#universal-selector">Universal
425 selector</a></td>
426 <td class="origin">2</td></tr>
427 <tr>
428 <td class="pattern">E</td>
429 <td class="meaning">an element of type E</td>
430 <td class="described"><a
431 href="#type-selectors">Type selector</a></td>
432 <td class="origin">1</td></tr>
433 <tr>
434 <td class="pattern">E[foo]</td>
435 <td class="meaning">an E element with a "foo" attribute</td>
436 <td class="described"><a
437 href="#attribute-selectors">Attribute
438 selectors</a></td>
439 <td class="origin">2</td></tr>
440 <tr>
441 <td class="pattern">E[foo="bar"]</td>
442 <td class="meaning">an E element whose "foo" attribute value is exactly
443 equal to "bar"</td>
444 <td class="described"><a
445 href="#attribute-selectors">Attribute
446 selectors</a></td>
447 <td class="origin">2</td></tr>
448 <tr>
449 <td class="pattern">E[foo~="bar"]</td>
450 <td class="meaning">an E element whose "foo" attribute value is a list of
451 space-separated values, one of which is exactly equal to "bar"</td>
452 <td class="described"><a
453 href="#attribute-selectors">Attribute
454 selectors</a></td>
455 <td class="origin">2</td></tr>
456 <tr>
457 <td class="pattern">E[foo^="bar"]</td>
458 <td class="meaning">an E element whose "foo" attribute value begins exactly
459 with the string "bar"</td>
460 <td class="described"><a
461 href="#attribute-selectors">Attribute
462 selectors</a></td>
463 <td class="origin">3</td></tr>
464 <tr>
465 <td class="pattern">E[foo$="bar"]</td>
466 <td class="meaning">an E element whose "foo" attribute value ends exactly
467 with the string "bar"</td>
468 <td class="described"><a
469 href="#attribute-selectors">Attribute
470 selectors</a></td>
471 <td class="origin">3</td></tr>
472 <tr>
473 <td class="pattern">E[foo*="bar"]</td>
474 <td class="meaning">an E element whose "foo" attribute value contains the
475 substring "bar"</td>
476 <td class="described"><a
477 href="#attribute-selectors">Attribute
478 selectors</a></td>
479 <td class="origin">3</td></tr>
480 <tr>
481 <td class="pattern">E[hreflang|="en"]</td>
482 <td class="meaning">an E element whose "hreflang" attribute has a hyphen-sep arated
483 list of values beginning (from the left) with "en"</td>
484 <td class="described"><a
485 href="#attribute-selectors">Attribute
486 selectors</a></td>
487 <td class="origin">2</td></tr>
488 <tr>
489 <td class="pattern">E:root</td>
490 <td class="meaning">an E element, root of the document</td>
491 <td class="described"><a
492 href="#structural-pseudos">Structural
493 pseudo-classes</a></td>
494 <td class="origin">3</td></tr>
495 <tr>
496 <td class="pattern">E:nth-child(n)</td>
497 <td class="meaning">an E element, the n-th child of its parent</td>
498 <td class="described"><a
499 href="#structural-pseudos">Structural
500 pseudo-classes</a></td>
501 <td class="origin">3</td></tr>
502 <tr>
503 <td class="pattern">E:nth-last-child(n)</td>
504 <td class="meaning">an E element, the n-th child of its parent, counting
505 from the last one</td>
506 <td class="described"><a
507 href="#structural-pseudos">Structural
508 pseudo-classes</a></td>
509 <td class="origin">3</td></tr>
510 <tr>
511 <td class="pattern">E:nth-of-type(n)</td>
512 <td class="meaning">an E element, the n-th sibling of its type</td>
513 <td class="described"><a
514 href="#structural-pseudos">Structural
515 pseudo-classes</a></td>
516 <td class="origin">3</td></tr>
517 <tr>
518 <td class="pattern">E:nth-last-of-type(n)</td>
519 <td class="meaning">an E element, the n-th sibling of its type, counting
520 from the last one</td>
521 <td class="described"><a
522 href="#structural-pseudos">Structural
523 pseudo-classes</a></td>
524 <td class="origin">3</td></tr>
525 <tr>
526 <td class="pattern">E:first-child</td>
527 <td class="meaning">an E element, first child of its parent</td>
528 <td class="described"><a
529 href="#structural-pseudos">Structural
530 pseudo-classes</a></td>
531 <td class="origin">2</td></tr>
532 <tr>
533 <td class="pattern">E:last-child</td>
534 <td class="meaning">an E element, last child of its parent</td>
535 <td class="described"><a
536 href="#structural-pseudos">Structural
537 pseudo-classes</a></td>
538 <td class="origin">3</td></tr>
539 <tr>
540 <td class="pattern">E:first-of-type</td>
541 <td class="meaning">an E element, first sibling of its type</td>
542 <td class="described"><a
543 href="#structural-pseudos">Structural
544 pseudo-classes</a></td>
545 <td class="origin">3</td></tr>
546 <tr>
547 <td class="pattern">E:last-of-type</td>
548 <td class="meaning">an E element, last sibling of its type</td>
549 <td class="described"><a
550 href="#structural-pseudos">Structural
551 pseudo-classes</a></td>
552 <td class="origin">3</td></tr>
553 <tr>
554 <td class="pattern">E:only-child</td>
555 <td class="meaning">an E element, only child of its parent</td>
556 <td class="described"><a
557 href="#structural-pseudos">Structural
558 pseudo-classes</a></td>
559 <td class="origin">3</td></tr>
560 <tr>
561 <td class="pattern">E:only-of-type</td>
562 <td class="meaning">an E element, only sibling of its type</td>
563 <td class="described"><a
564 href="#structural-pseudos">Structural
565 pseudo-classes</a></td>
566 <td class="origin">3</td></tr>
567 <tr>
568 <td class="pattern">E:empty</td>
569 <td class="meaning">an E element that has no children (including text
570 nodes)</td>
571 <td class="described"><a
572 href="#structural-pseudos">Structural
573 pseudo-classes</a></td>
574 <td class="origin">3</td></tr>
575 <tr>
576 <td class="pattern">E:link<br>E:visited</td>
577 <td class="meaning">an E element being the source anchor of a hyperlink of
578 which the target is not yet visited (:link) or already visited
579 (:visited)</td>
580 <td class="described"><a
581 href="#link">The link
582 pseudo-classes</a></td>
583 <td class="origin">1</td></tr>
584 <tr>
585 <td class="pattern">E:active<br>E:hover<br>E:focus</td>
586 <td class="meaning">an E element during certain user actions</td>
587 <td class="described"><a
588 href="#useraction-pseudos">The user
589 action pseudo-classes</a></td>
590 <td class="origin">1 and 2</td></tr>
591 <tr>
592 <td class="pattern">E:target</td>
593 <td class="meaning">an E element being the target of the referring URI</td>
594 <td class="described"><a
595 href="#target-pseudo">The target
596 pseudo-class</a></td>
597 <td class="origin">3</td></tr>
598 <tr>
599 <td class="pattern">E:lang(fr)</td>
600 <td class="meaning">an element of type E in language "fr" (the document
601 language specifies how language is determined)</td>
602 <td class="described"><a
603 href="#lang-pseudo">The :lang()
604 pseudo-class</a></td>
605 <td class="origin">2</td></tr>
606 <tr>
607 <td class="pattern">E:enabled<br>E:disabled</td>
608 <td class="meaning">a user interface element E which is enabled or
609 disabled</td>
610 <td class="described"><a
611 href="#UIstates">The UI element states
612 pseudo-classes</a></td>
613 <td class="origin">3</td></tr>
614 <tr>
615 <td class="pattern">E:checked<!--<br>E:indeterminate--></td>
616 <td class="meaning">a user interface element E which is checked<!-- or in an
617 indeterminate state--> (for instance a radio-button or checkbox)</td>
618 <td class="described"><a
619 href="#UIstates">The UI element states
620 pseudo-classes</a></td>
621 <td class="origin">3</td></tr>
622 <tr>
623 <td class="pattern">E::first-line</td>
624 <td class="meaning">the first formatted line of an E element</td>
625 <td class="described"><a
626 href="#first-line">The ::first-line
627 pseudo-element</a></td>
628 <td class="origin">1</td></tr>
629 <tr>
630 <td class="pattern">E::first-letter</td>
631 <td class="meaning">the first formatted letter of an E element</td>
632 <td class="described"><a
633 href="#first-letter">The ::first-letter
634 pseudo-element</a></td>
635 <td class="origin">1</td></tr>
636 <tr>
637 <td class="pattern">E::selection</td>
638 <td class="meaning">the portion of an E element that is currently
639 selected/highlighted by the user</td>
640 <td class="described"><a
641 href="#UIfragments">The UI element
642 fragments pseudo-elements</a></td>
643 <td class="origin">3</td></tr>
644 <tr>
645 <td class="pattern">E::before</td>
646 <td class="meaning">generated content before an E element</td>
647 <td class="described"><a
648 href="#gen-content">The ::before
649 pseudo-element</a></td>
650 <td class="origin">2</td></tr>
651 <tr>
652 <td class="pattern">E::after</td>
653 <td class="meaning">generated content after an E element</td>
654 <td class="described"><a
655 href="#gen-content">The ::after
656 pseudo-element</a></td>
657 <td class="origin">2</td></tr>
658 <tr>
659 <td class="pattern">E.warning</td>
660 <td class="meaning">an E element whose class is
661 "warning" (the document language specifies how class is determined).</td>
662 <td class="described"><a
663 href="#class-html">Class
664 selectors</a></td>
665 <td class="origin">1</td></tr>
666 <tr>
667 <td class="pattern">E#myid</td>
668 <td class="meaning">an E element with ID equal to "myid".</td>
669 <td class="described"><a
670 href="#id-selectors">ID
671 selectors</a></td>
672 <td class="origin">1</td></tr>
673 <tr>
674 <td class="pattern">E:not(s)</td>
675 <td class="meaning">an E element that does not match simple selector s</td>
676 <td class="described"><a
677 href="#negation">Negation
678 pseudo-class</a></td>
679 <td class="origin">3</td></tr>
680 <tr>
681 <td class="pattern">E F</td>
682 <td class="meaning">an F element descendant of an E element</td>
683 <td class="described"><a
684 href="#descendant-combinators">Descendant
685 combinator</a></td>
686 <td class="origin">1</td></tr>
687 <tr>
688 <td class="pattern">E &gt; F</td>
689 <td class="meaning">an F element child of an E element</td>
690 <td class="described"><a
691 href="#child-combinators">Child
692 combinator</a></td>
693 <td class="origin">2</td></tr>
694 <tr>
695 <td class="pattern">E + F</td>
696 <td class="meaning">an F element immediately preceded by an E element</td>
697 <td class="described"><a
698 href="#adjacent-sibling-combinators">Adjacent sibling combinator</a></td>
699 <td class="origin">2</td></tr>
700 <tr>
701 <td class="pattern">E ~ F</td>
702 <td class="meaning">an F element preceded by an E element</td>
703 <td class="described"><a
704 href="#general-sibling-combinators">General sibling combinator</a></td>
705 <td class="origin">3</td></tr></tbody></table>
706
707 <p>The meaning of each selector is derived from the table above by
708 prepending "matches" to the contents of each cell in the "Meaning"
709 column.</p>
710
711 <h2 id="testC10"><a name=casesens>3. Case sensitivity</a></h2>
712
713 <p>The case sensitivity of document language element names, attribute
714 names, and attribute values in selectors depends on the document
715 language. For example, in HTML, element names are case-insensitive,
716 but in XML, they are case-sensitive.</p>
717
718 <h2 id="testD10"><a name=selector-syntax>4. Selector syntax</a></h2>
719
720 <p>A <dfn><a name=selector>selector</a></dfn> is a chain of one
721 or more <a href="#sequence">sequences of simple selectors</a>
722 separated by <a href="#combinators">combinators</a>.</p>
723
724 <p>A <dfn><a name=sequence>sequence of simple selectors</a></dfn>
725 is a chain of <a href="#simple-selectors-dfn">simple selectors</a>
726 that are not separated by a <a href="#combinators">combinator</a>. It
727 always begins with a <a href="#type-selectors">type selector</a> or a
728 <a href="#universal-selector">universal selector</a>. No other type
729 selector or universal selector is allowed in the sequence.</p>
730
731 <p>A <dfn><a name=simple-selectors-dfn></a><a
732 href="#simple-selectors">simple selector</a></dfn> is either a <a
733 href="#type-selectors">type selector</a>, <a
734 href="#universal-selector">universal selector</a>, <a
735 href="#attribute-selectors">attribute selector</a>, <a
736 href="#class-html">class selector</a>, <a
737 href="#id-selectors">ID selector</a>, <a
738 href="#content-selectors">content selector</a>, or <a
739 href="#pseudo-classes">pseudo-class</a>. One <a
740 href="#pseudo-elements">pseudo-element</a> may be appended to the last
741 sequence of simple selectors.</p>
742
743 <p><dfn>Combinators</dfn> are: white space, &quot;greater-than
744 sign&quot; (U+003E, <code>&gt;</code>), &quot;plus sign&quot; (U+002B,
745 <code>+</code>) and &quot;tilde&quot; (U+007E, <code>~</code>). White
746 space may appear between a combinator and the simple selectors around
747 it. <a name=whitespace></a>Only the characters "space" (U+0020), "tab"
748 (U+0009), "line feed" (U+000A), "carriage return" (U+000D), and "form
749 feed" (U+000C) can occur in white space. Other space-like characters,
750 such as "em-space" (U+2003) and "ideographic space" (U+3000), are
751 never part of white space.</p>
752
753 <p>The elements of a document tree that are represented by a selector
754 are the <dfn><a name=subject></a>subjects of the selector</dfn>. A
755 selector consisting of a single sequence of simple selectors
756 represents any element satisfying its requirements. Prepending another
757 sequence of simple selectors and a combinator to a sequence imposes
758 additional matching constraints, so the subjects of a selector are
759 always a subset of the elements represented by the last sequence of
760 simple selectors.</p>
761
762 <p>An empty selector, containing no sequence of simple selectors and
763 no pseudo-element, is an <a href="#Conformance">invalid
764 selector</a>.</p>
765
766 <h2 id="testE10"><a name=grouping>5. Groups of selectors</a></h2>
767
768 <p>When several selectors share the same declarations, they may be
769 grouped into a comma-separated list. (A comma is U+002C.)</p>
770
771 <div class="example">
772 <p>CSS examples:</p>
773 <p>In this example, we condense three rules with identical
774 declarations into one. Thus,</p>
775 <pre>h1 { font-family: sans-serif }
776 h2 { font-family: sans-serif }
777 h3 { font-family: sans-serif }</pre>
778 <p>is equivalent to:</p>
779 <pre>h1, h2, h3 { font-family: sans-serif }</pre>
780 </div>
781
782 <p><strong>Warning</strong>: the equivalence is true in this example
783 because all the selectors are valid selectors. If just one of these
784 selectors were invalid, the entire group of selectors would be
785 invalid. This would invalidate the rule for all three heading
786 elements, whereas in the former case only one of the three individual
787 heading rules would be invalidated.</p>
788
789
790 <h2><a name=simple-selectors>6. Simple selectors</a></h2>
791
792 <h3><a name=type-selectors>6.1. Type selector</a></h3>
793
794 <p>A <dfn>type selector</dfn> is the name of a document language
795 element type. A type selector represents an instance of the element
796 type in the document tree.</p>
797
798 <div class="example">
799 <p>Example:</p>
800 <p>The following selector represents an <code>h1</code> element in the document tree:</p>
801 <pre>h1</pre>
802 </div>
803
804
805 <h4><a name=typenmsp>6.1.1. Type selectors and namespaces</a></h4>
806
807 <p>Type selectors allow an optional namespace (<a
808 href="#refsXMLNAMES">[XMLNAMES]</a>) component. A namespace prefix
809 that has been previously declared may be prepended to the element name
810 separated by the namespace separator &quot;vertical bar&quot;
811 (U+007C, <code>|</code>).</p>
812
813 <p>The namespace component may be left empty to indicate that the
814 selector is only to represent elements with no declared namespace.</p>
815
816 <p>An asterisk may be used for the namespace prefix, indicating that
817 the selector represents elements in any namespace (including elements
818 with no namespace).</p>
819
820 <p>Element type selectors that have no namespace component (no
821 namespace separator), represent elements without regard to the
822 element's namespace (equivalent to "<code>*|</code>") unless a default
823 namespace has been declared. If a default namespace has been declared,
824 the selector will represent only elements in the default
825 namespace.</p>
826
827 <p>A type selector containing a namespace prefix that has not been
828 previously declared is an <a href="#Conformance">invalid</a> selector.
829 The mechanism for declaring a namespace prefix is left up to the
830 language implementing Selectors. In CSS, such a mechanism is defined
831 in the General Syntax module.</p>
832
833 <p>In a namespace-aware client, element type selectors will only match
834 against the <a
835 href="http://www.w3.org/TR/REC-xml-names/#NT-LocalPart">local part</a>
836 of the element's <a
837 href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">qualified
838 name</a>. See <a href="#downlevel">below</a> for notes about matching
839 behaviors in down-level clients.</p>
840
841 <p>In summary:</p>
842
843 <dl>
844 <dt><code>ns|E</code></dt>
845 <dd>elements with name E in namespace ns</dd>
846 <dt><code>*|E</code></dt>
847 <dd>elements with name E in any namespace, including those without any
848 declared namespace</dd>
849 <dt><code>|E</code></dt>
850 <dd>elements with name E without any declared namespace</dd>
851 <dt><code>E</code></dt>
852 <dd>if no default namespace has been specified, this is equivalent to *|E.
853 Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
854 </dl>
855
856 <div class="example">
857 <p>CSS examples:</p>
858
859 <pre>@namespace foo url(http://www.example.com);
860 foo|h1 { color: blue }
861 foo|* { color: yellow }
862 |h1 { color: red }
863 *|h1 { color: green }
864 h1 { color: green }</pre>
865
866 <p>The first rule will match only <code>h1</code> elements in the
867 "http://www.example.com" namespace.</p>
868
869 <p>The second rule will match all elements in the
870 "http://www.example.com" namespace.</p>
871
872 <p>The third rule will match only <code>h1</code> elements without
873 any declared namespace.</p>
874
875 <p>The fourth rule will match <code>h1</code> elements in any
876 namespace (including those without any declared namespace).</p>
877
878 <p>The last rule is equivalent to the fourth rule because no default
879 namespace has been defined.</p>
880
881 </div>
882
883 <h3><a name=universal-selector>6.2. Universal selector</a> </h3>
884
885 <p>The <dfn>universal selector</dfn>, written &quot;asterisk&quot;
886 (<code>*</code>), represents the qualified name of any element
887 type. It represents any single element in the document tree in any
888 namespace (including those without any declared namespace) if no
889 default namespace has been specified. If a default namespace has been
890 specified, see <a href="#univnmsp">Universal selector and
891 Namespaces</a> below.</p>
892
893 <p>If the universal selector is not the only component of a sequence
894 of simple selectors, the <code>*</code> may be omitted.</p>
895
896 <div class="example">
897 <p>Examples:</p>
898 <ul>
899 <li><code>*[hreflang|=en]</code> and <code>[hreflang|=en]</code> are equivalen t,</li>
900 <li><code>*.warning</code> and <code>.warning</code> are equivalent,</li>
901 <li><code>*#myid</code> and <code>#myid</code> are equivalent.</li>
902 </ul>
903 </div>
904
905 <p class="note"><strong>Note:</strong> it is recommended that the
906 <code>*</code>, representing the universal selector, not be
907 omitted.</p>
908
909 <h4><a name=univnmsp>6.2.1. Universal selector and namespaces</a></h4>
910
911 <p>The universal selector allows an optional namespace component. It
912 is used as follows:</p>
913
914 <dl>
915 <dt><code>ns|*</code></dt>
916 <dd>all elements in namespace ns</dd>
917 <dt><code>*|*</code></dt>
918 <dd>all elements</dd>
919 <dt><code>|*</code></dt>
920 <dd>all elements without any declared namespace</dd>
921 <dt><code>*</code></dt>
922 <dd>if no default namespace has been specified, this is equivalent to *|*.
923 Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
924 </dl>
925
926 <p>A universal selector containing a namespace prefix that has not
927 been previously declared is an <a href="#Conformance">invalid</a>
928 selector. The mechanism for declaring a namespace prefix is left up
929 to the language implementing Selectors. In CSS, such a mechanism is
930 defined in the General Syntax module.</p>
931
932
933 <h3><a name=attribute-selectors>6.3. Attribute selectors</a></h3>
934
935 <p>Selectors allow the representation of an element's attributes. When
936 a selector is used as an expression to match against an element,
937 attribute selectors must be considered to match an element if that
938 element has an attribute that matches the attribute represented by the
939 attribute selector.</p>
940
941 <h4><a name=attribute-representation>6.3.1. Attribute presence and values
942 selectors</a></h4>
943
944 <p>CSS2 introduced four attribute selectors:</p>
945
946 <dl>
947 <dt><code>[att]</code>
948 <dd>Represents an element with the <code>att</code> attribute, whatever the va lue of
949 the attribute.</dd>
950 <dt><code>[att=val]</code></dt>
951 <dd>Represents an element with the <code>att</code> attribute whose value is e xactly
952 "val".</dd>
953 <dt><code>[att~=val]</code></dt>
954 <dd>Represents an element with the <code>att</code> attribute whose value is a <a
955 href="#whitespace">whitespace</a>-separated list of words, one of
956 which is exactly "val". If "val" contains whitespace, it will never
957 represent anything (since the words are <em>separated</em> by
958 spaces).</dd>
959 <dt><code>[att|=val]</code>
960 <dd>Represents an element with the <code>att</code> attribute, its value eithe r
961 being exactly "val" or beginning with "val" immediately followed by
962 "-" (U+002D). This is primarily intended to allow language subcode
963 matches (e.g., the <code>hreflang</code> attribute on the
964 <code>link</code> element in HTML) as described in RFC 3066 (<a
965 href="#refsRFC3066">[RFC3066]</a>). For <code>lang</code> (or
966 <code>xml:lang</code>) language subcode matching, please see <a
967 href="#lang-pseudo">the <code>:lang</code> pseudo-class</a>.</dd>
968 </dl>
969
970 <p>Attribute values must be identifiers or strings. The
971 case-sensitivity of attribute names and values in selectors depends on
972 the document language.</p>
973
974 <div class="example">
975
976 <p>Examples:</p>
977
978 <p>The following attribute selector represents an <code>h1</code>
979 element that carries the <code>title</code> attribute, whatever its
980 value:</p>
981
982 <pre>h1[title]</pre>
983
984 <p>In the following example, the selector represents a
985 <code>span</code> element whose <code>class</code> attribute has
986 exactly the value "example":</p>
987
988 <pre>span[class="example"]</pre>
989
990 <p>Multiple attribute selectors can be used to represent several
991 attributes of an element, or several conditions on the same
992 attribute. Here, the selector represents a <code>span</code> element
993 whose <code>hello</code> attribute has exactly the value "Cleveland"
994 and whose <code>goodbye</code> attribute has exactly the value
995 "Columbus":</p>
996
997 <pre>span[hello="Cleveland"][goodbye="Columbus"]</pre>
998
999 <p>The following selectors illustrate the differences between "="
1000 and "~=". The first selector will represent, for example, the value
1001 "copyright copyleft copyeditor" on a <code>rel</code> attribute. The
1002 second selector will only represent an <code>a</code> element with
1003 an <code>href</code> attribute having the exact value
1004 "http://www.w3.org/".</p>
1005
1006 <pre>a[rel~="copyright"]
1007 a[href="http://www.w3.org/"]</pre>
1008
1009 <p>The following selector represents a <code>link</code> element
1010 whose <code>hreflang</code> attribute is exactly "fr".</p>
1011
1012 <pre>link[hreflang=fr]</pre>
1013
1014 <p>The following selector represents a <code>link</code> element for
1015 which the values of the <code>hreflang</code> attribute begins with
1016 "en", including "en", "en-US", and "en-cockney":</p>
1017
1018 <pre>link[hreflang|="en"]</pre>
1019
1020 <p>Similarly, the following selectors represents a
1021 <code>DIALOGUE</code> element whenever it has one of two different
1022 values for an attribute <code>character</code>:</p>
1023
1024 <pre>DIALOGUE[character=romeo]
1025 DIALOGUE[character=juliet]</pre>
1026
1027 </div>
1028
1029 <h4><a name=attribute-substrings></a>6.3.2. Substring matching attribute
1030 selectors</h4>
1031
1032 <p>Three additional attribute selectors are provided for matching
1033 substrings in the value of an attribute:</p>
1034
1035 <dl>
1036 <dt><code>[att^=val]</code></dt>
1037 <dd>Represents an element with the <code>att</code> attribute whose value begi ns
1038 with the prefix "val".</dd>
1039 <dt><code>[att$=val]</code>
1040 <dd>Represents an element with the <code>att</code> attribute whose value ends with
1041 the suffix "val".</dd>
1042 <dt><code>[att*=val]</code>
1043 <dd>Represents an element with the <code>att</code> attribute whose value cont ains
1044 at least one instance of the substring "val".</dd>
1045 </dl>
1046
1047 <p>Attribute values must be identifiers or strings. The
1048 case-sensitivity of attribute names in selectors depends on the
1049 document language.</p>
1050
1051 <div class="example">
1052 <p>Examples:</p>
1053 <p>The following selector represents an HTML <code>object</code>, referencing a n
1054 image:</p>
1055 <pre>object[type^="image/"]</pre>
1056 <p>The following selector represents an HTML anchor <code>a</code> with an
1057 <code>href</code> attribute whose value ends with ".html".</p>
1058 <pre>a[href$=".html"]</pre>
1059 <p>The following selector represents an HTML paragraph with a <code>title</code >
1060 attribute whose value contains the substring "hello"</p>
1061 <pre>p[title*="hello"]</pre>
1062 </div>
1063
1064 <h4><a name=attrnmsp>6.3.3. Attribute selectors and namespaces</a></h4>
1065
1066 <p>Attribute selectors allow an optional namespace component to the
1067 attribute name. A namespace prefix that has been previously declared
1068 may be prepended to the attribute name separated by the namespace
1069 separator &quot;vertical bar&quot; (<code>|</code>). In keeping with
1070 the Namespaces in the XML recommendation, default namespaces do not
1071 apply to attributes, therefore attribute selectors without a namespace
1072 component apply only to attributes that have no declared namespace
1073 (equivalent to "<code>|attr</code>"). An asterisk may be used for the
1074 namespace prefix indicating that the selector is to match all
1075 attribute names without regard to the attribute's namespace.
1076
1077 <p>An attribute selector with an attribute name containing a namespace
1078 prefix that has not been previously declared is an <a
1079 href="#Conformance">invalid</a> selector. The mechanism for declaring
1080 a namespace prefix is left up to the language implementing Selectors.
1081 In CSS, such a mechanism is defined in the General Syntax module.
1082
1083 <div class="example">
1084 <p>CSS examples:</p>
1085 <pre>@namespace foo "http://www.example.com";
1086 [foo|att=val] { color: blue }
1087 [*|att] { color: yellow }
1088 [|att] { color: green }
1089 [att] { color: green }</pre>
1090
1091 <p>The first rule will match only elements with the attribute
1092 <code>att</code> in the "http://www.example.com" namespace with the
1093 value "val".</p>
1094
1095 <p>The second rule will match only elements with the attribute
1096 <code>att</code> regardless of the namespace of the attribute
1097 (including no declared namespace).</p>
1098
1099 <p>The last two rules are equivalent and will match only elements
1100 with the attribute <code>att</code> where the attribute is not
1101 declared to be in a namespace.</p>
1102
1103 </div>
1104
1105 <h4><a name=def-values>6.3.4. Default attribute values in DTDs</a></h4>
1106
1107 <p>Attribute selectors represent explicitly set attribute values in
1108 the document tree. Default attribute values may be defined in a DTD or
1109 elsewhere, but cannot always be selected by attribute
1110 selectors. Selectors should be designed so that they work even if the
1111 default values are not included in the document tree.</p>
1112
1113 <p>More precisely, a UA is <em>not</em> required to read an "external
1114 subset" of the DTD but <em>is</em> required to look for default
1115 attribute values in the document's "internal subset." (See <a
1116 href="#refsXML10">[XML10]</a> for definitions of these subsets.)</p>
1117
1118 <p>A UA that recognizes an XML namespace <a
1119 href="#refsXMLNAMES">[XMLNAMES]</a> is not required to use its
1120 knowledge of that namespace to treat default attribute values as if
1121 they were present in the document. (For example, an XHTML UA is not
1122 required to use its built-in knowledge of the XHTML DTD.)</p>
1123
1124 <p class="note"><strong>Note:</strong> Typically, implementations
1125 choose to ignore external subsets.</p>
1126
1127 <div class="example">
1128 <p>Example:</p>
1129
1130 <p>Consider an element EXAMPLE with an attribute "notation" that has a
1131 default value of "decimal". The DTD fragment might be</p>
1132
1133 <pre class="dtd-example">&lt;!ATTLIST EXAMPLE notation (decimal,octal) "decimal" ></pre>
1134
1135 <p>If the style sheet contains the rules</p>
1136
1137 <pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
1138 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1139
1140 <p>the first rule will not match elements whose "notation" attribute
1141 is set by default, i.e. not set explicitly. To catch all cases, the
1142 attribute selector for the default value must be dropped:</p>
1143
1144 <pre>EXAMPLE { /*... default property settings ...*/ }
1145 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1146
1147 <p>Here, because the selector <code>EXAMPLE[notation=octal]</code> is
1148 more specific than the tag
1149 selector alone, the style declarations in the second rule will override
1150 those in the first for elements that have a "notation" attribute value
1151 of "octal". Care has to be taken that all property declarations that
1152 are to apply only to the default case are overridden in the non-default
1153 cases' style rules.</p>
1154
1155 </div>
1156
1157 <h3><a name=class-html>6.4. Class selectors</a></h3>
1158
1159 <p>Working with HTML, authors may use the period (U+002E,
1160 <code>.</code>) notation as an alternative to the <code>~=</code>
1161 notation when representing the <code>class</code> attribute. Thus, for
1162 HTML, <code>div.value</code> and <code>div[class~=value]</code> have
1163 the same meaning. The attribute value must immediately follow the
1164 &quot;period&quot; (<code>.</code>).</p>
1165
1166 <p>UAs may apply selectors using the period (.) notation in XML
1167 documents if the UA has namespace-specific knowledge that allows it to
1168 determine which attribute is the &quot;class&quot; attribute for the
1169 respective namespace. One such example of namespace-specific knowledge
1170 is the prose in the specification for a particular namespace (e.g. SVG
1171 1.0 <a href="#refsSVG">[SVG]</a> describes the <a
1172 href="http://www.w3.org/TR/2001/PR-SVG-20010719/styling.html#ClassAttribute">SVG
1173 &quot;class&quot; attribute</a> and how a UA should interpret it, and
1174 similarly MathML 1.01 <a href="#refsMATH">[MATH]</a> describes the <a
1175 href="http://www.w3.org/1999/07/REC-MathML-19990707/chapter2.html#sec2.3.4">Math ML
1176 &quot;class&quot; attribute</a>.)</p>
1177
1178 <div class="example">
1179 <p>CSS examples:</p>
1180
1181 <p>We can assign style information to all elements with
1182 <code>class~="pastoral"</code> as follows:</p>
1183
1184 <pre>*.pastoral { color: green } /* all elements with class~=pastoral */</pre >
1185
1186 <p>or just</p>
1187
1188 <pre>.pastoral { color: green } /* all elements with class~=pastoral */</pre>
1189
1190 <p>The following assigns style only to H1 elements with
1191 <code>class~="pastoral"</code>:</p>
1192
1193 <pre>H1.pastoral { color: green } /* H1 elements with class~=pastoral */</pre >
1194
1195 <p>Given these rules, the first H1 instance below would not have
1196 green text, while the second would:</p>
1197
1198 <pre>&lt;H1&gt;Not green&lt;/H1&gt;
1199 &lt;H1 class="pastoral"&gt;Very green&lt;/H1&gt;</pre>
1200
1201 </div>
1202
1203 <p>To represent a subset of "class" values, each value must be preceded
1204 by a ".", in any order.</P>
1205
1206 <div class="example">
1207
1208 <p>CSS example:</p>
1209
1210 <p>The following rule matches any P element whose "class" attribute
1211 has been assigned a list of <a
1212 href="#whitespace">whitespace</a>-separated values that includes
1213 "pastoral" and "marine":</p>
1214
1215 <pre>p.pastoral.marine { color: green }</pre>
1216
1217 <p>This rule matches when <code>class="pastoral blue aqua
1218 marine"</code> but does not match for <code>class="pastoral
1219 blue"</code>.</p>
1220
1221 </div>
1222
1223 <p class="note"><strong>Note:</strong> Because CSS gives considerable
1224 power to the "class" attribute, authors could conceivably design their
1225 own "document language" based on elements with almost no associated
1226 presentation (such as DIV and SPAN in HTML) and assigning style
1227 information through the "class" attribute. Authors should avoid this
1228 practice since the structural elements of a document language often
1229 have recognized and accepted meanings and author-defined classes may
1230 not.</p>
1231
1232 <p class="note"><strong>Note:</strong> If an element has multiple
1233 class attributes, their values must be concatenated with spaces
1234 between the values before searching for the class. As of this time the
1235 working group is not aware of any manner in which this situation can
1236 be reached, however, so this behavior is explicitly non-normative in
1237 this specification.</p>
1238
1239 <h3><a name=id-selectors>6.5. ID selectors</a></h3>
1240
1241 <p>Document languages may contain attributes that are declared to be
1242 of type ID. What makes attributes of type ID special is that no two
1243 such attributes can have the same value in a document, regardless of
1244 the type of the elements that carry them; whatever the document
1245 language, an ID typed attribute can be used to uniquely identify its
1246 element. In HTML all ID attributes are named "id"; XML applications
1247 may name ID attributes differently, but the same restriction
1248 applies.</p>
1249
1250 <p>An ID-typed attribute of a document language allows authors to
1251 assign an identifier to one element instance in the document tree. W3C
1252 ID selectors represent an element instance based on its identifier. An
1253 ID selector contains a &quot;number sign&quot; (U+0023,
1254 <code>#</code>) immediately followed by the ID value, which must be an
1255 identifier.</p>
1256
1257 <p>Selectors does not specify how a UA knows the ID-typed attribute of
1258 an element. The UA may, e.g., read a document's DTD, have the
1259 information hard-coded or ask the user.
1260
1261 <div class="example">
1262 <p>Examples:</p>
1263 <p>The following ID selector represents an <code>h1</code> element
1264 whose ID-typed attribute has the value "chapter1":</p>
1265 <pre>h1#chapter1</pre>
1266 <p>The following ID selector represents any element whose ID-typed
1267 attribute has the value "chapter1":</p>
1268 <pre>#chapter1</pre>
1269 <p>The following selector represents any element whose ID-typed
1270 attribute has the value "z98y".</p>
1271 <pre>*#z98y</pre>
1272 </div>
1273
1274 <p class="note"><strong>Note.</strong> In XML 1.0 <a
1275 href="#refsXML10">[XML10]</a>, the information about which attribute
1276 contains an element's IDs is contained in a DTD or a schema. When
1277 parsing XML, UAs do not always read the DTD, and thus may not know
1278 what the ID of an element is (though a UA may have namespace-specific
1279 knowledge that allows it to determine which attribute is the ID
1280 attribute for that namespace). If a style sheet designer knows or
1281 suspects that a UA may not know what the ID of an element is, he
1282 should use normal attribute selectors instead:
1283 <code>[name=p371]</code> instead of <code>#p371</code>. Elements in
1284 XML 1.0 documents without a DTD do not have IDs at all.</p>
1285
1286 <p>If an element has multiple ID attributes, all of them must be
1287 treated as IDs for that element for the purposes of the ID
1288 selector. Such a situation could be reached using mixtures of xml:id,
1289 DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
1290
1291 <h3><a name=pseudo-classes>6.6. Pseudo-classes</a></h3>
1292
1293 <p>The pseudo-class concept is introduced to permit selection based on
1294 information that lies outside of the document tree or that cannot be
1295 expressed using the other simple selectors.</p>
1296
1297 <p>A pseudo-class always consists of a &quot;colon&quot;
1298 (<code>:</code>) followed by the name of the pseudo-class and
1299 optionally by a value between parentheses.</p>
1300
1301 <p>Pseudo-classes are allowed in all sequences of simple selectors
1302 contained in a selector. Pseudo-classes are allowed anywhere in
1303 sequences of simple selectors, after the leading type selector or
1304 universal selector (possibly omitted). Pseudo-class names are
1305 case-insensitive. Some pseudo-classes are mutually exclusive, while
1306 others can be applied simultaneously to the same
1307 element. Pseudo-classes may be dynamic, in the sense that an element
1308 may acquire or lose a pseudo-class while a user interacts with the
1309 document.</p>
1310
1311
1312 <h4><a name=dynamic-pseudos>6.6.1. Dynamic pseudo-classes</a></h4>
1313
1314 <p>Dynamic pseudo-classes classify elements on characteristics other
1315 than their name, attributes, or content, in principle characteristics
1316 that cannot be deduced from the document tree.</p>
1317
1318 <p>Dynamic pseudo-classes do not appear in the document source or
1319 document tree.</p>
1320
1321
1322 <h5>The <a name=link>link pseudo-classes: :link and :visited</a></h5>
1323
1324 <p>User agents commonly display unvisited links differently from
1325 previously visited ones. Selectors
1326 provides the pseudo-classes <code>:link</code> and
1327 <code>:visited</code> to distinguish them:</p>
1328
1329 <ul>
1330 <li>The <code>:link</code> pseudo-class applies to links that have
1331 not yet been visited.</li>
1332 <li>The <code>:visited</code> pseudo-class applies once the link has
1333 been visited by the user. </li>
1334 </ul>
1335
1336 <p>After some amount of time, user agents may choose to return a
1337 visited link to the (unvisited) ':link' state.</p>
1338
1339 <p>The two states are mutually exclusive.</p>
1340
1341 <div class="example">
1342
1343 <p>Example:</p>
1344
1345 <p>The following selector represents links carrying class
1346 <code>external</code> and already visited:</p>
1347
1348 <pre>a.external:visited</pre>
1349
1350 </div>
1351
1352 <p class="note"><strong>Note:</strong> It is possible for style sheet
1353 authors to abuse the :link and :visited pseudo-classes to determine
1354 which sites a user has visited without the user's consent.
1355
1356 <p>UAs may therefore treat all links as unvisited links, or implement
1357 other measures to preserve the user's privacy while rendering visited
1358 and unvisited links differently.</p>
1359
1360 <h5>The <a name=useraction-pseudos>user action pseudo-classes
1361 :hover, :active, and :focus</a></h5>
1362
1363 <p>Interactive user agents sometimes change the rendering in response
1364 to user actions. Selectors provides
1365 three pseudo-classes for the selection of an element the user is
1366 acting on.</p>
1367
1368 <ul>
1369
1370 <li>The <code>:hover</code> pseudo-class applies while the user
1371 designates an element with a pointing device, but does not activate
1372 it. For example, a visual user agent could apply this pseudo-class
1373 when the cursor (mouse pointer) hovers over a box generated by the
1374 element. User agents not that do not support <a
1375 href="http://www.w3.org/TR/REC-CSS2/media.html#interactive-media-group">intera ctive
1376 media</a> do not have to support this pseudo-class. Some conforming
1377 user agents that support <a
1378 href="http://www.w3.org/TR/REC-CSS2/media.html#interactive-media-group">intera ctive
1379 media</a> may not be able to support this pseudo-class (e.g., a pen
1380 device that does not detect hovering).</li>
1381
1382 <li>The <code>:active</code> pseudo-class applies while an element
1383 is being activated by the user. For example, between the times the
1384 user presses the mouse button and releases it.</li>
1385
1386 <li>The <code>:focus</code> pseudo-class applies while an element
1387 has the focus (accepts keyboard or mouse events, or other forms of
1388 input). </li>
1389
1390 </ul>
1391
1392 <p>There may be document language or implementation specific limits on
1393 which elements can become <code>:active</code> or acquire
1394 <code>:focus</code>.</p>
1395
1396 <p>These pseudo-classes are not mutually exclusive. An element may
1397 match several pseudo-classes at the same time.</p>
1398
1399 <p>Selectors doesn't define if the parent of an element that is
1400 ':active' or ':hover' is also in that state.</p>
1401
1402 <div class="example">
1403 <p>Examples:</p>
1404 <pre>a:link /* unvisited links */
1405 a:visited /* visited links */
1406 a:hover /* user hovers */
1407 a:active /* active links */</pre>
1408 <p>An example of combining dynamic pseudo-classes:</p>
1409 <pre>a:focus
1410 a:focus:hover</pre>
1411 <p>The last selector matches <code>a</code> elements that are in
1412 the pseudo-class :focus and in the pseudo-class :hover.</p>
1413 </div>
1414
1415 <p class="note"><strong>Note:</strong> An element can be both ':visited'
1416 and ':active' (or ':link' and ':active').</p>
1417
1418 <h4><a name=target-pseudo>6.6.2. The target pseudo-class :target</a></h4>
1419
1420 <p>Some URIs refer to a location within a resource. This kind of URI
1421 ends with a &quot;number sign&quot; (#) followed by an anchor
1422 identifier (called the fragment identifier).</p>
1423
1424 <p>URIs with fragment identifiers link to a certain element within the
1425 document, known as the target element. For instance, here is a URI
1426 pointing to an anchor named <code>section_2</code> in an HTML
1427 document:</p>
1428
1429 <pre>http://example.com/html/top.html#section_2</pre>
1430
1431 <p>A target element can be represented by the <code>:target</code>
1432 pseudo-class. If the document's URI has no fragment identifier, then
1433 the document has no target element.</p>
1434
1435 <div class="example">
1436 <p>Example:</p>
1437 <pre>p.note:target</pre>
1438 <p>This selector represents a <code>p</code> element of class
1439 <code>note</code> that is the target element of the referring
1440 URI.</p>
1441 </div>
1442
1443 <div class="example">
1444 <p>CSS example:</p>
1445 <p>Here, the <code>:target</code> pseudo-class is used to make the
1446 target element red and place an image before it, if there is one:</p>
1447 <pre>*:target { color : red }
1448 *:target::before { content : url(target.png) }</pre>
1449 </div>
1450
1451 <h4><a name=lang-pseudo>6.6.3. The language pseudo-class :lang</a></h4>
1452
1453 <p>If the document language specifies how the human language of an
1454 element is determined, it is possible to write selectors that
1455 represent an element based on its language. For example, in HTML <a
1456 href="#refsHTML4">[HTML4]</a>, the language is determined by a
1457 combination of the <code>lang</code> attribute, the <code>meta</code>
1458 element, and possibly by information from the protocol (such as HTTP
1459 headers). XML uses an attribute called <code>xml:lang</code>, and
1460 there may be other document language-specific methods for determining
1461 the language.</p>
1462
1463 <p>The pseudo-class <code>:lang(C)</code> represents an element that
1464 is in language C. Whether an element is represented by a
1465 <code>:lang()</code> selector is based solely on the identifier C
1466 being either equal to, or a hyphen-separated substring of, the
1467 element's language value, in the same way as if performed by the <a
1468 href="#attribute-representation">'|='</a> operator in attribute
1469 selectors. The identifier C does not have to be a valid language
1470 name.</p>
1471
1472 <p>C must not be empty. (If it is, the selector is invalid.)</p>
1473
1474 <p class="note"><strong>Note:</strong> It is recommended that
1475 documents and protocols indicate language using codes from RFC 3066 <a
1476 href="#refsRFC3066">[RFC3066]</a> or its successor, and by means of
1477 "xml:lang" attributes in the case of XML-based documents <a
1478 href="#refsXML10">[XML10]</a>. See <a
1479 href="http://www.w3.org/International/questions/qa-lang-2or3.html">
1480 "FAQ: Two-letter or three-letter language codes."</a></p>
1481
1482 <div class="example">
1483 <p>Examples:</p>
1484 <p>The two following selectors represent an HTML document that is in
1485 Belgian, French, or German. The two next selectors represent
1486 <code>q</code> quotations in an arbitrary element in Belgian, French,
1487 or German.</p>
1488 <pre>html:lang(fr-be)
1489 html:lang(de)
1490 :lang(fr-be) &gt; q
1491 :lang(de) &gt; q</pre>
1492 </div>
1493
1494 <h4><a name=UIstates>6.6.4. The UI element states pseudo-classes</a></h4>
1495
1496 <h5><a name=enableddisabled>The :enabled and :disabled pseudo-classes</a></h5>
1497
1498 <p>The <code>:enabled</code> pseudo-class allows authors to customize
1499 the look of user interface elements that are enabled &mdash; which the
1500 user can select or activate in some fashion (e.g. clicking on a button
1501 with a mouse). There is a need for such a pseudo-class because there
1502 is no way to programmatically specify the default appearance of say,
1503 an enabled <code>input</code> element without also specifying what it
1504 would look like when it was disabled.</p>
1505
1506 <p>Similar to <code>:enabled</code>, <code>:disabled</code> allows the
1507 author to specify precisely how a disabled or inactive user interface
1508 element should look.</p>
1509
1510 <p>Most elements will be neither enabled nor disabled. An element is
1511 enabled if the user can either activate it or transfer the focus to
1512 it. An element is disabled if it could be enabled, but the user cannot
1513 presently activate it or transfer focus to it.</p>
1514
1515
1516 <h5><a name=checked>The :checked pseudo-class</a></h5>
1517
1518 <p>Radio and checkbox elements can be toggled by the user. Some menu
1519 items are "checked" when the user selects them. When such elements are
1520 toggled "on" the <code>:checked</code> pseudo-class applies. The
1521 <code>:checked</code> pseudo-class initially applies to such elements
1522 that have the HTML4 <code>selected</code> and <code>checked</code>
1523 attributes as described in <a
1524 href="http://www.w3.org/TR/REC-html40/interact/forms.html#h-17.2.1">Section
1525 17.2.1 of HTML4</a>, but of course the user can toggle "off" such
1526 elements in which case the <code>:checked</code> pseudo-class would no
1527 longer apply. While the <code>:checked</code> pseudo-class is dynamic
1528 in nature, and is altered by user action, since it can also be based
1529 on the presence of the semantic HTML4 <code>selected</code> and
1530 <code>checked</code> attributes, it applies to all media.
1531
1532
1533 <h5><a name=indeterminate>The :indeterminate pseudo-class</a></h5>
1534
1535 <div class="note">
1536
1537 <p>Radio and checkbox elements can be toggled by the user, but are
1538 sometimes in an indeterminate state, neither checked nor unchecked.
1539 This can be due to an element attribute, or DOM manipulation.</p>
1540
1541 <p>A future version of this specification may introduce an
1542 <code>:indeterminate</code> pseudo-class that applies to such elements.
1543 <!--While the <code>:indeterminate</code> pseudo-class is dynamic in
1544 nature, and is altered by user action, since it can also be based on
1545 the presence of an element attribute, it applies to all media.</p>
1546
1547 <p>Components of a radio-group initialized with no pre-selected choice
1548 are an example of :indeterminate state.--></p>
1549
1550 </div>
1551
1552
1553 <h4><a name=structural-pseudos>6.6.5. Structural pseudo-classes</a></h4>
1554
1555 <p>Selectors introduces the concept of <dfn>structural
1556 pseudo-classes</dfn> to permit selection based on extra information that lies in
1557 the document tree but cannot be represented by other simple selectors or
1558 combinators.
1559
1560 <p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
1561 not counted when calculating the position of an element in the list of
1562 children of its parent. When calculating the position of an element in
1563 the list of children of its parent, the index numbering starts at 1.
1564
1565
1566 <h5><a name=root-pseudo>:root pseudo-class</a></h5>
1567
1568 <p>The <code>:root</code> pseudo-class represents an element that is
1569 the root of the document. In HTML 4, this is always the
1570 <code>HTML</code> element.
1571
1572
1573 <h5><a name=nth-child-pseudo>:nth-child() pseudo-class</a></h5>
1574
1575 <p>The
1576 <code>:nth-child(<var>a</var><code>n</code>+<var>b</var>)</code>
1577 pseudo-class notation represents an element that has
1578 <var>a</var><code>n</code>+<var>b</var>-1 siblings
1579 <strong>before</strong> it in the document tree, for a given positive
1580 integer or zero value of <code>n</code>, and has a parent element. In
1581 other words, this matches the <var>b</var>th child of an element after
1582 all the children have been split into groups of <var>a</var> elements
1583 each. For example, this allows the selectors to address every other
1584 row in a table, and could be used to alternate the color
1585 of paragraph text in a cycle of four. The <var>a</var> and
1586 <var>b</var> values must be zero, negative integers or positive
1587 integers. The index of the first child of an element is 1.
1588
1589 <p>In addition to this, <code>:nth-child()</code> can take
1590 '<code>odd</code>' and '<code>even</code>' as arguments instead.
1591 '<code>odd</code>' has the same signification as <code>2n+1</code>,
1592 and '<code>even</code>' has the same signification as <code>2n</code>.
1593
1594
1595 <div class="example">
1596 <p>Examples:</p>
1597 <pre>tr:nth-child(2n+1) /* represents every odd row of an HTML table */
1598 tr:nth-child(odd) /* same */
1599 tr:nth-child(2n) /* represents every even row of an HTML table */
1600 tr:nth-child(even) /* same */
1601
1602 /* Alternate paragraph colours in CSS */
1603 p:nth-child(4n+1) { color: navy; }
1604 p:nth-child(4n+2) { color: green; }
1605 p:nth-child(4n+3) { color: maroon; }
1606 p:nth-child(4n+4) { color: purple; }</pre>
1607 </div>
1608
1609 <p>When <var>a</var>=0, no repeating is used, so for example
1610 <code>:nth-child(0n+5)</code> matches only the fifth child. When
1611 <var>a</var>=0, the <var>a</var><code>n</code> part need not be
1612 included, so the syntax simplifies to
1613 <code>:nth-child(<var>b</var>)</code> and the last example simplifies
1614 to <code>:nth-child(5)</code>.
1615
1616 <div class="example">
1617 <p>Examples:</p>
1618 <pre>foo:nth-child(0n+1) /* represents an element foo, first child of its pare nt element */
1619 foo:nth-child(1) /* same */</pre>
1620 </div>
1621
1622 <p>When <var>a</var>=1, the number may be omitted from the rule.
1623
1624 <div class="example">
1625 <p>Examples:</p>
1626 <p>The following selectors are therefore equivalent:</p>
1627 <pre>bar:nth-child(1n+0) /* represents all bar elements, specificity (0,1,1) * /
1628 bar:nth-child(n+0) /* same */
1629 bar:nth-child(n) /* same */
1630 bar /* same but lower specificity (0,0,1) */</pre>
1631 </div>
1632
1633 <p>If <var>b</var>=0, then every <var>a</var>th element is picked. In
1634 such a case, the <var>b</var> part may be omitted.
1635
1636 <div class="example">
1637 <p>Examples:</p>
1638 <pre>tr:nth-child(2n+0) /* represents every even row of an HTML table */
1639 tr:nth-child(2n) /* same */</pre>
1640 </div>
1641
1642 <p>If both <var>a</var> and <var>b</var> are equal to zero, the
1643 pseudo-class represents no element in the document tree.</p>
1644
1645 <p>The value <var>a</var> can be negative, but only the positive
1646 values of <var>a</var><code>n</code>+<var>b</var>, for
1647 <code>n</code>&ge;0, may represent an element in the document
1648 tree.</p>
1649
1650 <div class="example">
1651 <p>Example:</p>
1652 <pre>html|tr:nth-child(-n+6) /* represents the 6 first rows of XHTML tables */< /pre>
1653 </div>
1654
1655 <p>When the value <var>b</var> is negative, the "+" character in the
1656 expression must be removed (it is effectively replaced by the "-"
1657 character indicating the negative value of <var>b</var>).</p>
1658
1659 <div class="example">
1660 <p>Examples:</p>
1661 <pre>:nth-child(10n-1) /* represents the 9th, 19th, 29th, etc, element */
1662 :nth-child(10n+9) /* Same */
1663 :nth-child(10n+-1) /* Syntactically invalid, and would be ignored */</pre>
1664 </div>
1665
1666
1667 <h5><a name=nth-last-child-pseudo>:nth-last-child() pseudo-class</a></h5>
1668
1669 <p>The <code>:nth-last-child(<var>a</var>n+<var>b</var>)</code>
1670 pseudo-class notation represents an element that has
1671 <var>a</var><code>n</code>+<var>b</var>-1 siblings
1672 <strong>after</strong> it in the document tree, for a given positive
1673 integer or zero value of <code>n</code>, and has a parent element. See
1674 <code>:nth-child()</code> pseudo-class for the syntax of its argument.
1675 It also accepts the '<code>even</code>' and '<code>odd</code>' values
1676 as arguments.
1677
1678
1679 <div class="example">
1680 <p>Examples:</p>
1681 <pre>tr:nth-last-child(-n+2) /* represents the two last rows of an HTML table */
1682
1683 foo:nth-last-child(odd) /* represents all odd foo elements in their parent el ement,
1684 counting from the last one */</pre>
1685 </div>
1686
1687
1688 <h5><a name=nth-of-type-pseudo>:nth-of-type() pseudo-class</a></h5>
1689
1690 <p>The <code>:nth-of-type(<var>a</var>n+<var>b</var>)</code>
1691 pseudo-class notation represents an element that has
1692 <var>a</var><code>n</code>+<var>b</var>-1 siblings with the same
1693 element name <strong>before</strong> it in the document tree, for a
1694 given zero or positive integer value of <code>n</code>, and has a
1695 parent element. In other words, this matches the <var>b</var>th child
1696 of that type after all the children of that type have been split into
1697 groups of a elements each. See <code>:nth-child()</code> pseudo-class
1698 for the syntax of its argument. It also accepts the
1699 '<code>even</code>' and '<code>odd</code>' values.
1700
1701
1702 <div class="example">
1703 <p>CSS example:</p>
1704 <p>This allows an author to alternate the position of floated images:</p>
1705 <pre>img:nth-of-type(2n+1) { float: right; }
1706 img:nth-of-type(2n) { float: left; }</pre>
1707 </div>
1708
1709
1710 <h5><a name=nth-last-of-type-pseudo>:nth-last-of-type() pseudo-class</a></h5>
1711
1712 <p>The <code>:nth-last-of-type(<var>a</var>n+<var>b</var>)</code>
1713 pseudo-class notation represents an element that has
1714 <var>a</var><code>n</code>+<var>b</var>-1 siblings with the same
1715 element name <strong>after</strong> it in the document tree, for a
1716 given zero or positive integer value of <code>n</code>, and has a
1717 parent element. See <code>:nth-child()</code> pseudo-class for the
1718 syntax of its argument. It also accepts the '<code>even</code>' and '<code>odd</ code>' values.
1719
1720
1721 <div class="example">
1722 <p>Example:</p>
1723 <p>To represent all <code>h2</code> children of an XHTML
1724 <code>body</code> except the first and last, one could use the
1725 following selector:</p>
1726 <pre>body &gt; h2:nth-of-type(n+2):nth-last-of-type(n+2)</pre>
1727 <p>In this case, one could also use <code>:not()</code>, although the
1728 selector ends up being just as long:</p>
1729 <pre>body &gt; h2:not(:first-of-type):not(:last-of-type)</pre>
1730 </div>
1731
1732
1733 <h5><a name=first-child-pseudo>:first-child pseudo-class</a></h5>
1734
1735 <p>Same as <code>:nth-child(1)</code>. The <code>:first-child</code> pseudo-clas s
1736 represents an element that is the first child of some other element.
1737
1738
1739 <div class="example">
1740 <p>Examples:</p>
1741 <p>The following selector represents a <code>p</code> element that is
1742 the first child of a <code>div</code> element:</p>
1743 <pre>div &gt; p:first-child</pre>
1744 <p>This selector can represent the <code>p</code> inside the
1745 <code>div</code> of the following fragment:</p>
1746 <pre>&lt;p&gt; The last P before the note.&lt;/p&gt;
1747 &lt;div class="note"&gt;
1748 &lt;p&gt; The first P inside the note.&lt;/p&gt;
1749 &lt;/div&gt;</pre>but cannot represent the second <code>p</code> in the followin g
1750 fragment:
1751 <pre>&lt;p&gt; The last P before the note.&lt;/p&gt;
1752 &lt;div class="note"&gt;
1753 &lt;h2&gt; Note &lt;/h2&gt;
1754 &lt;p&gt; The first P inside the note.&lt;/p&gt;
1755 &lt;/div&gt;</pre>
1756 <p>The following two selectors are usually equivalent:</p>
1757 <pre>* &gt; a:first-child /* a is first child of any element */
1758 a:first-child /* Same (assuming a is not the root element) */</pre>
1759 </div>
1760
1761 <h5><a name=last-child-pseudo>:last-child pseudo-class</a></h5>
1762
1763 <p>Same as <code>:nth-last-child(1)</code>. The <code>:last-child</code> pseudo- class
1764 represents an element that is the last child of some other element.
1765
1766 <div class="example">
1767 <p>Example:</p>
1768 <p>The following selector represents a list item <code>li</code> that
1769 is the last child of an ordered list <code>ol</code>.
1770 <pre>ol &gt; li:last-child</pre>
1771 </div>
1772
1773 <h5><a name=first-of-type-pseudo>:first-of-type pseudo-class</a></h5>
1774
1775 <p>Same as <code>:nth-of-type(1)</code>. The <code>:first-of-type</code> pseudo- class
1776 represents an element that is the first sibling of its type in the list of
1777 children of its parent element.
1778
1779 <div class="example">
1780 <p>Example:</p>
1781 <p>The following selector represents a definition title
1782 <code>dt</code> inside a definition list <code>dl</code>, this
1783 <code>dt</code> being the first of its type in the list of children of
1784 its parent element.</p>
1785 <pre>dl dt:first-of-type</pre>
1786 <p>It is a valid description for the first two <code>dt</code>
1787 elements in the following example but not for the third one:</p>
1788 <pre>&lt;dl&gt;
1789 &lt;dt&gt;gigogne&lt;/dt&gt;
1790 &lt;dd&gt;
1791 &lt;dl&gt;
1792 &lt;dt&gt;fus&eacute;e&lt;/dt&gt;
1793 &lt;dd&gt;multistage rocket&lt;/dd&gt;
1794 &lt;dt&gt;table&lt;/dt&gt;
1795 &lt;dd&gt;nest of tables&lt;/dd&gt;
1796 &lt;/dl&gt;
1797 &lt;/dd&gt;
1798 &lt;/dl&gt;</pre>
1799 </div>
1800
1801 <h5><a name=last-of-type-pseudo>:last-of-type pseudo-class</a></h5>
1802
1803 <p>Same as <code>:nth-last-of-type(1)</code>. The
1804 <code>:last-of-type</code> pseudo-class represents an element that is
1805 the last sibling of its type in the list of children of its parent
1806 element.</p>
1807
1808 <div class="example">
1809 <p>Example:</p>
1810 <p>The following selector represents the last data cell
1811 <code>td</code> of a table row.</p>
1812 <pre>tr &gt; td:last-of-type</pre>
1813 </div>
1814
1815 <h5><a name=only-child-pseudo>:only-child pseudo-class</a></h5>
1816
1817 <p>Represents an element that has a parent element and whose parent
1818 element has no other element children. Same as
1819 <code>:first-child:last-child</code> or
1820 <code>:nth-child(1):nth-last-child(1)</code>, but with a lower
1821 specificity.</p>
1822
1823 <h5><a name=only-of-type-pseudo>:only-of-type pseudo-class</a></h5>
1824
1825 <p>Represents an element that has a parent element and whose parent
1826 element has no other element children with the same element name. Same
1827 as <code>:first-of-type:last-of-type</code> or
1828 <code>:nth-of-type(1):nth-last-of-type(1)</code>, but with a lower
1829 specificity.</p>
1830
1831
1832 <h5><a name=empty-pseudo></a>:empty pseudo-class</h5>
1833
1834 <p>The <code>:empty</code> pseudo-class represents an element that has
1835 no children at all. In terms of the DOM, only element nodes and text
1836 nodes (including CDATA nodes and entity references) whose data has a
1837 non-zero length must be considered as affecting emptiness; comments,
1838 PIs, and other nodes must not affect whether an element is considered
1839 empty or not.</p>
1840
1841 <div class="example">
1842 <p>Examples:</p>
1843 <p><code>p:empty</code> is a valid representation of the following fragment:</p >
1844 <pre>&lt;p&gt;&lt;/p&gt;</pre>
1845 <p><code>foo:empty</code> is not a valid representation for the
1846 following fragments:</p>
1847 <pre>&lt;foo&gt;bar&lt;/foo&gt;</pre>
1848 <pre>&lt;foo&gt;&lt;bar&gt;bla&lt;/bar&gt;&lt;/foo&gt;</pre>
1849 <pre>&lt;foo&gt;this is not &lt;bar&gt;:empty&lt;/bar&gt;&lt;/foo&gt;</pre>
1850 </div>
1851
1852 <h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appe ndix H!!! Run away! -->
1853
1854 <p>This section intentionally left blank.</p>
1855 <!-- (used to be :contains()) -->
1856
1857 <h4><a name=negation></a>6.6.7. The negation pseudo-class</h4>
1858
1859 <p>The negation pseudo-class, <code>:not(<var>X</var>)</code>, is a
1860 functional notation taking a <a href="#simple-selectors-dfn">simple
1861 selector</a> (excluding the negation pseudo-class itself and
1862 pseudo-elements) as an argument. It represents an element that is not
1863 represented by the argument.
1864
1865 <!-- pseudo-elements are not simple selectors, so the above paragraph
1866 may be a bit confusing -->
1867
1868 <div class="example">
1869 <p>Examples:</p>
1870 <p>The following CSS selector matches all <code>button</code>
1871 elements in an HTML document that are not disabled.</p>
1872 <pre>button:not([DISABLED])</pre>
1873 <p>The following selector represents all but <code>FOO</code>
1874 elements.</p>
1875 <pre>*:not(FOO)</pre>
1876 <p>The following group of selectors represents all HTML elements
1877 except links.</p>
1878 <pre>html|*:not(:link):not(:visited)</pre>
1879 </div>
1880
1881 <p>Default namespace declarations do not affect the argument of the
1882 negation pseudo-class unless the argument is a universal selector or a
1883 type selector.</p>
1884
1885 <div class="example">
1886 <p>Examples:</p>
1887 <p>Assuming that the default namespace is bound to
1888 "http://example.com/", the following selector represents all
1889 elements that are not in that namespace:</p>
1890 <pre>*|*:not(*)</pre>
1891 <p>The following CSS selector matches any element being hovered,
1892 regardless of its namespace. In particular, it is not limited to
1893 only matching elements in the default namespace that are not being
1894 hovered, and elements not in the default namespace don't match the
1895 rule when they <em>are</em> being hovered.</p>
1896 <pre>*|*:not(:hover)</pre>
1897 </div>
1898
1899 <p class="note"><strong>Note</strong>: the :not() pseudo allows
1900 useless selectors to be written. For instance <code>:not(*|*)</code>,
1901 which represents no element at all, or <code>foo:not(bar)</code>,
1902 which is equivalent to <code>foo</code> but with a higher
1903 specificity.</p>
1904
1905 <h3><a name=pseudo-elements>7. Pseudo-elements</a></h3>
1906
1907 <p>Pseudo-elements create abstractions about the document tree beyond
1908 those specified by the document language. For instance, document
1909 languages do not offer mechanisms to access the first letter or first
1910 line of an element's content. Pseudo-elements allow designers to refer
1911 to this otherwise inaccessible information. Pseudo-elements may also
1912 provide designers a way to refer to content that does not exist in the
1913 source document (e.g., the <code>::before</code> and
1914 <code>::after</code> pseudo-elements give access to generated
1915 content).</p>
1916
1917 <p>A pseudo-element is made of two colons (<code>::</code>) followed
1918 by the name of the pseudo-element.</p>
1919
1920 <p>This <code>::</code> notation is introduced by the current document
1921 in order to establish a discrimination between pseudo-classes and
1922 pseudo-elements. For compatibility with existing style sheets, user
1923 agents must also accept the previous one-colon notation for
1924 pseudo-elements introduced in CSS levels 1 and 2 (namely,
1925 <code>:first-line</code>, <code>:first-letter</code>,
1926 <code>:before</code> and <code>:after</code>). This compatibility is
1927 not allowed for the new pseudo-elements introduced in CSS level 3.</p>
1928
1929 <p>Only one pseudo-element may appear per selector, and if present it
1930 must appear after the sequence of simple selectors that represents the
1931 <a href="#subject">subjects</a> of the selector. <span class="note">A
1932 future version of this specification may allow multiple
1933 pesudo-elements per selector.</span></p>
1934
1935 <h4><a name=first-line>7.1. The ::first-line pseudo-element</a></h4>
1936
1937 <p>The <code>::first-line</code> pseudo-element describes the contents
1938 of the first formatted line of an element.
1939
1940 <div class="example">
1941 <p>CSS example:</p>
1942 <pre>p::first-line { text-transform: uppercase }</pre>
1943 <p>The above rule means "change the letters of the first line of every
1944 paragraph to uppercase".</p>
1945 </div>
1946
1947 <p>The selector <code>p::first-line</code> does not match any real
1948 HTML element. It does match a pseudo-element that conforming user
1949 agents will insert at the beginning of every paragraph.</p>
1950
1951 <p>Note that the length of the first line depends on a number of
1952 factors, including the width of the page, the font size, etc. Thus,
1953 an ordinary HTML paragraph such as:</p>
1954
1955 <pre>
1956 &lt;P&gt;This is a somewhat long HTML
1957 paragraph that will be broken into several
1958 lines. The first line will be identified
1959 by a fictional tag sequence. The other lines
1960 will be treated as ordinary lines in the
1961 paragraph.&lt;/P&gt;
1962 </pre>
1963
1964 <p>the lines of which happen to be broken as follows:
1965
1966 <pre>
1967 THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
1968 will be broken into several lines. The first
1969 line will be identified by a fictional tag
1970 sequence. The other lines will be treated as
1971 ordinary lines in the paragraph.
1972 </pre>
1973
1974 <p>This paragraph might be "rewritten" by user agents to include the
1975 <em>fictional tag sequence</em> for <code>::first-line</code>. This
1976 fictional tag sequence helps to show how properties are inherited.</p>
1977
1978 <pre>
1979 &lt;P&gt;<b>&lt;P::first-line&gt;</b> This is a somewhat long HTML
1980 paragraph that <b>&lt;/P::first-line&gt;</b> will be broken into several
1981 lines. The first line will be identified
1982 by a fictional tag sequence. The other lines
1983 will be treated as ordinary lines in the
1984 paragraph.&lt;/P&gt;
1985 </pre>
1986
1987 <p>If a pseudo-element breaks up a real element, the desired effect
1988 can often be described by a fictional tag sequence that closes and
1989 then re-opens the element. Thus, if we mark up the previous paragraph
1990 with a <code>span</code> element:</p>
1991
1992 <pre>
1993 &lt;P&gt;<b>&lt;SPAN class="test"&gt;</b> This is a somewhat long HTML
1994 paragraph that will be broken into several
1995 lines.<b>&lt;/SPAN&gt;</b> The first line will be identified
1996 by a fictional tag sequence. The other lines
1997 will be treated as ordinary lines in the
1998 paragraph.&lt;/P&gt;
1999 </pre>
2000
2001 <p>the user agent could simulate start and end tags for
2002 <code>span</code> when inserting the fictional tag sequence for
2003 <code>::first-line</code>.
2004
2005 <pre>
2006 &lt;P&gt;&lt;P::first-line&gt;<b>&lt;SPAN class="test"&gt;</b> This is a
2007 somewhat long HTML
2008 paragraph that will <b>&lt;/SPAN&gt;</b>&lt;/P::first-line&gt;<b>&lt;SPAN class= "test"&gt;</b> be
2009 broken into several
2010 lines.<b>&lt;/SPAN&gt;</b> The first line will be identified
2011 by a fictional tag sequence. The other lines
2012 will be treated as ordinary lines in the
2013 paragraph.&lt;/P&gt;
2014 </pre>
2015
2016 <p>In CSS, the <code>::first-line</code> pseudo-element can only be
2017 attached to a block-level element, an inline-block, a table-caption,
2018 or a table-cell.</p>
2019
2020 <p><a name="first-formatted-line"></a>The "first formatted line" of an
2021 element may occur inside a
2022 block-level descendant in the same flow (i.e., a block-level
2023 descendant that is not positioned and not a float). E.g., the first
2024 line of the <code>div</code> in <code>&lt;DIV>&lt;P>This
2025 line...&lt;/P>&lt/DIV></code> is the first line of the <code>p</code> (assuming
2026 that both <code>p</code> and <code>div</code> are block-level).
2027
2028 <p>The first line of a table-cell or inline-block cannot be the first
2029 formatted line of an ancestor element. Thus, in <code>&lt;DIV&gt;&lt;P
2030 STYLE="display: inline-block">Hello&lt;BR&gt;Goodbye&lt;/P&gt;
2031 etcetera&lt;/DIV&gt;</code> the first formatted line of the
2032 <code>div</code> is not the line "Hello".
2033
2034 <p class="note">Note that the first line of the <code>p</code> in this
2035 fragment: <code>&lt;p&gt&lt;br&gt;First...</code> doesn't contain any
2036 letters (assuming the default style for <code>br</code> in HTML
2037 4). The word "First" is not on the first formatted line.
2038
2039 <p>A UA should act as if the fictional start tags of the
2040 <code>::first-line</code> pseudo-elements were nested just inside the
2041 innermost enclosing block-level element. (Since CSS1 and CSS2 were
2042 silent on this case, authors should not rely on this behavior.) Here
2043 is an example. The fictional tag sequence for</p>
2044
2045 <pre>
2046 &lt;DIV>
2047 &lt;P>First paragraph&lt;/P>
2048 &lt;P>Second paragraph&lt;/P>
2049 &lt;/DIV>
2050 </pre>
2051
2052 <p>is</p>
2053
2054 <pre>
2055 &lt;DIV>
2056 &lt;P>&lt;DIV::first-line>&lt;P::first-line>First paragraph&lt;/P::first-line> &lt;/DIV::first-line>&lt;/P>
2057 &lt;P>&lt;P::first-line>Second paragraph&lt;/P::first-line>&lt;/P>
2058 &lt;/DIV>
2059 </pre>
2060
2061 <p>The <code>::first-line</code> pseudo-element is similar to an
2062 inline-level element, but with certain restrictions. In CSS, the
2063 following properties apply to a <code>::first-line</code>
2064 pseudo-element: font properties, color property, background
2065 properties, 'word-spacing', 'letter-spacing', 'text-decoration',
2066 'vertical-align', 'text-transform', 'line-height'. UAs may apply other
2067 properties as well.</p>
2068
2069
2070 <h4><a name=first-letter>7.2. The ::first-letter pseudo-element</a></h4>
2071
2072 <p>The <code>::first-letter</code> pseudo-element represents the first
2073 letter of the first line of a block, if it is not preceded by any
2074 other content (such as images or inline tables) on its line. The
2075 ::first-letter pseudo-element may be used for "initial caps" and "drop
2076 caps", which are common typographical effects. This type of initial
2077 letter is similar to an inline-level element if its 'float' property
2078 is 'none'; otherwise, it is similar to a floated element.</p>
2079
2080 <p>In CSS, these are the properties that apply to <code>::first-letter</code>
2081 pseudo-elements: font properties, 'text-decoration', 'text-transform',
2082 'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
2083 'float', 'vertical-align' (only if 'float' is 'none'), margin
2084 properties, padding properties, border properties, color property,
2085 background properties. UAs may apply other properties as well. To
2086 allow UAs to render a typographically correct drop cap or initial cap,
2087 the UA may choose a line-height, width and height based on the shape
2088 of the letter, unlike for normal elements.</p>
2089
2090 <div class="example">
2091 <p>Example:</p>
2092 <p>This example shows a possible rendering of an initial cap. Note
2093 that the 'line-height' that is inherited by the <code>::first-letter</code>
2094 pseudo-element is 1.1, but the UA in this example has computed the
2095 height of the first letter differently, so that it doesn't cause any
2096 unnecessary space between the first two lines. Also note that the
2097 fictional start tag of the first letter is inside the <span>span</span>, and thu s
2098 the font weight of the first letter is normal, not bold as the <span>span</span> :
2099 <pre>
2100 p { line-height: 1.1 }
2101 p::first-letter { font-size: 3em; font-weight: normal }
2102 span { font-weight: bold }
2103 ...
2104 &lt;p>&lt;span>Het hemelsche&lt;/span> gerecht heeft zich ten lange lesten&lt;br >
2105 Erbarremt over my en mijn benaeuwde vesten&lt;br>
2106 En arme burgery, en op mijn volcx gebed&lt;br>
2107 En dagelix geschrey de bange stad ontzet.
2108 </pre>
2109 <div class="figure">
2110 <p><img src="initial-cap.png" alt="Image illustrating the ::first-letter pseudo- element">
2111 </div>
2112 </div>
2113
2114 <div class="example">
2115 <p>The following CSS will make a drop cap initial letter span about two lines:</ p>
2116
2117 <pre>
2118 &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"&gt;
2119 &lt;HTML&gt;
2120 &lt;HEAD&gt;
2121 &lt;TITLE&gt;Drop cap initial letter&lt;/TITLE&gt;
2122 &lt;STYLE type="text/css"&gt;
2123 P { font-size: 12pt; line-height: 1.2 }
2124 P::first-letter { font-size: 200%; font-weight: bold; float: left }
2125 SPAN { text-transform: uppercase }
2126 &lt;/STYLE&gt;
2127 &lt;/HEAD&gt;
2128 &lt;BODY&gt;
2129 &lt;P&gt;&lt;SPAN&gt;The first&lt;/SPAN&gt; few words of an article
2130 in The Economist.&lt;/P&gt;
2131 &lt;/BODY&gt;
2132 &lt;/HTML&gt;
2133 </pre>
2134
2135 <p>This example might be formatted as follows:</p>
2136
2137 <div class="figure">
2138 <P><img src="first-letter.gif" alt="Image illustrating the combined effect of th e ::first-letter and ::first-line pseudo-elements"></p>
2139 </div>
2140
2141 <p>The <span class="index-inst" title="fictional tag
2142 sequence">fictional tag sequence</span> is:</p>
2143
2144 <pre>
2145 &lt;P&gt;
2146 &lt;SPAN&gt;
2147 &lt;P::first-letter&gt;
2148 T
2149 &lt;/P::first-letter&gt;he first
2150 &lt;/SPAN&gt;
2151 few words of an article in the Economist.
2152 &lt;/P&gt;
2153 </pre>
2154
2155 <p>Note that the <code>::first-letter</code> pseudo-element tags abut
2156 the content (i.e., the initial character), while the ::first-line
2157 pseudo-element start tag is inserted right after the start tag of the
2158 block element.</p> </div>
2159
2160 <p>In order to achieve traditional drop caps formatting, user agents
2161 may approximate font sizes, for example to align baselines. Also, the
2162 glyph outline may be taken into account when formatting.</p>
2163
2164 <p>Punctuation (i.e, characters defined in Unicode in the "open" (Ps),
2165 "close" (Pe), "initial" (Pi). "final" (Pf) and "other" (Po)
2166 punctuation classes), that precedes or follows the first letter should
2167 be included. <a href="#refsUNICODE">[UNICODE]</a></p>
2168
2169 <div class="figure">
2170 <P><img src="first-letter2.gif" alt="Quotes that precede the
2171 first letter should be included."></p>
2172 </div>
2173
2174 <p>The <code>::first-letter</code> also applies if the first letter is
2175 in fact a digit, e.g., the "6" in "67 million dollars is a lot of
2176 money."</p>
2177
2178 <p>In CSS, the <code>::first-letter</code> pseudo-element applies to
2179 block, list-item, table-cell, table-caption, and inline-block
2180 elements. <span class="note">A future version of this specification
2181 may allow this pesudo-element to apply to more element
2182 types.</span></p>
2183
2184 <p>The <code>::first-letter</code> pseudo-element can be used with all
2185 such elements that contain text, or that have a descendant in the same
2186 flow that contains text. A UA should act as if the fictional start tag
2187 of the ::first-letter pseudo-element is just before the first text of
2188 the element, even if that first text is in a descendant.</p>
2189
2190 <div class="example">
2191 <p>Example:</p>
2192 <p>The fictional tag sequence for this HTMLfragment:
2193 <pre>&lt;div>
2194 &lt;p>The first text.</pre>
2195 <p>is:
2196 <pre>&lt;div>
2197 &lt;p>&lt;div::first-letter>&lt;p::first-letter>T&lt;/...>&lt;/...>he first text .</pre>
2198 </div>
2199
2200 <p>The first letter of a table-cell or inline-block cannot be the
2201 first letter of an ancestor element. Thus, in <code>&lt;DIV&gt;&lt;P
2202 STYLE="display: inline-block">Hello&lt;BR&gt;Goodbye&lt;/P&gt;
2203 etcetera&lt;/DIV&gt;</code> the first letter of the <code>div</code> is not the
2204 letter "H". In fact, the <code>div</code> doesn't have a first letter.
2205
2206 <p>The first letter must occur on the <a
2207 href="#first-formatted-line">first formatted line.</a> For example, in
2208 this fragment: <code>&lt;p&gt&lt;br&gt;First...</code> the first line
2209 doesn't contain any letters and <code>::first-letter</code> doesn't
2210 match anything (assuming the default style for <code>br</code> in HTML
2211 4). In particular, it does not match the "F" of "First."
2212
2213 <p>In CSS, if an element is a list item ('display: list-item'), the
2214 <code>::first-letter</code> applies to the first letter in the
2215 principal box after the marker. UAs may ignore
2216 <code>::first-letter</code> on list items with 'list-style-position:
2217 inside'. If an element has <code>::before</code> or
2218 <code>::after</code> content, the <code>::first-letter</code> applies
2219 to the first letter of the element <em>including</em> that content.
2220
2221 <div class="example">
2222 <p>Example:</p>
2223 <p>After the rule 'p::before {content: "Note: "}', the selector
2224 'p::first-letter' matches the "N" of "Note".</p>
2225 </div>
2226
2227 <p>Some languages may have specific rules about how to treat certain
2228 letter combinations. In Dutch, for example, if the letter combination
2229 "ij" appears at the beginning of a word, both letters should be
2230 considered within the <code>::first-letter</code> pseudo-element.
2231
2232 <p>If the letters that would form the ::first-letter are not in the
2233 same element, such as "'T" in <code>&lt;p>'&lt;em>T...</code>, the UA
2234 may create a ::first-letter pseudo-element from one of the elements,
2235 both elements, or simply not create a pseudo-element.</p>
2236
2237 <p>Similarly, if the first letter(s) of the block are not at the start
2238 of the line (for example due to bidirectional reordering), then the UA
2239 need not create the pseudo-element(s).
2240
2241 <div class="example">
2242 <p>Example:</p>
2243 <p><a name="overlapping-example">The following example</a> illustrates
2244 how overlapping pseudo-elements may interact. The first letter of
2245 each P element will be green with a font size of '24pt'. The rest of
2246 the first formatted line will be 'blue' while the rest of the
2247 paragraph will be 'red'.</p>
2248
2249 <pre>p { color: red; font-size: 12pt }
2250 p::first-letter { color: green; font-size: 200% }
2251 p::first-line { color: blue }
2252
2253 &lt;P&gt;Some text that ends up on two lines&lt;/P&gt;</pre>
2254
2255 <p>Assuming that a line break will occur before the word "ends", the
2256 <span class="index-inst" title="fictional tag sequence">fictional tag
2257 sequence</span> for this fragment might be:</p>
2258
2259 <pre>&lt;P&gt;
2260 &lt;P::first-line&gt;
2261 &lt;P::first-letter&gt;
2262 S
2263 &lt;/P::first-letter&gt;ome text that
2264 &lt;/P::first-line&gt;
2265 ends up on two lines
2266 &lt;/P&gt;</pre>
2267
2268 <p>Note that the <code>::first-letter</code> element is inside the <code>::first -line</code>
2269 element. Properties set on <code>::first-line</code> are inherited by
2270 <code>::first-letter</code>, but are overridden if the same property is set on
2271 <code>::first-letter</code>.</p>
2272 </div>
2273
2274
2275 <h4><a name=UIfragments>7.3.</a> <a name=selection>The ::selection pseudo-elemen t</a></h4>
2276
2277 <p>The <code>::selection</code> pseudo-element applies to the portion
2278 of a document that has been highlighted by the user. This also
2279 applies, for example, to selected text within an editable text
2280 field. This pseudo-element should not be confused with the <code><a
2281 href="#checked">:checked</a></code> pseudo-class (which used to be
2282 named <code>:selected</code>)
2283
2284 <p>Although the <code>::selection</code> pseudo-element is dynamic in
2285 nature, and is altered by user action, it is reasonable to expect that
2286 when a UA re-renders to a static medium (such as a printed page, see
2287 <a href="#refsCSS21">[CSS21]</a>) which was originally rendered to a
2288 dynamic medium (like screen), the UA may wish to transfer the current
2289 <code>::selection</code> state to that other medium, and have all the
2290 appropriate formatting and rendering take effect as well. This is not
2291 required &mdash; UAs may omit the <code>::selection</code>
2292 pseudo-element for static media.
2293
2294 <p>These are the CSS properties that apply to <code>::selection</code>
2295 pseudo-elements: color, background, cursor (optional), outline
2296 (optional). The computed value of the 'background-image' property on
2297 <code>::selection</code> may be ignored.
2298
2299
2300 <h4><a name=gen-content>7.4. The ::before and ::after pseudo-elements</a></h4>
2301
2302 <p>The <code>::before</code> and <code>::after</code> pseudo-elements
2303 can be used to describe generated content before or after an element's
2304 content. They are explained in CSS 2.1 <a
2305 href="#refsCSS21">[CSS21]</a>.</p>
2306
2307 <p>When the <code>::first-letter</code> and <code>::first-line</code>
2308 pseudo-elements are combined with <code>::before</code> and
2309 <code>::after</code>, they apply to the first letter or line of the
2310 element including the inserted text.</p>
2311
2312 <h2><a name=combinators>8. Combinators</a></h2>
2313
2314 <h3><a name=descendant-combinators>8.1. Descendant combinator</a></h3>
2315
2316 <p>At times, authors may want selectors to describe an element that is
2317 the descendant of another element in the document tree (e.g., "an
2318 <code>EM</code> element that is contained within an <code>H1</code>
2319 element"). Descendant combinators express such a relationship. A
2320 descendant combinator is <a href="#whitespace">white space</a> that
2321 separates two sequences of simple selectors. A selector of the form
2322 "<code>A B</code>" represents an element <code>B</code> that is an
2323 arbitrary descendant of some ancestor element <code>A</code>.
2324
2325 <div class="example">
2326 <p>Examples:</p>
2327 <p>For example, consider the following selector:</p>
2328 <pre>h1 em</pre>
2329 <p>It represents an <code>em</code> element being the descendant of
2330 an <code>h1</code> element. It is a correct and valid, but partial,
2331 description of the following fragment:</p>
2332 <pre>&lt;h1&gt;This &lt;span class="myclass"&gt;headline
2333 is &lt;em&gt;very&lt;/em&gt; important&lt;/span&gt;&lt;/h1&gt;</pre>
2334 <p>The following selector:</p>
2335 <pre>div * p</pre>
2336 <p>represents a <code>p</code> element that is a grandchild or later
2337 descendant of a <code>div</code> element. Note the whitespace on
2338 either side of the "*" is not part of the universal selector; the
2339 whitespace is a combinator indicating that the DIV must be the
2340 ancestor of some element, and that that element must be an ancestor
2341 of the P.</p>
2342 <p>The following selector, which combines descendant combinators and
2343 <a href="#attribute-selectors">attribute selectors</a>, represents an
2344 element that (1) has the <code>href</code> attribute set and (2) is
2345 inside a <code>p</code> that is itself inside a <code>div</code>:</p>
2346 <pre>div p *[href]</pre>
2347 </div>
2348
2349 <h3><a name=child-combinators>8.2. Child combinators</a></h3>
2350
2351 <p>A <dfn>child combinator</dfn> describes a childhood relationship
2352 between two elements. A child combinator is made of the
2353 &quot;greater-than sign&quot; (<code>&gt;</code>) character and
2354 separates two sequences of simple selectors.
2355
2356
2357 <div class="example">
2358 <p>Examples:</p>
2359 <p>The following selector represents a <code>p</code> element that is
2360 child of <code>body</code>:</p>
2361 <pre>body &gt; p</pre>
2362 <p>The following example combines descendant combinators and child
2363 combinators.</p>
2364 <pre>div ol&gt;li p</pre><!-- LEAVE THOSE SPACES OUT! see below -->
2365 <p>It represents a <code>p</code> element that is a descendant of an
2366 <code>li</code> element; the <code>li</code> element must be the
2367 child of an <code>ol</code> element; the <code>ol</code> element must
2368 be a descendant of a <code>div</code>. Notice that the optional white
2369 space around the "&gt;" combinator has been left out.</p>
2370 </div>
2371
2372 <p>For information on selecting the first child of an element, please
2373 see the section on the <code><a
2374 href="#structural-pseudos">:first-child</a></code> pseudo-class
2375 above.</p>
2376
2377 <h3><a name=sibling-combinators>8.3. Sibling combinators</a></h3>
2378
2379 <p>There are two different sibling combinators: the adjacent sibling
2380 combinator and the general sibling combinator. In both cases,
2381 non-element nodes (e.g. text between elements) are ignored when
2382 considering adjacency of elements.</p>
2383
2384 <h4><a name=adjacent-sibling-combinators>8.3.1. Adjacent sibling combinator</a>< /h4>
2385
2386 <p>The adjacent sibling combinator is made of the &quot;plus
2387 sign&quot; (U+002B, <code>+</code>) character that separates two
2388 sequences of simple selectors. The elements represented by the two
2389 sequences share the same parent in the document tree and the element
2390 represented by the first sequence immediately precedes the element
2391 represented by the second one.</p>
2392
2393 <div class="example">
2394 <p>Examples:</p>
2395 <p>The following selector represents a <code>p</code> element
2396 immediately following a <code>math</code> element:</p>
2397 <pre>math + p</pre>
2398 <p>The following selector is conceptually similar to the one in the
2399 previous example, except that it adds an attribute selector &mdash; it
2400 adds a constraint to the <code>h1</code> element, that it must have
2401 <code>class="opener"</code>:</p>
2402 <pre>h1.opener + h2</pre>
2403 </div>
2404
2405
2406 <h4><a name=general-sibling-combinators>8.3.2. General sibling combinator</a></h 4>
2407
2408 <p>The general sibling combinator is made of the &quot;tilde&quot;
2409 (U+007E, <code>~</code>) character that separates two sequences of
2410 simple selectors. The elements represented by the two sequences share
2411 the same parent in the document tree and the element represented by
2412 the first sequence precedes (not necessarily immediately) the element
2413 represented by the second one.</p>
2414
2415 <div class="example">
2416 <p>Example:</p>
2417 <pre>h1 ~ pre</pre>
2418 <p>represents a <code>pre</code> element following an <code>h1</code>. It
2419 is a correct and valid, but partial, description of:</p>
2420 <pre>&lt;h1&gt;Definition of the function a&lt;/h1&gt;
2421 &lt;p&gt;Function a(x) has to be applied to all figures in the table.&lt;/p&gt;
2422 &lt;pre&gt;function a(x) = 12x/13.5&lt;/pre&gt;</pre>
2423 </div>
2424
2425 <h2><a name=specificity>9. Calculating a selector's specificity</a></h2>
2426
2427 <p>A selector's specificity is calculated as follows:</p>
2428
2429 <ul>
2430 <li>count the number of ID selectors in the selector (= a)</li>
2431 <li>count the number of class selectors, attributes selectors, and pseudo-clas ses in the selector (= b)</li>
2432 <li>count the number of element names in the selector (= c)</li>
2433 <li>ignore pseudo-elements</li>
2434 </ul>
2435
2436 <p>Selectors inside <a href="#negation">the negation pseudo-class</a>
2437 are counted like any other, but the negation itself does not count as
2438 a pseudo-class.</p>
2439
2440 <p>Concatenating the three numbers a-b-c (in a number system with a
2441 large base) gives the specificity.</p>
2442
2443 <div class="example">
2444 <p>Examples:</p>
2445 <pre>* /* a=0 b=0 c=0 -&gt; specificity = 0 */
2446 LI /* a=0 b=0 c=1 -&gt; specificity = 1 */
2447 UL LI /* a=0 b=0 c=2 -&gt; specificity = 2 */
2448 UL OL+LI /* a=0 b=0 c=3 -&gt; specificity = 3 */
2449 H1 + *[REL=up] /* a=0 b=1 c=1 -&gt; specificity = 11 */
2450 UL OL LI.red /* a=0 b=1 c=3 -&gt; specificity = 13 */
2451 LI.red.level /* a=0 b=2 c=1 -&gt; specificity = 21 */
2452 #x34y /* a=1 b=0 c=0 -&gt; specificity = 100 */
2453 #s12:not(FOO) /* a=1 b=0 c=1 -&gt; specificity = 101 */
2454 </pre>
2455 </div>
2456
2457 <p class="note"><strong>Note:</strong> the specificity of the styles
2458 specified in an HTML <code>style</code> attribute is described in CSS
2459 2.1. <a href="#refsCSS21">[CSS21]</a>.</p>
2460
2461 <h2><a name=w3cselgrammar>10. The grammar of Selectors</a></h2>
2462
2463 <h3><a name=grammar>10.1. Grammar</a></h3>
2464
2465 <p>The grammar below defines the syntax of Selectors. It is globally
2466 LL(1) and can be locally LL(2) (but note that most UA's should not use
2467 it directly, since it doesn't express the parsing conventions). The
2468 format of the productions is optimized for human consumption and some
2469 shorthand notations beyond Yacc (see <a href="#refsYACC">[YACC]</a>)
2470 are used:</p>
2471
2472 <ul>
2473 <li><b>*</b>: 0 or more
2474 <li><b>+</b>: 1 or more
2475 <li><b>?</b>: 0 or 1
2476 <li><b>|</b>: separates alternatives
2477 <li><b>[ ]</b>: grouping </li>
2478 </ul>
2479
2480 <p>The productions are:</p>
2481
2482 <pre>selectors_group
2483 : selector [ COMMA S* selector ]*
2484 ;
2485
2486 selector
2487 : simple_selector_sequence [ combinator simple_selector_sequence ]*
2488 ;
2489
2490 combinator
2491 /* combinators can be surrounded by white space */
2492 : PLUS S* | GREATER S* | TILDE S* | S+
2493 ;
2494
2495 simple_selector_sequence
2496 : [ type_selector | universal ]
2497 [ HASH | class | attrib | pseudo | negation ]*
2498 | [ HASH | class | attrib | pseudo | negation ]+
2499 ;
2500
2501 type_selector
2502 : [ namespace_prefix ]? element_name
2503 ;
2504
2505 namespace_prefix
2506 : [ IDENT | '*' ]? '|'
2507 ;
2508
2509 element_name
2510 : IDENT
2511 ;
2512
2513 universal
2514 : [ namespace_prefix ]? '*'
2515 ;
2516
2517 class
2518 : '.' IDENT
2519 ;
2520
2521 attrib
2522 : '[' S* [ namespace_prefix ]? IDENT S*
2523 [ [ PREFIXMATCH |
2524 SUFFIXMATCH |
2525 SUBSTRINGMATCH |
2526 '=' |
2527 INCLUDES |
2528 DASHMATCH ] S* [ IDENT | STRING ] S*
2529 ]? ']'
2530 ;
2531
2532 pseudo
2533 /* '::' starts a pseudo-element, ':' a pseudo-class */
2534 /* Exceptions: :first-line, :first-letter, :before and :after. */
2535 /* Note that pseudo-elements are restricted to one per selector and */
2536 /* occur only in the last simple_selector_sequence. */
2537 : ':' ':'? [ IDENT | functional_pseudo ]
2538 ;
2539
2540 functional_pseudo
2541 : FUNCTION S* expression ')'
2542 ;
2543
2544 expression
2545 /* In CSS3, the expressions are identifiers, strings, */
2546 /* or of the form "an+b" */
2547 : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
2548 ;
2549
2550 negation
2551 : NOT S* negation_arg S* ')'
2552 ;
2553
2554 negation_arg
2555 : type_selector | universal | HASH | class | attrib | pseudo
2556 ;</pre>
2557
2558
2559 <h3><a name=lex>10.2. Lexical scanner</a></h3>
2560
2561 <p>The following is the <a name=x3>tokenizer</a>, written in Flex (see
2562 <a href="#refsFLEX">[FLEX]</a>) notation. The tokenizer is
2563 case-insensitive.</p>
2564
2565 <p>The two occurrences of "\377" represent the highest character
2566 number that current versions of Flex can deal with (decimal 255). They
2567 should be read as "\4177777" (decimal 1114111), which is the highest
2568 possible code point in Unicode/ISO-10646. <a
2569 href="#refsUNICODE">[UNICODE]</a></p>
2570
2571 <pre>%option case-insensitive
2572
2573 ident [-]?{nmstart}{nmchar}*
2574 name {nmchar}+
2575 nmstart [_a-z]|{nonascii}|{escape}
2576 nonascii [^\0-\177]
2577 unicode \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?
2578 escape {unicode}|\\[^\n\r\f0-9a-f]
2579 nmchar [_a-z0-9-]|{nonascii}|{escape}
2580 num [0-9]+|[0-9]*\.[0-9]+
2581 string {string1}|{string2}
2582 string1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*\"
2583 string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
2584 invalid {invalid1}|{invalid2}
2585 invalid1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*
2586 invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
2587 nl \n|\r\n|\r|\f
2588 w [ \t\r\n\f]*
2589
2590 %%
2591
2592 [ \t\r\n\f]+ return S;
2593
2594 "~=" return INCLUDES;
2595 "|=" return DASHMATCH;
2596 "^=" return PREFIXMATCH;
2597 "$=" return SUFFIXMATCH;
2598 "*=" return SUBSTRINGMATCH;
2599 {ident} return IDENT;
2600 {string} return STRING;
2601 {ident}"(" return FUNCTION;
2602 {num} return NUMBER;
2603 "#"{name} return HASH;
2604 {w}"+" return PLUS;
2605 {w}"&gt;" return GREATER;
2606 {w}"," return COMMA;
2607 {w}"~" return TILDE;
2608 ":not(" return NOT;
2609 @{ident} return ATKEYWORD;
2610 {invalid} return INVALID;
2611 {num}% return PERCENTAGE;
2612 {num}{ident} return DIMENSION;
2613 "&lt;!--" return CDO;
2614 "--&gt;" return CDC;
2615
2616 "url("{w}{string}{w}")" return URI;
2617 "url("{w}([!#$%&*-~]|{nonascii}|{escape})*{w}")" return URI;
2618 U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
2619
2620 \/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
2621
2622 . return *yytext;</pre>
2623
2624
2625
2626 <h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
2627
2628 <p>An important issue is the interaction of CSS selectors with XML
2629 documents in web clients that were produced prior to this
2630 document. Unfortunately, due to the fact that namespaces must be
2631 matched based on the URI which identifies the namespace, not the
2632 namespace prefix, some mechanism is required to identify namespaces in
2633 CSS by their URI as well. Without such a mechanism, it is impossible
2634 to construct a CSS style sheet which will properly match selectors in
2635 all cases against a random set of XML documents. However, given
2636 complete knowledge of the XML document to which a style sheet is to be
2637 applied, and a limited use of namespaces within the XML document, it
2638 is possible to construct a style sheet in which selectors would match
2639 elements and attributes correctly.</p>
2640
2641 <p>It should be noted that a down-level CSS client will (if it
2642 properly conforms to CSS forward compatible parsing rules) ignore all
2643 <code>@namespace</code> at-rules, as well as all style rules that make
2644 use of namespace qualified element type or attribute selectors. The
2645 syntax of delimiting namespace prefixes in CSS was deliberately chosen
2646 so that down-level CSS clients would ignore the style rules rather
2647 than possibly match them incorrectly.</p>
2648
2649 <p>The use of default namespaces in CSS makes it possible to write
2650 element type selectors that will function in both namespace aware CSS
2651 clients as well as down-level clients. It should be noted that
2652 down-level clients may incorrectly match selectors against XML
2653 elements in other namespaces.</p>
2654
2655 <p>The following are scenarios and examples in which it is possible to
2656 construct style sheets which would function properly in web clients
2657 that do not implement this proposal.</p>
2658
2659 <ol>
2660 <li>
2661
2662 <p>The XML document does not use namespaces.</p>
2663
2664 <ul>
2665
2666 <li>In this case, it is obviously not necessary to declare or use
2667 namespaces in the style sheet. Standard CSS element type and
2668 attribute selectors will function adequately in a down-level
2669 client.</li>
2670
2671 <li>In a CSS namespace aware client, the default behavior of
2672 element selectors matching without regard to namespace will
2673 function properly against all elements, since no namespaces are
2674 present. However, the use of specific element type selectors that
2675 match only elements that have no namespace ("<code>|name</code>")
2676 will guarantee that selectors will match only XML elements that do
2677 not have a declared namespace. </li>
2678
2679 </ul>
2680
2681 </li>
2682
2683 <li>
2684
2685 <p>The XML document defines a single, default namespace used
2686 throughout the document. No namespace prefixes are used in element
2687 names.</p>
2688
2689 <ul>
2690
2691 <li>In this case, a down-level client will function as if
2692 namespaces were not used in the XML document at all. Standard CSS
2693 element type and attribute selectors will match against all
2694 elements. </li>
2695
2696 </ul>
2697
2698 </li>
2699
2700 <li>
2701
2702 <p>The XML document does <b>not</b> use a default namespace, all
2703 namespace prefixes used are known to the style sheet author, and
2704 there is a direct mapping between namespace prefixes and namespace
2705 URIs. (A given prefix may only be mapped to one namespace URI
2706 throughout the XML document; there may be multiple prefixes mapped
2707 to the same URI).</p>
2708
2709 <ul>
2710
2711 <li>In this case, the down-level client will view and match
2712 element type and attribute selectors based on their fully
2713 qualified name, not the local part as outlined in the <a
2714 href="#typenmsp">Type selectors and Namespaces</a> section. CSS
2715 selectors may be declared using an escaped colon "<code>\:</code>"
2716 to describe the fully qualified names, e.g.
2717 "<code>html\:h1</code>" will match
2718 <code>&lt;html:h1&gt;</code>. Selectors using the qualified name
2719 will only match XML elements that use the same prefix. Other
2720 namespace prefixes used in the XML that are mapped to the same URI
2721 will not match as expected unless additional CSS style rules are
2722 declared for them.</li>
2723
2724 <li>Note that selectors declared in this fashion will
2725 <em>only</em> match in down-level clients. A CSS namespace aware
2726 client will match element type and attribute selectors based on
2727 the name's local part. Selectors declared with the fully
2728 qualified name will not match (unless there is no namespace prefix
2729 in the fully qualified name).</li>
2730
2731 </ul>
2732
2733 </li>
2734
2735 </ol>
2736
2737 <p>In other scenarios: when the namespace prefixes used in the XML are
2738 not known in advance by the style sheet author; or a combination of
2739 elements with no namespace are used in conjunction with elements using
2740 a default namespace; or the same namespace prefix is mapped to
2741 <em>different</em> namespace URIs within the same document, or in
2742 different documents; it is impossible to construct a CSS style sheet
2743 that will function properly against all elements in those documents,
2744 unless, the style sheet is written using a namespace URI syntax (as
2745 outlined in this document or similar) and the document is processed by
2746 a CSS and XML namespace aware client.</p>
2747
2748 <h2><a name=profiling>12. Profiles</a></h2>
2749
2750 <p>Each specification using Selectors must define the subset of W3C
2751 Selectors it allows and excludes, and describe the local meaning of
2752 all the components of that subset.</p>
2753
2754 <p>Non normative examples:
2755
2756 <div class="profile">
2757 <table class="tprofile">
2758 <tbody>
2759 <tr>
2760 <th class="title" colspan=2>Selectors profile</th></tr>
2761 <tr>
2762 <th>Specification</th>
2763 <td>CSS level 1</td></tr>
2764 <tr>
2765 <th>Accepts</th>
2766 <td>type selectors<br>class selectors<br>ID selectors<br>:link,
2767 :visited and :active pseudo-classes<br>descendant combinator
2768 <br>::first-line and ::first-letter pseudo-elements</td></tr>
2769 <tr>
2770 <th>Excludes</th>
2771 <td>
2772
2773 <p>universal selector<br>attribute selectors<br>:hover and :focus
2774 pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
2775 element states pseudo-classes<br>all structural
2776 pseudo-classes<br>negation pseudo-class<br>all
2777 UI element fragments pseudo-elements<br>::before and ::after
2778 pseudo-elements<br>child combinators<br>sibling combinators
2779
2780 <p>namespaces</td></tr>
2781 <tr>
2782 <th>Extra constraints</th>
2783 <td>only one class selector allowed per sequence of simple
2784 selectors</td></tr></tbody></table><br><br>
2785 <table class="tprofile">
2786 <tbody>
2787 <tr>
2788 <th class="title" colspan=2>Selectors profile</th></tr>
2789 <tr>
2790 <th>Specification</th>
2791 <td>CSS level 2</td></tr>
2792 <tr>
2793 <th>Accepts</th>
2794 <td>type selectors<br>universal selector<br>attribute presence and
2795 values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
2796 :active, :hover, :focus, :lang() and :first-child pseudo-classes
2797 <br>descendant combinator<br>child combinator<br>adjacent sibling
2798 combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
2799 and ::after pseudo-elements</td></tr>
2800 <tr>
2801 <th>Excludes</th>
2802 <td>
2803
2804 <p>content selectors<br>substring matching attribute
2805 selectors<br>:target pseudo-classes<br>all UI element
2806 states pseudo-classes<br>all structural pseudo-classes other
2807 than :first-child<br>negation pseudo-class<br>all UI element
2808 fragments pseudo-elements<br>general sibling combinators
2809
2810 <p>namespaces</td></tr>
2811 <tr>
2812 <th>Extra constraints</th>
2813 <td>more than one class selector per sequence of simple selectors (CSS1
2814 constraint) allowed</td></tr></tbody></table>
2815
2816 <p>In CSS, selectors express pattern matching rules that determine which style
2817 rules apply to elements in the document tree.
2818
2819 <p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</c ode>
2820 with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
2821 <pre>h1 a[name]</pre>
2822
2823 <p>All CSS declarations attached to such a selector are applied to elements
2824 matching it. </div>
2825
2826 <div class="profile">
2827 <table class="tprofile">
2828 <tbody>
2829 <tr>
2830 <th class="title" colspan=2>Selectors profile</th></tr>
2831 <tr>
2832 <th>Specification</th>
2833 <td>STTS 3</td>
2834 </tr>
2835 <tr>
2836 <th>Accepts</th>
2837 <td>
2838
2839 <p>type selectors<br>universal selectors<br>attribute selectors<br>class
2840 selectors<br>ID selectors<br>all structural pseudo-classes<br>
2841 all combinators
2842
2843 <p>namespaces</td></tr>
2844 <tr>
2845 <th>Excludes</th>
2846 <td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
2847 <tr>
2848 <th>Extra constraints</th>
2849 <td>some selectors and combinators are not allowed in fragment
2850 descriptions on the right side of STTS declarations.</td></tr></tbody></ta ble>
2851 <form>
2852 <input type="text" name="test10"/>
2853 <input type="text" name="foo"/>
2854 <input type="text" name="foo"/>
2855 <input type="text" name="foo"/>
2856 <input type="text" name="foo"/>
2857 <input type="text" name="foo"/>
2858 <input type="text" name="foo"/>
2859 <input type="text" name="foo"/>
2860 <input type="text" name="foo"/>
2861 <input type="text" name="foo"/>
2862 <input type="text" name="foo"/>
2863 <input type="text" name="foo"/>
2864 <input type="text" name="foo"/>
2865 <input type="text" name="foo"/>
2866 <input type="text" name="foo"/>
2867 <input type="text" name="foo"/>
2868 <input type="text" name="foo"/>
2869 <input type="text" name="foo"/>
2870 <input type="text" name="foo"/>
2871 <input type="text" name="foo"/>
2872 <input type="text" name="foo"/>
2873 <input type="text" name="foo"/>
2874 <input type="text" name="foo"/>
2875 <input type="text" name="foo"/>
2876 <input type="text" name="foo"/>
2877 </form>
2878
2879 <p>Selectors can be used in STTS 3 in two different
2880 manners:
2881 <ol>
2882 <li>a selection mechanism equivalent to CSS selection mechanism: declarations
2883 attached to a given selector are applied to elements matching that selector,
2884 <li>fragment descriptions that appear on the right side of declarations.
2885 </li></ol></div>
2886
2887 <h2><a name=Conformance></a>13. Conformance and requirements</h2>
2888
2889 <p>This section defines conformance with the present specification only.
2890
2891 <p>The inability of a user agent to implement part of this specification due to
2892 the limitations of a particular device (e.g., non interactive user agents will
2893 probably not implement dynamic pseudo-classes because they make no sense without
2894 interactivity) does not imply non-conformance.
2895
2896 <p>All specifications reusing Selectors must contain a <a
2897 href="#profiling">Profile</a> listing the
2898 subset of Selectors it accepts or excludes, and describing the constraints
2899 it adds to the current specification.
2900
2901 <p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a toke n
2902 which is not allowed at the current parsing point.
2903
2904 <p>User agents must observe the rules for handling parsing errors:
2905 <ul>
2906 <li>a simple selector containing an undeclared namespace prefix is invalid</li >
2907 <li>a selector containing an invalid simple selector, an invalid combinator
2908 or an invalid token is invalid. </li>
2909 <li>a group of selectors containing an invalid selector is invalid.</li>
2910 </ul>
2911
2912 <p class="foo test10 bar">Specifications reusing Selectors must define how to ha ndle parsing
2913 errors. (In the case of CSS, the entire rule in which the selector is
2914 used is dropped.)</p>
2915
2916 <!-- Apparently all these references are out of date:
2917 <p>Implementations of this specification must behave as
2918 "recipients of text data" as defined by <a href="#refsCWWW">[CWWW]</a>
2919 when parsing selectors and attempting matches. (In particular,
2920 implementations must assume the data is normalized and must not
2921 normalize it.) Normative rules for matching strings are defined in
2922 <a href="#refsCWWW">[CWWW]</a> and <a
2923 href="#refsUNICODE">[UNICODE]</a> and apply to implementations of this
2924 specification.</p>-->
2925
2926 <h2><a name=Tests></a>14. Tests</h2>
2927
2928 <p>This specification has <a
2929 href="http://www.w3.org/Style/CSS/Test/CSS3/Selectors/current/">a test
2930 suite</a> allowing user agents to verify their basic conformance to
2931 the specification. This test suite does not pretend to be exhaustive
2932 and does not cover all possible combined cases of Selectors.</p>
2933
2934 <h2><a name=ACKS></a>15. Acknowledgements</h2>
2935
2936 <p>The CSS working group would like to thank everyone who has sent
2937 comments on this specification over the years.</p>
2938
2939 <p>The working group would like to extend special thanks to Donna
2940 McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
2941 the final editorial review.</p>
2942
2943 <h2><a name=references>16. References</a></h2>
2944
2945 <dl class="refs">
2946
2947 <dt>[CSS1]
2948 <dd><a name=refsCSS1></a> Bert Bos, H&aring;kon Wium Lie; "<cite>Cascading Sty le Sheets, level 1</cite>", W3C Recommendation, 17 Dec 1996, revised 11 Jan 1999
2949 <dd>(<code><a href="http://www.w3.org/TR/REC-CSS1">http://www.w3.org/TR/REC-CS S1</a></code>)
2950
2951 <dt>[CSS21]
2952 <dd><a name=refsCSS21></a> Bert Bos, Tantek &Ccedil;elik, Ian Hickson, H&aring ;kon Wium Lie, editors; "<cite>Cascading Style Sheets, level 2 revision 1</cite> ", W3C Working Draft, 13 June 2005
2953 <dd>(<code><a href="http://www.w3.org/TR/CSS21">http://www.w3.org/TR/CSS21</a> </code>)
2954
2955 <dt>[CWWW]
2956 <dd><a name=refsCWWW></a> Martin J. D&uuml;rst, Fran&ccedil;ois Yergeau, Misha Wolf, Asmus Freytag, Tex Texin, editors; "<cite>Character Model for the World W ide Web</cite>", W3C Recommendation, 15 February 2005
2957 <dd>(<code><a href="http://www.w3.org/TR/charmod/">http://www.w3.org/TR/charmo d/</a></code>)
2958
2959 <dt>[FLEX]
2960 <dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>" , Version 2.3.7, ISBN 1882114213
2961
2962 <dt>[HTML4]
2963 <dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
2964 <dd>(<a href="http://www.w3.org/TR/html4/"><code>http://www.w3.org/TR/html4/</ code></a>)
2965
2966 <dt>[MATH]
2967 <dd><a name="refsMATH"></a> Patrick Ion, Robert Miner, editors; "<cite>Mathema tical Markup Language (MathML) 1.01</cite>", W3C Recommendation, revision of 7 J uly 1999
2968 <dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC -MathML/</a></code>)
2969
2970 <dt>[RFC3066]
2971 <dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identificati on of Languages</cite>", Request for Comments 3066, January 2001
2972 <dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/r fc/rfc3066.txt</code></a>)
2973
2974 <dt>[STTS]
2975 <dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sh eets 3</cite>", Electricit&eacute; de France, submission to the W3C, 11 November 1998
2976 <dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE -STTS3</a></code>)
2977
2978 <dt>[SVG]
2979 <dd><a name="refsSVG"></a> Jon Ferraiolo, &#34276;&#27810; &#28147;, Dean Jack son, editors; "<cite>Scalable Vector Graphics (SVG) 1.1 Specification</cite>", W 3C Recommendation, 14 January 2003
2980 <dd>(<code><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></ code>)
2981
2982 <dt>[UNICODE]</dt>
2983 <dd><a name="refsUNICODE"></a> <cite><a
2984 href="http://www.unicode.org/versions/Unicode4.1.0/">The Unicode Standard, Ve rsion 4.1</a></cite>, The Unicode Consortium. Boston, MA, Addison-Wesley, March 2005. ISBN 0-321-18578-1, as amended by <a href="http://www.unicode.org/versions /Unicode4.0.1/">Unicode 4.0.1</a> and <a href="http://www.unicode.org/versions/U nicode4.1.0/">Unicode 4.1.0</a>.
2985 <dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/v ersions/</a></code>)</dd>
2986
2987 <dt>[XML10]
2988 <dd><a name="refsXML10"></a> Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, Fran&ccedil;ois Yergeau, editors; "<cite>Extensible Markup Language (XML ) 1.0 (Third Edition)</cite>", W3C Recommendation, 4 February 2004
2989 <dd>(<a href="http://www.w3.org/TR/REC-xml/"><code>http://www.w3.org/TR/REC-xm l/</code></a>)
2990
2991 <dt>[XMLNAMES]
2992 <dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, edito rs; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
2993 <dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/ REC-xml-names/</code></a>)
2994
2995 <dt>[YACC]
2996 <dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC &mdash; Yet another com piler compiler</cite>", Technical Report, Murray Hill, 1975
2997
2998 </dl>
2999 </body>
3000 </html>
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