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80 <p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org/Icons/w3c_home" width=72></a>
86 <dl>
88 <dt>This version:
93 <dt>Latest version:
96 http://www.w3.org/TR/css3-selectors</a>
98 <dt>Previous version:
107 <dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/">Tantek Çelik</a> (Invited Expert)
115 <dd class="vcard"><span class="fn">John Williams</span> (former editor, <span class="company"><a
118 </dl>
129 <a
131 <a
133 <a
135 use</a> rules apply.
139 </div>
144 tree. Selectors have been optimized for use with HTML and XML, and
145 are designed to be usable in performance-critical code.</p>
148 Style Sheets) is a language for describing the rendering of <acronym
151 screen, on paper, in speech, etc. CSS uses Selectors for binding
152 style properties to elements in the document. This document
153 describes extensions to the selectors defined in CSS level 2. These
154 extended selectors will be used by CSS level 3.
160 <p>That is, given an element and a selector, this specification
161 defines whether that element matches the selector.</p>
163 <p>These expressions can also be used, for instance, to select a set
164 of elements, or a single element from a set of elements, by
165 evaluating the expression across all the elements in a
172 <p><em>This section describes the status of this document at the
173 time of its publication. Other documents may supersede this
174 document. A list of current W3C publications and the latest revision
175 of this technical report can be found in the <a
177 http://www.w3.org/TR/.</a></em></p>
185 <p>The CSS Working Group doesn't expect that all implementations of
186 CSS3 will have to implement all selectors. Instead, there will
187 probably be a small number of variants of CSS3, called profiles. For
188 example, it may be that only a profile for interactive user agents
189 will include all of the selectors.</p>
194 document is a revision of the <a
197 implementation feedback received in the past few years. It is
198 expected that this last call will proceed straight to Proposed
199 Recommendation stage since it is believed that interoperability will
200 be demonstrable.</p>
202 <p>All persons are encouraged to review and implement this
203 specification and return comments to the (<a
205 public mailing list <a
208 Members can also send comments directly to the CSS Working
209 Group.
212 <p>This is still a draft document and may be updated, replaced, or
213 obsoleted by other documents at any time. It is inappropriate to
218 The English version of this specification is the only normative
219 version.
227 <ul>
231 </ul>
241 </ul>
243 <ul>
245 </ul>
248 <li class="tocline4"><a href="#attribute-representation">6.3.1. Representation of attributes and attributes values</a>
252 </ul>
262 <ul>
275 </ul>
277 </ul>
278 </li>
279 </ul>
281 <ul>
286 </ul>
293 <li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adjacent sibling combinator</a>
294 <li class="tocline4"><a href="#general-sibling-combinators">8.3.2. General sibling combinator</a></li>
295 </ul>
296 </li>
297 </ul>
303 </ul>
310 </ul>
312 </div>
318 <p>Some features of this specification are specific to CSS, or have
319 particular limitations or rules specific to CSS. In this
320 specification, these have been described in terms of CSS2.1. <a
325 <p>All of the text of this specification is normative except
326 examples, notes, and sections explicitly marked as
327 non-normative.</p>
333 <p>The main differences between the selectors in CSS2 and those in
334 Selectors are:
336 <ul>
338 <li>the list of basic definitions (selector, group of selectors,
339 simple selector, etc.) has been changed; in particular, what was
340 referred to in CSS2 as a simple selector is now called a sequence
341 of simple selectors, and the term "simple selector" is now used for
342 the components of this sequence</li>
344 <li>an optional namespace component is now allowed in type element
345 selectors, the universal selector and attribute selectors</li>
349 <li>new simple selectors including substring matching attribute
350 selectors, and new pseudo-classes</li>
353 for pseudo-elements</li>
357 <li>profiles to be added to specifications integrating Selectors
358 and defining the set of selectors which is actually supported by
359 each specification</li>
361 <li>Selectors are now a CSS3 Module and an independent
362 specification; other specifications can now refer to this document
363 independently of CSS</li>
367 </ul>
371 <p><em>This section is non-normative, as it merely summarizes the
372 following sections.</em></p>
374 <p>A Selector represents a structure. This structure can be used as a
375 condition (e.g. in a CSS rule) that determines which elements a
376 selector matches in the document tree, or as a flat description of the
377 HTML or XML fragment corresponding to that structure.</p>
379 <p>Selectors may range from simple element names to rich contextual
380 representations.</p>
385 <thead>
386 <tr>
391 <tbody>
392 <tr>
397 selector</a></td>
399 <tr>
405 <tr>
410 selectors</a></td>
412 <tr>
418 selectors</a></td>
420 <tr>
426 selectors</a></td>
428 <tr>
434 selectors</a></td>
436 <tr>
442 selectors</a></td>
444 <tr>
450 selectors</a></td>
452 <tr>
458 selectors</a></td>
460 <tr>
465 pseudo-classes</a></td>
467 <tr>
472 pseudo-classes</a></td>
474 <tr>
477 from the last one</td>
480 pseudo-classes</a></td>
482 <tr>
487 pseudo-classes</a></td>
489 <tr>
492 from the last one</td>
495 pseudo-classes</a></td>
497 <tr>
502 pseudo-classes</a></td>
504 <tr>
509 pseudo-classes</a></td>
511 <tr>
516 pseudo-classes</a></td>
518 <tr>
523 pseudo-classes</a></td>
525 <tr>
530 pseudo-classes</a></td>
532 <tr>
537 pseudo-classes</a></td>
539 <tr>
542 nodes)</td>
545 pseudo-classes</a></td>
547 <tr>
550 which the target is not yet visited (:link) or already visited
551 (:visited)</td>
554 pseudo-classes</a></td>
556 <tr>
561 action pseudo-classes</a></td>
563 <tr>
568 pseudo-class</a></td>
570 <tr>
573 language specifies how language is determined)</td>
576 pseudo-class</a></td>
578 <tr>
581 disabled</td>
584 pseudo-classes</a></td>
586 <tr>
592 pseudo-classes</a></td>
594 <tr>
599 pseudo-element</a></td>
601 <tr>
606 pseudo-element</a></td>
608 <tr>
611 selected/highlighted by the user</td>
614 fragments pseudo-elements</a></td>
616 <tr>
621 pseudo-element</a></td>
623 <tr>
628 pseudo-element</a></td>
630 <tr>
636 selectors</a></td>
638 <tr>
643 selectors</a></td>
645 <tr>
650 pseudo-class</a></td>
652 <tr>
657 combinator</a></td>
659 <tr>
664 combinator</a></td>
666 <tr>
672 <tr>
679 <p>The meaning of each selector is derived from the table above by
681 column.</p>
685 <p>The case sensitivity of document language element names, attribute
686 names, and attribute values in selectors depends on the document
687 language. For example, in HTML, element names are case-insensitive,
688 but in XML, they are case-sensitive.</p>
701 selector or universal selector is allowed in the sequence.</p>
713 sequence of simple selectors.</p>
718 space may appear between a combinator and the simple selectors around
723 never part of white space.</p>
725 <p>The elements of a document tree that are represented by a selector
727 selector consisting of a single sequence of simple selectors
728 represents any element satisfying its requirements. Prepending another
729 sequence of simple selectors and a combinator to a sequence imposes
730 additional matching constraints, so the subjects of a selector are
731 always a subset of the elements represented by the last sequence of
732 simple selectors.</p>
734 <p>An empty selector, containing no sequence of simple selectors and
740 <p>When several selectors share the same declarations, they may be
745 <p>In this example, we condense three rules with identical
746 declarations into one. Thus,</p>
747 <pre>h1 { font-family: sans-serif }
748 h2 { font-family: sans-serif }
749 h3 { font-family: sans-serif }</pre>
752 </div>
755 because all the selectors are valid selectors. If just one of these
756 selectors were invalid, the entire group of selectors would be
757 invalid. This would invalidate the rule for all three heading
758 elements, whereas in the former case only one of the three individual
759 heading rules would be invalidated.</p>
767 element type. A type selector represents an instance of the element
768 type in the document tree.</p>
774 </div>
781 that has been previously declared may be prepended to the element name
785 <p>The namespace component may be left empty to indicate that the
786 selector is only to represent elements with no declared namespace.</p>
788 <p>An asterisk may be used for the namespace prefix, indicating that
789 the selector represents elements in any namespace (including elements
790 with no namespace).</p>
792 <p>Element type selectors that have no namespace component (no
793 namespace separator), represent elements without regard to the
794 element's namespace (equivalent to "<code>*|</code>") unless a default
795 namespace has been declared. If a default namespace has been declared,
796 the selector will represent only elements in the default
797 namespace.</p>
799 <p>A type selector containing a namespace prefix that has not been
801 The mechanism for declaring a namespace prefix is left up to the
802 language implementing Selectors. In CSS, such a mechanism is defined
803 in the General Syntax module.</p>
805 <p>In a namespace-aware client, element type selectors will only match
806 against the <a
808 of the element's <a
811 behaviors in down-level clients.</p>
815 <dl>
819 <dd>elements with name E in any namespace, including those without any
820 declared namespace</dd>
824 <dd>if no default namespace has been specified, this is equivalent to *|E.
825 Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
826 </dl>
831 <pre>@namespace foo url(http://www.example.com);
832 foo|h1 { color: blue }
833 foo|* { color: yellow }
834 |h1 { color: red }
835 *|h1 { color: green }
836 h1 { color: green }</pre>
841 <p>The second rule will match all elements in the
845 any declared namespace.</p>
848 namespace (including those without any declared namespace).</p>
850 <p>The last rule is equivalent to the fourth rule because no default
851 namespace has been defined.</p>
853 </div>
859 type. It represents any single element in the document tree in any
860 namespace (including those without any declared namespace) if no
861 default namespace has been specified. If a default namespace has been
865 <p>If the universal selector is not the only component of a sequence
870 <ul>
874 </ul>
875 </div>
879 omitted.</p>
883 <p>The universal selector allows an optional namespace component. It
884 is used as follows:</p>
886 <dl>
894 <dd>if no default namespace has been specified, this is equivalent to *|*.
895 Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
896 </dl>
898 <p>A universal selector containing a namespace prefix that has not
900 selector. The mechanism for declaring a namespace prefix is left up
901 to the language implementing Selectors. In CSS, such a mechanism is
902 defined in the General Syntax module.</p>
907 <p>Selectors allow the representation of an element's attributes. When
908 a selector is used as an expression to match against an element,
909 attribute selectors must be considered to match an element if that
910 element has an attribute that matches the attribute represented by the
911 attribute selector.</p>
914 selectors</a></h4>
918 <dl>
921 the attribute.</dd>
930 spaces).</dd>
940 </dl>
942 <p>Attribute values must be identifiers or strings. The
943 case-sensitivity of attribute names and values in selectors depends on
944 the document language.</p>
952 value:</p>
956 <p>In the following example, the selector represents a
962 <p>Multiple attribute selectors can be used to represent several
963 attributes of an element, or several conditions on the same
972 and "~=". The first selector will represent, for example, the value
992 <p>Similarly, the following selectors represents a
996 <pre>DIALOGUE[character=romeo]
997 DIALOGUE[character=juliet]</pre>
999 </div>
1002 selectors</h4>
1004 <p>Three additional attribute selectors are provided for matching
1005 substrings in the value of an attribute:</p>
1007 <dl>
1017 </dl>
1019 <p>Attribute values must be identifiers or strings. The
1020 case-sensitivity of attribute names in selectors depends on the
1021 document language.</p>
1026 image:</p>
1034 </div>
1038 <p>Attribute selectors allow an optional namespace component to the
1039 attribute name. A namespace prefix that has been previously declared
1040 may be prepended to the attribute name separated by the namespace
1042 the Namespaces in the XML recommendation, default namespaces do not
1043 apply to attributes, therefore attribute selectors without a namespace
1044 component apply only to attributes that have no declared namespace
1045 (equivalent to "<code>|attr</code>"). An asterisk may be used for the
1046 namespace prefix indicating that the selector is to match all
1047 attribute names without regard to the attribute's namespace.
1049 <p>An attribute selector with an attribute name containing a namespace
1050 prefix that has not been previously declared is an <a
1052 a namespace prefix is left up to the language implementing Selectors.
1053 In CSS, such a mechanism is defined in the General Syntax module.
1058 [foo|att=val] { color: blue }
1059 [*|att] { color: yellow }
1060 [|att] { color: green }
1061 [att] { color: green }</pre>
1063 <p>The first rule will match only elements with the attribute
1067 <p>The second rule will match only elements with the attribute
1069 (including no declared namespace).</p>
1071 <p>The last two rules are equivalent and will match only elements
1073 declared to be in a namespace.</p>
1075 </div>
1079 <p>Attribute selectors represent explicitly set attribute values in
1080 the document tree. Default attribute values may be defined in a DTD or
1081 elsewhere, but cannot always be selected by attribute
1082 selectors. Selectors should be designed so that they work even if the
1083 default values are not included in the document tree.</p>
1092 knowledge of that namespace to treat default attribute values as if
1093 they were present in the document. (For example, an XHTML UA is not
1094 required to use its built-in knowledge of the XHTML DTD.)</p>
1097 choose to ignore external subsets.</p>
1109 <pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
1110 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1113 is set by default, i.e. not set explicitly. To catch all cases, the
1114 attribute selector for the default value must be dropped:</p>
1116 <pre>EXAMPLE { /*... default property settings ...*/ }
1117 EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
1120 more specific than the tag
1121 selector alone, the style declarations in the second rule will override
1122 those in the first for elements that have a "notation" attribute value
1123 of "octal". Care has to be taken that all property declarations that
1124 are to apply only to the default case are overridden in the non-default
1125 cases' style rules.</p>
1127 </div>
1135 the same meaning. The attribute value must immediately follow the
1138 <p>UAs may apply selectors using the period (.) notation in XML
1139 documents if the UA has namespace-specific knowledge that allows it to
1141 respective namespace. One such example of namespace-specific knowledge
1142 is the prose in the specification for a particular namespace (e.g. SVG
1153 <p>We can assign style information to all elements with
1162 <p>The following assigns style only to H1 elements with
1167 <p>Given these rules, the first H1 instance below would not have
1168 green text, while the second would:</p>
1173 </div>
1183 has been assigned a list of <a
1193 </div>
1196 power to the "class" attribute, authors could conceivably design their
1197 own "document language" based on elements with almost no associated
1198 presentation (such as DIV and SPAN in HTML) and assigning style
1199 information through the "class" attribute. Authors should avoid this
1200 practice since the structural elements of a document language often
1201 have recognized and accepted meanings and author-defined classes may
1202 not.</p>
1205 class attributes, their values must be concatenated with spaces
1206 between the values before searching for the class. As of this time the
1207 working group is not aware of any manner in which this situation can
1208 be reached, however, so this behavior is explicitly non-normative in
1209 this specification.</p>
1213 <p>Document languages may contain attributes that are declared to be
1214 of type ID. What makes attributes of type ID special is that no two
1215 such attributes can have the same value in a document, regardless of
1216 the type of the elements that carry them; whatever the document
1217 language, an ID typed attribute can be used to uniquely identify its
1218 element. In HTML all ID attributes are named "id"; XML applications
1219 may name ID attributes differently, but the same restriction
1220 applies.</p>
1222 <p>An ID-typed attribute of a document language allows authors to
1223 assign an identifier to one element instance in the document tree. W3C
1224 ID selectors represent an element instance based on its identifier. An
1227 identifier.</p>
1229 <p>Selectors does not specify how a UA knows the ID-typed attribute of
1230 an element. The UA may, e.g., read a document's DTD, have the
1231 information hard-coded or ask the user.
1238 <p>The following ID selector represents any element whose ID-typed
1241 <p>The following selector represents any element whose ID-typed
1244 </div>
1248 contains an element's IDs is contained in a DTD or a schema. When
1249 parsing XML, UAs do not always read the DTD, and thus may not know
1250 what the ID of an element is (though a UA may have namespace-specific
1251 knowledge that allows it to determine which attribute is the ID
1252 attribute for that namespace). If a style sheet designer knows or
1253 suspects that a UA may not know what the ID of an element is, he
1254 should use normal attribute selectors instead:
1258 <p>If an element has multiple ID attributes, all of them must be
1259 treated as IDs for that element for the purposes of the ID
1260 selector. Such a situation could be reached using mixtures of xml:id,
1261 DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
1265 <p>The pseudo-class concept is introduced to permit selection based on
1266 information that lies outside of the document tree or that cannot be
1267 expressed using the other simple selectors.</p>
1271 optionally by a value between parentheses.</p>
1273 <p>Pseudo-classes are allowed in all sequences of simple selectors
1274 contained in a selector. Pseudo-classes are allowed anywhere in
1275 sequences of simple selectors, after the leading type selector or
1276 universal selector (possibly omitted). Pseudo-class names are
1277 case-insensitive. Some pseudo-classes are mutually exclusive, while
1278 others can be applied simultaneously to the same
1279 element. Pseudo-classes may be dynamic, in the sense that an element
1280 may acquire or lose a pseudo-class while a user interacts with the
1281 document.</p>
1286 <p>Dynamic pseudo-classes classify elements on characteristics other
1287 than their name, attributes, or content, in principle characteristics
1288 that cannot be deduced from the document tree.</p>
1290 <p>Dynamic pseudo-classes do not appear in the document source or
1291 document tree.</p>
1296 <p>User agents commonly display unvisited links differently from
1297 previously visited ones. Selectors
1301 <ul>
1303 not yet been visited.</li>
1305 been visited by the user. </li>
1306 </ul>
1308 <p>After some amount of time, user agents may choose to return a
1309 visited link to the (unvisited) ':link' state.</p>
1317 <p>The following selector represents links carrying class
1322 </div>
1325 authors to abuse the :link and :visited pseudo-classes to determine
1326 which sites a user has visited without the user's consent.
1328 <p>UAs may therefore treat all links as unvisited links, or implement
1329 other measures to preserve the user's privacy while rendering visited
1330 and unvisited links differently.</p>
1333 :hover, :active, and :focus</a></h5>
1335 <p>Interactive user agents sometimes change the rendering in response
1336 to user actions. Selectors provides
1337 three pseudo-classes for the selection of an element the user is
1338 acting on.</p>
1340 <ul>
1343 designates an element with a pointing device, but does not activate
1344 it. For example, a visual user agent could apply this pseudo-class
1345 when the cursor (mouse pointer) hovers over a box generated by the
1346 element. User agents not that do not support <a
1348 media</a> do not have to support this pseudo-class. Some conforming
1349 user agents that support <a
1351 media</a> may not be able to support this pseudo-class (e.g., a pen
1352 device that does not detect hovering).</li>
1355 is being activated by the user. For example, between the times the
1356 user presses the mouse button and releases it.</li>
1359 has the focus (accepts keyboard or mouse events, or other forms of
1360 input). </li>
1362 </ul>
1364 <p>There may be document language or implementation specific limits on
1368 <p>These pseudo-classes are not mutually exclusive. An element may
1369 match several pseudo-classes at the same time.</p>
1371 <p>Selectors doesn't define if the parent of an element that is
1372 ':active' or ':hover' is also in that state.</p>
1376 <pre>a:link /* unvisited links */
1377 a:visited /* visited links */
1378 a:hover /* user hovers */
1379 a:active /* active links */</pre>
1381 <pre>a:focus
1382 a:focus:hover</pre>
1384 the pseudo-class :focus and in the pseudo-class :hover.</p>
1385 </div>
1388 and ':active' (or ':link' and ':active').</p>
1392 <p>Some URIs refer to a location within a resource. This kind of URI
1394 identifier (called the fragment identifier).</p>
1396 <p>URIs with fragment identifiers link to a certain element within the
1397 document, known as the target element. For instance, here is a URI
1399 document:</p>
1404 pseudo-class. If the document's URI has no fragment identifier, then
1405 the document has no target element.</p>
1412 URI.</p>
1413 </div>
1418 target element red and place an image before it, if there is one:</p>
1419 <pre>*:target { color : red }
1420 *:target::before { content : url(target.png) }</pre>
1421 </div>
1425 <p>If the document language specifies how the human language of an
1426 element is determined, it is possible to write selectors that
1427 represent an element based on its language. For example, in HTML <a
1430 element, and possibly by information from the protocol (such as HTTP
1432 there may be other document language-specific methods for determining
1433 the language.</p>
1436 is in language C. Whether an element is represented by a
1438 being either equal to, or a hyphen-separated substring of, the
1439 element's language value, in the same way as if performed by the <a
1441 selectors. The identifier C does not have to be a valid language
1442 name.</p>
1456 <p>The two following selectors represent an HTML document that is in
1457 Belgian, French, or German. The two next selectors represent
1459 or German.</p>
1460 <pre>html:lang(fr-be)
1461 html:lang(de)
1462 :lang(fr-be) > q
1464 </div>
1471 the look of user interface elements that are enabled — which the
1472 user can select or activate in some fashion (e.g. clicking on a button
1473 with a mouse). There is a need for such a pseudo-class because there
1474 is no way to programmatically specify the default appearance of say,
1476 would look like when it was disabled.</p>
1479 author to specify precisely how a disabled or inactive user interface
1480 element should look.</p>
1482 <p>Most elements will be neither enabled nor disabled. An element is
1483 enabled if the user can either activate it or transfer the focus to
1484 it. An element is disabled if it could be enabled, but the user cannot
1485 presently activate it or transfer focus to it.</p>
1490 <p>Radio and checkbox elements can be toggled by the user. Some menu
1491 items are "checked" when the user selects them. When such elements are
1495 attributes as described in <a
1500 in nature, and is altered by user action, since it can also be based
1509 <p>Radio and checkbox elements can be toggled by the user, but are
1510 sometimes in an indeterminate state, neither checked nor unchecked.
1511 This can be due to an element attribute, or DOM manipulation.</p>
1513 <p>A future version of this specification may introduce an
1515 <!--While the <code>:indeterminate</code> pseudo-class is dynamic in
1516 nature, and is altered by user action, since it can also be based on
1517 the presence of an element attribute, it applies to all media.</p>
1519 <p>Components of a radio-group initialized with no pre-selected choice
1522 </div>
1528 pseudo-classes</dfn> to permit selection based on extra information that lies in
1529 the document tree but cannot be represented by other simple selectors or
1530 combinators.
1532 <p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
1533 not counted when calculating the position of an element in the list of
1534 children of its parent. When calculating the position of an element in
1535 the list of children of its parent, the index numbering starts at 1.
1541 the root of the document. In HTML 4, this is always the
1547 <p>The
1549 pseudo-class notation represents an element that has
1555 each. For example, this allows the selectors to address every other
1556 row in a table, and could be used to alternate the color
1559 integers. The index of the first child of an element is 1.
1570 tr:nth-child(odd) /* same */
1571 tr:nth-child(2n) /* represents every even row of an HTML table */
1572 tr:nth-child(even) /* same */
1574 /* Alternate paragraph colours in CSS */
1579 </div>
1584 included, so the syntax simplifies to
1592 </div>
1600 bar:nth-child(n+0) /* same */
1601 bar:nth-child(n) /* same */
1603 </div>
1612 </div>
1615 pseudo-class represents no element in the document tree.</p>
1620 tree.</p>
1625 </div>
1628 expression must be removed (it is effectively replaced by the "-"
1636 </div>
1642 pseudo-class notation represents an element that has
1648 as arguments.
1655 foo:nth-last-child(odd) /* represents all odd foo elements in their parent element,
1656 counting from the last one */</pre>
1657 </div>
1663 pseudo-class notation represents an element that has
1668 of that type after all the children of that type have been split into
1670 for the syntax of its argument. It also accepts the
1679 </div>
1685 pseudo-class notation represents an element that has
1697 following selector:</p>
1700 selector ends up being just as long:</p>
1702 </div>
1708 represents an element that is the first child of some other element.
1722 fragment:
1730 a:first-child /* Same (assuming a is not the root element) */</pre>
1731 </div>
1736 represents an element that is the last child of some other element.
1743 </div>
1748 represents an element that is the first sibling of its type in the list of
1749 children of its parent element.
1753 <p>The following selector represents a definition title
1756 its parent element.</p>
1759 elements in the following example but not for the third one:</p>
1771 </div>
1777 the last sibling of its type in the list of children of its parent
1778 element.</p>
1782 <p>The following selector represents the last data cell
1785 </div>
1789 <p>Represents an element that has a parent element and whose parent
1790 element has no other element children. Same as
1793 specificity.</p>
1797 <p>Represents an element that has a parent element and whose parent
1798 element has no other element children with the same element name. Same
1801 specificity.</p>
1807 no children at all. In terms of the DOM, only element nodes and text
1808 nodes (including CDATA nodes and entity references) whose data has a
1809 non-zero length must be considered as affecting emptiness; comments,
1810 PIs, and other nodes must not affect whether an element is considered
1811 empty or not.</p>
1818 following fragments:</p>
1822 </div>
1824 <h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appendix H!!! Run away! -->
1827 <!-- (used to be :contains()) -->
1833 selector</a> (excluding the negation pseudo-class itself and
1834 pseudo-elements) as an argument. It represents an element that is not
1835 represented by the argument.
1837 <!-- pseudo-elements are not simple selectors, so the above paragraph
1838 may be a bit confusing -->
1843 elements in an HTML document that are not disabled.</p>
1846 elements.</p>
1848 <p>The following group of selectors represents all HTML elements
1849 except links.</p>
1851 </div>
1853 <p>Default namespace declarations do not affect the argument of the
1854 negation pseudo-class unless the argument is a universal selector or a
1855 type selector.</p>
1859 <p>Assuming that the default namespace is bound to
1860 "http://example.com/", the following selector represents all
1861 elements that are not in that namespace:</p>
1863 <p>The following CSS selector matches any element being hovered,
1864 regardless of its namespace. In particular, it is not limited to
1865 only matching elements in the default namespace that are not being
1866 hovered, and elements not in the default namespace don't match the
1869 </div>
1875 specificity.</p>
1879 <p>Pseudo-elements create abstractions about the document tree beyond
1880 those specified by the document language. For instance, document
1881 languages do not offer mechanisms to access the first letter or first
1882 line of an element's content. Pseudo-elements allow designers to refer
1883 to this otherwise inaccessible information. Pseudo-elements may also
1884 provide designers a way to refer to content that does not exist in the
1887 content).</p>
1890 by the name of the pseudo-element.</p>
1893 in order to establish a discrimination between pseudo-classes and
1894 pseudo-elements. For compatibility with existing style sheets, user
1895 agents must also accept the previous one-colon notation for
1901 <p>Only one pseudo-element may appear per selector, and if present it
1902 must appear after the sequence of simple selectors that represents the
1904 future version of this specification may allow multiple
1905 pesudo-elements per selector.</span></p>
1910 of the first formatted line of an element.
1917 </div>
1920 HTML element. It does match a pseudo-element that conforming user
1921 agents will insert at the beginning of every paragraph.</p>
1923 <p>Note that the length of the first line depends on a number of
1924 factors, including the width of the page, the font size, etc. Thus,
1925 an ordinary HTML paragraph such as:</p>
1927 <pre>
1929 paragraph that will be broken into several
1930 lines. The first line will be identified
1931 by a fictional tag sequence. The other lines
1932 will be treated as ordinary lines in the
1934 </pre>
1936 <p>the lines of which happen to be broken as follows:
1938 <pre>
1939 THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
1940 will be broken into several lines. The first
1941 line will be identified by a fictional tag
1942 sequence. The other lines will be treated as
1943 ordinary lines in the paragraph.
1944 </pre>
1948 fictional tag sequence helps to show how properties are inherited.</p>
1950 <pre>
1953 lines. The first line will be identified
1954 by a fictional tag sequence. The other lines
1955 will be treated as ordinary lines in the
1957 </pre>
1959 <p>If a pseudo-element breaks up a real element, the desired effect
1960 can often be described by a fictional tag sequence that closes and
1961 then re-opens the element. Thus, if we mark up the previous paragraph
1964 <pre>
1966 paragraph that will be broken into several
1968 by a fictional tag sequence. The other lines
1969 will be treated as ordinary lines in the
1971 </pre>
1973 <p>the user agent could simulate start and end tags for
1977 <pre>
1979 somewhat long HTML
1980 paragraph that will <b></SPAN></b></P::first-line><b><SPAN class="test"></b> be
1981 broken into several
1983 by a fictional tag sequence. The other lines
1984 will be treated as ordinary lines in the
1986 </pre>
1989 attached to a block-level element, an inline-block, a table-caption,
1990 or a table-cell.</p>
1993 element may occur inside a
1994 block-level descendant in the same flow (i.e., a block-level
1995 descendant that is not positioned and not a float). E.g., the first
2000 <p>The first line of a table-cell or inline-block cannot be the first
2011 <p>A UA should act as if the fictional start tags of the
2013 innermost enclosing block-level element. (Since CSS1 and CSS2 were
2014 silent on this case, authors should not rely on this behavior.) Here
2015 is an example. The fictional tag sequence for</p>
2017 <pre>
2022 </pre>
2026 <pre>
2028 <P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P>
2031 </pre>
2034 inline-level element, but with certain restrictions. In CSS, the
2036 pseudo-element: font properties, color property, background
2037 properties, 'word-spacing', 'letter-spacing', 'text-decoration',
2038 'vertical-align', 'text-transform', 'line-height'. UAs may apply other
2039 properties as well.</p>
2045 letter of the first line of a block, if it is not preceded by any
2046 other content (such as images or inline tables) on its line. The
2048 caps", which are common typographical effects. This type of initial
2049 letter is similar to an inline-level element if its 'float' property
2050 is 'none'; otherwise, it is similar to a floated element.</p>
2053 pseudo-elements: font properties, 'text-decoration', 'text-transform',
2054 'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
2055 'float', 'vertical-align' (only if 'float' is 'none'), margin
2056 properties, padding properties, border properties, color property,
2057 background properties. UAs may apply other properties as well. To
2058 allow UAs to render a typographically correct drop cap or initial cap,
2059 the UA may choose a line-height, width and height based on the shape
2060 of the letter, unlike for normal elements.</p>
2064 <p>This example shows a possible rendering of an initial cap. Note
2066 pseudo-element is 1.1, but the UA in this example has computed the
2067 height of the first letter differently, so that it doesn't cause any
2068 unnecessary space between the first two lines. Also note that the
2071 <pre>
2072 p { line-height: 1.1 }
2073 p::first-letter { font-size: 3em; font-weight: normal }
2074 span { font-weight: bold }
2075 ...
2079 En dagelix geschrey de bange stad ontzet.
2080 </pre>
2083 </div>
2084 </div>
2089 <pre>
2096 P::first-letter { font-size: 200%; font-weight: bold; float: left }
2097 SPAN { text-transform: uppercase }
2105 </pre>
2110 <P><img src="first-letter.gif" alt="Image illustrating the combined effect of the ::first-letter and ::first-line pseudo-elements"></p>
2111 </div>
2116 <pre>
2120 T
2123 few words of an article in the Economist.
2125 </pre>
2128 the content (i.e., the initial character), while the ::first-line
2129 pseudo-element start tag is inserted right after the start tag of the
2130 block element.</p> </div>
2132 <p>In order to achieve traditional drop caps formatting, user agents
2133 may approximate font sizes, for example to align baselines. Also, the
2134 glyph outline may be taken into account when formatting.</p>
2138 punctuation classes), that precedes or follows the first letter should
2144 </div>
2151 block, list-item, table-cell, table-caption, and inline-block
2153 may allow this pesudo-element to apply to more element
2154 types.</span></p>
2157 such elements that contain text, or that have a descendant in the same
2158 flow that contains text. A UA should act as if the fictional start tag
2159 of the ::first-letter pseudo-element is just before the first text of
2160 the element, even if that first text is in a descendant.</p>
2164 <p>The fictional tag sequence for this HTMLfragment:
2167 <p>is:
2170 </div>
2172 <p>The first letter of a table-cell or inline-block cannot be the
2185 <p>In CSS, if an element is a list item ('display: list-item'), the
2187 principal box after the marker. UAs may ignore
2197 </div>
2199 <p>Some languages may have specific rules about how to treat certain
2200 letter combinations. In Dutch, for example, if the letter combination
2201 "ij" appears at the beginning of a word, both letters should be
2204 <p>If the letters that would form the ::first-letter are not in the
2206 may create a ::first-letter pseudo-element from one of the elements,
2207 both elements, or simply not create a pseudo-element.</p>
2209 <p>Similarly, if the first letter(s) of the block are not at the start
2210 of the line (for example due to bidirectional reordering), then the UA
2211 need not create the pseudo-element(s).
2216 how overlapping pseudo-elements may interact. The first letter of
2217 each P element will be green with a font size of '24pt'. The rest of
2218 the first formatted line will be 'blue' while the rest of the
2219 paragraph will be 'red'.</p>
2222 p::first-letter { color: green; font-size: 200% }
2223 p::first-line { color: blue }
2234 S
2237 ends up on two lines
2244 </div>
2250 of a document that has been highlighted by the user. This also
2251 applies, for example, to selected text within an editable text
2252 field. This pseudo-element should not be confused with the <code><a
2257 nature, and is altered by user action, it is reasonable to expect that
2258 when a UA re-renders to a static medium (such as a printed page, see
2260 dynamic medium (like screen), the UA may wish to transfer the current
2262 appropriate formatting and rendering take effect as well. This is not
2264 pseudo-element for static media.
2267 pseudo-elements: color, background, cursor (optional), outline
2268 (optional). The computed value of the 'background-image' property on
2275 can be used to describe generated content before or after an element's
2282 element including the inserted text.</p>
2288 <p>At times, authors may want selectors to describe an element that is
2289 the descendant of another element in the document tree (e.g., "an
2290 <code>EM</code> element that is contained within an <code>H1</code>
2291 element"). Descendant combinators express such a relationship. A
2293 separates two sequences of simple selectors. A selector of the form
2303 description of the following fragment:</p>
2310 either side of the "*" is not part of the universal selector; the
2311 whitespace is a combinator indicating that the DIV must be the
2312 ancestor of some element, and that that element must be an ancestor
2313 of the P.</p>
2314 <p>The following selector, which combines descendant combinators and
2319 </div>
2324 between two elements. A child combinator is made of the
2326 separates two sequences of simple selectors.
2334 <p>The following example combines descendant combinators and child
2335 combinators.</p>
2342 </div>
2344 <p>For information on selecting the first child of an element, please
2345 see the section on the <code><a
2347 above.</p>
2351 <p>There are two different sibling combinators: the adjacent sibling
2352 combinator and the general sibling combinator. In both cases,
2353 non-element nodes (e.g. text between elements) are ignored when
2354 considering adjacency of elements.</p>
2360 sequences of simple selectors. The elements represented by the two
2361 sequences share the same parent in the document tree and the element
2362 represented by the first sequence immediately precedes the element
2363 represented by the second one.</p>
2370 <p>The following selector is conceptually similar to the one in the
2371 previous example, except that it adds an attribute selector — it
2375 </div>
2382 simple selectors. The elements represented by the two sequences share
2383 the same parent in the document tree and the element represented by
2384 the first sequence precedes (not necessarily immediately) the element
2385 represented by the second one.</p>
2391 is a correct and valid, but partial, description of:</p>
2395 </div>
2401 <ul>
2403 <li>count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)</li>
2406 </ul>
2409 are counted like any other, but the negation itself does not count as
2410 a pseudo-class.</p>
2412 <p>Concatenating the three numbers a-b-c (in a number system with a
2413 large base) gives the specificity.</p>
2426 </pre>
2427 </div>
2437 <p>The grammar below defines the syntax of Selectors. It is globally
2439 it directly, since it doesn't express the parsing conventions). The
2440 format of the productions is optimized for human consumption and some
2442 are used:</p>
2444 <ul>
2450 </ul>
2454 <pre>selectors_group
2455 : selector [ COMMA S* selector ]*
2456 ;
2458 selector
2459 : simple_selector_sequence [ combinator simple_selector_sequence ]*
2460 ;
2462 combinator
2463 /* combinators can be surrounded by white space */
2464 : PLUS S* | GREATER S* | TILDE S* | S+
2465 ;
2467 simple_selector_sequence
2468 : [ type_selector | universal ]
2469 [ HASH | class | attrib | pseudo | negation ]*
2470 | [ HASH | class | attrib | pseudo | negation ]+
2471 ;
2473 type_selector
2474 : [ namespace_prefix ]? element_name
2475 ;
2477 namespace_prefix
2478 : [ IDENT | '*' ]? '|'
2479 ;
2481 element_name
2482 : IDENT
2483 ;
2485 universal
2486 : [ namespace_prefix ]? '*'
2487 ;
2489 class
2490 : '.' IDENT
2491 ;
2493 attrib
2494 : '[' S* [ namespace_prefix ]? IDENT S*
2495 [ [ PREFIXMATCH |
2496 SUFFIXMATCH |
2497 SUBSTRINGMATCH |
2498 '=' |
2499 INCLUDES |
2500 DASHMATCH ] S* [ IDENT | STRING ] S*
2501 ]? ']'
2502 ;
2504 pseudo
2505 /* '::' starts a pseudo-element, ':' a pseudo-class */
2506 /* Exceptions: :first-line, :first-letter, :before and :after. */
2507 /* Note that pseudo-elements are restricted to one per selector and */
2508 /* occur only in the last simple_selector_sequence. */
2509 : ':' ':'? [ IDENT | functional_pseudo ]
2510 ;
2512 functional_pseudo
2513 : FUNCTION S* expression ')'
2514 ;
2516 expression
2517 /* In CSS3, the expressions are identifiers, strings, */
2518 /* or of the form "an+b" */
2519 : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
2520 ;
2522 negation
2523 : NOT S* negation_arg S* ')'
2524 ;
2526 negation_arg
2527 : type_selector | universal | HASH | class | attrib | pseudo
2528 ;</pre>
2535 case-insensitive.</p>
2538 number that current versions of Flex can deal with (decimal 255). They
2543 <pre>%option case-insensitive
2545 ident [-]?{nmstart}{nmchar}*
2546 name {nmchar}+
2547 nmstart [_a-z]|{nonascii}|{escape}
2550 escape {unicode}|\\[^\n\r\f0-9a-f]
2551 nmchar [_a-z0-9-]|{nonascii}|{escape}
2553 string {string1}|{string2}
2555 string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
2556 invalid {invalid1}|{invalid2}
2558 invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
2559 nl \n|\r\n|\r|\f
2560 w [ \t\r\n\f]*
2562 %%
2564 [ \t\r\n\f]+ return S;
2571 {ident} return IDENT;
2572 {string} return STRING;
2574 {num} return NUMBER;
2581 @{ident} return ATKEYWORD;
2582 {invalid} return INVALID;
2583 {num}% return PERCENTAGE;
2584 {num}{ident} return DIMENSION;
2590 U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
2592 \/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
2594 . return *yytext;</pre>
2598 <h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
2600 <p>An important issue is the interaction of CSS selectors with XML
2601 documents in web clients that were produced prior to this
2602 document. Unfortunately, due to the fact that namespaces must be
2603 matched based on the URI which identifies the namespace, not the
2604 namespace prefix, some mechanism is required to identify namespaces in
2605 CSS by their URI as well. Without such a mechanism, it is impossible
2606 to construct a CSS style sheet which will properly match selectors in
2607 all cases against a random set of XML documents. However, given
2608 complete knowledge of the XML document to which a style sheet is to be
2609 applied, and a limited use of namespaces within the XML document, it
2610 is possible to construct a style sheet in which selectors would match
2611 elements and attributes correctly.</p>
2613 <p>It should be noted that a down-level CSS client will (if it
2614 properly conforms to CSS forward compatible parsing rules) ignore all
2615 <code>@namespace</code> at-rules, as well as all style rules that make
2616 use of namespace qualified element type or attribute selectors. The
2617 syntax of delimiting namespace prefixes in CSS was deliberately chosen
2618 so that down-level CSS clients would ignore the style rules rather
2619 than possibly match them incorrectly.</p>
2621 <p>The use of default namespaces in CSS makes it possible to write
2622 element type selectors that will function in both namespace aware CSS
2623 clients as well as down-level clients. It should be noted that
2624 down-level clients may incorrectly match selectors against XML
2625 elements in other namespaces.</p>
2627 <p>The following are scenarios and examples in which it is possible to
2628 construct style sheets which would function properly in web clients
2629 that do not implement this proposal.</p>
2631 <ol>
2632 <li>
2634 <p>The XML document does not use namespaces.</p>
2636 <ul>
2638 <li>In this case, it is obviously not necessary to declare or use
2639 namespaces in the style sheet. Standard CSS element type and
2640 attribute selectors will function adequately in a down-level
2641 client.</li>
2643 <li>In a CSS namespace aware client, the default behavior of
2644 element selectors matching without regard to namespace will
2645 function properly against all elements, since no namespaces are
2646 present. However, the use of specific element type selectors that
2648 will guarantee that selectors will match only XML elements that do
2649 not have a declared namespace. </li>
2651 </ul>
2653 </li>
2655 <li>
2657 <p>The XML document defines a single, default namespace used
2658 throughout the document. No namespace prefixes are used in element
2659 names.</p>
2661 <ul>
2663 <li>In this case, a down-level client will function as if
2664 namespaces were not used in the XML document at all. Standard CSS
2665 element type and attribute selectors will match against all
2666 elements. </li>
2668 </ul>
2670 </li>
2672 <li>
2674 <p>The XML document does <b>not</b> use a default namespace, all
2675 namespace prefixes used are known to the style sheet author, and
2676 there is a direct mapping between namespace prefixes and namespace
2677 URIs. (A given prefix may only be mapped to one namespace URI
2678 throughout the XML document; there may be multiple prefixes mapped
2679 to the same URI).</p>
2681 <ul>
2683 <li>In this case, the down-level client will view and match
2684 element type and attribute selectors based on their fully
2685 qualified name, not the local part as outlined in the <a
2688 to describe the fully qualified names, e.g.
2690 <code><html:h1></code>. Selectors using the qualified name
2691 will only match XML elements that use the same prefix. Other
2692 namespace prefixes used in the XML that are mapped to the same URI
2693 will not match as expected unless additional CSS style rules are
2694 declared for them.</li>
2696 <li>Note that selectors declared in this fashion will
2697 <em>only</em> match in down-level clients. A CSS namespace aware
2698 client will match element type and attribute selectors based on
2699 the name's local part. Selectors declared with the fully
2700 qualified name will not match (unless there is no namespace prefix
2701 in the fully qualified name).</li>
2703 </ul>
2705 </li>
2707 </ol>
2709 <p>In other scenarios: when the namespace prefixes used in the XML are
2710 not known in advance by the style sheet author; or a combination of
2711 elements with no namespace are used in conjunction with elements using
2712 a default namespace; or the same namespace prefix is mapped to
2713 <em>different</em> namespace URIs within the same document, or in
2714 different documents; it is impossible to construct a CSS style sheet
2715 that will function properly against all elements in those documents,
2716 unless, the style sheet is written using a namespace URI syntax (as
2717 outlined in this document or similar) and the document is processed by
2718 a CSS and XML namespace aware client.</p>
2720 <h2><a name=profiling>12. Profiles</a></h2>
2722 <p>Each specification using Selectors must define the subset of W3C
2723 Selectors it allows and excludes, and describe the local meaning of
2724 all the components of that subset.</p>
2726 <p>Non normative examples:
2730 <tbody>
2731 <tr>
2733 <tr>
2734 <th>Specification</th>
2735 <td>CSS level 1</td></tr>
2736 <tr>
2737 <th>Accepts</th>
2738 <td>type selectors<br>class selectors<br>ID selectors<br>:link,
2739 :visited and :active pseudo-classes<br>descendant combinator
2740 <br>::first-line and ::first-letter pseudo-elements</td></tr>
2741 <tr>
2742 <th>Excludes</th>
2743 <td>
2745 <p>universal selector<br>attribute selectors<br>:hover and :focus
2746 pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
2747 element states pseudo-classes<br>all structural
2748 pseudo-classes<br>negation pseudo-class<br>all
2749 UI element fragments pseudo-elements<br>::before and ::after
2750 pseudo-elements<br>child combinators<br>sibling combinators
2752 <p>namespaces</td></tr>
2753 <tr>
2754 <th>Extra constraints</th>
2755 <td>only one class selector allowed per sequence of simple
2756 selectors</td></tr></tbody></table><br><br>
2758 <tbody>
2759 <tr>
2761 <tr>
2762 <th>Specification</th>
2763 <td>CSS level 2</td></tr>
2764 <tr>
2765 <th>Accepts</th>
2766 <td>type selectors<br>universal selector<br>attribute presence and
2767 values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
2768 :active, :hover, :focus, :lang() and :first-child pseudo-classes
2769 <br>descendant combinator<br>child combinator<br>adjacent sibling
2770 combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
2771 and ::after pseudo-elements</td></tr>
2772 <tr>
2773 <th>Excludes</th>
2774 <td>
2776 <p>content selectors<br>substring matching attribute
2777 selectors<br>:target pseudo-classes<br>all UI element
2778 states pseudo-classes<br>all structural pseudo-classes other
2779 than :first-child<br>negation pseudo-class<br>all UI element
2780 fragments pseudo-elements<br>general sibling combinators
2782 <p>namespaces</td></tr>
2783 <tr>
2784 <th>Extra constraints</th>
2785 <td>more than one class selector per sequence of simple selectors (CSS1
2786 constraint) allowed</td></tr></tbody></table>
2788 <p>In CSS, selectors express pattern matching rules that determine which style
2789 rules apply to elements in the document tree.
2791 <p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</code>
2792 with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
2793 <pre>h1 a[name]</pre>
2795 <p>All CSS declarations attached to such a selector are applied to elements
2796 matching it. </div>
2800 <tbody>
2801 <tr>
2803 <tr>
2804 <th>Specification</th>
2805 <td>STTS 3</td>
2806 </tr>
2807 <tr>
2808 <th>Accepts</th>
2809 <td>
2811 <p>type selectors<br>universal selectors<br>attribute selectors<br>class
2812 selectors<br>ID selectors<br>all structural pseudo-classes<br>
2813 all combinators
2815 <p>namespaces</td></tr>
2816 <tr>
2817 <th>Excludes</th>
2818 <td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
2819 <tr>
2820 <th>Extra constraints</th>
2821 <td>some selectors and combinators are not allowed in fragment
2822 descriptions on the right side of STTS declarations.</td></tr></tbody></table>
2823 <form>
2849 </form>
2851 <p>Selectors can be used in STTS 3 in two different
2852 manners:
2853 <ol>
2854 <li>a selection mechanism equivalent to CSS selection mechanism: declarations
2855 attached to a given selector are applied to elements matching that selector,
2856 <li>fragment descriptions that appear on the right side of declarations.
2857 </li></ol></div>
2859 <h2><a name=Conformance></a>13. Conformance and requirements</h2>
2861 <p>This section defines conformance with the present specification only.
2863 <p>The inability of a user agent to implement part of this specification due to
2864 the limitations of a particular device (e.g., non interactive user agents will
2865 probably not implement dynamic pseudo-classes because they make no sense without
2866 interactivity) does not imply non-conformance.
2868 <p>All specifications reusing Selectors must contain a <a
2870 subset of Selectors it accepts or excludes, and describing the constraints
2871 it adds to the current specification.
2873 <p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a token
2874 which is not allowed at the current parsing point.
2876 <p>User agents must observe the rules for handling parsing errors:
2877 <ul>
2878 <li>a simple selector containing an undeclared namespace prefix is invalid</li>
2879 <li>a selector containing an invalid simple selector, an invalid combinator
2880 or an invalid token is invalid. </li>
2881 <li>a group of selectors containing an invalid selector is invalid.</li>
2882 </ul>
2885 errors. (In the case of CSS, the entire rule in which the selector is
2886 used is dropped.)</p>
2888 <!-- Apparently all these references are out of date:
2889 <p>Implementations of this specification must behave as
2891 when parsing selectors and attempting matches. (In particular,
2892 implementations must assume the data is normalized and must not
2893 normalize it.) Normative rules for matching strings are defined in
2896 specification.</p>-->
2898 <h2><a name=Tests></a>14. Tests</h2>
2900 <p>This specification has <a
2902 suite</a> allowing user agents to verify their basic conformance to
2903 the specification. This test suite does not pretend to be exhaustive
2904 and does not cover all possible combined cases of Selectors.</p>
2906 <h2><a name=ACKS></a>15. Acknowledgements</h2>
2908 <p>The CSS working group would like to thank everyone who has sent
2909 comments on this specification over the years.</p>
2911 <p>The working group would like to extend special thanks to Donna
2912 McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
2913 the final editorial review.</p>
2915 <h2><a name=references>16. References</a></h2>
2919 <dt>[CSS1]
2920 <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
2923 <dt>[CSS21]
2924 <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
2927 <dt>[CWWW]
2928 <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
2931 <dt>[FLEX]
2932 <dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>", Version 2.3.7, ISBN 1882114213
2934 <dt>[HTML4]
2935 <dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
2938 <dt>[MATH]
2939 <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
2940 <dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC-MathML/</a></code>)
2942 <dt>[RFC3066]
2943 <dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identification of Languages</cite>", Request for Comments 3066, January 2001
2944 <dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/rfc/rfc3066.txt</code></a>)
2946 <dt>[STTS]
2947 <dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sheets 3</cite>", Electricité de France, submission to the W3C, 11 November 1998
2948 <dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE-STTS3</a></code>)
2950 <dt>[SVG]
2951 <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
2954 <dt>[UNICODE]</dt>
2956 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>.
2957 <dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/versions/</a></code>)</dd>
2959 <dt>[XML10]
2960 <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
2963 <dt>[XMLNAMES]
2964 <dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, editors; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
2965 <dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/REC-xml-names/</code></a>)
2967 <dt>[YACC]
2968 <dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC — Yet another compiler compiler</cite>", Technical Report, Murray Hill, 1975
2970 </dl>
2971 </body>
2972 </html>