WHATWG Wiki - User contributions [en]

HTML vs. XHTML

2011-07-05T12:37:19Z

Loveservice:

== Differences Between HTML and XHTML ==

This page is currently being revised. Some information is incomplete or missing.

Please note that the information in here is based upon the current spec for (X)HTML5. Some of the issues technically do not apply to previous versions of HTML.

Although HTML and XHTML appear to have similarities in their syntax, they are significantly different in many ways.

:'''Note''': As the current WHATWG document is a draft, this section will need to track to a moving target.

The document at http://dev.w3.org/html5/html-xhtml-author-guide/html-xhtml-authoring-guide.html provides a similar analysis.

=== Overlap Language ===

There is a community who find it valuable to be able to serve HTML5 documents which are also valid XML documents. They may, for example, use XML tools to generate the document, and they and others may process the document using XML tools. These documents are served as text/html.

This language is sometimes called "polyglot". It is the overlap language of documents which are both HTML5 documents and XML documents. Guidelines are listed below for how one can construct such a polyglot document which will work in either environment. Besides following the well-formedness rules of XML, there are some other restrictions to which one must adhere (for the sake of text/html documents).

This wiki web page is an example of such a document. You can parse it with an XML parser or an HTML parser.

=== MIME Types ===

{| class="wikitable" border="1"
|-
! Feature
! HTML Requirement
! XHTML Requirement
! Notes
|-
| Mime Type
| Must use <code>text/html</code>.
| Must use an XML MIME type, such as <code>application/xml</code> or <code>application/xhtml+xml</code>.
| It is the MIME type that determines what type of document you are using. Any document, including a document authored with the intention of being XHTML, served as <code>text/html</code> is technically an HTML document.
|}

Note that XHTML 1.0 previously defined that documents adhering to the compatibility guidelines were allowed to be served as <code>text/html</code>, but HTML 5 now defines that such documents are HTML, not XHTML.

=== Syntax and Parsing ===

XHTML uses XML parsing requirements. HTML uses its own which are defined much more closely to the way browsers actually handle HTML today. The following table describes the differences between how each is parsed.

The column on "Guidance for XHTML-HTML compatibility" lists ways in which a document can be crafted to work in either XHTML or HTML. The item will be bolded if it is a requirement for XHTML-compliant code to be changed, since XHTML will otherwise usually work as HTML, at least if its full features are constrained.

{| class="wikitable" border="1"
|-
! Feature
! HTML Requirement
! XHTML Requirement
! Notes
! Guidance for XHTML-HTML compatibility
|-
!Parsing Modes
|Three parsing modes are defined: ''no quirks mode'', ''quirks mode'' and ''limited quirks mode''. The mode is only ever changed from the default by the HTML parser, based on the presence, absence, or value of the DOCTYPE string, respectively.
|XML parsing rules are used. There is only one mode.
|The parsing modes in HTML also have an effect upon script and stylesheet processing. XHTML is considered to be in ''no quirks mode'' for these purposes.
| '''Use an explicit <code><!DOCTYPE html></code> (case insensitively) or legacy-compat version <code><!DOCTYPE html SYSTEM "about:legacy-compat"></code> for the sake of HTML and thus trigger no quirks parsing.'''
|-
!Error Handling
|HTML does not have a well-formedness constraint, no errors are fatal. Graceful error handling and recovery procedures are thoroughly defined.
|Well-formedness errors are fatal
|
| Ensure there are no well-formedness errors.
|-
! Character Encoding (including XML Declaration, <code>meta</code>)
| The XML declaration is forbidden (treated as a bogus comment, but such style of comments are deprecated), but the <code>meta</code> element with a <code>charset</code> attribute may be used instead.
If the encoding is unspecified in HTML, it should be determined through implementation specific heuristics or fallback to a default value (Note: this section of the spec is not yet finished).
| The XML declaration may be used to [http://wiki.whatwg.org/wiki/FAQ#How_do_I_specify_the_character_encoding.3F specify the character encoding], while <code>meta</code> is only allowed as case-insensitive "UTF-8" (and is ignored if included).
The default character encoding for XHTML is, according to XML rules, <code>UTF-8</code> or <code>UTF-16</code>.
|
| '''If you need to include XML 1.1-only markup, if you do not wish to convert the encoding of the document to UTF-8 or UTF-16 (since use of other encodings also requires a declaration), or if you wish to define an external SYSTEM DTD in the DOCTYPE but use standalone=yes (redundant?), you must use an XML Declaration for XHTML, but this may not be allowable in the future in HTML. For future compatibility, it would be best to avoid XML 1.1-only markup, convert to UTF-8 or UTF-16 (probably UTF-8 which could allow use of a <code>meta</code> tag), and avoid use of a SYSTEM DTD (rendering the standalone=yes unnecessary), respectively. Do not use a <code>meta</code> tag, unless it is UTF-8 (and included in the first 512 bytes of the document), in which case it is probably a good idea to include it for the sake of HTML (as <nowiki><meta charset="UTF-8"></nowiki>) in case you cannot specify such in a content header.'''
|-
!Namespaced elements
|Elements and attributes for known vocabularies (HTML, SVG and MathML) are implicitly assigned to appropriate namespaces, according to the rules specified in the parsing algorithm. Elements in the HTML, SVG, or MathML namespaces may have an <code>xmlns</code> attribute explicitly specified, if, and only if, it has the exact value <code>"http://www.w3.org/1999/xhtml"</code> (see [http://wiki.whatwg.org/wiki/FAQ#What_is_the_namespace_declaration.3F namespace declaration]). The attribute has absolutely no effect. It is basically a talisman. It is allowed merely to make migration to and from XHTML mildly easier. When parsed by an HTML parser, the xmlns attribute itself ends up in no namespace. Foreign elements are also not treated as being in another namespace and will have no effect except for displaying by default as inline elements (and be aware that self-closing elements cannot be used as such since unrecognized elements will be treated as though they are non-void; thus one cannot, for example, type <code><caesura /></code> in HTML or it will be treated as though there is no immediate closing tag). Namespaced prefixes are not allowed on HTML elements; a prefixed xmlns attribute cannot be used even if it is defined in the XHTML namespace.
| The XHTML namespace must be declared for HTML elements according to the rules defined by the ''[http://www.w3.org/TR/REC-xml-names/ Namespaces in XML]'' specification. Namespaces must be explicitly declared. The <code>xmlns</code> attribute ends up in the <code>"http://www.w3.org/2000/xmlns"</code> namespace. Foreign elements can be used independently of HTML elements, as long as they are assigned to their own namespace.
|
| Declare HTML namespaces (or other namespaces) explicitly and do not prefix XHTML elements. '''Do not depend on the behavior of foreign namespaced elements in an HTML setting; if you need to include these, you will probably wish to set this foreign markup via CSS to <code>display:none</code>. You should explicitly close (not self-close) all empty elements defined in a non-XHTML namespace, since otherwise when used in HTML, HTML will treat them as though they have not been closed.'''
|-
!Namespaced attributes on HTML elements
| Attributes of the form <code>xmlns:<var>prefix</var></code> may not be used on HTML elements.
| The <code>xmlns:<var>prefix</var></code> attributes end up in the <code>"http://www.w3.org/2000/xmlns"</code> namespace.
|
| '''Do not use namespaced attributes on HTML elements. Do not depend on the behavior of foreign attributes in an HTML setting.'''
|-
!Namespace attributes on foreign elements
|
Elements in the SVG namespace may have an <code>xmlns</code> attribute specified, if, and only if, it has the exact value <code>"http://www.w3.org/2000/svg"</code>. The attribute is optional because the namespace is implied during parsing.

Elements in the MathML namespace may have an <code>xmlns</code> attribute specified, if, and only if, it has the exact value <code>"http://www.w3.org/1998/Math/MathML"</code>. The attribute is optional because the namespace is implied during parsing.

Foreign elements may also have an <code>xmlns:xlink</code> attribute specified, if, and only if, it has the exact value <code>"http://www.w3.org/1999/xlink"</code>. This attribute is optional, even if XLink attributes are used, because the namespaces for XLink attributes is implied during parsing.

When parsed by an HTML parser, the <code>xmlns</code> and <code>xmlns:xlink</code> attributes end up in the <code>"http://www.w3.org/2000/xmlns"</code> namespace.
|The SVG and MathML namespaces must be declared for SVG and MathML elements, respectively, according to the rules defined by ''Namespaces in XML''. The <code>xmlns</code> and <code>xmlns:<var>prefix</var></code> attributes end up in the <code>"http://www.w3.org/2000/xmlns"</code> namespace.
|
|-
!XLink attributes
|Foreign elements may use the attributes <code>xlink:actuate</code>, <code>xlink:arcrole</code>, <code>xlink:href</code>, <code>xlink:role</code>, <code>xlink:show</code>, <code>xlink:title</code> and <code>xlink:type</code>. These attributes are placed in the <code>"http://www.w3.org/1999/xlink"</code>. The prefix used must be "<code>xlink</code>".
|XLink attributes may be specified on foreign elements using any prefix, subject to the conformance rules defined by ''Namespaces in XML''. The XLink namespace must be declared according to the conformance rules defined by ''Namespaces in XML'' if XLink attributes are used within the document.
|
| '''Do not use XLink attributes on HTML elements and do not depend on them on foreign elements as will not work as such in HTML.''' If being used, ensure they have the appropriate XLink namespace defined.
|-
!XML attributes
|
Foreign elements may use the attributes <code>xml:lang</code>, <code>xml:id</code>, <code>xml:base</code> and <code>xml:space</code>. These attributes are placed in the <code>"http://www.w3.org/XML/1998/namespace"</code>. The prefix used must be "<code>xml</code>".

HTML elements may use the <code>xml:lang</code> attribute. The attribute in no namespace with no prefix and with the literal localname "<code>xml:lang</code>" has no effect on language processing (as does "<code>lang</code>". HTML elements must not use the <code>xml:base</code>, <code>xml:space</code>, or <code>xml:id</code> attributes.
| Any element, including HTML elements, may use the attributes <code>xml:lang</code>, <code>xml:id</code>, <code>xml:base</code> and <code>xml:space</code>. These attributes are placed in the <code>"http://www.w3.org/XML/1998/namespace"</code>. The prefix used must be "<code>xml</code>".
|
| '''Though they can be used on foreign elements, do not use <code>xml:base</code>, <code>xml:id</code>, or <code>xml:space</code> on HTML elements; use both xml:lang and lang attributes whenever one is to be needed on HTML elements.'''
|-
!Attributes
| Names are not case sensitive. Attribute minimization is allowed (i.e. omitting the equals sign and the value).
| Names are case sensitive (and lower case). Attribute minimization is not allowed.
|
| Use lower case attribute names. Do not minimize attributes. Non-namespaced attributes not belonging to HTML will be included in the DOM tree and accessible to script and stylesheets, but it is discouraged to use these due to the potential for future naming conflicts; <code>data-</code> attributes can be used instead, or if in an XML-only environment, namespaced attributes.
|-
!Attribute values
| White space characters are not normalized. Unquoted attribute values are allowed. Fixed or default attribute values ...?
| White space characters are [http://www.w3.org/TR/REC-xml/#AVNormalize normalized] to single spaces (unless attribute is of CDATA type?). Unquoted attribute values are not allowed. Default attribute values could conceivably be defined with a DTD.
|
| Create whitespace in attribute values which is already normalized (converted to single spaces). Always quote attribute values. '''Do not rely on defining default or fixed attribute values (or elements with exclusively element content) in a DTD (unless it matches HTML behavior).'''
|-
!Space characters
|The space characters are defined as:
* U+0009 CHARACTER TABULATION
* U+000A LINE FEED
* U+000C FORM FEED
* U+000D CARRIAGE RETURN
* U+0020 SPACE
|The space characters are defined as:
* U+0009 CHARACTER TABULATION
* U+000A LINE FEED
* U+000D CARRIAGE RETURN
* U+0020 SPACE
|The difference is the inclusion of Form Feed. Form feed characters are discouraged in XML 1.1.
| Do not use the form feed character.
|-
! The DOCTYPE
|
A DOCTYPE is a mostly useless, but required, header. The DOCTYPE is used during parsing to determing the parsing mode. The keywords "<code>DOCTYPE</code>", "<code>PUBLIC</code>" and "<code>SYSTEM</code>", and the name "<code>html</code>" are treated case insensitively. The system identifier <code>"about:legacy-compat"</code> (and the public and system identifiers for previous versions of HTML) are case sensitive.

Conforming HTML documents are required to use <code><!DOCTYPE html></code> (case insensitively) or the legacy-compat version <code><!DOCTYPE html SYSTEM "about:legacy-compat"></code>.

When using the obsolete but conforming DOCTYPEs based on the HTML 4.0 and 4.01 Strict DTDs, the system identifier is optional. The obsolete but conforming DOCTYPEs based on XHTML 1.0 Strict and XHTML 1.1 may also be specified.

Use of an internal subset is forbidden. The system identifier is never de-referenced by HTML implementations.
|
The DOCTYPE is optional. XML rules for case sensitivity apply (everything is case sensitive).

Either of the DOCTYPEs defined in HTML5 may be used, or any other custom DOCTYPE. If the public identifier is specified, the system identifier must also be specified. The obsolete status of the ''obsolete permitted DOCTYPEs'' defined for HTML does not apply to XHTML. Any DOCTYPE may be used, subject to the conformance rules defined by XML.

Use of an internal subset is permitted according to the requirements of XML. Some validating XML processors may dereference the system identifier, if used, but most browsers use non-validating processors.
|
| '''Use the empty DOCTYPE with no SYSTEM or PUBLIC identifiers and no use of internet subset.'''
|-
! Element names
| Element names are case insensitive.
| Element names are case sensitive and lower-case.
|
| Only use lower-case element names (as with attributes).
|-
! Void vs. Non-void Elements
| Void elements only have a start tag; end tags must not be specified for void elements, and it is impossible for them to contain any content. A trailing slash may optionally be inserted at the end of the element's tag, immediately before the closing greater-than sign. For non-void elements (e.g., <nowiki><script></nowiki>), the trailing slash is a parsing error (ignored and thus treated as unclosed).
| Void elements may use either the empty-element tag syntax (''EmptyElemTag'') or use a start tag immediately followed by an end tag, with no content in between. While it is possible for the element to contain content, this is non-conforming.
|
| '''For void elements (e.g., <nowiki> </nowiki>), do not include content or use a closing tag; only use a self-closing element with closing slash at the end (with a space preceding it for the sake of older browsers). For non-void elements, i.e., where content can exist (e.g., <nowiki><script></nowiki>), always use an explicit closing tag (not a self-closing tag) even if there is no content.'''
|-
! Unexpected end tags
| Unexpected end tags (in HTML, an unexpected <code></code> or <code></code> can cause the start tag to be implied before it).
| Unexpected end tags are well-formedness errors.
|
| Do not add end tags unless there is an explicit and properly nested open tag before it.
|-
! End tag with attributes
| ?
| An end tag with attributes is not allowed.
|
| Do not use end tags with attributes.
|-
! Raw text elements
|
|
|
|-
! RCDATA elements
|
|
|
|-
! Foreign elements
|
|
|
|-
! Normal elements
|
|
|
|-
! Optional tags
|
For [[#HTML_Elements_with_Optional_Tags|some elements]], the start and/or end tags are optional and are implied by certain specified conditions. For example, the end tag for the <code>p</code> element is implied by a subsequent <code>p</code> element.

Omitting the end tag for other elements is a parse error and various error recovery procedures are applied appropriately.
| End tags must be explicitly included for all elements, except empty elements using the ''EmptyElemTag'' syntax.
|
| Always use end tags (or self-closing tags for void elements).
|-
! Comment syntax
| Comments must start with the four character sequence "<code></code>" (bogus comments such as those beginning with "<?" are deprecated). The content of comments must not start with a single U+003E GREATER-THAN SIGN ('>') character, nor start with a U+002D HYPHEN-MINUS (-) character followed by a U+003E GREATER-THAN SIGN ('>') character, nor contain two consecutive U+002D HYPHEN-MINUS (-) characters, nor end with a U+002D HYPHEN-MINUS (-) character. Violating these constraints is a parse error and various error recovery procedures are applied appropriately.
| The content of comments must not contain two consecutive U+002D HYPHEN-MINUS (-) characters, nor end with a hyphen. Violating this is a well-formedness error.
|
| Only use comments of the "<code></code>" variety. Do not use two consecutive U+002D HYPHEN-MINUS (-) characters in comment content or end with such a hyphen (especially for the sake of XML). '''Do not begin comments with a single U+003E GREATER-THAN SIGN ('>') character, nor with a U+002D HYPHEN-MINUS (-) character followed by a U+003E GREATER-THAN SIGN ('>') character.'''
|-
!Processing Instructions
| HTML does not allow processing instructions and deprecates the bogus comments which appear in their form, whether in the form <code><?foo ...></code> (without a closing '?') or <code><?foo ...?></code>.
| XHTML allows the use of XML processing instructions which are only closed by "?>".
|
| '''Avoid ">" inside processing instructions (as these will close the "instruction" (comment) prematurely) (or one must strip out processing instructions entirely). Processing instructions might need to be avoided entirely in case HTML may in future disallow them completely.'''
|-
!CDATA sections
| <code><![CDATA[...]]></code> is a a bogus comment. The sequence of characters "<code>]]></code>" in content when it does not mark the end of a <code>CDATA</code> section is just regular character data.
| <code><![CDATA[...]]></code> is a <code>CDATA</code> section. The sequence of characters "<code>]]></code>" in content when it does not mark the end of a <code>CDATA</code> section is a well-formedness error.
|
| Ensure sequence "<code>]]></code>" in content is escaped (not necessary to escape in attribute values). '''Do not use CDATA sections.'''
|-
! Unescaped Special Characters
|
Unescaped ampersands (U+0026 AMPERSAND - <code>&</code>, instead of <code>&amp;</code>) are permitted within the content of ''normal elements'', ''RCDATA elements'', ''foreign elements'' and ''attribute values'' where they are not considered to be ''ambiguous ampersands'', and within ''Raw text elements''.

Unescaped less than signs (U+003C LESS-THAN SIGN - <code><</code>, instead of <code>&lt;</code>) are permitted in ''Raw text elements'', ''RCDATA elements'' and ''attribute values'', excluding the ''unquoted attribute value syntax''.
| Unescaped ampersands and less-than signs may not appear within ''CharData'' or ''AttValue'' (basically, the normal text content of elements and attribute values.) Violation of this constraint is a well-formedness error.
|
| Always escape ampersands and less-than signs in text content and attribute values. See CDATA for need to escape sequence "<code>]]></code>" in text content.
|-
!Character References
|
|
|
|-
!Entity References
| In HTML, all entity references are predefined and do not require a DTD.
| There is no formal DTD for XHTML5, but one could provide an exteranl DTD (if not an internal subset?) for use with one's entity-checking (or validating) parser, but be aware that browsers do not universally use external entity-checking (or validating) parsers and may not read the external DTD. (Some still have bugs in that they mistakenly create a well-formedness error out of such missing entities instead of showing them as missing, making them clickable, or using a entity-checking or validating parser.)
|
| Do not use entity references in XHTML (except for the 5 predefined entities: <code>&amp;</code>, <code>&lt;</code>, <code>&gt;</code>, <code>&quot;</code> and <code>&apos;)</code>; use the equivalent Unicode or numeric character reference sequence instead.
|-
! Character data
|
|
| The valid set of unicode characters in XML 1.0 is limited beyond that in HTML (we need to specify this here).
|
|}

====Element-specific parsing====
* In HTML, the <code>script</code> and <code>style</code> elements are parsed as <code>CDATA</code> elements. (Note: the definition of <code>CDATA</code> differs from that in XML). In XML, they're parsed as normal elements (which means that things that look like comments are treated as real comments, and things that look like start tags actually are start tags).
* In HTML, the <code>title</code> and <code>textarea</code> elements are parsed as <code>RCDATA</code> elements. (Note: The definition of <code>RCDATA</code> differs from that in SGML and there is no <code>RCDATA</code> in XML).
* In HTML, if scripting is enabled, the <code>noscript</code> element is parsed as an <code>CDATA</code> element. If scripting is disabled, it's parsed as a normal element. In XHTML, the element is always parsed as a normal element, and can't really be used to stop content from being present when script is disabled.
* In HTML, the <code>iframe</code>, <code>noembed</code> and <code>noframes</code> elements are parsed as <code>CDATA</code> elements. In XHTML, they are parsed as normal elements, and therefore do not stop content from being used.
* In HTML, tags for certain elements, which appear out of context, are ignored. This includes <code>caption</code>, <code>col</code>, <code>colgroup</code>, <code>frame</code>, <code>frameset</code>, <code>head</code>, <code>option</code>, <code>optgroup</code>, <code>tbody</code>, <code>td</code>, <code>tfoot</code>, <code>th</code>, <code>thead</code>, <code>tr</code>.
* In XHTML, <code>table</code> elements may contain child <code>tr</code> elements. In the HTML serialisation, due to backwards compatibility constraints, this is not possible (though it may be done through DOM manipulation).
* The <code>plaintext</code> element has a special parsing requirement in HTML. (It is, however, forbidden.)
* In HTML, a line feed that immediately follows a <code>pre</code>, <code>listing</code> or <code>textarea</code> start tag is ignored.
* Many other special handling of edge cases and error conditions, not all of which are listed here, occur in HTML. (such as?)
* The following are void elements in HTML (see void elements in table): In head (<code>base</code>, <code>link</code>, <code>meta</code>), in body (<code>area</code>,<code>br</code>, <code>col</code>, <code>embed</code>, <code>hr</code>, <code>img</code>, <code>input</code>, <code>param</code>)

==== HTML Elements with Optional Tags ====

{| class="wikitable" border="1"
|-
! Element
! Start Tag
! End Tag
|-
!html
|optional
|optional
|-
!head
|optional
|optional
|-
!body
|optional
|optional
|-
!li
|required
|optional
|-
!dt
|required
|optional
|-
!dt
|required
|optional
|-
!p
|required
|optional
|-
!colgroup
|optional
|optional
|-
!thead
|required
|optional
|-
!tbody
|optional
|optional
|-
!tfoot
|required
|optional
|-
!tr
|required
|optional
|-
!th
|required
|optional
|-
!td
|required
|optional
|-
!rt
|required
|optional
|-
!rp
|required
|optional
|-
!optgroup
|required
|optional
|-
!option
|required
|optional
|}

=== Scripts ===

* <code>document.write()</code> and <code>document.writeln()</code> cannot be used in XHTML, they can in HTML.
* In XHTML, the use of the <code>innerHTML</code> property requires that the string be a well-formed fragment of XML.
* DOM APIs are case sensitive in XHTML and some are case insensitive in HTML. (This does not apply to elements which are not in the HTML namespace)
** Element.tagName and Node.nodeName return the value in uppercase in HTML but lower-case in XHTML (Node.localName is consistent now, as of HTML5).
** Document.createElement() is case insensitive (the canonical form is lowercase).
** Element.setAttributeNode() will change the attribute name to lowercase.
** Element.setAttribute() is case insensitive (the canonical form is lowercase).
** Document.getElementsByTagName() and Element.getElementsByTagName() are case insensitive.
** Document.renameNode(). If the new namespace is the HTML namespace, then the new qualified name will be lowercased before the rename takes place.
* In HTML, Document.createElement() will create an element in the HTML namespace. In XML (including XHTML), the namespace is defined by both DOM2 and DOM3 to be null.
** In XHTML, browsers lack interoperability in this area. In Firefox and Safari, the namespace is dependent upon the MIME type. In Opera, it's dependent upon the root element.
* XPath expressions targeted at pre-HTML5 browsers need to use the XHTML namespace for XHTML and null for HTML. (HTML5 browsers would use the XHTML namespace even in HTML.)

=== Stylesheets ===

* Selectors, as used in CSS, match case sensitively in XHTML, but case insensitively in HTML.
* CSS requires special handling of the body element in HTML for painting backgrounds on the canvas, which do not apply to XHTML.
* For polyglot documents, use lower-case element selectors and style the html and body elements appropriately (?).

== Differences Between HTML4 and HTML5 ==

See [http://dev.w3.org/html5/html4-differences/ HTML5 differences from HTML4].

== Differences Between DOM Level 2.0, 3.0 and the HTML 5 DOM APIs ==

'''This section might belong on a separate page.'''

* TODO (need to talk about the changes to the DOM API that HTML5 is making, compared with DOM2 and DOM3)

== Translations ==

* [http://meiert.com/de/publications/translations/whatwg.org/html-vs-xhtml/ German translation: "HTML 5 und XHTML 5 im Vergleich (WHATWG)"]
* [http://dancewithnet.com/2007/10/28/differences-between-html-and-xhtml/ Chinese translation: "HTML和XHTML的不同"]
*[http://www.thegrizasonline.com/ Business Solutions & Tools]
*[http://buycheapdeals.net/ cheap Halloween costumes]

RelExtensions

2011-07-05T12:35:54Z

Loveservice:

=This page is obsolete=

'''The HTML specification no longer references this page. It now references the Microformats "existing-rel-values" registry: http://microformats.org/wiki/existing-rel-values'''

==Historical contents==

''The following are the contents of this page before it was replaced.''

This page lists the allowed extension values for the rel="" attribute in HTML5. You may add your own values to this list, which makes them legal HTML5 rel values. We ask that you try to avoid redundancy; if someone has already defined a value that does roughly what you want, please reuse it. Note that rel tokens are ASCII-lowercase before comparison against canonical value, so the canonical values should be listed without uppercase ASCII letters.

{| class="wikitable sortable"
|-
! Keyword
! Effect on <code>link</code>
! Effect on <code>a</code>, <code>area</code>
! Brief description
! Link to more details
! Synonyms
! Status
|-
| pronunciation
| external resource
| not allowed
| The referenced file contains a set of rules that associates strings of characters (e.g. words) with pronunciation instructions. For example, a rule can define whether the word "tomato" is to be spoken in the british or north-american way. These pronunciation rules should be processed by voice-enabled user-agents (e.g. web browsers that support TTS rendering), but conversely, "pronunciation" link/rel files can be completely ignored by systems that do not have speech capabilities. An example of possible format is W3C PLS (Pronunciation Lexicon Specification), with the MIME type "application/pls+xml" (and usually, the extension ".pls"). When several pronunciation lexicons are referenced within a single HTML document, and/or when a pronunciation rule is specified more than once for a given string of characters, the last occurrence of the rule takes precedence (in document order), such that any previously-defined pronunciation rule gets overridden.
| [http://www.w3.org/TR/pronunciation-lexicon/ Pronunciation Lexicon Specification (PLS) Version 1.0 (W3C Recommendation 14 October 2008)] [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7601 Previously-filed bug #7601]
|
| Proposal
|-
| accessibility
| hyperlink
| hyperlink
| The linked document contains accessibility information for the linking document.
| [http://www.brucelawson.co.uk/2009/rel-accessibility/ Bruce Lawson]
|
| Proposal
|-
| acquaintance
| hyperlink
| hyperlink
| the person represented by the current document considers the person represented by the referenced document to be an acquaintance
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| admin
| hyperlink
| hyperlink
| The linked document contains administrative option(s) for the current document and related pages.
|
| option
| Proposal
|-
| ajax
| not allowed
| hyperlink
| The link is controlled through javascript, and will load the page linked to though an ajax interface. Without javascript, it should behave as a normal "a" tag, and content change is done server side.
|
|
| Proposal
|-
| alternate
|colspan=6| See HTML5
|-
| answer
| hyperlink
| hyperlink
| A link to the answer to the question this section or document asks, e.g. in a FAQ or in a sample exam. Unlike ‘reply’ or ‘comment’ this resource necessarily solves the problem.
| [[Talk:RelExtensions#Q_and_A|Q&A]]
| (reply, comment)
| Proposal
|-
| application-manifest
| external resource
| Not allowed
| A manifest for this web application. The manifest contains metadata about the web application, such as its name, description, and permissions the application might require.
|
|
| Proposal
|-
| archives
|colspan=6| See HTML5
|-
| author
|colspan=6| See HTML5
|-
| bookmark
|colspan=6| See HTML5
|-
| canonical
| hyperlink
| not allowed
| Robots (e.g., search engines) should treat the document containing the tag as a minor variation of the linked document, which may result in the removal of the former from a web index and in the consolidation of its quality signals in the latter. Links with rel=canonical must not specify a language, type, or different kind of media; the referenced document must have the same language, type and target media.
| [http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html]
|
| Proposal
|-
| canonical-domain
| external resource
| not allowed
| More than one domain may have largely similar or identical content but only one of the domains should be indexed for search engines. E.g., a company may have short and long domain names for the same content.
For security against traffic theft, rev must be meaningless.
| [http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=139066 Google's analogous service] and [[Talk:RelExtensions#On_canonical-domain.2C_canonical-wwwnone.2C_and_canonical-first|Talk for this page]]
|
| Proposal
|-
| canonical-first
| external resource
| hyperlink
| Where the canonical value should point to a group of pages, but the link can point to only one page, the group of pages can be clarified by choosing the first page in the group and assigning the URL for this rel link.
For security against traffic theft, rev must be meaningless. 
This is only shorthand for providing two link elements, one on the noncanonical page to a "canonical" page and the other on the canonical page to the "first" page of the group.
Where the group of pages corresponds to a subdirectory and a canonical URL value can point to the subdirectory resulting in a user arriving at the subdirectory's index page which is part of the group, this shorthand is unnecessary and one rel="canonical" will suffice.
| [[Talk:RelExtensions#On_canonical-domain.2C_canonical-wwwnone.2C_and_canonical-first|Talk for this page]]
|
| Proposal
|-
| canonical-human
| external resource
| hyperlink
| Pages about a person across many websites can be associated based on name, nationality, birthplace, dates of birth and death, when flourished, and other identifiers.
Search engines could more consistently aggregate same-person pages with less confusion due to name similarity.
| [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7681 W3C Bug 7681]
|
| Proposal
|-
| canonical-organization
| external resource
| hyperlink
| Pages about an organization across many websites can be associated based on name, headquarters site, and other identifiers.
Search engines could more consistently aggregate same-organization pages with less confusion due to name similarity.
| [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7682 W3C Bug 7682]
|
| Proposal
|-
| canonical-wwwnone
| external resource
| hyperlink
| Both bare and www-prefixed domain names usually direct to the same site. Especially when external links to a site vary in the form used, search engine indexing concentrated on only one domain form may raise its credibility. The rel value is the form preferred for indexing, e.g., href="http://example.net". Nothing to the right of the top-level domain is needed.
For security against traffic theft, rev must be meaningless.
| [http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=139066 Google's analogous service] and [[Talk:RelExtensions#On_canonical-domain.2C_canonical-wwwnone.2C_and_canonical-first|Talk for this page]]
|
| Proposal
|-
| chapter
| hyperlink
| hyperlink
| Target document is a subdocument of the current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
| section, subsection, appendix
| Proposal
|-
| child
| hyperlink
| hyperlink
| the referenced person is a child of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| co-resident
| hyperlink
| hyperlink
| the referenced person lives in the same residence as the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| co-worker
| hyperlink
| hyperlink
| the referenced person is a co-worker of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| colleague
| hyperlink
| hyperlink
| the referenced person is a colleague of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| contact
| hyperlink
| hyperlink
| the person represented by the current document considers the person represented by the referenced document to be a contact
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| contributor
| hyperlink
| hyperlink
| The linked document is the page/email an agent (people or firm or...) involved in the production of the content, but not his main author(s).
|
|
| Proposal
|-
| crush
| hyperlink
| hyperlink
| this person considers the referenced person to be a crush (i.e. has a crush on the referenced person)
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| date
| hyperlink
| hyperlink
| this person considers the referenced person to be a date (i.e. is dating the referenced person)
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| dns-prefetch
| external resource
| not allowed
| Force the DNS lookup of specific hostnames.
| [https://developer.mozilla.org/En/Controlling_DNS_prefetching Mozilla DNS Prefetching], [http://dev.chromium.org/developers/design-documents/dns-prefetching Chromium DNS Prefetching]
|
| Proposal
|-
| edit
| hyperlink
| hyperlink
| Target document is an editable version of the current document.
| [http://bitworking.org/projects/atom/draft-ietf-atompub-protocol-11.html#new-link-relation Atom Protocol]
|
| Proposal
|-
| edituri
| hyperlink
| not allowed
| a link to an RSD file describing how to edit the given page.
| [http://cyber.law.harvard.edu/blogs/gems/tech/rsd.htm rsd]
|
| Proposal
|-
| enclosure
| hyperlink
| hyperlink
| the destination of the hyperlink is intended to be downloaded and cached.
| [http://microformats.org/wiki/rel-enclosure rel-enclosure]
|
| Proposal
|-
| enlarged
| not allowed
| hyperlink
| For anchors that have one child image element, indicates that the linked document is an image file which is the same as the child image element of the link except a larger size (dimensions).
| [http://dvdgoss.wordpress.com/2010/04/26/the-case-for-relenlarge-in-html5/ David Goss]
|
| Proposal
|-
| external
|colspan=6| See HTML5
|-
| extension
| hyperlink
| hyperlink
| Browser extension
| [http://mozillalabs.com/jetpack/2010/05/12/indexing-and-auto-detecting-browser-extensions-on-the-web/ Mozilla Labs]
|
| Proposal
|-
| first
|colspan=6| See HTML5
|-
| friend
| hyperlink
| hyperlink
| the person represented by the current document considers the person represented by the referenced document to be a friend
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| gallery
| hyperlink
| hyperlink
| A ''graphic'' index that the current document or section is a part of or that illustrates the same topic.
|
| (index, list)
| Proposal
|-
| glossary
| hyperlink
| hyperlink
| Target document provides definitions for words in current document.
| [http://www.w3.org/TR/html4/types.html#h-6.12 HTML4]
|
| Proposal
|-
| help
|colspan=6| See HTML5
|-
| hub
| hyperlink
| not allowed
| Indicates a URL which implements both sides of the PubSubHubbub protocol.
| [http://code.google.com/p/pubsubhubbub/ PubSubHubbub]
|
| Proposal
|-
| i18nrules
| hyperlink
| not allowed
| Target document provides ITS (Internationalization tag Set) rules for processing the current document.
| [http://www.w3.org/TR/its/ ITS]
|
| Proposal
|-
| icon
|colspan=6| See HTML5
|-
| index
|colspan=6| See HTML5
|-
| jump
| not allowed
| hyperlink
| Indicates a same page jump from the current fragment to another fragment. (E.g. sometimes online newspapers insert direct text saying "article continues below the image/advert" - they could instead use "jump" link. Ultimately, it indicates a page internal link.)
| [[Talk:RelExtensions#On_footnote.2C_note.2C_and_jump|Talk]]
|
| Proposal
|-
| kin
| hyperlink
| hyperlink
| the referenced person is part of the extended family of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| lang-alt-[ISO 639-1 code]
| hyperlink
| hyperlink
| The linked document contains a version of the current document in an alternative language. "[ISO 639-1 code]" is replaced with the appropriate [http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes ISO 639-1 language code]. The ISO 639-1 code is used when the browser (or other user agent) wants to display either the full name of the language or a flag, as a visual aid for the end user.
|
|
| Proposal
|-
| lang-orig-[ISO 639-1 code]
| hyperlink
| hyperlink
| The linked document contains a version of the current document in the language the document was originally written in. "[ISO 639-1 code]" is replaced with the appropriate [http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes ISO 639-1 language code]. The ISO 639-1 code is used when the browser (or other user agent) wants to display either the full name of the language or a flag, as a visual aid for the end user.
|
|
| Proposal
|-
| last
|colspan=6| See HTML5
|-
| latest-version
| hyperlink
| hyperlink
| The referenced document is the latest version of the current document.
| [http://www.iana.org/assignments/link-relations/link-relations.txt], [http://tools.ietf.org/search/rfc5829#section-3.2 RFC5829]
|
| Proposal
|-
| license
|colspan=6| See HTML5
|-
| login
| hyperlink
| hyperlink
| The login keyword indicates that the referenced document provides an interface (user, pwd) to authenticate a registered user of the page/or to registrate a new user.
|
| search
| Proposal
|-
| logout
| external resource
| not allowed
| The linked document provides a resource for the UA to request when all currently open documents of the same "group" are closed (to facilitate logging out the current user).
| [[LogoutRelExtension]]
|
| Proposal
|-
| longdesc
| hyperlink
| hyperlink
| Related to [http://www.w3.org/html/wg/tracker/issues/30 ISSUE-30]. <abbr title="Assistive Technology">AT</abbr> should treat an element wrapped in a link with <code>rel="longdesc"</code> as equivalent to an element with <code>longdesc="URI"</code>.
| (1) [http://lists.w3.org/Archives/Public/public-html/2007Jun/0738.html Eric Eggert's original proposal, 25th of June 2007], (2) [http://lists.w3.org/Archives/Public/public-html/2007Jun/0798.html Maciej's comment, 25th of June 2007], (3) [http://www.w3.org/Bugs/Public/show_bug.cgi?id=10434 Bug 10434, the HTMLwg, 2010] (4) [http://microformats.org/wiki/existing-rel-values#POSH_usage rel="longdesc" listed as POSH in Microformats.org]
| <code><foo longdesc="URL"/></code> is synonymous to <code><a rel="longdesc" href="URL"><foo/></a></code>
| Proposal
|-
| map
| hyperlink
| hyperlink
| the referenced document represents a map of the location of the subject of the current document; parsers ''may'' use the URI or target page to determine coordinates.
| to follow
|
| Proposal
|-
| me
| hyperlink
| hyperlink
| the referenced document represents the same person as does the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| met
| hyperlink
| hyperlink
| this person has met the referenced person
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| meta
| external resource
| hyperlink
| publishing RDF/FOAF files
| [http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#transport RDF], [http://xmlns.com/foaf/spec/#sec-autodesc FOAF]
|
| Proposal
|-
| muse
| hyperlink
| hyperlink
| the referenced person inspires the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| neighbor
| hyperlink
| hyperlink
| the referenced person lives nearby the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| next
|colspan=6| See HTML5
|-
| next-archive
| hyperlink
| hyperlink
| A URI that refers to the immediately following archive document.
| [http://www.iana.org/assignments/link-relations/link-relations.xhtml Atom Link Relations], [http://tools.ietf.org/html/rfc5005 RFC5005]
|
| Proposal
|-
| nofollow
|colspan=6| See HTML5
|-
| noreferrer
|colspan=6| See HTML5
|-
| noprefetch
| external resource
| hyperlink
| Denies prefetching (not fetching) as a cost-control option for website owners, especially where pages are dynamic, leading to prefetching of wrong and useless pages. 
The link provides a per-page denial whereas a and area provide a per-element denial. 
For link, attributes rel="noprefetch" denies prefetching of the page at the href URL and rev="noprefetch" denies prefetching of the page bearing the link. 
For a and area, rel is as above and rev is meaningless.
| [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7918 W3C Bug 7918]
|
| Proposal
|-
| note
| not allowed
| hyperlink
| An in-page or out-page jump to a footnote. This encompasses ''note'', ''footnote'', ''endnote'', and ''sidenote''.
| [[Talk:RelExtensions#On_footnote.2C_note.2C_and_jump|Talk]]
|
| Proposal
|-
| openid.delegate
| external resource
| not allowed
| OpenID 1.1 authentication delegation
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID specification]
|
| Proposal
|-
| openid.server
| external resource
| not allowed
| OpenID 1.1 authentication delegation
| [http://openid.net/specs/openid-authentication-1_1.html#delegating_authentication OpenID specification]
|
| Proposal
|-
| openid2.local_id
| external resource
| not allowed
| OpenID 2.0 authentication delegation
| [http://openid.net/specs/openid-authentication-2_0.html#html_disco OpenID Auth 2.0 section 7.3.3]
|
| Proposal
|-
| openid2.provider
| external resource
| not allowed
| OpenID 2.0 authentication endpoint
| [http://openid.net/specs/openid-authentication-2_0.html#html_disco OpenID Auth 2.0 section 7.3.3]
|
| Proposal
|-
| parent
| hyperlink
| hyperlink
| the referenced person is a parent of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| payment
| hyperlink
| hyperlink
| A URI where payment is accepted.
| [http://www.iana.org/assignments/link-relations/link-relations.xhtml Atom Link Relations]
|
| Proposal
|-
| pgpkey
| hyperlink
| not allowed
| The linked document is the PGP public key file (which may contain multiple keys) of the author(s) of the page.
| [http://purl.org/net/pgpkey/], [http://golem.ph.utexas.edu/~distler/blog/archives/000320.html]
|
| Proposal
|-
| pingback
|colspan=6| See HTML5
|-
| prefetch
|colspan=6| See HTML5
|-
| prerender
| external resource
| not allowed
| Prerender the specified URL including all subresources and running all scripts.
| [http://dev.chromium.org/developers/design-documents/prerender Chromium Prerendering]
|
| Proposal
|-
| presentation
| external resource
| hyperlink
| Like ‘print’ this relation references a resource that represents the same content or topic, but in a ''very'' different manner. It is similar to media=projection, but is to be used where text is substituted by graphics, animations and sounds, which goes beyond mere style switching.
This relation is also appropriate for links from thumbnail to full resolution images.
|
| slides, slideshow
| Proposal
|-
| prev
|colspan=6| See HTML5
|-
| prev-archive
| hyperlink
| hyperlink
| A URI that refers to the immediately preceding archive document.
| [http://www.iana.org/assignments/link-relations/link-relations.xhtml Atom Link Relations], [http://tools.ietf.org/html/rfc5005 RFC5005]
|
| Proposal
|-
| print
| external resource
| hyperlink
| The referenced document is recommended for printing, even though the referent document is capable of being printed and both documents are of the same type, medium, and language. A typical case is where content spread over multiple pages is also available on a single page that is more convenient to print.
This is semantically more specific than "canonical" and "alternate". Where type, medium, and/or language differ, consider "alternate"; where any of them differ but the purpose is printing, consider applying both values.
| [http://www.w3.org/Bugs/Public/show_bug.cgi?id=7645 W3C Bug 7645]
|
| Proposal
|-
| profile
| hyperlink
| hyperlink
| this referenced link is a metadata profile for the current document
| [http://www.w3.org/TR/html401/struct/global.html#profiles HTML Meta data profiles], [http://www.w3.org/2003/g/glean-profile Example of profile in a-elements]
|
| Proposal
|-
| question
| hyperlink
| hyperlink
| A link to the question this section or document answers, e.g. in a FAQ or in a sample exam.
| [[Talk:RelExtensions#Q_and_A|Q&A]]
| topic, subject, problem, (up)
| Proposal
|-
| related
| hyperlink
| hyperlink
| this referenced link identifies a resource related to the current document
| [http://tools.ietf.org/html/rfc4287#section-4.2.7 Atom Syndication Format]
|
| Proposal
|-
| reply
| hyperlink
| hyperlink
| A follow-up posting to this document or section or in the thread this document or section is an index of.
| [[Talk:RelExtensions#Threading|Thread]]
| posting, comment
| Proposal
|-
| resource-package
| external resource
| not allowed
| The linked document is a zipped resource package
| [http://limi.net/articles/resource-packages/ Resource Packages]
|
| Proposal
|-
| resources
| external resource
| not allowed
| a higher level alternative to HTTP Content Negotiation for other resources linked from the document, in a yet to be specified format
|
| resource-description, content-negotiation
| Proposal
|-
| reviewer
| hyperlink
| not allowed
| The linked document is the page/email an agent (people or firm or...) responsible for reviewing the content.
| [http://wiki.csswg.org/test/css2.1/format#reviewer]
|
| Proposal
|-
| script
| not allowed
| not allowed
| Was proposed to replace <script>. Use <script> instead.
| none
|
| Rejected
|-
| search
|colspan=6| See HTML5
|-
| self
| hyperlink
| hyperlink
| A URI that refers to a resource equivalent to the containing element.
| [http://www.iana.org/assignments/link-relations/link-relations.xhtml Atom Link Relations], [http://tools.ietf.org/html/rfc4287 RFC4287]
|
| Proposal
|-
| service
| external resource
| not allowed
| Points to a resource describing a service API
| [[ServiceRelExtension]]
|
| Proposal
|-
| shortlink
| hyperlink
| hyperlink
| Identifies a shorter form of the URL for the current document, provided by the document owner.
| [http://code.google.com/p/shortlink/wiki/Specification shortlink Specification]
|
| Proposal
|-
| sibling
| hyperlink
| hyperlink
| the referenced person is a sibling of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| sidebar
|colspan=6| See HTML5
|-
| spouse
| hyperlink
| hyperlink
| the referenced person is a spouse of the person represented by the current document
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| statechart
| external resource
| not allowed
| A reference to an SCXML document that controls the application-flow of the current HTML document
| [http://www.w3.org/TR/scxml/ SCXML]
|
| Proposal
|-
| stylesheet
|colspan=6| See HTML5
|-
| subresource
| hyperlink
| not allowed
| The referenced document is a subresource of the current document.
|
|
| Proposal
|-
| sweetheart
| hyperlink
| hyperlink
| this person considers the referenced person to be their sweetheart
| [http://gmpg.org/xfn/11 XFN]
|
| Accepted
|-
| tag
|colspan=6| See HTML5
|-
| technicalauthor
| hyperlink
| hyperlink
| The linked document is the page/email an agent (people or firm or...) responsible for the technical construction of the page (i.e. the HTML/CSS/PHP code), not for the content.
|
|
| Proposal
|-
| thread
| hyperlink
| hyperlink
| A hierarchic list of topic(s) and replies where this document or section belongs to either one.
| [[Talk:RelExtensions#Threading|Thread]]
| (index)
| Proposal
|-
| timesheet
| external resource
| not allowed
| SMIL Timesheet
| [http://www.w3.org/TR/timesheets/#smilTimesheetsNS-Elements-Timesheet SMIL Timesheets 1.0]
|
| Proposal
|-
| topic
| hyperlink
| hyperlink
| The initial posting this document or section is a reply to or index of.
| [[Talk:RelExtensions#Threading|Thread]]
| subject, (top)
| Proposal
|-
| translatedfrom
| hyperlink
| hyperlink
| The linked document is the page/email that has been translation source for the current document. It also indicates that the current document is a translation and not an original work.
|
|
| Proposal
|-
| translator
| hyperlink
| hyperlink
| The linked document is the page/email an agent (people or firm or...) responsible for the translation of the page. It also indicates that the current page is a translation of an other document, which should be linked through a rel="translatedfrom".
|
|
| Proposal
|-
| up
|colspan=6| See HTML5
|-
| us
| hyperlink
| hyperlink
| The referenced document represents the same organisation as does the current document [cf rel-me]
|
|
| Proposal
|-
| webmaster
| hyperlink
| hyperlink
| The linked document is the page/email an agent (people or firm or...) available for requests about the content of the page.
|
| maintainer
| Proposal
|-
| widget
| hyperlink
| hyperlink
| Points to a widget.
| [http://dev.w3.org/2006/waf/widgets/Overview.html#autodiscovery Widgets 1.0 Editor's draft]
|
| Proposal
|-
| wlwmanifest
| hyperlink
| not allowed
| A link to a manifest for Windows Live Writer.
| [http://msdn.microsoft.com/en-us/library/bb463263.aspx msdn]
|
| Proposal
|}


The "Effect on link" column must either say "not allowed" if the rel value is not allowed on <link> elements, "hyperlink" if the rel value creates a hyperlink, or "external resource" if the rel value creates a link to an external resource.

The "Effect on a and area" column must either say "not allowed" or "hyperlink".

For the "Status" section to be changed to "Accepted", the proposed keyword must either have been through the [http://microformats.org/wiki/process Microformats process], and been approved by the Microformats community; or must be defined by a W3C specification in the Candidate Recommendation or Recommendation state. If it fails to go through this process, it is "Rejected".

For more details, see [http://whatwg.org/specs/web-apps/current-work/#linkTypes the HTML5 specification].

===See also===
*[http://microformats.org/wiki/existing-rel-values the Microformats wiki page on this matter].
*[http://blogs.plos.org/mfenner/2011/02/14/how-to-use-citation-typing-ontology-cito-in-your-blog-posts/ How to use Citation Typing Ontology (CiTO) in your blog posts] - proposes several values for marking up academic citations, but confuses the direction of the relationship
*[http://www.hostgatorcouponsreview.com HostGator Coupons]
*[http://www.thegrizasonline.com/inmotion-hosting-review-inmotion-hosting-coupon InMotion Review]
(note comments)

[[Category:Registries]]

Main Page

2011-07-05T12:34:53Z

Loveservice:

Welcome to the WHATWG Wiki!

You can be a part of our community, making proposals for the next version of HTML. This wiki is made available for you for drafting proposals, for writing essays, for keeping track of HTML-related issues, and so forth. Anyone can create an account and contribute content.

Before you begin, you may wish to read our [[WHATWG Wiki:Contribution Guidelines|contribution guidelines]].

==Quick Links==
* [[FAQ]]
* [[What you can do]] — '''[[Reviewing|Review our work!]]
* [[:Category:Implementations|Implementations]]
* [[Presentations]]
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==Web Developers==
* [[Authoring|Using HTML in your Web site]]
* [[Presentational elements and attributes]]
* [[HTML vs. XHTML]]
* [http://www.hostgatorcouponsreview.com HostGator Coupons]

==Spec Development==
* [[:Category:Spec coordination|Spec coordination]]
* [[:Category:Proposals|Proposals]]
* [[:Category:Registries|Registries]]
* [[Issue Discussion]]
* [[Testsuite]]

==WHATWG Specifications==
* [http://whatwg.org/html HTML]
* [http://whatwg.org/ww Web Workers]
* [http://whatwg.org/C Web Applications 1.0] (all-in-one)
* See also [[FAQ#What_are_the_various_versions_of_the_spec.3F|What are the various versions of the spec?]] in the FAQ.

==Communicating with the community==
The WHATWG community has several channels of communication:
* [[IRC]] and [http://www.whatwg.org/mailing-list mailing lists]
* [http://forums.whatwg.org/ Forums]
* [http://blog.whatwg.org/ The WHATWG Blog], including [http://blog.whatwg.org/category/weekly-review WHATWG Weekly]
* [http://twitter.com/WHATWG @WHATWG] on twitter
* [http://www.w3.org/html/planet/ W3C's Planet HTML5]