Simple HTML DOM Test
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Selectors
- -W3C Working Draft 15 December 2005
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- This version: - -
- - http://www.w3.org/TR/2005/WD-css3-selectors-20051215 - -
- Latest version: - -
- - http://www.w3.org/TR/css3-selectors - -
- Previous version: - -
- - http://www.w3.org/TR/2001/CR-css3-selectors-20011113 - -
- Editors: - -
- Daniel Glazman (Invited Expert) - -
- Tantek Çelik (Invited Expert)
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-
- Ian Hickson (Google) - -
- Peter Linss (former editor, Netscape/AOL) - -
- John Williams (former editor, Quark, Inc.) - -
- Ian Hickson (Google) - -
- Copyright © 2005 W3C® - (MIT, ERCIM, Keio), All Rights Reserved. W3C - liability, - trademark, - document - use rules apply. - -
- -
Abstract
- -Selectors are patterns that match against elements in a - tree. Selectors have been optimized for use with HTML and XML, and - are designed to be usable in performance-critical code.
- -CSS (Cascading - Style Sheets) is a language for describing the rendering of HTML and XML documents on - screen, on paper, in speech, etc. CSS uses Selectors for binding - style properties to elements in the document. This document - describes extensions to the selectors defined in CSS level 2. These - extended selectors will be used by CSS level 3. - -
Selectors define the following function:
- -expression ∗ element → boolean- -
That is, given an element and a selector, this specification - defines whether that element matches the selector.
- -These expressions can also be used, for instance, to select a set - of elements, or a single element from a set of elements, by - evaluating the expression across all the elements in a - subtree. STTS (Simple Tree Transformation Sheets), a - language for transforming XML trees, uses this mechanism. [STTS]
- -Status of this document
- -This section describes the status of this document at the - time of its publication. Other documents may supersede this - document. A list of current W3C publications and the latest revision - of this technical report can be found in the W3C technical reports index at - http://www.w3.org/TR/.
- -This document describes the selectors that already exist in CSS1 and CSS2, and - also proposes new selectors for CSS3 and other languages that may need them.
- -The CSS Working Group doesn't expect that all implementations of - CSS3 will have to implement all selectors. Instead, there will - probably be a small number of variants of CSS3, called profiles. For - example, it may be that only a profile for interactive user agents - will include all of the selectors.
- -This specification is a last call working draft for the the CSS Working Group - (Style Activity). This - document is a revision of the Candidate - Recommendation dated 2001 November 13, and has incorporated - implementation feedback received in the past few years. It is - expected that this last call will proceed straight to Proposed - Recommendation stage since it is believed that interoperability will - be demonstrable.
- -All persons are encouraged to review and implement this - specification and return comments to the (archived) - public mailing list www-style - (see instructions). W3C - Members can also send comments directly to the CSS Working - Group. - The deadline for comments is 14 January 2006.
- -This is still a draft document and may be updated, replaced, or - obsoleted by other documents at any time. It is inappropriate to - cite a W3C Working Draft as other than "work in progress". - -
This document may be available in translation. - The English version of this specification is the only normative - version. - -
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- Table of contents
- --
-
- 1. Introduction - -
- 2. Selectors -
- 3. Case sensitivity -
- 4. Selector syntax -
- 5. Groups of selectors -
- 6. Simple selectors
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-
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- 6.1. Type selectors - -
- 6.2. Universal selector - -
- 6.3. Attribute selectors - -
- 6.4. Class selectors -
- 6.5. ID selectors -
- 6.6. Pseudo-classes
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- 6.6.1. Dynamic pseudo-classes -
- 6.6.2. The :target pseudo-class -
- 6.6.3. The :lang() pseudo-class -
- 6.6.4. UI element states pseudo-classes -
- 6.6.5. Structural pseudo-classes
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- :root pseudo-class -
- :nth-child() pseudo-class -
- :nth-last-child() -
- :nth-of-type() pseudo-class -
- :nth-last-of-type() -
- :first-child pseudo-class -
- :last-child pseudo-class -
- :first-of-type pseudo-class -
- :last-of-type pseudo-class -
- :only-child pseudo-class -
- :only-of-type pseudo-class -
- :empty pseudo-class -
- 6.6.7. The negation pseudo-class -
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- 7. Pseudo-elements - -
- 8. Combinators - -
- 9. Calculating a selector's specificity -
- 10. The grammar of Selectors - -
- 11. Namespaces and down-level clients -
- 12. Profiles -
- 13. Conformance and requirements -
- 14. Tests -
- 15. Acknowledgements -
- 16. References -
1. Introduction
- -1.1. Dependencies
- -Some features of this specification are specific to CSS, or have - particular limitations or rules specific to CSS. In this - specification, these have been described in terms of CSS2.1. [CSS21]
- -1.2. Terminology
- -All of the text of this specification is normative except - examples, notes, and sections explicitly marked as - non-normative.
- -1.3. Changes from CSS2
- -This section is non-normative.
- -The main differences between the selectors in CSS2 and those in - Selectors are: - -
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-
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- the list of basic definitions (selector, group of selectors, - simple selector, etc.) has been changed; in particular, what was - referred to in CSS2 as a simple selector is now called a sequence - of simple selectors, and the term "simple selector" is now used for - the components of this sequence - -
- an optional namespace component is now allowed in type element - selectors, the universal selector and attribute selectors - -
- a new combinator has been introduced - -
- new simple selectors including substring matching attribute - selectors, and new pseudo-classes - -
- new pseudo-elements, and introduction of the "::" convention - for pseudo-elements - -
- the grammar has been rewritten - -
- profiles to be added to specifications integrating Selectors - and defining the set of selectors which is actually supported by - each specification - -
- Selectors are now a CSS3 Module and an independent - specification; other specifications can now refer to this document - independently of CSS - -
- the specification now has its own test suite - -
2. Selectors
- -This section is non-normative, as it merely summarizes the -following sections.
- -A Selector represents a structure. This structure can be used as a -condition (e.g. in a CSS rule) that determines which elements a -selector matches in the document tree, or as a flat description of the -HTML or XML fragment corresponding to that structure.
- -Selectors may range from simple element names to rich contextual -representations.
- -The following table summarizes the Selector syntax:
- -| Pattern | -Meaning | -Described in section | -First defined in CSS level |
|---|---|---|---|
| * | -any element | -Universal - selector | -2 |
| E | -an element of type E | -Type selector | -1 |
| E[foo] | -an E element with a "foo" attribute | -Attribute - selectors | -2 |
| E[foo="bar"] | -an E element whose "foo" attribute value is exactly - equal to "bar" | -Attribute - selectors | -2 |
| E[foo~="bar"] | -an E element whose "foo" attribute value is a list of - space-separated values, one of which is exactly equal to "bar" | -Attribute - selectors | -2 |
| E[foo^="bar"] | -an E element whose "foo" attribute value begins exactly - with the string "bar" | -Attribute - selectors | -3 |
| E[foo$="bar"] | -an E element whose "foo" attribute value ends exactly - with the string "bar" | -Attribute - selectors | -3 |
| E[foo*="bar"] | -an E element whose "foo" attribute value contains the - substring "bar" | -Attribute - selectors | -3 |
| E[hreflang|="en"] | -an E element whose "hreflang" attribute has a hyphen-separated - list of values beginning (from the left) with "en" | -Attribute - selectors | -2 |
| E:root | -an E element, root of the document | -Structural - pseudo-classes | -3 |
| E:nth-child(n) | -an E element, the n-th child of its parent | -Structural - pseudo-classes | -3 |
| E:nth-last-child(n) | -an E element, the n-th child of its parent, counting - from the last one | -Structural - pseudo-classes | -3 |
| E:nth-of-type(n) | -an E element, the n-th sibling of its type | -Structural - pseudo-classes | -3 |
| E:nth-last-of-type(n) | -an E element, the n-th sibling of its type, counting - from the last one | -Structural - pseudo-classes | -3 |
| E:first-child | -an E element, first child of its parent | -Structural - pseudo-classes | -2 |
| E:last-child | -an E element, last child of its parent | -Structural - pseudo-classes | -3 |
| E:first-of-type | -an E element, first sibling of its type | -Structural - pseudo-classes | -3 |
| E:last-of-type | -an E element, last sibling of its type | -Structural - pseudo-classes | -3 |
| E:only-child | -an E element, only child of its parent | -Structural - pseudo-classes | -3 |
| E:only-of-type | -an E element, only sibling of its type | -Structural - pseudo-classes | -3 |
| E:empty | -an E element that has no children (including text - nodes) | -Structural - pseudo-classes | -3 |
| E:link E:visited |
- an E element being the source anchor of a hyperlink of - which the target is not yet visited (:link) or already visited - (:visited) | -The link - pseudo-classes | -1 |
| E:active E:hover E:focus |
- an E element during certain user actions | -The user - action pseudo-classes | -1 and 2 |
| E:target | -an E element being the target of the referring URI | -The target - pseudo-class | -3 |
| E:lang(fr) | -an element of type E in language "fr" (the document - language specifies how language is determined) | -The :lang() - pseudo-class | -2 |
| E:enabled E:disabled |
- a user interface element E which is enabled or - disabled | -The UI element states - pseudo-classes | -3 |
| E:checked | -a user interface element E which is checked (for instance a radio-button or checkbox) | -The UI element states - pseudo-classes | -3 |
| E::first-line | -the first formatted line of an E element | -The ::first-line - pseudo-element | -1 |
| E::first-letter | -the first formatted letter of an E element | -The ::first-letter - pseudo-element | -1 |
| E::selection | -the portion of an E element that is currently - selected/highlighted by the user | -The UI element - fragments pseudo-elements | -3 |
| E::before | -generated content before an E element | -The ::before - pseudo-element | -2 |
| E::after | -generated content after an E element | -The ::after - pseudo-element | -2 |
| E.warning | -an E element whose class is -"warning" (the document language specifies how class is determined). | -Class - selectors | -1 |
| E#myid | -an E element with ID equal to "myid". | -ID - selectors | -1 |
| E:not(s) | -an E element that does not match simple selector s | -Negation - pseudo-class | -3 |
| E F | -an F element descendant of an E element | -Descendant - combinator | -1 |
| E > F | -an F element child of an E element | -Child - combinator | -2 |
| E + F | -an F element immediately preceded by an E element | -Adjacent sibling combinator | -2 |
| E ~ F | -an F element preceded by an E element | -General sibling combinator | -3 |
The meaning of each selector is derived from the table above by -prepending "matches" to the contents of each cell in the "Meaning" -column.
- -3. Case sensitivity
- -The case sensitivity of document language element names, attribute -names, and attribute values in selectors depends on the document -language. For example, in HTML, element names are case-insensitive, -but in XML, they are case-sensitive.
- -4. Selector syntax
- -A selector is a chain of one -or more sequences of simple selectors -separated by combinators.
- -A sequence of simple selectors -is a chain of simple selectors -that are not separated by a combinator. It -always begins with a type selector or a -universal selector. No other type -selector or universal selector is allowed in the sequence.
- -A simple selector is either a type selector, universal selector, attribute selector, class selector, ID selector, content selector, or pseudo-class. One pseudo-element may be appended to the last -sequence of simple selectors.
- -Combinators are: white space, "greater-than
-sign" (U+003E, >), "plus sign" (U+002B,
-+) and "tilde" (U+007E, ~). White
-space may appear between a combinator and the simple selectors around
-it. Only the characters "space" (U+0020), "tab"
-(U+0009), "line feed" (U+000A), "carriage return" (U+000D), and "form
-feed" (U+000C) can occur in white space. Other space-like characters,
-such as "em-space" (U+2003) and "ideographic space" (U+3000), are
-never part of white space.
The elements of a document tree that are represented by a selector -are the subjects of the selector. A -selector consisting of a single sequence of simple selectors -represents any element satisfying its requirements. Prepending another -sequence of simple selectors and a combinator to a sequence imposes -additional matching constraints, so the subjects of a selector are -always a subset of the elements represented by the last sequence of -simple selectors.
- -An empty selector, containing no sequence of simple selectors and -no pseudo-element, is an invalid -selector.
- -5. Groups of selectors
- -When several selectors share the same declarations, they may be -grouped into a comma-separated list. (A comma is U+002C.)
- -
-
-
-CSS examples:
-In this example, we condense three rules with identical -declarations into one. Thus,
-h1 { font-family: sans-serif }
-h2 { font-family: sans-serif }
-h3 { font-family: sans-serif }
-is equivalent to:
-h1, h2, h3 { font-family: sans-serif }
-Warning: the equivalence is true in this example -because all the selectors are valid selectors. If just one of these -selectors were invalid, the entire group of selectors would be -invalid. This would invalidate the rule for all three heading -elements, whereas in the former case only one of the three individual -heading rules would be invalidated.
- - -6. Simple selectors
- -6.1. Type selector
- -A type selector is the name of a document language -element type. A type selector represents an instance of the element -type in the document tree.
- -
-
-
-
-Example:
-The following selector represents an h1 element in the document tree:
h1-
6.1.1. Type selectors and namespaces
- -Type selectors allow an optional namespace ([XMLNAMES]) component. A namespace prefix
-that has been previously declared may be prepended to the element name
-separated by the namespace separator "vertical bar"
-(U+007C, |).
The namespace component may be left empty to indicate that the -selector is only to represent elements with no declared namespace.
- -An asterisk may be used for the namespace prefix, indicating that -the selector represents elements in any namespace (including elements -with no namespace).
- -Element type selectors that have no namespace component (no
-namespace separator), represent elements without regard to the
-element's namespace (equivalent to "*|") unless a default
-namespace has been declared. If a default namespace has been declared,
-the selector will represent only elements in the default
-namespace.
A type selector containing a namespace prefix that has not been -previously declared is an invalid selector. -The mechanism for declaring a namespace prefix is left up to the -language implementing Selectors. In CSS, such a mechanism is defined -in the General Syntax module.
- -In a namespace-aware client, element type selectors will only match -against the local part -of the element's qualified -name. See below for notes about matching -behaviors in down-level clients.
- -In summary:
- --
-
ns|E
- - elements with name E in namespace ns -
*|E
- - elements with name E in any namespace, including those without any - declared namespace -
|E
- - elements with name E without any declared namespace -
E
- - if no default namespace has been specified, this is equivalent to *|E. - Otherwise it is equivalent to ns|E where ns is the default namespace. -
-
-
-CSS examples:
- -@namespace foo url(http://www.example.com);
- foo|h1 { color: blue }
- foo|* { color: yellow }
- |h1 { color: red }
- *|h1 { color: green }
- h1 { color: green }
-
- The first rule will match only h1 elements in the
- "http://www.example.com" namespace.
The second rule will match all elements in the - "http://www.example.com" namespace.
- -The third rule will match only h1 elements without
- any declared namespace.
The fourth rule will match h1 elements in any
- namespace (including those without any declared namespace).
The last rule is equivalent to the fourth rule because no default - namespace has been defined.
- -6.2. Universal selector
- -The universal selector, written "asterisk"
-(*), represents the qualified name of any element
-type. It represents any single element in the document tree in any
-namespace (including those without any declared namespace) if no
-default namespace has been specified. If a default namespace has been
-specified, see Universal selector and
-Namespaces below.
If the universal selector is not the only component of a sequence
-of simple selectors, the * may be omitted.
-
-
-Examples:
--
-
*[hreflang|=en]and[hreflang|=en]are equivalent,
- *.warningand.warningare equivalent,
- *#myidand#myidare equivalent.
-
Note: it is recommended that the
-*, representing the universal selector, not be
-omitted.
6.2.1. Universal selector and namespaces
- -The universal selector allows an optional namespace component. It -is used as follows:
- --
-
ns|*
- - all elements in namespace ns -
*|*
- - all elements -
|*
- - all elements without any declared namespace -
*
- - if no default namespace has been specified, this is equivalent to *|*. - Otherwise it is equivalent to ns|* where ns is the default namespace. -
A universal selector containing a namespace prefix that has not -been previously declared is an invalid -selector. The mechanism for declaring a namespace prefix is left up -to the language implementing Selectors. In CSS, such a mechanism is -defined in the General Syntax module.
- - -6.3. Attribute selectors
- -Selectors allow the representation of an element's attributes. When -a selector is used as an expression to match against an element, -attribute selectors must be considered to match an element if that -element has an attribute that matches the attribute represented by the -attribute selector.
- -6.3.1. Attribute presence and values -selectors
- -CSS2 introduced four attribute selectors:
- --
-
[att]-- Represents an element with the
attattribute, whatever the value of - the attribute.
- [att=val]
- - Represents an element with the
attattribute whose value is exactly - "val".
- [att~=val]
- - Represents an element with the
attattribute whose value is a whitespace-separated list of words, one of - which is exactly "val". If "val" contains whitespace, it will never - represent anything (since the words are separated by - spaces).
- [att|=val]-- Represents an element with the
attattribute, its value either - being exactly "val" or beginning with "val" immediately followed by - "-" (U+002D). This is primarily intended to allow language subcode - matches (e.g., thehreflangattribute on the -linkelement in HTML) as described in RFC 3066 ([RFC3066]). Forlang(or -xml:lang) language subcode matching, please see the:langpseudo-class.
-
Attribute values must be identifiers or strings. The -case-sensitivity of attribute names and values in selectors depends on -the document language.
- -
-
-
-
-Examples:
- -The following attribute selector represents an h1
- element that carries the title attribute, whatever its
- value:
h1[title]- -
In the following example, the selector represents a
- span element whose class attribute has
- exactly the value "example":
span[class="example"]- -
Multiple attribute selectors can be used to represent several
- attributes of an element, or several conditions on the same
- attribute. Here, the selector represents a span element
- whose hello attribute has exactly the value "Cleveland"
- and whose goodbye attribute has exactly the value
- "Columbus":
span[hello="Cleveland"][goodbye="Columbus"]- -
The following selectors illustrate the differences between "="
- and "~=". The first selector will represent, for example, the value
- "copyright copyleft copyeditor" on a rel attribute. The
- second selector will only represent an a element with
- an href attribute having the exact value
- "http://www.w3.org/".
a[rel~="copyright"] -a[href="http://www.w3.org/"]- -
The following selector represents a link element
- whose hreflang attribute is exactly "fr".
link[hreflang=fr]- -
The following selector represents a link element for
- which the values of the hreflang attribute begins with
- "en", including "en", "en-US", and "en-cockney":
link[hreflang|="en"]- -
Similarly, the following selectors represents a
- DIALOGUE element whenever it has one of two different
- values for an attribute character:
DIALOGUE[character=romeo] -DIALOGUE[character=juliet]- -
6.3.2. Substring matching attribute -selectors
- -Three additional attribute selectors are provided for matching -substrings in the value of an attribute:
- --
-
[att^=val]
- - Represents an element with the
attattribute whose value begins - with the prefix "val".
- [att$=val]-- Represents an element with the
attattribute whose value ends with - the suffix "val".
- [att*=val]-- Represents an element with the
attattribute whose value contains - at least one instance of the substring "val".
-
Attribute values must be identifiers or strings. The -case-sensitivity of attribute names in selectors depends on the -document language.
- -
-
-
-Examples:
-The following selector represents an HTML object, referencing an
- image:
object[type^="image/"]-
The following selector represents an HTML anchor a with an
- href attribute whose value ends with ".html".
a[href$=".html"]-
The following selector represents an HTML paragraph with a title
- attribute whose value contains the substring "hello"
p[title*="hello"]-
6.3.3. Attribute selectors and namespaces
- -Attribute selectors allow an optional namespace component to the
-attribute name. A namespace prefix that has been previously declared
-may be prepended to the attribute name separated by the namespace
-separator "vertical bar" (|). In keeping with
-the Namespaces in the XML recommendation, default namespaces do not
-apply to attributes, therefore attribute selectors without a namespace
-component apply only to attributes that have no declared namespace
-(equivalent to "|attr"). An asterisk may be used for the
-namespace prefix indicating that the selector is to match all
-attribute names without regard to the attribute's namespace.
-
-
An attribute selector with an attribute name containing a namespace -prefix that has not been previously declared is an invalid selector. The mechanism for declaring -a namespace prefix is left up to the language implementing Selectors. -In CSS, such a mechanism is defined in the General Syntax module. - -
-
-
-CSS examples:
-@namespace foo "http://www.example.com";
-[foo|att=val] { color: blue }
-[*|att] { color: yellow }
-[|att] { color: green }
-[att] { color: green }
-
- The first rule will match only elements with the attribute
- att in the "http://www.example.com" namespace with the
- value "val".
The second rule will match only elements with the attribute
- att regardless of the namespace of the attribute
- (including no declared namespace).
The last two rules are equivalent and will match only elements
- with the attribute att where the attribute is not
- declared to be in a namespace.
6.3.4. Default attribute values in DTDs
- -Attribute selectors represent explicitly set attribute values in -the document tree. Default attribute values may be defined in a DTD or -elsewhere, but cannot always be selected by attribute -selectors. Selectors should be designed so that they work even if the -default values are not included in the document tree.
- -More precisely, a UA is not required to read an "external -subset" of the DTD but is required to look for default -attribute values in the document's "internal subset." (See [XML10] for definitions of these subsets.)
- -A UA that recognizes an XML namespace [XMLNAMES] is not required to use its -knowledge of that namespace to treat default attribute values as if -they were present in the document. (For example, an XHTML UA is not -required to use its built-in knowledge of the XHTML DTD.)
- -Note: Typically, implementations -choose to ignore external subsets.
- -
-
-
-Example:
- -Consider an element EXAMPLE with an attribute "notation" that has a -default value of "decimal". The DTD fragment might be
- -<!ATTLIST EXAMPLE notation (decimal,octal) "decimal">- -
If the style sheet contains the rules
- -EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
-EXAMPLE[notation=octal] { /*... other settings...*/ }
-
-the first rule will not match elements whose "notation" attribute -is set by default, i.e. not set explicitly. To catch all cases, the -attribute selector for the default value must be dropped:
- -EXAMPLE { /*... default property settings ...*/ }
-EXAMPLE[notation=octal] { /*... other settings...*/ }
-
-Here, because the selector EXAMPLE[notation=octal] is
-more specific than the tag
-selector alone, the style declarations in the second rule will override
-those in the first for elements that have a "notation" attribute value
-of "octal". Care has to be taken that all property declarations that
-are to apply only to the default case are overridden in the non-default
-cases' style rules.
6.4. Class selectors
- -Working with HTML, authors may use the period (U+002E,
-.) notation as an alternative to the ~=
-notation when representing the class attribute. Thus, for
-HTML, div.value and div[class~=value] have
-the same meaning. The attribute value must immediately follow the
-"period" (.).
UAs may apply selectors using the period (.) notation in XML -documents if the UA has namespace-specific knowledge that allows it to -determine which attribute is the "class" attribute for the -respective namespace. One such example of namespace-specific knowledge -is the prose in the specification for a particular namespace (e.g. SVG -1.0 [SVG] describes the SVG -"class" attribute and how a UA should interpret it, and -similarly MathML 1.01 [MATH] describes the MathML -"class" attribute.)
- -
-
-
-CSS examples:
- -We can assign style information to all elements with
- class~="pastoral" as follows:
*.pastoral { color: green } /* all elements with class~=pastoral */
-
- or just
- -.pastoral { color: green } /* all elements with class~=pastoral */
-
- The following assigns style only to H1 elements with
- class~="pastoral":
H1.pastoral { color: green } /* H1 elements with class~=pastoral */
-
- Given these rules, the first H1 instance below would not have - green text, while the second would:
- -<H1>Not green</H1> -<H1 class="pastoral">Very green</H1>- -
To represent a subset of "class" values, each value must be preceded -by a ".", in any order.
- -
-
-
-
-CSS example:
- -The following rule matches any P element whose "class" attribute - has been assigned a list of whitespace-separated values that includes - "pastoral" and "marine":
- -p.pastoral.marine { color: green }
-
- This rule matches when class="pastoral blue aqua
- marine" but does not match for class="pastoral
- blue".
Note: Because CSS gives considerable -power to the "class" attribute, authors could conceivably design their -own "document language" based on elements with almost no associated -presentation (such as DIV and SPAN in HTML) and assigning style -information through the "class" attribute. Authors should avoid this -practice since the structural elements of a document language often -have recognized and accepted meanings and author-defined classes may -not.
- -Note: If an element has multiple -class attributes, their values must be concatenated with spaces -between the values before searching for the class. As of this time the -working group is not aware of any manner in which this situation can -be reached, however, so this behavior is explicitly non-normative in -this specification.
- -6.5. ID selectors
- -Document languages may contain attributes that are declared to be -of type ID. What makes attributes of type ID special is that no two -such attributes can have the same value in a document, regardless of -the type of the elements that carry them; whatever the document -language, an ID typed attribute can be used to uniquely identify its -element. In HTML all ID attributes are named "id"; XML applications -may name ID attributes differently, but the same restriction -applies.
- -An ID-typed attribute of a document language allows authors to
-assign an identifier to one element instance in the document tree. W3C
-ID selectors represent an element instance based on its identifier. An
-ID selector contains a "number sign" (U+0023,
-#) immediately followed by the ID value, which must be an
-identifier.
Selectors does not specify how a UA knows the ID-typed attribute of -an element. The UA may, e.g., read a document's DTD, have the -information hard-coded or ask the user. - -
-
-
-Examples:
-The following ID selector represents an h1 element
- whose ID-typed attribute has the value "chapter1":
h1#chapter1-
The following ID selector represents any element whose ID-typed - attribute has the value "chapter1":
-#chapter1-
The following selector represents any element whose ID-typed - attribute has the value "z98y".
-*#z98y-
Note. In XML 1.0 [XML10], the information about which attribute
-contains an element's IDs is contained in a DTD or a schema. When
-parsing XML, UAs do not always read the DTD, and thus may not know
-what the ID of an element is (though a UA may have namespace-specific
-knowledge that allows it to determine which attribute is the ID
-attribute for that namespace). If a style sheet designer knows or
-suspects that a UA may not know what the ID of an element is, he
-should use normal attribute selectors instead:
-[name=p371] instead of #p371. Elements in
-XML 1.0 documents without a DTD do not have IDs at all.
If an element has multiple ID attributes, all of them must be -treated as IDs for that element for the purposes of the ID -selector. Such a situation could be reached using mixtures of xml:id, -DOM3 Core, XML DTDs, and namespace-specific knowledge.
- -6.6. Pseudo-classes
- -The pseudo-class concept is introduced to permit selection based on -information that lies outside of the document tree or that cannot be -expressed using the other simple selectors.
- -A pseudo-class always consists of a "colon"
-(:) followed by the name of the pseudo-class and
-optionally by a value between parentheses.
Pseudo-classes are allowed in all sequences of simple selectors -contained in a selector. Pseudo-classes are allowed anywhere in -sequences of simple selectors, after the leading type selector or -universal selector (possibly omitted). Pseudo-class names are -case-insensitive. Some pseudo-classes are mutually exclusive, while -others can be applied simultaneously to the same -element. Pseudo-classes may be dynamic, in the sense that an element -may acquire or lose a pseudo-class while a user interacts with the -document.
- - -6.6.1. Dynamic pseudo-classes
- -Dynamic pseudo-classes classify elements on characteristics other -than their name, attributes, or content, in principle characteristics -that cannot be deduced from the document tree.
- -Dynamic pseudo-classes do not appear in the document source or -document tree.
- - -The link pseudo-classes: :link and :visited
- -User agents commonly display unvisited links differently from
-previously visited ones. Selectors
-provides the pseudo-classes :link and
-:visited to distinguish them:
-
-
- The
:linkpseudo-class applies to links that have - not yet been visited.
- - The
:visitedpseudo-class applies once the link has - been visited by the user.
-
After some amount of time, user agents may choose to return a -visited link to the (unvisited) ':link' state.
- -The two states are mutually exclusive.
- -
-
-
-
-Example:
- -The following selector represents links carrying class
- external and already visited:
a.external:visited- -
Note: It is possible for style sheet -authors to abuse the :link and :visited pseudo-classes to determine -which sites a user has visited without the user's consent. - -
UAs may therefore treat all links as unvisited links, or implement -other measures to preserve the user's privacy while rendering visited -and unvisited links differently.
- -The user action pseudo-classes -:hover, :active, and :focus
- -Interactive user agents sometimes change the rendering in response -to user actions. Selectors provides -three pseudo-classes for the selection of an element the user is -acting on.
- --
-
-
- The
:hoverpseudo-class applies while the user - designates an element with a pointing device, but does not activate - it. For example, a visual user agent could apply this pseudo-class - when the cursor (mouse pointer) hovers over a box generated by the - element. User agents not that do not support interactive - media do not have to support this pseudo-class. Some conforming - user agents that support interactive - media may not be able to support this pseudo-class (e.g., a pen - device that does not detect hovering).
-
- - The
:activepseudo-class applies while an element - is being activated by the user. For example, between the times the - user presses the mouse button and releases it.
-
- - The
:focuspseudo-class applies while an element - has the focus (accepts keyboard or mouse events, or other forms of - input).
-
-
There may be document language or implementation specific limits on
-which elements can become :active or acquire
-:focus.
These pseudo-classes are not mutually exclusive. An element may -match several pseudo-classes at the same time.
- -Selectors doesn't define if the parent of an element that is -':active' or ':hover' is also in that state.
- -
-
-
-Examples:
-a:link /* unvisited links */ -a:visited /* visited links */ -a:hover /* user hovers */ -a:active /* active links */-
An example of combining dynamic pseudo-classes:
-a:focus -a:focus:hover-
The last selector matches a elements that are in
- the pseudo-class :focus and in the pseudo-class :hover.
Note: An element can be both ':visited' -and ':active' (or ':link' and ':active').
- -6.6.2. The target pseudo-class :target
- -Some URIs refer to a location within a resource. This kind of URI -ends with a "number sign" (#) followed by an anchor -identifier (called the fragment identifier).
- -URIs with fragment identifiers link to a certain element within the
-document, known as the target element. For instance, here is a URI
-pointing to an anchor named section_2 in an HTML
-document:
http://example.com/html/top.html#section_2- -
A target element can be represented by the :target
-pseudo-class. If the document's URI has no fragment identifier, then
-the document has no target element.
-
-
-Example:
-p.note:target-
This selector represents a p element of class
- note that is the target element of the referring
- URI.
-
-
-CSS example:
-Here, the :target pseudo-class is used to make the
- target element red and place an image before it, if there is one:
*:target { color : red }
-*:target::before { content : url(target.png) }
-6.6.3. The language pseudo-class :lang
- -If the document language specifies how the human language of an
-element is determined, it is possible to write selectors that
-represent an element based on its language. For example, in HTML [HTML4], the language is determined by a
-combination of the lang attribute, the meta
-element, and possibly by information from the protocol (such as HTTP
-headers). XML uses an attribute called xml:lang, and
-there may be other document language-specific methods for determining
-the language.
The pseudo-class :lang(C) represents an element that
-is in language C. Whether an element is represented by a
-:lang() selector is based solely on the identifier C
-being either equal to, or a hyphen-separated substring of, the
-element's language value, in the same way as if performed by the '|=' operator in attribute
-selectors. The identifier C does not have to be a valid language
-name.
C must not be empty. (If it is, the selector is invalid.)
- -Note: It is recommended that -documents and protocols indicate language using codes from RFC 3066 [RFC3066] or its successor, and by means of -"xml:lang" attributes in the case of XML-based documents [XML10]. See -"FAQ: Two-letter or three-letter language codes."
- -
-
-
-Examples:
-The two following selectors represent an HTML document that is in
- Belgian, French, or German. The two next selectors represent
- q quotations in an arbitrary element in Belgian, French,
- or German.
html:lang(fr-be) -html:lang(de) -:lang(fr-be) > q -:lang(de) > q-
6.6.4. The UI element states pseudo-classes
- -The :enabled and :disabled pseudo-classes
- -The :enabled pseudo-class allows authors to customize
-the look of user interface elements that are enabled — which the
-user can select or activate in some fashion (e.g. clicking on a button
-with a mouse). There is a need for such a pseudo-class because there
-is no way to programmatically specify the default appearance of say,
-an enabled input element without also specifying what it
-would look like when it was disabled.
Similar to :enabled, :disabled allows the
-author to specify precisely how a disabled or inactive user interface
-element should look.
Most elements will be neither enabled nor disabled. An element is -enabled if the user can either activate it or transfer the focus to -it. An element is disabled if it could be enabled, but the user cannot -presently activate it or transfer focus to it.
- - -The :checked pseudo-class
- -Radio and checkbox elements can be toggled by the user. Some menu
-items are "checked" when the user selects them. When such elements are
-toggled "on" the :checked pseudo-class applies. The
-:checked pseudo-class initially applies to such elements
-that have the HTML4 selected and checked
-attributes as described in Section
-17.2.1 of HTML4, but of course the user can toggle "off" such
-elements in which case the :checked pseudo-class would no
-longer apply. While the :checked pseudo-class is dynamic
-in nature, and is altered by user action, since it can also be based
-on the presence of the semantic HTML4 selected and
-checked attributes, it applies to all media.
-
-
-
The :indeterminate pseudo-class
- -
-
-
-
-
-Radio and checkbox elements can be toggled by the user, but are -sometimes in an indeterminate state, neither checked nor unchecked. -This can be due to an element attribute, or DOM manipulation.
- -A future version of this specification may introduce an
-:indeterminate pseudo-class that applies to such elements.
-
6.6.5. Structural pseudo-classes
- -Selectors introduces the concept of structural -pseudo-classes to permit selection based on extra information that lies in -the document tree but cannot be represented by other simple selectors or -combinators. - -
Note that standalone pieces of PCDATA (text nodes in the DOM) are -not counted when calculating the position of an element in the list of -children of its parent. When calculating the position of an element in -the list of children of its parent, the index numbering starts at 1. - - -
:root pseudo-class
- -The :root pseudo-class represents an element that is
-the root of the document. In HTML 4, this is always the
-HTML element.
-
-
-
:nth-child() pseudo-class
- -The
-:nth-child(a
-pseudo-class notation represents an element that has
-an+b)n+b-1 siblings
-before it in the document tree, for a given positive
-integer or zero value of n, and has a parent element. In
-other words, this matches the bth child of an element after
-all the children have been split into groups of a elements
-each. For example, this allows the selectors to address every other
-row in a table, and could be used to alternate the color
-of paragraph text in a cycle of four. The a and
-b values must be zero, negative integers or positive
-integers. The index of the first child of an element is 1.
-
-
In addition to this, :nth-child() can take
-'odd' and 'even' as arguments instead.
-'odd' has the same signification as 2n+1,
-and 'even' has the same signification as 2n.
-
-
-
-
-
-Examples:
-tr:nth-child(2n+1) /* represents every odd row of an HTML table */
-tr:nth-child(odd) /* same */
-tr:nth-child(2n) /* represents every even row of an HTML table */
-tr:nth-child(even) /* same */
-
-/* Alternate paragraph colours in CSS */
-p:nth-child(4n+1) { color: navy; }
-p:nth-child(4n+2) { color: green; }
-p:nth-child(4n+3) { color: maroon; }
-p:nth-child(4n+4) { color: purple; }
-When a=0, no repeating is used, so for example
-:nth-child(0n+5) matches only the fifth child. When
-a=0, the an part need not be
-included, so the syntax simplifies to
-:nth-child(b) and the last example simplifies
-to :nth-child(5).
-
-
-
-
-Examples:
-foo:nth-child(0n+1) /* represents an element foo, first child of its parent element */ -foo:nth-child(1) /* same */-
When a=1, the number may be omitted from the rule. - -
-
-
-Examples:
-The following selectors are therefore equivalent:
-bar:nth-child(1n+0) /* represents all bar elements, specificity (0,1,1) */ -bar:nth-child(n+0) /* same */ -bar:nth-child(n) /* same */ -bar /* same but lower specificity (0,0,1) */-
If b=0, then every ath element is picked. In -such a case, the b part may be omitted. - -
-
-
-Examples:
-tr:nth-child(2n+0) /* represents every even row of an HTML table */ -tr:nth-child(2n) /* same */-
If both a and b are equal to zero, the -pseudo-class represents no element in the document tree.
- -The value a can be negative, but only the positive
-values of an+b, for
-n≥0, may represent an element in the document
-tree.
-
-
-Example:
-html|tr:nth-child(-n+6) /* represents the 6 first rows of XHTML tables */-
When the value b is negative, the "+" character in the -expression must be removed (it is effectively replaced by the "-" -character indicating the negative value of b).
- -
-
-
-
-Examples:
-:nth-child(10n-1) /* represents the 9th, 19th, 29th, etc, element */ -:nth-child(10n+9) /* Same */ -:nth-child(10n+-1) /* Syntactically invalid, and would be ignored */-
:nth-last-child() pseudo-class
- -The :nth-last-child(an+b)
-pseudo-class notation represents an element that has
-an+b-1 siblings
-after it in the document tree, for a given positive
-integer or zero value of n, and has a parent element. See
-:nth-child() pseudo-class for the syntax of its argument.
-It also accepts the 'even' and 'odd' values
-as arguments.
-
-
-
-
-
-
-Examples:
-tr:nth-last-child(-n+2) /* represents the two last rows of an HTML table */ - -foo:nth-last-child(odd) /* represents all odd foo elements in their parent element, - counting from the last one */-
:nth-of-type() pseudo-class
- -The :nth-of-type(an+b)
-pseudo-class notation represents an element that has
-an+b-1 siblings with the same
-element name before it in the document tree, for a
-given zero or positive integer value of n, and has a
-parent element. In other words, this matches the bth child
-of that type after all the children of that type have been split into
-groups of a elements each. See :nth-child() pseudo-class
-for the syntax of its argument. It also accepts the
-'even' and 'odd' values.
-
-
-
-
-
-
-CSS example:
-This allows an author to alternate the position of floated images:
-img:nth-of-type(2n+1) { float: right; }
-img:nth-of-type(2n) { float: left; }
-:nth-last-of-type() pseudo-class
- -The :nth-last-of-type(an+b)
-pseudo-class notation represents an element that has
-an+b-1 siblings with the same
-element name after it in the document tree, for a
-given zero or positive integer value of n, and has a
-parent element. See :nth-child() pseudo-class for the
-syntax of its argument. It also accepts the 'even' and 'odd' values.
-
-
-
-
-
-
-Example:
-To represent all h2 children of an XHTML
- body except the first and last, one could use the
- following selector:
body > h2:nth-of-type(n+2):nth-last-of-type(n+2)-
In this case, one could also use :not(), although the
- selector ends up being just as long:
body > h2:not(:first-of-type):not(:last-of-type)-
:first-child pseudo-class
- -Same as :nth-child(1). The :first-child pseudo-class
-represents an element that is the first child of some other element.
-
-
-
-
-
-Examples:
-The following selector represents a p element that is
- the first child of a div element:
div > p:first-child-
This selector can represent the p inside the
- div of the following fragment:
<p> The last P before the note.</p> -<div class="note"> - <p> The first P inside the note.</p> -</div>but cannot represent the second
p in the following
-fragment:
- <p> The last P before the note.</p> -<div class="note"> - <h2> Note </h2> - <p> The first P inside the note.</p> -</div>-
The following two selectors are usually equivalent:
-* > a:first-child /* a is first child of any element */ -a:first-child /* Same (assuming a is not the root element) */-
:last-child pseudo-class
- -Same as :nth-last-child(1). The :last-child pseudo-class
-represents an element that is the last child of some other element.
-
-
-
-
-Example:
-The following selector represents a list item li that
- is the last child of an ordered list ol.
-
ol > li:last-child-
:first-of-type pseudo-class
- -Same as :nth-of-type(1). The :first-of-type pseudo-class
-represents an element that is the first sibling of its type in the list of
-children of its parent element.
-
-
-
-
-Example:
-The following selector represents a definition title
-dt inside a definition list dl, this
-dt being the first of its type in the list of children of
-its parent element.
dl dt:first-of-type-
It is a valid description for the first two dt
-elements in the following example but not for the third one:
<dl> - <dt>gigogne</dt> - <dd> - <dl> - <dt>fusée</dt> - <dd>multistage rocket</dd> - <dt>table</dt> - <dd>nest of tables</dd> - </dl> - </dd> -</dl>-
:last-of-type pseudo-class
- -Same as :nth-last-of-type(1). The
-:last-of-type pseudo-class represents an element that is
-the last sibling of its type in the list of children of its parent
-element.
-
-
-Example:
-The following selector represents the last data cell
- td of a table row.
tr > td:last-of-type-
:only-child pseudo-class
- -Represents an element that has a parent element and whose parent
-element has no other element children. Same as
-:first-child:last-child or
-:nth-child(1):nth-last-child(1), but with a lower
-specificity.
:only-of-type pseudo-class
- -Represents an element that has a parent element and whose parent
-element has no other element children with the same element name. Same
-as :first-of-type:last-of-type or
-:nth-of-type(1):nth-last-of-type(1), but with a lower
-specificity.
:empty pseudo-class
- -The :empty pseudo-class represents an element that has
-no children at all. In terms of the DOM, only element nodes and text
-nodes (including CDATA nodes and entity references) whose data has a
-non-zero length must be considered as affecting emptiness; comments,
-PIs, and other nodes must not affect whether an element is considered
-empty or not.
-
-
-Examples:
-p:empty is a valid representation of the following fragment:
<p></p>-
foo:empty is not a valid representation for the
- following fragments:
<foo>bar</foo>-
<foo><bar>bla</bar></foo>-
<foo>this is not <bar>:empty</bar></foo>-
6.6.6. Blank
- -This section intentionally left blank.
- - -6.6.7. The negation pseudo-class
- -The negation pseudo-class, :not(X), is a
-functional notation taking a simple
-selector (excluding the negation pseudo-class itself and
-pseudo-elements) as an argument. It represents an element that is not
-represented by the argument.
-
-
-
-
-
-
-Examples:
-The following CSS selector matches all button
- elements in an HTML document that are not disabled.
button:not([DISABLED])-
The following selector represents all but FOO
- elements.
*:not(FOO)-
The following group of selectors represents all HTML elements - except links.
-html|*:not(:link):not(:visited)-
Default namespace declarations do not affect the argument of the -negation pseudo-class unless the argument is a universal selector or a -type selector.
- -
-
-
-Examples:
-Assuming that the default namespace is bound to - "http://example.com/", the following selector represents all - elements that are not in that namespace:
-*|*:not(*)-
The following CSS selector matches any element being hovered, - regardless of its namespace. In particular, it is not limited to - only matching elements in the default namespace that are not being - hovered, and elements not in the default namespace don't match the - rule when they are being hovered.
-*|*:not(:hover)-
Note: the :not() pseudo allows
-useless selectors to be written. For instance :not(*|*),
-which represents no element at all, or foo:not(bar),
-which is equivalent to foo but with a higher
-specificity.
7. Pseudo-elements
- -Pseudo-elements create abstractions about the document tree beyond
-those specified by the document language. For instance, document
-languages do not offer mechanisms to access the first letter or first
-line of an element's content. Pseudo-elements allow designers to refer
-to this otherwise inaccessible information. Pseudo-elements may also
-provide designers a way to refer to content that does not exist in the
-source document (e.g., the ::before and
-::after pseudo-elements give access to generated
-content).
A pseudo-element is made of two colons (::) followed
-by the name of the pseudo-element.
This :: notation is introduced by the current document
-in order to establish a discrimination between pseudo-classes and
-pseudo-elements. For compatibility with existing style sheets, user
-agents must also accept the previous one-colon notation for
-pseudo-elements introduced in CSS levels 1 and 2 (namely,
-:first-line, :first-letter,
-:before and :after). This compatibility is
-not allowed for the new pseudo-elements introduced in CSS level 3.
Only one pseudo-element may appear per selector, and if present it -must appear after the sequence of simple selectors that represents the -subjects of the selector. A -future version of this specification may allow multiple -pesudo-elements per selector.
- -7.1. The ::first-line pseudo-element
- -The ::first-line pseudo-element describes the contents
-of the first formatted line of an element.
-
-
-
-
-CSS example:
-p::first-line { text-transform: uppercase }
-The above rule means "change the letters of the first line of every -paragraph to uppercase".
-The selector p::first-line does not match any real
-HTML element. It does match a pseudo-element that conforming user
-agents will insert at the beginning of every paragraph.
Note that the length of the first line depends on a number of -factors, including the width of the page, the font size, etc. Thus, -an ordinary HTML paragraph such as:
- --<P>This is a somewhat long HTML -paragraph that will be broken into several -lines. The first line will be identified -by a fictional tag sequence. The other lines -will be treated as ordinary lines in the -paragraph.</P> -- -
the lines of which happen to be broken as follows: - -
-THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT -will be broken into several lines. The first -line will be identified by a fictional tag -sequence. The other lines will be treated as -ordinary lines in the paragraph. -- -
This paragraph might be "rewritten" by user agents to include the
-fictional tag sequence for ::first-line. This
-fictional tag sequence helps to show how properties are inherited.
-<P><P::first-line> This is a somewhat long HTML -paragraph that </P::first-line> will be broken into several -lines. The first line will be identified -by a fictional tag sequence. The other lines -will be treated as ordinary lines in the -paragraph.</P> -- -
If a pseudo-element breaks up a real element, the desired effect
-can often be described by a fictional tag sequence that closes and
-then re-opens the element. Thus, if we mark up the previous paragraph
-with a span element:
-<P><SPAN class="test"> This is a somewhat long HTML -paragraph that will be broken into several -lines.</SPAN> The first line will be identified -by a fictional tag sequence. The other lines -will be treated as ordinary lines in the -paragraph.</P> -- -
the user agent could simulate start and end tags for
-span when inserting the fictional tag sequence for
-::first-line.
-
-
-<P><P::first-line><SPAN class="test"> This is a -somewhat long HTML -paragraph that will </SPAN></P::first-line><SPAN class="test"> be -broken into several -lines.</SPAN> The first line will be identified -by a fictional tag sequence. The other lines -will be treated as ordinary lines in the -paragraph.</P> -- -
In CSS, the ::first-line pseudo-element can only be
-attached to a block-level element, an inline-block, a table-caption,
-or a table-cell.
The "first formatted line" of an
-element may occur inside a
-block-level descendant in the same flow (i.e., a block-level
-descendant that is not positioned and not a float). E.g., the first
-line of the div in <DIV><P>This
-line...</P></DIV> is the first line of the p (assuming
-that both p and div are block-level).
-
-
The first line of a table-cell or inline-block cannot be the first
-formatted line of an ancestor element. Thus, in <DIV><P
-STYLE="display: inline-block">Hello<BR>Goodbye</P>
-etcetera</DIV> the first formatted line of the
-div is not the line "Hello".
-
-
Note that the first line of the p in this
-fragment: <p><br>First... doesn't contain any
-letters (assuming the default style for br in HTML
-4). The word "First" is not on the first formatted line.
-
-
A UA should act as if the fictional start tags of the
-::first-line pseudo-elements were nested just inside the
-innermost enclosing block-level element. (Since CSS1 and CSS2 were
-silent on this case, authors should not rely on this behavior.) Here
-is an example. The fictional tag sequence for
-<DIV> - <P>First paragraph</P> - <P>Second paragraph</P> -</DIV> -- -
is
- --<DIV> - <P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P> - <P><P::first-line>Second paragraph</P::first-line></P> -</DIV> -- -
The ::first-line pseudo-element is similar to an
-inline-level element, but with certain restrictions. In CSS, the
-following properties apply to a ::first-line
-pseudo-element: font properties, color property, background
-properties, 'word-spacing', 'letter-spacing', 'text-decoration',
-'vertical-align', 'text-transform', 'line-height'. UAs may apply other
-properties as well.
7.2. The ::first-letter pseudo-element
- -The ::first-letter pseudo-element represents the first
-letter of the first line of a block, if it is not preceded by any
-other content (such as images or inline tables) on its line. The
-::first-letter pseudo-element may be used for "initial caps" and "drop
-caps", which are common typographical effects. This type of initial
-letter is similar to an inline-level element if its 'float' property
-is 'none'; otherwise, it is similar to a floated element.
In CSS, these are the properties that apply to ::first-letter
-pseudo-elements: font properties, 'text-decoration', 'text-transform',
-'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
-'float', 'vertical-align' (only if 'float' is 'none'), margin
-properties, padding properties, border properties, color property,
-background properties. UAs may apply other properties as well. To
-allow UAs to render a typographically correct drop cap or initial cap,
-the UA may choose a line-height, width and height based on the shape
-of the letter, unlike for normal elements.
-
-
-Example:
-This example shows a possible rendering of an initial cap. Note
-that the 'line-height' that is inherited by the ::first-letter
-pseudo-element is 1.1, but the UA in this example has computed the
-height of the first letter differently, so that it doesn't cause any
-unnecessary space between the first two lines. Also note that the
-fictional start tag of the first letter is inside the span, and thus
-the font weight of the first letter is normal, not bold as the span:
-
-p { line-height: 1.1 }
-p::first-letter { font-size: 3em; font-weight: normal }
-span { font-weight: bold }
-...
-<p><span>Het hemelsche</span> gerecht heeft zich ten lange lesten<br>
-Erbarremt over my en mijn benaeuwde vesten<br>
-En arme burgery, en op mijn volcx gebed<br>
-En dagelix geschrey de bange stad ontzet.
-
-
-
-
-
-
-
-The following CSS will make a drop cap initial letter span about two lines:
- -
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
-<HTML>
- <HEAD>
- <TITLE>Drop cap initial letter</TITLE>
- <STYLE type="text/css">
- P { font-size: 12pt; line-height: 1.2 }
- P::first-letter { font-size: 200%; font-weight: bold; float: left }
- SPAN { text-transform: uppercase }
- </STYLE>
- </HEAD>
- <BODY>
- <P><SPAN>The first</SPAN> few words of an article
- in The Economist.</P>
- </BODY>
-</HTML>
-
-
-This example might be formatted as follows:
- -
-
-
-
The fictional tag sequence is:
- --<P> -<SPAN> -<P::first-letter> -T -</P::first-letter>he first -</SPAN> -few words of an article in the Economist. -</P> -- -
Note that the ::first-letter pseudo-element tags abut
-the content (i.e., the initial character), while the ::first-line
-pseudo-element start tag is inserted right after the start tag of the
-block element.
In order to achieve traditional drop caps formatting, user agents -may approximate font sizes, for example to align baselines. Also, the -glyph outline may be taken into account when formatting.
- -Punctuation (i.e, characters defined in Unicode in the "open" (Ps), -"close" (Pe), "initial" (Pi). "final" (Pf) and "other" (Po) -punctuation classes), that precedes or follows the first letter should -be included. [UNICODE]
- -
-
-
-
The ::first-letter also applies if the first letter is
-in fact a digit, e.g., the "6" in "67 million dollars is a lot of
-money."
In CSS, the ::first-letter pseudo-element applies to
-block, list-item, table-cell, table-caption, and inline-block
-elements. A future version of this specification
-may allow this pesudo-element to apply to more element
-types.
The ::first-letter pseudo-element can be used with all
-such elements that contain text, or that have a descendant in the same
-flow that contains text. A UA should act as if the fictional start tag
-of the ::first-letter pseudo-element is just before the first text of
-the element, even if that first text is in a descendant.
-
-
-Example:
-The fictional tag sequence for this HTMLfragment: -
<div> -<p>The first text.-
is: -
<div> -<p><div::first-letter><p::first-letter>T</...></...>he first text.-
The first letter of a table-cell or inline-block cannot be the
-first letter of an ancestor element. Thus, in <DIV><P
-STYLE="display: inline-block">Hello<BR>Goodbye</P>
-etcetera</DIV> the first letter of the div is not the
-letter "H". In fact, the div doesn't have a first letter.
-
-
The first letter must occur on the first formatted line. For example, in
-this fragment: <p><br>First... the first line
-doesn't contain any letters and ::first-letter doesn't
-match anything (assuming the default style for br in HTML
-4). In particular, it does not match the "F" of "First."
-
-
In CSS, if an element is a list item ('display: list-item'), the
-::first-letter applies to the first letter in the
-principal box after the marker. UAs may ignore
-::first-letter on list items with 'list-style-position:
-inside'. If an element has ::before or
-::after content, the ::first-letter applies
-to the first letter of the element including that content.
-
-
-
-
-Example:
-After the rule 'p::before {content: "Note: "}', the selector -'p::first-letter' matches the "N" of "Note".
-Some languages may have specific rules about how to treat certain
-letter combinations. In Dutch, for example, if the letter combination
-"ij" appears at the beginning of a word, both letters should be
-considered within the ::first-letter pseudo-element.
-
-
If the letters that would form the ::first-letter are not in the
-same element, such as "'T" in <p>'<em>T..., the UA
-may create a ::first-letter pseudo-element from one of the elements,
-both elements, or simply not create a pseudo-element.
Similarly, if the first letter(s) of the block are not at the start -of the line (for example due to bidirectional reordering), then the UA -need not create the pseudo-element(s). - -
-
-
-
-Example:
-The following example illustrates -how overlapping pseudo-elements may interact. The first letter of -each P element will be green with a font size of '24pt'. The rest of -the first formatted line will be 'blue' while the rest of the -paragraph will be 'red'.
- -p { color: red; font-size: 12pt }
-p::first-letter { color: green; font-size: 200% }
-p::first-line { color: blue }
-
-<P>Some text that ends up on two lines</P>
-
-Assuming that a line break will occur before the word "ends", the -fictional tag -sequence for this fragment might be:
- -<P> -<P::first-line> -<P::first-letter> -S -</P::first-letter>ome text that -</P::first-line> -ends up on two lines -</P>- -
Note that the ::first-letter element is inside the ::first-line
-element. Properties set on ::first-line are inherited by
-::first-letter, but are overridden if the same property is set on
-::first-letter.
7.3. The ::selection pseudo-element
- -The ::selection pseudo-element applies to the portion
-of a document that has been highlighted by the user. This also
-applies, for example, to selected text within an editable text
-field. This pseudo-element should not be confused with the :checked pseudo-class (which used to be
-named :selected)
-
-
Although the ::selection pseudo-element is dynamic in
-nature, and is altered by user action, it is reasonable to expect that
-when a UA re-renders to a static medium (such as a printed page, see
-[CSS21]) which was originally rendered to a
-dynamic medium (like screen), the UA may wish to transfer the current
-::selection state to that other medium, and have all the
-appropriate formatting and rendering take effect as well. This is not
-required — UAs may omit the ::selection
-pseudo-element for static media.
-
-
These are the CSS properties that apply to ::selection
-pseudo-elements: color, background, cursor (optional), outline
-(optional). The computed value of the 'background-image' property on
-::selection may be ignored.
-
-
-
7.4. The ::before and ::after pseudo-elements
- -The ::before and ::after pseudo-elements
-can be used to describe generated content before or after an element's
-content. They are explained in CSS 2.1 [CSS21].
When the ::first-letter and ::first-line
-pseudo-elements are combined with ::before and
-::after, they apply to the first letter or line of the
-element including the inserted text.
8. Combinators
- -8.1. Descendant combinator
- -At times, authors may want selectors to describe an element that is
-the descendant of another element in the document tree (e.g., "an
-EM element that is contained within an H1
-element"). Descendant combinators express such a relationship. A
-descendant combinator is white space that
-separates two sequences of simple selectors. A selector of the form
-"A B" represents an element B that is an
-arbitrary descendant of some ancestor element A.
-
-
-
-
-Examples:
-For example, consider the following selector:
-h1 em-
It represents an em element being the descendant of
- an h1 element. It is a correct and valid, but partial,
- description of the following fragment:
<h1>This <span class="myclass">headline -is <em>very</em> important</span></h1>-
The following selector:
-div * p-
represents a p element that is a grandchild or later
- descendant of a div element. Note the whitespace on
- either side of the "*" is not part of the universal selector; the
- whitespace is a combinator indicating that the DIV must be the
- ancestor of some element, and that that element must be an ancestor
- of the P.
The following selector, which combines descendant combinators and
- attribute selectors, represents an
- element that (1) has the href attribute set and (2) is
- inside a p that is itself inside a div:
div p *[href]-
8.2. Child combinators
- -A child combinator describes a childhood relationship
-between two elements. A child combinator is made of the
-"greater-than sign" (>) character and
-separates two sequences of simple selectors.
-
-
-
-
-
-Examples:
-The following selector represents a p element that is
- child of body:
body > p-
The following example combines descendant combinators and child - combinators.
-div ol>li p-
It represents a p element that is a descendant of an
- li element; the li element must be the
- child of an ol element; the ol element must
- be a descendant of a div. Notice that the optional white
- space around the ">" combinator has been left out.
For information on selecting the first child of an element, please
-see the section on the :first-child pseudo-class
-above.
8.3. Sibling combinators
- -There are two different sibling combinators: the adjacent sibling -combinator and the general sibling combinator. In both cases, -non-element nodes (e.g. text between elements) are ignored when -considering adjacency of elements.
- -8.3.1. Adjacent sibling combinator
- -The adjacent sibling combinator is made of the "plus
-sign" (U+002B, +) character that separates two
-sequences of simple selectors. The elements represented by the two
-sequences share the same parent in the document tree and the element
-represented by the first sequence immediately precedes the element
-represented by the second one.
-
-
-
-Examples:
-The following selector represents a p element
- immediately following a math element:
math + p-
The following selector is conceptually similar to the one in the
- previous example, except that it adds an attribute selector — it
- adds a constraint to the h1 element, that it must have
- class="opener":
h1.opener + h2-
8.3.2. General sibling combinator
- -The general sibling combinator is made of the "tilde"
-(U+007E, ~) character that separates two sequences of
-simple selectors. The elements represented by the two sequences share
-the same parent in the document tree and the element represented by
-the first sequence precedes (not necessarily immediately) the element
-represented by the second one.
-
-
-Example:
-h1 ~ pre-
represents a pre element following an h1. It
- is a correct and valid, but partial, description of:
<h1>Definition of the function a</h1> -<p>Function a(x) has to be applied to all figures in the table.</p> -<pre>function a(x) = 12x/13.5</pre>-
9. Calculating a selector's specificity
- -A selector's specificity is calculated as follows:
- --
-
- count the number of ID selectors in the selector (= a) -
- count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b) -
- count the number of element names in the selector (= c) -
- ignore pseudo-elements -
Selectors inside the negation pseudo-class -are counted like any other, but the negation itself does not count as -a pseudo-class.
- -Concatenating the three numbers a-b-c (in a number system with a -large base) gives the specificity.
- -
-
-
-Examples:
-* /* a=0 b=0 c=0 -> specificity = 0 */ -LI /* a=0 b=0 c=1 -> specificity = 1 */ -UL LI /* a=0 b=0 c=2 -> specificity = 2 */ -UL OL+LI /* a=0 b=0 c=3 -> specificity = 3 */ -H1 + *[REL=up] /* a=0 b=1 c=1 -> specificity = 11 */ -UL OL LI.red /* a=0 b=1 c=3 -> specificity = 13 */ -LI.red.level /* a=0 b=2 c=1 -> specificity = 21 */ -#x34y /* a=1 b=0 c=0 -> specificity = 100 */ -#s12:not(FOO) /* a=1 b=0 c=1 -> specificity = 101 */ --
Note: the specificity of the styles
-specified in an HTML style attribute is described in CSS
-2.1. [CSS21].
10. The grammar of Selectors
- -10.1. Grammar
- -The grammar below defines the syntax of Selectors. It is globally -LL(1) and can be locally LL(2) (but note that most UA's should not use -it directly, since it doesn't express the parsing conventions). The -format of the productions is optimized for human consumption and some -shorthand notations beyond Yacc (see [YACC]) -are used:
- --
-
- *: 0 or more -
- +: 1 or more -
- ?: 0 or 1 -
- |: separates alternatives -
- [ ]: grouping -
The productions are:
- -selectors_group - : selector [ COMMA S* selector ]* - ; - -selector - : simple_selector_sequence [ combinator simple_selector_sequence ]* - ; - -combinator - /* combinators can be surrounded by white space */ - : PLUS S* | GREATER S* | TILDE S* | S+ - ; - -simple_selector_sequence - : [ type_selector | universal ] - [ HASH | class | attrib | pseudo | negation ]* - | [ HASH | class | attrib | pseudo | negation ]+ - ; - -type_selector - : [ namespace_prefix ]? element_name - ; - -namespace_prefix - : [ IDENT | '*' ]? '|' - ; - -element_name - : IDENT - ; - -universal - : [ namespace_prefix ]? '*' - ; - -class - : '.' IDENT - ; - -attrib - : '[' S* [ namespace_prefix ]? IDENT S* - [ [ PREFIXMATCH | - SUFFIXMATCH | - SUBSTRINGMATCH | - '=' | - INCLUDES | - DASHMATCH ] S* [ IDENT | STRING ] S* - ]? ']' - ; - -pseudo - /* '::' starts a pseudo-element, ':' a pseudo-class */ - /* Exceptions: :first-line, :first-letter, :before and :after. */ - /* Note that pseudo-elements are restricted to one per selector and */ - /* occur only in the last simple_selector_sequence. */ - : ':' ':'? [ IDENT | functional_pseudo ] - ; - -functional_pseudo - : FUNCTION S* expression ')' - ; - -expression - /* In CSS3, the expressions are identifiers, strings, */ - /* or of the form "an+b" */ - : [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+ - ; - -negation - : NOT S* negation_arg S* ')' - ; - -negation_arg - : type_selector | universal | HASH | class | attrib | pseudo - ;- - -
10.2. Lexical scanner
- -The following is the tokenizer, written in Flex (see -[FLEX]) notation. The tokenizer is -case-insensitive.
- -The two occurrences of "\377" represent the highest character -number that current versions of Flex can deal with (decimal 255). They -should be read as "\4177777" (decimal 1114111), which is the highest -possible code point in Unicode/ISO-10646. [UNICODE]
- -%option case-insensitive
-
-ident [-]?{nmstart}{nmchar}*
-name {nmchar}+
-nmstart [_a-z]|{nonascii}|{escape}
-nonascii [^\0-\177]
-unicode \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?
-escape {unicode}|\\[^\n\r\f0-9a-f]
-nmchar [_a-z0-9-]|{nonascii}|{escape}
-num [0-9]+|[0-9]*\.[0-9]+
-string {string1}|{string2}
-string1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*\"
-string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
-invalid {invalid1}|{invalid2}
-invalid1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*
-invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
-nl \n|\r\n|\r|\f
-w [ \t\r\n\f]*
-
-%%
-
-[ \t\r\n\f]+ return S;
-
-"~=" return INCLUDES;
-"|=" return DASHMATCH;
-"^=" return PREFIXMATCH;
-"$=" return SUFFIXMATCH;
-"*=" return SUBSTRINGMATCH;
-{ident} return IDENT;
-{string} return STRING;
-{ident}"(" return FUNCTION;
-{num} return NUMBER;
-"#"{name} return HASH;
-{w}"+" return PLUS;
-{w}">" return GREATER;
-{w}"," return COMMA;
-{w}"~" return TILDE;
-":not(" return NOT;
-@{ident} return ATKEYWORD;
-{invalid} return INVALID;
-{num}% return PERCENTAGE;
-{num}{ident} return DIMENSION;
-"<!--" return CDO;
-"-->" return CDC;
-
-"url("{w}{string}{w}")" return URI;
-"url("{w}([!#$%&*-~]|{nonascii}|{escape})*{w}")" return URI;
-U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
-
-\/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
-
-. return *yytext;
-
-
-
-11. Namespaces and down-level clients
- -An important issue is the interaction of CSS selectors with XML -documents in web clients that were produced prior to this -document. Unfortunately, due to the fact that namespaces must be -matched based on the URI which identifies the namespace, not the -namespace prefix, some mechanism is required to identify namespaces in -CSS by their URI as well. Without such a mechanism, it is impossible -to construct a CSS style sheet which will properly match selectors in -all cases against a random set of XML documents. However, given -complete knowledge of the XML document to which a style sheet is to be -applied, and a limited use of namespaces within the XML document, it -is possible to construct a style sheet in which selectors would match -elements and attributes correctly.
- -It should be noted that a down-level CSS client will (if it
-properly conforms to CSS forward compatible parsing rules) ignore all
-@namespace at-rules, as well as all style rules that make
-use of namespace qualified element type or attribute selectors. The
-syntax of delimiting namespace prefixes in CSS was deliberately chosen
-so that down-level CSS clients would ignore the style rules rather
-than possibly match them incorrectly.
The use of default namespaces in CSS makes it possible to write -element type selectors that will function in both namespace aware CSS -clients as well as down-level clients. It should be noted that -down-level clients may incorrectly match selectors against XML -elements in other namespaces.
- -The following are scenarios and examples in which it is possible to -construct style sheets which would function properly in web clients -that do not implement this proposal.
- --
-
-
-
-
The XML document does not use namespaces.
- --
-
-
- In this case, it is obviously not necessary to declare or use - namespaces in the style sheet. Standard CSS element type and - attribute selectors will function adequately in a down-level - client. - -
- In a CSS namespace aware client, the default behavior of
- element selectors matching without regard to namespace will
- function properly against all elements, since no namespaces are
- present. However, the use of specific element type selectors that
- match only elements that have no namespace ("
|name") - will guarantee that selectors will match only XML elements that do - not have a declared namespace.
-
-
-
- -
-
-
The XML document defines a single, default namespace used - throughout the document. No namespace prefixes are used in element - names.
- --
-
-
- In this case, a down-level client will function as if - namespaces were not used in the XML document at all. Standard CSS - element type and attribute selectors will match against all - elements. - -
-
- -
-
-
The XML document does not use a default namespace, all - namespace prefixes used are known to the style sheet author, and - there is a direct mapping between namespace prefixes and namespace - URIs. (A given prefix may only be mapped to one namespace URI - throughout the XML document; there may be multiple prefixes mapped - to the same URI).
- --
-
-
- In this case, the down-level client will view and match
- element type and attribute selectors based on their fully
- qualified name, not the local part as outlined in the Type selectors and Namespaces section. CSS
- selectors may be declared using an escaped colon "
\:" - to describe the fully qualified names, e.g. - "html\:h1" will match -<html:h1>. Selectors using the qualified name - will only match XML elements that use the same prefix. Other - namespace prefixes used in the XML that are mapped to the same URI - will not match as expected unless additional CSS style rules are - declared for them.
-
- - Note that selectors declared in this fashion will - only match in down-level clients. A CSS namespace aware - client will match element type and attribute selectors based on - the name's local part. Selectors declared with the fully - qualified name will not match (unless there is no namespace prefix - in the fully qualified name). - -
-
- - In this case, the down-level client will view and match
- element type and attribute selectors based on their fully
- qualified name, not the local part as outlined in the Type selectors and Namespaces section. CSS
- selectors may be declared using an escaped colon "
In other scenarios: when the namespace prefixes used in the XML are -not known in advance by the style sheet author; or a combination of -elements with no namespace are used in conjunction with elements using -a default namespace; or the same namespace prefix is mapped to -different namespace URIs within the same document, or in -different documents; it is impossible to construct a CSS style sheet -that will function properly against all elements in those documents, -unless, the style sheet is written using a namespace URI syntax (as -outlined in this document or similar) and the document is processed by -a CSS and XML namespace aware client.
- -12. Profiles
- -Each specification using Selectors must define the subset of W3C -Selectors it allows and excludes, and describe the local meaning of -all the components of that subset.
- -Non normative examples: - -
-
-
-
-
-
-
-
-
-
-| Selectors profile | |
|---|---|
| Specification | -CSS level 1 |
| Accepts | -type selectors class selectors ID selectors :link, - :visited and :active pseudo-classes descendant combinator - ::first-line and ::first-letter pseudo-elements |
| Excludes | -
-
- universal selector namespaces |
| Extra constraints | -only one class selector allowed per sequence of simple - selectors |
-
| Selectors profile | |
|---|---|
| Specification | -CSS level 2 |
| Accepts | -type selectors universal selector attribute presence and - values selectors class selectors ID selectors :link, :visited, - :active, :hover, :focus, :lang() and :first-child pseudo-classes - descendant combinator child combinator adjacent sibling - combinator ::first-line and ::first-letter pseudo-elements ::before - and ::after pseudo-elements |
| Excludes | -
-
- content selectors namespaces |
| Extra constraints | -more than one class selector per sequence of simple selectors (CSS1 - constraint) allowed |
In CSS, selectors express pattern matching rules that determine which style -rules apply to elements in the document tree. - -
The following selector (CSS level 2) will match all anchors a
-with attribute name set inside a section 1 header h1:
-
h1 a[name]- -
All CSS declarations attached to such a selector are applied to elements -matching it.
-
-
-
-
-
-
-| Selectors profile | |
|---|---|
| Specification | -STTS 3 | -
| Accepts | -
-
- type selectors namespaces |
| Excludes | -non-accepted pseudo-classes pseudo-elements |
| Extra constraints | -some selectors and combinators are not allowed in fragment - descriptions on the right side of STTS declarations. |
Selectors can be used in STTS 3 in two different - manners: -
-
-
- a selection mechanism equivalent to CSS selection mechanism: declarations - attached to a given selector are applied to elements matching that selector, -
- fragment descriptions that appear on the right side of declarations. -
13. Conformance and requirements
- -This section defines conformance with the present specification only. - -
The inability of a user agent to implement part of this specification due to -the limitations of a particular device (e.g., non interactive user agents will -probably not implement dynamic pseudo-classes because they make no sense without -interactivity) does not imply non-conformance. - -
All specifications reusing Selectors must contain a Profile listing the -subset of Selectors it accepts or excludes, and describing the constraints -it adds to the current specification. - -
Invalidity is caused by a parsing error, e.g. an unrecognized token or a token -which is not allowed at the current parsing point. - -
User agents must observe the rules for handling parsing errors: -
-
-
- a simple selector containing an undeclared namespace prefix is invalid -
- a selector containing an invalid simple selector, an invalid combinator - or an invalid token is invalid. -
- a group of selectors containing an invalid selector is invalid. -
Specifications reusing Selectors must define how to handle parsing -errors. (In the case of CSS, the entire rule in which the selector is -used is dropped.)
- - - -14. Tests
- -This specification has a test -suite allowing user agents to verify their basic conformance to -the specification. This test suite does not pretend to be exhaustive -and does not cover all possible combined cases of Selectors.
- -15. Acknowledgements
- -The CSS working group would like to thank everyone who has sent -comments on this specification over the years.
- -The working group would like to extend special thanks to Donna -McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed -the final editorial review.
- -16. References
- --
-
-
- [CSS1] -
- Bert Bos, Håkon Wium Lie; "Cascading Style Sheets, level 1", W3C Recommendation, 17 Dec 1996, revised 11 Jan 1999
-
- (
http://www.w3.org/TR/REC-CSS1) - - - (
- [CSS21] -
- Bert Bos, Tantek Çelik, Ian Hickson, Håkon Wium Lie, editors; "Cascading Style Sheets, level 2 revision 1", W3C Working Draft, 13 June 2005
-
- (
http://www.w3.org/TR/CSS21) - - - (
- [CWWW] -
- Martin J. Dürst, François Yergeau, Misha Wolf, Asmus Freytag, Tex Texin, editors; "Character Model for the World Wide Web", W3C Recommendation, 15 February 2005
-
- (
http://www.w3.org/TR/charmod/) - - - (
- [FLEX] -
- "Flex: The Lexical Scanner Generator", Version 2.3.7, ISBN 1882114213 - -
- [HTML4] -
- Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "HTML 4.01 Specification", W3C Recommendation, 24 December 1999
-
- (
http://www.w3.org/TR/html4/) - - - (
- [MATH] -
- Patrick Ion, Robert Miner, editors; "Mathematical Markup Language (MathML) 1.01", W3C Recommendation, revision of 7 July 1999
-
- (
http://www.w3.org/TR/REC-MathML/) - - - (
- [RFC3066] -
- H. Alvestrand; "Tags for the Identification of Languages", Request for Comments 3066, January 2001
-
- (
http://www.ietf.org/rfc/rfc3066.txt) - - - (
- [STTS] -
- Daniel Glazman; "Simple Tree Transformation Sheets 3", Electricité de France, submission to the W3C, 11 November 1998
-
- (
http://www.w3.org/TR/NOTE-STTS3) - - - (
- [SVG] -
- Jon Ferraiolo, 藤沢 淳, Dean Jackson, editors; "Scalable Vector Graphics (SVG) 1.1 Specification", W3C Recommendation, 14 January 2003
-
- (
http://www.w3.org/TR/SVG/) - - - (
- [UNICODE] -
- The Unicode Standard, Version 4.1, The Unicode Consortium. Boston, MA, Addison-Wesley, March 2005. ISBN 0-321-18578-1, as amended by Unicode 4.0.1 and Unicode 4.1.0.
-
- (
- -http://www.unicode.org/versions/) - (
- [XML10] -
- Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, François Yergeau, editors; "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C Recommendation, 4 February 2004
-
- (
http://www.w3.org/TR/REC-xml/) - - - (
- [XMLNAMES] -
- Tim Bray, Dave Hollander, Andrew Layman, editors; "Namespaces in XML", W3C Recommendation, 14 January 1999
-
- (
http://www.w3.org/TR/REC-xml-names/) - - - (
- [YACC] -
- S. C. Johnson; "YACC — Yet another compiler compiler", Technical Report, Murray Hill, 1975 - -