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2 <head>
4 <script>
8 // Try to force real results
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46 };
47 </script>
48 </head>
49 <body>
51 <p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org/Icons/w3c_home" width=72></a>
57 <dl>
59 <dt>This version:
64 <dt>Latest version:
67 http://www.w3.org/TR/css3-selectors</a>
69 <dt>Previous version:
78 <dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/">Tantek Çelik</a> (Invited Expert)
89 </dl>
100 <a
102 <a
104 <a
106 use</a> rules apply.
110 </div>
115 tree. Selectors have been optimized for use with HTML and XML, and
116 are designed to be usable in performance-critical code.</p>
119 Style Sheets) is a language for describing the rendering of <acronym
122 screen, on paper, in speech, etc. CSS uses Selectors for binding
123 style properties to elements in the document. This document
124 describes extensions to the selectors defined in CSS level 2. These
125 extended selectors will be used by CSS level 3.
131 <p>That is, given an element and a selector, this specification
132 defines whether that element matches the selector.</p>
134 <p>These expressions can also be used, for instance, to select a set
135 of elements, or a single element from a set of elements, by
136 evaluating the expression across all the elements in a
143 <p><em>This section describes the status of this document at the
144 time of its publication. Other documents may supersede this
145 document. A list of current W3C publications and the latest revision
146 of this technical report can be found in the <a
148 http://www.w3.org/TR/.</a></em></p>
156 <p>The CSS Working Group doesn't expect that all implementations of
157 CSS3 will have to implement all selectors. Instead, there will
158 probably be a small number of variants of CSS3, called profiles. For
159 example, it may be that only a profile for interactive user agents
160 will include all of the selectors.</p>
165 document is a revision of the <a
168 implementation feedback received in the past few years. It is
169 expected that this last call will proceed straight to Proposed
170 Recommendation stage since it is believed that interoperability will
171 be demonstrable.</p>
173 <p>All persons are encouraged to review and implement this
174 specification and return comments to the (<a
176 public mailing list <a
179 Members can also send comments directly to the CSS Working
180 Group.
183 <p>This is still a draft document and may be updated, replaced, or
184 obsoleted by other documents at any time. It is inappropriate to
189 The English version of this specification is the only normative
190 version.
198 <ul>
202 </ul>
212 </ul>
214 <ul>
216 </ul>
219 <li class="tocline4"><a href="#attribute-representation">6.3.1. Representation of attributes and attributes values</a>
223 </ul>
233 <ul>
246 </ul>
248 </ul>
249 </li>
250 </ul>
252 <ul>
257 </ul>
264 <li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adjacent sibling combinator</a>
265 <li class="tocline4"><a href="#general-sibling-combinators">8.3.2. General sibling combinator</a></li>
266 </ul>
267 </li>
268 </ul>
274 </ul>
281 </ul>
283 </div>
289 <p>Some features of this specification are specific to CSS, or have
290 particular limitations or rules specific to CSS. In this
291 specification, these have been described in terms of CSS2.1. <a
296 <p>All of the text of this specification is normative except
297 examples, notes, and sections explicitly marked as
298 non-normative.</p>
304 <p>The main differences between the selectors in CSS2 and those in
305 Selectors are:
307 <ul>
309 <li>the list of basic definitions (selector, group of selectors,
310 simple selector, etc.) has been changed; in particular, what was
311 referred to in CSS2 as a simple selector is now called a sequence
312 of simple selectors, and the term "simple selector" is now used for
313 the components of this sequence</li>
315 <li>an optional namespace component is now allowed in type element
316 selectors, the universal selector and attribute selectors</li>
320 <li>new simple selectors including substring matching attribute
321 selectors, and new pseudo-classes</li>
324 for pseudo-elements</li>
328 <li>profiles to be added to specifications integrating Selectors
329 and defining the set of selectors which is actually supported by
330 each specification</li>
332 <li>Selectors are now a CSS3 Module and an independent
333 specification; other specifications can now refer to this document
334 independently of CSS</li>
338 </ul>
342 <p><em>This section is non-normative, as it merely summarizes the
343 following sections.</em></p>
345 <p>A Selector represents a structure. This structure can be used as a
346 condition (e.g. in a CSS rule) that determines which elements a
347 selector matches in the document tree, or as a flat description of the
348 HTML or XML fragment corresponding to that structure.</p>
350 <p>Selectors may range from simple element names to rich contextual
351 representations.</p>
356 <thead>
357 <tr>
362 <tbody>
363 <tr>
368 selector</a></td>
370 <tr>
376 <tr>
381 selectors</a></td>
383 <tr>
389 selectors</a></td>
391 <tr>
397 selectors</a></td>
399 <tr>
405 selectors</a></td>
407 <tr>
413 selectors</a></td>
415 <tr>
421 selectors</a></td>
423 <tr>
429 selectors</a></td>
431 <tr>
436 pseudo-classes</a></td>
438 <tr>
443 pseudo-classes</a></td>
445 <tr>
448 from the last one</td>
451 pseudo-classes</a></td>
453 <tr>
458 pseudo-classes</a></td>
460 <tr>
463 from the last one</td>
466 pseudo-classes</a></td>
468 <tr>
473 pseudo-classes</a></td>
475 <tr>
480 pseudo-classes</a></td>
482 <tr>
487 pseudo-classes</a></td>
489 <tr>
494 pseudo-classes</a></td>
496 <tr>
501 pseudo-classes</a></td>
503 <tr>
508 pseudo-classes</a></td>
510 <tr>
513 nodes)</td>
516 pseudo-classes</a></td>
518 <tr>
521 which the target is not yet visited (:link) or already visited
522 (:visited)</td>
525 pseudo-classes</a></td>
527 <tr>
532 action pseudo-classes</a></td>
534 <tr>
539 pseudo-class</a></td>
541 <tr>
544 language specifies how language is determined)</td>
547 pseudo-class</a></td>
549 <tr>
552 disabled</td>
555 pseudo-classes</a></td>
557 <tr>
563 pseudo-classes</a></td>
565 <tr>
570 pseudo-element</a></td>
572 <tr>
577 pseudo-element</a></td>
579 <tr>
582 selected/highlighted by the user</td>
585 fragments pseudo-elements</a></td>
587 <tr>
592 pseudo-element</a></td>
594 <tr>
599 pseudo-element</a></td>
601 <tr>
607 selectors</a></td>
609 <tr>
614 selectors</a></td>
616 <tr>
621 pseudo-class</a></td>
623 <tr>
628 combinator</a></td>
630 <tr>
635 combinator</a></td>
637 <tr>
643 <tr>
650 <p>The meaning of each selector is derived from the table above by
652 column.</p>
656 <p>The case sensitivity of document language element names, attribute
657 names, and attribute values in selectors depends on the document
658 language. For example, in HTML, element names are case-insensitive,
659 but in XML, they are case-sensitive.</p>
672 selector or universal selector is allowed in the sequence.</p>
684 sequence of simple selectors.</p>
689 space may appear between a combinator and the simple selectors around
694 never part of white space.</p>
696 <p>The elements of a document tree that are represented by a selector
698 selector consisting of a single sequence of simple selectors
699 represents any element satisfying its requirements. Prepending another
700 sequence of simple selectors and a combinator to a sequence imposes
701 additional matching constraints, so the subjects of a selector are
702 always a subset of the elements represented by the last sequence of
703 simple selectors.</p>
705 <p>An empty selector, containing no sequence of simple selectors and
711 <p>When several selectors share the same declarations, they may be
716 <p>In this example, we condense three rules with identical
717 declarations into one. Thus,</p>
718 <pre>h1 { font-family: sans-serif }
719 h2 { font-family: sans-serif }
720 h3 { font-family: sans-serif }</pre>
723 </div>
726 because all the selectors are valid selectors. If just one of these
727 selectors were invalid, the entire group of selectors would be
728 invalid. This would invalidate the rule for all three heading
729 elements, whereas in the former case only one of the three individual
730 heading rules would be invalidated.</p>
738 element type. A type selector represents an instance of the element
739 type in the document tree.</p>
745 </div>
752 that has been previously declared may be prepended to the element name
756 <p>The namespace component may be left empty to indicate that the
757 selector is only to represent elements with no declared namespace.</p>
759 <p>An asterisk may be used for the namespace prefix, indicating that
760 the selector represents elements in any namespace (including elements
761 with no namespace).</p>
763 <p>Element type selectors that have no namespace component (no
764 namespace separator), represent elements without regard to the
765 element's namespace (equivalent to "<code>*|</code>") unless a default
766 namespace has been declared. If a default namespace has been declared,
767 the selector will represent only elements in the default
768 namespace.</p>
770 <p>A type selector containing a namespace prefix that has not been
772 The mechanism for declaring a namespace prefix is left up to the
773 language implementing Selectors. In CSS, such a mechanism is defined
774 in the General Syntax module.</p>
776 <p>In a namespace-aware client, element type selectors will only match
777 against the <a
779 of the element's <a
782 behaviors in down-level clients.</p>
786 <dl>
790 <dd>elements with name E in any namespace, including those without any
791 declared namespace</dd>
795 <dd>if no default namespace has been specified, this is equivalent to *|E.
796 Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
797 </dl>
802 <pre>@namespace foo url(http://www.example.com);
803 foo|h1 { color: blue }
804 foo|* { color: yellow }
805 |h1 { color: red }
806 *|h1 { color: green }
807 h1 { color: green }</pre>
812 <p>The second rule will match all elements in the
816 any declared namespace.</p>
819 namespace (including those without any declared namespace).</p>
821 <p>The last rule is equivalent to the fourth rule because no default
822 namespace has been defined.</p>
824 </div>
830 type. It represents any single element in the document tree in any
831 namespace (including those without any declared namespace) if no
832 default namespace has been specified. If a default namespace has been
836 <p>If the universal selector is not the only component of a sequence
841 <ul>
845 </ul>
846 </div>
850 omitted.</p>
854 <p>The universal selector allows an optional namespace component. It
855 is used as follows:</p>
857 <dl>
865 <dd>if no default namespace has been specified, this is equivalent to *|*.
866 Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
867 </dl>
869 <p>A universal selector containing a namespace prefix that has not
871 selector. The mechanism for declaring a namespace prefix is left up
872 to the language implementing Selectors. In CSS, such a mechanism is
873 defined in the General Syntax module.</p>
878 <p>Selectors allow the representation of an element's attributes. When
879 a selector is used as an expression to match against an element,
880 attribute selectors must be considered to match an element if that
881 element has an attribute that matches the attribute represented by the
882 attribute selector.</p>
885 selectors</a></h4>
889 <dl>
892 the attribute.</dd>
901 spaces).</dd>
911 </dl>
913 <p>Attribute values must be identifiers or strings. The
914 case-sensitivity of attribute names and values in selectors depends on
915 the document language.</p>
923 value:</p>
927 <p>In the following example, the selector represents a
933 <p>Multiple attribute selectors can be used to represent several
934 attributes of an element, or several conditions on the same
943 and "~=". The first selector will represent, for example, the value
963 <p>Similarly, the following selectors represents a
967 <pre>DIALOGUE[character=romeo]
968 DIALOGUE[character=juliet]</pre>
970 </div>
973 selectors</h4>
975 <p>Three additional attribute selectors are provided for matching
976 substrings in the value of an attribute:</p>
978 <dl>
988 </dl>
990 <p>Attribute values must be identifiers or strings. The
991 case-sensitivity of attribute names in selectors depends on the
992 document language.</p>
997 image:</p>
1005 </div>
1009 <p>Attribute selectors allow an optional namespace component to the
1010 attribute name. A namespace prefix that has been previously declared
1011 may be prepended to the attribute name separated by the namespace
1013 the Namespaces in the XML recommendation, default namespaces do not
1014 apply to attributes, therefore attribute selectors without a namespace
1015 component apply only to attributes that have no declared namespace
1016 (equivalent to "<code>|attr</code>"). An asterisk may be used for the
1017 namespace prefix indicating that the selector is to match all
1018 attribute names without regard to the attribute's namespace.
1020 <p>An attribute selector with an attribute name containing a namespace
1021 prefix that has not been previously declared is an <a
1023 a namespace prefix is left up to the language implementing Selectors.
1024 In CSS, such a mechanism is defined in the General Syntax module.
1029 [foo|att=val] { color: blue }
1030 [*|att] { color: yellow }
1031 [|att] { color: green }
1032 [att] { color: green }</pre>
1034 <p>The first rule will match only elements with the attribute
1038 <p>The second rule will match only elements with the attribute
1040 (including no declared namespace).</p>
1042 <p>The last two rules are equivalent and will match only elements
1044 declared to be in a namespace.</p>
1046 </div>
1050 <p>Attribute selectors represent explicitly set attribute values in
1051 the document tree. Default attribute values may be defined in a DTD or
1052 elsewhere, but cannot always be selected by attribute
1053 selectors. Selectors should be designed so that they work even if the
1054 default values are not included in the document tree.</p>
1063 knowledge of that namespace to treat default attribute values as if
1064 they were present in the document. (For example, an XHTML UA is not
1065 required to use its built-in knowledge of the XHTML DTD.)</p>
1068 choose to ignore external subsets.</p>
1080 <pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
1081 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1084 is set by default, i.e. not set explicitly. To catch all cases, the
1085 attribute selector for the default value must be dropped:</p>
1087 <pre>EXAMPLE { /*... default property settings ...*/ }
1088 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1091 more specific than the tag
1092 selector alone, the style declarations in the second rule will override
1093 those in the first for elements that have a "notation" attribute value
1094 of "octal". Care has to be taken that all property declarations that
1095 are to apply only to the default case are overridden in the non-default
1096 cases' style rules.</p>
1098 </div>
1106 the same meaning. The attribute value must immediately follow the
1109 <p>UAs may apply selectors using the period (.) notation in XML
1110 documents if the UA has namespace-specific knowledge that allows it to
1112 respective namespace. One such example of namespace-specific knowledge
1113 is the prose in the specification for a particular namespace (e.g. SVG
1124 <p>We can assign style information to all elements with
1133 <p>The following assigns style only to H1 elements with
1138 <p>Given these rules, the first H1 instance below would not have
1139 green text, while the second would:</p>
1144 </div>
1154 has been assigned a list of <a
1164 </div>
1167 power to the "class" attribute, authors could conceivably design their
1168 own "document language" based on elements with almost no associated
1169 presentation (such as DIV and SPAN in HTML) and assigning style
1170 information through the "class" attribute. Authors should avoid this
1171 practice since the structural elements of a document language often
1172 have recognized and accepted meanings and author-defined classes may
1173 not.</p>
1176 class attributes, their values must be concatenated with spaces
1177 between the values before searching for the class. As of this time the
1178 working group is not aware of any manner in which this situation can
1179 be reached, however, so this behavior is explicitly non-normative in
1180 this specification.</p>
1184 <p>Document languages may contain attributes that are declared to be
1185 of type ID. What makes attributes of type ID special is that no two
1186 such attributes can have the same value in a document, regardless of
1187 the type of the elements that carry them; whatever the document
1188 language, an ID typed attribute can be used to uniquely identify its
1189 element. In HTML all ID attributes are named "id"; XML applications
1190 may name ID attributes differently, but the same restriction
1191 applies.</p>
1193 <p>An ID-typed attribute of a document language allows authors to
1194 assign an identifier to one element instance in the document tree. W3C
1195 ID selectors represent an element instance based on its identifier. An
1198 identifier.</p>
1200 <p>Selectors does not specify how a UA knows the ID-typed attribute of
1201 an element. The UA may, e.g., read a document's DTD, have the
1202 information hard-coded or ask the user.
1209 <p>The following ID selector represents any element whose ID-typed
1212 <p>The following selector represents any element whose ID-typed
1215 </div>
1219 contains an element's IDs is contained in a DTD or a schema. When
1220 parsing XML, UAs do not always read the DTD, and thus may not know
1221 what the ID of an element is (though a UA may have namespace-specific
1222 knowledge that allows it to determine which attribute is the ID
1223 attribute for that namespace). If a style sheet designer knows or
1224 suspects that a UA may not know what the ID of an element is, he
1225 should use normal attribute selectors instead:
1229 <p>If an element has multiple ID attributes, all of them must be
1230 treated as IDs for that element for the purposes of the ID
1231 selector. Such a situation could be reached using mixtures of xml:id,
1232 DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
1236 <p>The pseudo-class concept is introduced to permit selection based on
1237 information that lies outside of the document tree or that cannot be
1238 expressed using the other simple selectors.</p>
1242 optionally by a value between parentheses.</p>
1244 <p>Pseudo-classes are allowed in all sequences of simple selectors
1245 contained in a selector. Pseudo-classes are allowed anywhere in
1246 sequences of simple selectors, after the leading type selector or
1247 universal selector (possibly omitted). Pseudo-class names are
1248 case-insensitive. Some pseudo-classes are mutually exclusive, while
1249 others can be applied simultaneously to the same
1250 element. Pseudo-classes may be dynamic, in the sense that an element
1251 may acquire or lose a pseudo-class while a user interacts with the
1252 document.</p>
1257 <p>Dynamic pseudo-classes classify elements on characteristics other
1258 than their name, attributes, or content, in principle characteristics
1259 that cannot be deduced from the document tree.</p>
1261 <p>Dynamic pseudo-classes do not appear in the document source or
1262 document tree.</p>
1267 <p>User agents commonly display unvisited links differently from
1268 previously visited ones. Selectors
1272 <ul>
1274 not yet been visited.</li>
1276 been visited by the user. </li>
1277 </ul>
1279 <p>After some amount of time, user agents may choose to return a
1280 visited link to the (unvisited) ':link' state.</p>
1288 <p>The following selector represents links carrying class
1293 </div>
1296 authors to abuse the :link and :visited pseudo-classes to determine
1297 which sites a user has visited without the user's consent.
1299 <p>UAs may therefore treat all links as unvisited links, or implement
1300 other measures to preserve the user's privacy while rendering visited
1301 and unvisited links differently.</p>
1304 :hover, :active, and :focus</a></h5>
1306 <p>Interactive user agents sometimes change the rendering in response
1307 to user actions. Selectors provides
1308 three pseudo-classes for the selection of an element the user is
1309 acting on.</p>
1311 <ul>
1314 designates an element with a pointing device, but does not activate
1315 it. For example, a visual user agent could apply this pseudo-class
1316 when the cursor (mouse pointer) hovers over a box generated by the
1317 element. User agents not that do not support <a
1319 media</a> do not have to support this pseudo-class. Some conforming
1320 user agents that support <a
1322 media</a> may not be able to support this pseudo-class (e.g., a pen
1323 device that does not detect hovering).</li>
1326 is being activated by the user. For example, between the times the
1327 user presses the mouse button and releases it.</li>
1330 has the focus (accepts keyboard or mouse events, or other forms of
1331 input). </li>
1333 </ul>
1335 <p>There may be document language or implementation specific limits on
1339 <p>These pseudo-classes are not mutually exclusive. An element may
1340 match several pseudo-classes at the same time.</p>
1342 <p>Selectors doesn't define if the parent of an element that is
1343 ':active' or ':hover' is also in that state.</p>
1347 <pre>a:link /* unvisited links */
1348 a:visited /* visited links */
1349 a:hover /* user hovers */
1350 a:active /* active links */</pre>
1352 <pre>a:focus
1353 a:focus:hover</pre>
1355 the pseudo-class :focus and in the pseudo-class :hover.</p>
1356 </div>
1359 and ':active' (or ':link' and ':active').</p>
1363 <p>Some URIs refer to a location within a resource. This kind of URI
1365 identifier (called the fragment identifier).</p>
1367 <p>URIs with fragment identifiers link to a certain element within the
1368 document, known as the target element. For instance, here is a URI
1370 document:</p>
1375 pseudo-class. If the document's URI has no fragment identifier, then
1376 the document has no target element.</p>
1383 URI.</p>
1384 </div>
1389 target element red and place an image before it, if there is one:</p>
1390 <pre>*:target { color : red }
1391 *:target::before { content : url(target.png) }</pre>
1392 </div>
1396 <p>If the document language specifies how the human language of an
1397 element is determined, it is possible to write selectors that
1398 represent an element based on its language. For example, in HTML <a
1401 element, and possibly by information from the protocol (such as HTTP
1403 there may be other document language-specific methods for determining
1404 the language.</p>
1407 is in language C. Whether an element is represented by a
1409 being either equal to, or a hyphen-separated substring of, the
1410 element's language value, in the same way as if performed by the <a
1412 selectors. The identifier C does not have to be a valid language
1413 name.</p>
1427 <p>The two following selectors represent an HTML document that is in
1428 Belgian, French, or German. The two next selectors represent
1430 or German.</p>
1431 <pre>html:lang(fr-be)
1432 html:lang(de)
1433 :lang(fr-be) > q
1435 </div>
1442 the look of user interface elements that are enabled — which the
1443 user can select or activate in some fashion (e.g. clicking on a button
1444 with a mouse). There is a need for such a pseudo-class because there
1445 is no way to programmatically specify the default appearance of say,
1447 would look like when it was disabled.</p>
1450 author to specify precisely how a disabled or inactive user interface
1451 element should look.</p>
1453 <p>Most elements will be neither enabled nor disabled. An element is
1454 enabled if the user can either activate it or transfer the focus to
1455 it. An element is disabled if it could be enabled, but the user cannot
1456 presently activate it or transfer focus to it.</p>
1461 <p>Radio and checkbox elements can be toggled by the user. Some menu
1462 items are "checked" when the user selects them. When such elements are
1466 attributes as described in <a
1471 in nature, and is altered by user action, since it can also be based
1480 <p>Radio and checkbox elements can be toggled by the user, but are
1481 sometimes in an indeterminate state, neither checked nor unchecked.
1482 This can be due to an element attribute, or DOM manipulation.</p>
1484 <p>A future version of this specification may introduce an
1486 <!--While the <code>:indeterminate</code> pseudo-class is dynamic in
1487 nature, and is altered by user action, since it can also be based on
1488 the presence of an element attribute, it applies to all media.</p>
1490 <p>Components of a radio-group initialized with no pre-selected choice
1493 </div>
1499 pseudo-classes</dfn> to permit selection based on extra information that lies in
1500 the document tree but cannot be represented by other simple selectors or
1501 combinators.
1503 <p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
1504 not counted when calculating the position of an element in the list of
1505 children of its parent. When calculating the position of an element in
1506 the list of children of its parent, the index numbering starts at 1.
1512 the root of the document. In HTML 4, this is always the
1518 <p>The
1520 pseudo-class notation represents an element that has
1526 each. For example, this allows the selectors to address every other
1527 row in a table, and could be used to alternate the color
1530 integers. The index of the first child of an element is 1.
1541 tr:nth-child(odd) /* same */
1542 tr:nth-child(2n) /* represents every even row of an HTML table */
1543 tr:nth-child(even) /* same */
1545 /* Alternate paragraph colours in CSS */
1550 </div>
1555 included, so the syntax simplifies to
1563 </div>
1571 bar:nth-child(n+0) /* same */
1572 bar:nth-child(n) /* same */
1574 </div>
1583 </div>
1586 pseudo-class represents no element in the document tree.</p>
1591 tree.</p>
1596 </div>
1599 expression must be removed (it is effectively replaced by the "-"
1607 </div>
1613 pseudo-class notation represents an element that has
1619 as arguments.
1626 foo:nth-last-child(odd) /* represents all odd foo elements in their parent element,
1627 counting from the last one */</pre>
1628 </div>
1634 pseudo-class notation represents an element that has
1639 of that type after all the children of that type have been split into
1641 for the syntax of its argument. It also accepts the
1650 </div>
1656 pseudo-class notation represents an element that has
1668 following selector:</p>
1671 selector ends up being just as long:</p>
1673 </div>
1679 represents an element that is the first child of some other element.
1693 fragment:
1701 a:first-child /* Same (assuming a is not the root element) */</pre>
1702 </div>
1707 represents an element that is the last child of some other element.
1714 </div>
1719 represents an element that is the first sibling of its type in the list of
1720 children of its parent element.
1724 <p>The following selector represents a definition title
1727 its parent element.</p>
1730 elements in the following example but not for the third one:</p>
1742 </div>
1748 the last sibling of its type in the list of children of its parent
1749 element.</p>
1753 <p>The following selector represents the last data cell
1756 </div>
1760 <p>Represents an element that has a parent element and whose parent
1761 element has no other element children. Same as
1764 specificity.</p>
1768 <p>Represents an element that has a parent element and whose parent
1769 element has no other element children with the same element name. Same
1772 specificity.</p>
1778 no children at all. In terms of the DOM, only element nodes and text
1779 nodes (including CDATA nodes and entity references) whose data has a
1780 non-zero length must be considered as affecting emptiness; comments,
1781 PIs, and other nodes must not affect whether an element is considered
1782 empty or not.</p>
1789 following fragments:</p>
1793 </div>
1795 <h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appendix H!!! Run away! -->
1798 <!-- (used to be :contains()) -->
1804 selector</a> (excluding the negation pseudo-class itself and
1805 pseudo-elements) as an argument. It represents an element that is not
1806 represented by the argument.
1808 <!-- pseudo-elements are not simple selectors, so the above paragraph
1809 may be a bit confusing -->
1814 elements in an HTML document that are not disabled.</p>
1817 elements.</p>
1819 <p>The following group of selectors represents all HTML elements
1820 except links.</p>
1822 </div>
1824 <p>Default namespace declarations do not affect the argument of the
1825 negation pseudo-class unless the argument is a universal selector or a
1826 type selector.</p>
1830 <p>Assuming that the default namespace is bound to
1831 "http://example.com/", the following selector represents all
1832 elements that are not in that namespace:</p>
1834 <p>The following CSS selector matches any element being hovered,
1835 regardless of its namespace. In particular, it is not limited to
1836 only matching elements in the default namespace that are not being
1837 hovered, and elements not in the default namespace don't match the
1840 </div>
1846 specificity.</p>
1850 <p>Pseudo-elements create abstractions about the document tree beyond
1851 those specified by the document language. For instance, document
1852 languages do not offer mechanisms to access the first letter or first
1853 line of an element's content. Pseudo-elements allow designers to refer
1854 to this otherwise inaccessible information. Pseudo-elements may also
1855 provide designers a way to refer to content that does not exist in the
1858 content).</p>
1861 by the name of the pseudo-element.</p>
1864 in order to establish a discrimination between pseudo-classes and
1865 pseudo-elements. For compatibility with existing style sheets, user
1866 agents must also accept the previous one-colon notation for
1872 <p>Only one pseudo-element may appear per selector, and if present it
1873 must appear after the sequence of simple selectors that represents the
1875 future version of this specification may allow multiple
1876 pesudo-elements per selector.</span></p>
1881 of the first formatted line of an element.
1888 </div>
1891 HTML element. It does match a pseudo-element that conforming user
1892 agents will insert at the beginning of every paragraph.</p>
1894 <p>Note that the length of the first line depends on a number of
1895 factors, including the width of the page, the font size, etc. Thus,
1896 an ordinary HTML paragraph such as:</p>
1898 <pre>
1900 paragraph that will be broken into several
1901 lines. The first line will be identified
1902 by a fictional tag sequence. The other lines
1903 will be treated as ordinary lines in the
1905 </pre>
1907 <p>the lines of which happen to be broken as follows:
1909 <pre>
1910 THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
1911 will be broken into several lines. The first
1912 line will be identified by a fictional tag
1913 sequence. The other lines will be treated as
1914 ordinary lines in the paragraph.
1915 </pre>
1919 fictional tag sequence helps to show how properties are inherited.</p>
1921 <pre>
1924 lines. The first line will be identified
1925 by a fictional tag sequence. The other lines
1926 will be treated as ordinary lines in the
1928 </pre>
1930 <p>If a pseudo-element breaks up a real element, the desired effect
1931 can often be described by a fictional tag sequence that closes and
1932 then re-opens the element. Thus, if we mark up the previous paragraph
1935 <pre>
1937 paragraph that will be broken into several
1939 by a fictional tag sequence. The other lines
1940 will be treated as ordinary lines in the
1942 </pre>
1944 <p>the user agent could simulate start and end tags for
1948 <pre>
1950 somewhat long HTML
1951 paragraph that will <b></SPAN></b></P::first-line><b><SPAN class="test"></b> be
1952 broken into several
1954 by a fictional tag sequence. The other lines
1955 will be treated as ordinary lines in the
1957 </pre>
1960 attached to a block-level element, an inline-block, a table-caption,
1961 or a table-cell.</p>
1964 element may occur inside a
1965 block-level descendant in the same flow (i.e., a block-level
1966 descendant that is not positioned and not a float). E.g., the first
1971 <p>The first line of a table-cell or inline-block cannot be the first
1982 <p>A UA should act as if the fictional start tags of the
1984 innermost enclosing block-level element. (Since CSS1 and CSS2 were
1985 silent on this case, authors should not rely on this behavior.) Here
1986 is an example. The fictional tag sequence for</p>
1988 <pre>
1993 </pre>
1997 <pre>
1999 <P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P>
2002 </pre>
2005 inline-level element, but with certain restrictions. In CSS, the
2007 pseudo-element: font properties, color property, background
2008 properties, 'word-spacing', 'letter-spacing', 'text-decoration',
2009 'vertical-align', 'text-transform', 'line-height'. UAs may apply other
2010 properties as well.</p>
2016 letter of the first line of a block, if it is not preceded by any
2017 other content (such as images or inline tables) on its line. The
2019 caps", which are common typographical effects. This type of initial
2020 letter is similar to an inline-level element if its 'float' property
2021 is 'none'; otherwise, it is similar to a floated element.</p>
2024 pseudo-elements: font properties, 'text-decoration', 'text-transform',
2025 'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
2026 'float', 'vertical-align' (only if 'float' is 'none'), margin
2027 properties, padding properties, border properties, color property,
2028 background properties. UAs may apply other properties as well. To
2029 allow UAs to render a typographically correct drop cap or initial cap,
2030 the UA may choose a line-height, width and height based on the shape
2031 of the letter, unlike for normal elements.</p>
2035 <p>This example shows a possible rendering of an initial cap. Note
2037 pseudo-element is 1.1, but the UA in this example has computed the
2038 height of the first letter differently, so that it doesn't cause any
2039 unnecessary space between the first two lines. Also note that the
2042 <pre>
2043 p { line-height: 1.1 }
2044 p::first-letter { font-size: 3em; font-weight: normal }
2045 span { font-weight: bold }
2046 ...
2050 En dagelix geschrey de bange stad ontzet.
2051 </pre>
2054 </div>
2055 </div>
2060 <pre>
2067 P::first-letter { font-size: 200%; font-weight: bold; float: left }
2068 SPAN { text-transform: uppercase }
2076 </pre>
2081 <P><img src="first-letter.gif" alt="Image illustrating the combined effect of the ::first-letter and ::first-line pseudo-elements"></p>
2082 </div>
2087 <pre>
2091 T
2094 few words of an article in the Economist.
2096 </pre>
2099 the content (i.e., the initial character), while the ::first-line
2100 pseudo-element start tag is inserted right after the start tag of the
2101 block element.</p> </div>
2103 <p>In order to achieve traditional drop caps formatting, user agents
2104 may approximate font sizes, for example to align baselines. Also, the
2105 glyph outline may be taken into account when formatting.</p>
2109 punctuation classes), that precedes or follows the first letter should
2115 </div>
2122 block, list-item, table-cell, table-caption, and inline-block
2124 may allow this pesudo-element to apply to more element
2125 types.</span></p>
2128 such elements that contain text, or that have a descendant in the same
2129 flow that contains text. A UA should act as if the fictional start tag
2130 of the ::first-letter pseudo-element is just before the first text of
2131 the element, even if that first text is in a descendant.</p>
2135 <p>The fictional tag sequence for this HTMLfragment:
2138 <p>is:
2141 </div>
2143 <p>The first letter of a table-cell or inline-block cannot be the
2156 <p>In CSS, if an element is a list item ('display: list-item'), the
2158 principal box after the marker. UAs may ignore
2168 </div>
2170 <p>Some languages may have specific rules about how to treat certain
2171 letter combinations. In Dutch, for example, if the letter combination
2172 "ij" appears at the beginning of a word, both letters should be
2175 <p>If the letters that would form the ::first-letter are not in the
2177 may create a ::first-letter pseudo-element from one of the elements,
2178 both elements, or simply not create a pseudo-element.</p>
2180 <p>Similarly, if the first letter(s) of the block are not at the start
2181 of the line (for example due to bidirectional reordering), then the UA
2182 need not create the pseudo-element(s).
2187 how overlapping pseudo-elements may interact. The first letter of
2188 each P element will be green with a font size of '24pt'. The rest of
2189 the first formatted line will be 'blue' while the rest of the
2190 paragraph will be 'red'.</p>
2193 p::first-letter { color: green; font-size: 200% }
2194 p::first-line { color: blue }
2205 S
2208 ends up on two lines
2215 </div>
2221 of a document that has been highlighted by the user. This also
2222 applies, for example, to selected text within an editable text
2223 field. This pseudo-element should not be confused with the <code><a
2228 nature, and is altered by user action, it is reasonable to expect that
2229 when a UA re-renders to a static medium (such as a printed page, see
2231 dynamic medium (like screen), the UA may wish to transfer the current
2233 appropriate formatting and rendering take effect as well. This is not
2235 pseudo-element for static media.
2238 pseudo-elements: color, background, cursor (optional), outline
2239 (optional). The computed value of the 'background-image' property on
2246 can be used to describe generated content before or after an element's
2253 element including the inserted text.</p>
2259 <p>At times, authors may want selectors to describe an element that is
2260 the descendant of another element in the document tree (e.g., "an
2261 <code>EM</code> element that is contained within an <code>H1</code>
2262 element"). Descendant combinators express such a relationship. A
2264 separates two sequences of simple selectors. A selector of the form
2274 description of the following fragment:</p>
2281 either side of the "*" is not part of the universal selector; the
2282 whitespace is a combinator indicating that the DIV must be the
2283 ancestor of some element, and that that element must be an ancestor
2284 of the P.</p>
2285 <p>The following selector, which combines descendant combinators and
2290 </div>
2295 between two elements. A child combinator is made of the
2297 separates two sequences of simple selectors.
2305 <p>The following example combines descendant combinators and child
2306 combinators.</p>
2313 </div>
2315 <p>For information on selecting the first child of an element, please
2316 see the section on the <code><a
2318 above.</p>
2322 <p>There are two different sibling combinators: the adjacent sibling
2323 combinator and the general sibling combinator. In both cases,
2324 non-element nodes (e.g. text between elements) are ignored when
2325 considering adjacency of elements.</p>
2331 sequences of simple selectors. The elements represented by the two
2332 sequences share the same parent in the document tree and the element
2333 represented by the first sequence immediately precedes the element
2334 represented by the second one.</p>
2341 <p>The following selector is conceptually similar to the one in the
2342 previous example, except that it adds an attribute selector — it
2346 </div>
2353 simple selectors. The elements represented by the two sequences share
2354 the same parent in the document tree and the element represented by
2355 the first sequence precedes (not necessarily immediately) the element
2356 represented by the second one.</p>
2362 is a correct and valid, but partial, description of:</p>
2366 </div>
2372 <ul>
2374 <li>count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)</li>
2377 </ul>
2380 are counted like any other, but the negation itself does not count as
2381 a pseudo-class.</p>
2383 <p>Concatenating the three numbers a-b-c (in a number system with a
2384 large base) gives the specificity.</p>
2397 </pre>
2398 </div>
2408 <p>The grammar below defines the syntax of Selectors. It is globally
2410 it directly, since it doesn't express the parsing conventions). The
2411 format of the productions is optimized for human consumption and some
2413 are used:</p>
2415 <ul>
2421 </ul>
2425 <pre>selectors_group
2426 : selector [ COMMA S* selector ]*
2427 ;
2429 selector
2430 : simple_selector_sequence [ combinator simple_selector_sequence ]*
2431 ;
2433 combinator
2434 /* combinators can be surrounded by white space */
2435 : PLUS S* | GREATER S* | TILDE S* | S+
2436 ;
2438 simple_selector_sequence
2439 : [ type_selector | universal ]
2440 [ HASH | class | attrib | pseudo | negation ]*
2441 | [ HASH | class | attrib | pseudo | negation ]+
2442 ;
2444 type_selector
2445 : [ namespace_prefix ]? element_name
2446 ;
2448 namespace_prefix
2449 : [ IDENT | '*' ]? '|'
2450 ;
2452 element_name
2453 : IDENT
2454 ;
2456 universal
2457 : [ namespace_prefix ]? '*'
2458 ;
2460 class
2461 : '.' IDENT
2462 ;
2464 attrib
2465 : '[' S* [ namespace_prefix ]? IDENT S*
2466 [ [ PREFIXMATCH |
2467 SUFFIXMATCH |
2468 SUBSTRINGMATCH |
2469 '=' |
2470 INCLUDES |
2471 DASHMATCH ] S* [ IDENT | STRING ] S*
2472 ]? ']'
2473 ;
2475 pseudo
2476 /* '::' starts a pseudo-element, ':' a pseudo-class */
2477 /* Exceptions: :first-line, :first-letter, :before and :after. */
2478 /* Note that pseudo-elements are restricted to one per selector and */
2479 /* occur only in the last simple_selector_sequence. */
2480 : ':' ':'? [ IDENT | functional_pseudo ]
2481 ;
2483 functional_pseudo
2484 : FUNCTION S* expression ')'
2485 ;
2487 expression
2488 /* In CSS3, the expressions are identifiers, strings, */
2489 /* or of the form "an+b" */
2490 : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
2491 ;
2493 negation
2494 : NOT S* negation_arg S* ')'
2495 ;
2497 negation_arg
2498 : type_selector | universal | HASH | class | attrib | pseudo
2499 ;</pre>
2506 case-insensitive.</p>
2509 number that current versions of Flex can deal with (decimal 255). They
2514 <pre>%option case-insensitive
2516 ident [-]?{nmstart}{nmchar}*
2517 name {nmchar}+
2518 nmstart [_a-z]|{nonascii}|{escape}
2521 escape {unicode}|\\[^\n\r\f0-9a-f]
2522 nmchar [_a-z0-9-]|{nonascii}|{escape}
2524 string {string1}|{string2}
2526 string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
2527 invalid {invalid1}|{invalid2}
2529 invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
2530 nl \n|\r\n|\r|\f
2531 w [ \t\r\n\f]*
2533 %%
2535 [ \t\r\n\f]+ return S;
2542 {ident} return IDENT;
2543 {string} return STRING;
2545 {num} return NUMBER;
2552 @{ident} return ATKEYWORD;
2553 {invalid} return INVALID;
2554 {num}% return PERCENTAGE;
2555 {num}{ident} return DIMENSION;
2561 U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
2563 \/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
2565 . return *yytext;</pre>
2569 <h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
2571 <p>An important issue is the interaction of CSS selectors with XML
2572 documents in web clients that were produced prior to this
2573 document. Unfortunately, due to the fact that namespaces must be
2574 matched based on the URI which identifies the namespace, not the
2575 namespace prefix, some mechanism is required to identify namespaces in
2576 CSS by their URI as well. Without such a mechanism, it is impossible
2577 to construct a CSS style sheet which will properly match selectors in
2578 all cases against a random set of XML documents. However, given
2579 complete knowledge of the XML document to which a style sheet is to be
2580 applied, and a limited use of namespaces within the XML document, it
2581 is possible to construct a style sheet in which selectors would match
2582 elements and attributes correctly.</p>
2584 <p>It should be noted that a down-level CSS client will (if it
2585 properly conforms to CSS forward compatible parsing rules) ignore all
2586 <code>@namespace</code> at-rules, as well as all style rules that make
2587 use of namespace qualified element type or attribute selectors. The
2588 syntax of delimiting namespace prefixes in CSS was deliberately chosen
2589 so that down-level CSS clients would ignore the style rules rather
2590 than possibly match them incorrectly.</p>
2592 <p>The use of default namespaces in CSS makes it possible to write
2593 element type selectors that will function in both namespace aware CSS
2594 clients as well as down-level clients. It should be noted that
2595 down-level clients may incorrectly match selectors against XML
2596 elements in other namespaces.</p>
2598 <p>The following are scenarios and examples in which it is possible to
2599 construct style sheets which would function properly in web clients
2600 that do not implement this proposal.</p>
2602 <ol>
2603 <li>
2605 <p>The XML document does not use namespaces.</p>
2607 <ul>
2609 <li>In this case, it is obviously not necessary to declare or use
2610 namespaces in the style sheet. Standard CSS element type and
2611 attribute selectors will function adequately in a down-level
2612 client.</li>
2614 <li>In a CSS namespace aware client, the default behavior of
2615 element selectors matching without regard to namespace will
2616 function properly against all elements, since no namespaces are
2617 present. However, the use of specific element type selectors that
2619 will guarantee that selectors will match only XML elements that do
2620 not have a declared namespace. </li>
2622 </ul>
2624 </li>
2626 <li>
2628 <p>The XML document defines a single, default namespace used
2629 throughout the document. No namespace prefixes are used in element
2630 names.</p>
2632 <ul>
2634 <li>In this case, a down-level client will function as if
2635 namespaces were not used in the XML document at all. Standard CSS
2636 element type and attribute selectors will match against all
2637 elements. </li>
2639 </ul>
2641 </li>
2643 <li>
2645 <p>The XML document does <b>not</b> use a default namespace, all
2646 namespace prefixes used are known to the style sheet author, and
2647 there is a direct mapping between namespace prefixes and namespace
2648 URIs. (A given prefix may only be mapped to one namespace URI
2649 throughout the XML document; there may be multiple prefixes mapped
2650 to the same URI).</p>
2652 <ul>
2654 <li>In this case, the down-level client will view and match
2655 element type and attribute selectors based on their fully
2656 qualified name, not the local part as outlined in the <a
2659 to describe the fully qualified names, e.g.
2661 <code><html:h1></code>. Selectors using the qualified name
2662 will only match XML elements that use the same prefix. Other
2663 namespace prefixes used in the XML that are mapped to the same URI
2664 will not match as expected unless additional CSS style rules are
2665 declared for them.</li>
2667 <li>Note that selectors declared in this fashion will
2668 <em>only</em> match in down-level clients. A CSS namespace aware
2669 client will match element type and attribute selectors based on
2670 the name's local part. Selectors declared with the fully
2671 qualified name will not match (unless there is no namespace prefix
2672 in the fully qualified name).</li>
2674 </ul>
2676 </li>
2678 </ol>
2680 <p>In other scenarios: when the namespace prefixes used in the XML are
2681 not known in advance by the style sheet author; or a combination of
2682 elements with no namespace are used in conjunction with elements using
2683 a default namespace; or the same namespace prefix is mapped to
2684 <em>different</em> namespace URIs within the same document, or in
2685 different documents; it is impossible to construct a CSS style sheet
2686 that will function properly against all elements in those documents,
2687 unless, the style sheet is written using a namespace URI syntax (as
2688 outlined in this document or similar) and the document is processed by
2689 a CSS and XML namespace aware client.</p>
2691 <h2><a name=profiling>12. Profiles</a></h2>
2693 <p>Each specification using Selectors must define the subset of W3C
2694 Selectors it allows and excludes, and describe the local meaning of
2695 all the components of that subset.</p>
2697 <p>Non normative examples:
2701 <tbody>
2702 <tr>
2704 <tr>
2705 <th>Specification</th>
2706 <td>CSS level 1</td></tr>
2707 <tr>
2708 <th>Accepts</th>
2709 <td>type selectors<br>class selectors<br>ID selectors<br>:link,
2710 :visited and :active pseudo-classes<br>descendant combinator
2711 <br>::first-line and ::first-letter pseudo-elements</td></tr>
2712 <tr>
2713 <th>Excludes</th>
2714 <td>
2716 <p>universal selector<br>attribute selectors<br>:hover and :focus
2717 pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
2718 element states pseudo-classes<br>all structural
2719 pseudo-classes<br>negation pseudo-class<br>all
2720 UI element fragments pseudo-elements<br>::before and ::after
2721 pseudo-elements<br>child combinators<br>sibling combinators
2723 <p>namespaces</td></tr>
2724 <tr>
2725 <th>Extra constraints</th>
2726 <td>only one class selector allowed per sequence of simple
2727 selectors</td></tr></tbody></table><br><br>
2729 <tbody>
2730 <tr>
2732 <tr>
2733 <th>Specification</th>
2734 <td>CSS level 2</td></tr>
2735 <tr>
2736 <th>Accepts</th>
2737 <td>type selectors<br>universal selector<br>attribute presence and
2738 values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
2739 :active, :hover, :focus, :lang() and :first-child pseudo-classes
2740 <br>descendant combinator<br>child combinator<br>adjacent sibling
2741 combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
2742 and ::after pseudo-elements</td></tr>
2743 <tr>
2744 <th>Excludes</th>
2745 <td>
2747 <p>content selectors<br>substring matching attribute
2748 selectors<br>:target pseudo-classes<br>all UI element
2749 states pseudo-classes<br>all structural pseudo-classes other
2750 than :first-child<br>negation pseudo-class<br>all UI element
2751 fragments pseudo-elements<br>general sibling combinators
2753 <p>namespaces</td></tr>
2754 <tr>
2755 <th>Extra constraints</th>
2756 <td>more than one class selector per sequence of simple selectors (CSS1
2757 constraint) allowed</td></tr></tbody></table>
2759 <p>In CSS, selectors express pattern matching rules that determine which style
2760 rules apply to elements in the document tree.
2762 <p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</code>
2763 with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
2764 <pre>h1 a[name]</pre>
2766 <p>All CSS declarations attached to such a selector are applied to elements
2767 matching it. </div>
2771 <tbody>
2772 <tr>
2774 <tr>
2775 <th>Specification</th>
2776 <td>STTS 3</td>
2777 </tr>
2778 <tr>
2779 <th>Accepts</th>
2780 <td>
2782 <p>type selectors<br>universal selectors<br>attribute selectors<br>class
2783 selectors<br>ID selectors<br>all structural pseudo-classes<br>
2784 all combinators
2786 <p>namespaces</td></tr>
2787 <tr>
2788 <th>Excludes</th>
2789 <td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
2790 <tr>
2791 <th>Extra constraints</th>
2792 <td>some selectors and combinators are not allowed in fragment
2793 descriptions on the right side of STTS declarations.</td></tr></tbody></table>
2794 <form>
2820 </form>
2822 <p>Selectors can be used in STTS 3 in two different
2823 manners:
2824 <ol>
2825 <li>a selection mechanism equivalent to CSS selection mechanism: declarations
2826 attached to a given selector are applied to elements matching that selector,
2827 <li>fragment descriptions that appear on the right side of declarations.
2828 </li></ol></div>
2830 <h2><a name=Conformance></a>13. Conformance and requirements</h2>
2832 <p>This section defines conformance with the present specification only.
2834 <p>The inability of a user agent to implement part of this specification due to
2835 the limitations of a particular device (e.g., non interactive user agents will
2836 probably not implement dynamic pseudo-classes because they make no sense without
2837 interactivity) does not imply non-conformance.
2839 <p>All specifications reusing Selectors must contain a <a
2841 subset of Selectors it accepts or excludes, and describing the constraints
2842 it adds to the current specification.
2844 <p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a token
2845 which is not allowed at the current parsing point.
2847 <p>User agents must observe the rules for handling parsing errors:
2848 <ul>
2849 <li>a simple selector containing an undeclared namespace prefix is invalid</li>
2850 <li>a selector containing an invalid simple selector, an invalid combinator
2851 or an invalid token is invalid. </li>
2852 <li>a group of selectors containing an invalid selector is invalid.</li>
2853 </ul>
2856 errors. (In the case of CSS, the entire rule in which the selector is
2857 used is dropped.)</p>
2859 <!-- Apparently all these references are out of date:
2860 <p>Implementations of this specification must behave as
2862 when parsing selectors and attempting matches. (In particular,
2863 implementations must assume the data is normalized and must not
2864 normalize it.) Normative rules for matching strings are defined in
2867 specification.</p>-->
2869 <h2><a name=Tests></a>14. Tests</h2>
2871 <p>This specification has <a
2873 suite</a> allowing user agents to verify their basic conformance to
2874 the specification. This test suite does not pretend to be exhaustive
2875 and does not cover all possible combined cases of Selectors.</p>
2877 <h2><a name=ACKS></a>15. Acknowledgements</h2>
2879 <p>The CSS working group would like to thank everyone who has sent
2880 comments on this specification over the years.</p>
2882 <p>The working group would like to extend special thanks to Donna
2883 McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
2884 the final editorial review.</p>
2886 <h2><a name=references>16. References</a></h2>
2890 <dt>[CSS1]
2891 <dd><a name=refsCSS1></a> Bert Bos, Håkon Wium Lie; "<cite>Cascading Style Sheets, level 1</cite>", W3C Recommendation, 17 Dec 1996, revised 11 Jan 1999
2894 <dt>[CSS21]
2895 <dd><a name=refsCSS21></a> Bert Bos, Tantek Çelik, Ian Hickson, Håkon Wium Lie, editors; "<cite>Cascading Style Sheets, level 2 revision 1</cite>", W3C Working Draft, 13 June 2005
2898 <dt>[CWWW]
2899 <dd><a name=refsCWWW></a> Martin J. Dürst, François Yergeau, Misha Wolf, Asmus Freytag, Tex Texin, editors; "<cite>Character Model for the World Wide Web</cite>", W3C Recommendation, 15 February 2005
2902 <dt>[FLEX]
2903 <dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>", Version 2.3.7, ISBN 1882114213
2905 <dt>[HTML4]
2906 <dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
2909 <dt>[MATH]
2910 <dd><a name="refsMATH"></a> Patrick Ion, Robert Miner, editors; "<cite>Mathematical Markup Language (MathML) 1.01</cite>", W3C Recommendation, revision of 7 July 1999
2911 <dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC-MathML/</a></code>)
2913 <dt>[RFC3066]
2914 <dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identification of Languages</cite>", Request for Comments 3066, January 2001
2915 <dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/rfc/rfc3066.txt</code></a>)
2917 <dt>[STTS]
2918 <dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sheets 3</cite>", Electricité de France, submission to the W3C, 11 November 1998
2919 <dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE-STTS3</a></code>)
2921 <dt>[SVG]
2922 <dd><a name="refsSVG"></a> Jon Ferraiolo, 藤沢 淳, Dean Jackson, editors; "<cite>Scalable Vector Graphics (SVG) 1.1 Specification</cite>", W3C Recommendation, 14 January 2003
2925 <dt>[UNICODE]</dt>
2927 href="http://www.unicode.org/versions/Unicode4.1.0/">The Unicode Standard, Version 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/Unicode4.1.0/">Unicode 4.1.0</a>.
2928 <dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/versions/</a></code>)</dd>
2930 <dt>[XML10]
2931 <dd><a name="refsXML10"></a> Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, François Yergeau, editors; "<cite>Extensible Markup Language (XML) 1.0 (Third Edition)</cite>", W3C Recommendation, 4 February 2004
2934 <dt>[XMLNAMES]
2935 <dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, editors; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
2936 <dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/REC-xml-names/</code></a>)
2938 <dt>[YACC]
2939 <dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC — Yet another compiler compiler</cite>", Technical Report, Murray Hill, 1975
2941 </dl>
2942 </body>
2943 </html>