rel-faq - Revision history

Tantek: is rev a perfect use case for anything? no it's unusable.

2013-06-26T00:46:53Z

is rev a perfect use case for anything? no it's unusable.

@@ Line 105: / Line 105: @@
 * http://philip.html5.org/data/link-rel-rev.txt - 127249 random pages from dmoz.org downloaded on 2008-02-26.
 which demonstrates poor understanding of the rev attribute, e.g. <code class="html">&lt;link rev="1.02" ...&gt;</code>
 == See Also ==

Tantek: incorrect use of rev

2009-04-14T20:29:45Z

incorrect use of rev

← Older revision		Revision as of 20:29, 14 April 2009
Line 102:		Line 102:
	No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.		No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.

	More data on use of rel/rev ~~which demonstrates poor understanding of the rev attribute~~:		More data on use of rel/rev:
	* http://philip.html5.org/data/link-rel-rev.txt - 127249 random pages from dmoz.org downloaded on 2008-02-26. e.g. <code class="html"><link rev="1.02" ...></code>		* http://philip.html5.org/data/link-rel-rev.txt - 127249 random pages from dmoz.org downloaded on 2008-02-26.
			which demonstrates poor understanding of the rev attribute, e.g. <code class="html"><link rev="1.02" ...></code>

	== See Also ==		== See Also ==

Tantek: /* Should rev even be used */ more data on poor use of rev

2009-04-14T20:25:50Z

Should rev even be used: more data on poor use of rev

← Older revision		Revision as of 20:25, 14 April 2009
Line 101:		Line 101:

	No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.		No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.

			More data on use of rel/rev which demonstrates poor understanding of the rev attribute:
			* http://philip.html5.org/data/link-rel-rev.txt - 127249 random pages from dmoz.org downloaded on 2008-02-26. e.g. <code class="html"><link rev="1.02" ...></code>

	== See Also ==		== See Also ==

Tantek: remove author section, as many people have contributed to FAQ, can be viewed in page history, no apparent need for editors with more responsibility, spans many microformats

2008-08-06T17:27:13Z

remove author section, as many people have contributed to FAQ, can be viewed in page history, no apparent need for editors with more responsibility, spans many microformats

← Older revision		Revision as of 17:27, 6 August 2008
Line 1:		Line 1:
	<h1> "rel" attribute frequently asked questions </h1>		<h1> "rel" attribute frequently asked questions </h1>
			{{TOC-right}}
	This document serves to answer and discuss frequently asked questions about the HTML4 "rel" and "rev" attributes, and their linktype values. Specifically this document explores a number of issues common to and exposed by the various [[microformats]] which extend the HTML4 rel attribute.		This document serves to answer and discuss frequently asked questions about the HTML4 "rel" and "rev" attributes, and their linktype values. Specifically this document explores a number of issues common to and exposed by the various [[microformats]] which extend the HTML4 rel attribute.

	~~__TOC__~~

	~~== Authors ==~~
	* John Allsopp, [http://westciv.com Western Civilisation]
	* [http://tantek.com Tantek Çelik], [http://technorati.com Technorati, Inc]
	* [[User:AndyMabbett\|Andy Mabbett]]

	== FAQ ==		== FAQ ==

Tantek: add emphasis

2008-08-06T17:13:28Z

add emphasis

← Older revision		Revision as of 17:13, 6 August 2008
Line 103:		Line 103:
	However, given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?		However, given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?

	The short answer is unfortunately "no". Use of "rev" {{should}} be avoided.		The short answer is unfortunately "'''NO'''". Use of "rev" {{should}} be avoided.

	However, VoteLinks' use of rev has been [[glossary#grandfathered\|grandfathered]] since it was such an early use. No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.		However, VoteLinks' use of rev has been [[glossary#grandfathered\|grandfathered]] since it was such an early use.

			No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.

	== See Also ==		== See Also ==

Tantek: moved "usage" section from existing-rel-values to first question here for better discoverability, clean punct from headers, incorporated "rev" section into "should rev even be used" question

2007-09-24T19:23:17Z

moved "usage" section from existing-rel-values to first question here for better discoverability, clean punct from headers, incorporated "rev" section into "should rev even be used" question

← Older revision		Revision as of 19:23, 24 September 2007
Line 12:		Line 12:
	== FAQ ==		== FAQ ==

	===What microformats use "rel"? ===		===How is rel used ===
			''How is the '<code>rel</code>' attribute used?''

			<code>rel</code> values indicate the relationship '''''of''''' the target resource '''''to''''' the resource on which they appear. In microformats, <code>rel</code> are used on links (e.g. <code><nowiki><a rel="home" href="http://example.org"></nowiki></code>). Elsewhere, they are also used on <code>link</code> headers (e.g. <code><nowiki><link rel="start" href="http://example.org/section/page1.htm"></nowiki></code>.

			Multiple values may be used, in the same manner as multiple <code>class</code> values (e.g. <code><nowiki><a rel="home me contents" href="http://example.org"></nowiki></code>).

			===What microformats use rel ===
			''What microformats use '<code>rel</code>'?''
	*[[rel-directory]]		*[[rel-directory]]
	*[[rel-license]]		*[[rel-license]]
Line 21:		Line 29:
	*[http://gmpg.org/xfn/ XFN]		*[http://gmpg.org/xfn/ XFN]

	=== What is the proper use of the 'rel' attribute? ~~===~~		=== What is the proper use of the rel attribute ===
			''What is the proper use of the '<code>rel</code>' attribute?''

	First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.		First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.

	=== What does a rel value really mean? ===		=== What does a rel value really mean? ===
			''What does a '<code>rel</code>' value really mean?''

	The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.		The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.

	=== Then what does "rev" mean? ===		=== Then what does rev mean ===
			''Then what does '<code>rev</code>' mean?''

	"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.		"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.

	=== Is rel single or bi directional? ===		=== Is rel single or bi directional ===
			''Is rel single or bi-directional?''

	Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".		Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".

	=== Are "rel" attributes, and linktypes in general, just document to document? ===		=== Are rel attributes and linktypes in general just document to document ===
			''Are "rel" attributes, and linktypes in general, just document to document?''

			The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense.

			Two more notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document.

			The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing.

			Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the [[rel-tag]] specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document.

			Finally, [[XFN]] probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted from emergent publishing behavior on the Web. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.

			=== Do rel values refer to a relationship to the page or the contents of the page or both ===
			''When a 'rel' value refers to a relationship to or from a page or document, is it referring to just the page, or the contents of the page, or both?''

	The ~~vast majority of the~~ rel values ~~defined in HTML4~~ are ~~from a document~~ to ~~a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in~~ the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, ~~[http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an~~ example ~~of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document~~ to ~~a whole document or a part~~ of ~~a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally~~, ~~XFN probably stretches rel the farthest~~, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.		The consensus (and convention; '''citation needed''') is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.

	=== Is/Was VoteLinks a proper use of rel? ~~===~~		=== Was VoteLinks a proper use of rel ===
			''Is/Was VoteLinks a proper use of rel?''

	No. The problem with using rel for VoteLinks is made apparent with the following example:		No. The problem with using rel for VoteLinks is made apparent with the following example:
Line 69:		Line 96:
	And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.		And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.

	=== Should 'rev' even be used ===		=== Should rev even be used ===
			''Should 'rev' even be used?''

	~~Given~~ that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?		In (X)HTML, the same values may be used as <code>rev</code> ("reverse relationship") values, to indicate the relationship '''''of''''' the resource on which they appear '''''to''''' the target resource.

			However, given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?

	The short answer is unfortunately "no". Use of "rev" {{should}} be avoided.		The short answer is unfortunately "no". Use of "rev" {{should}} be avoided.

	However, VoteLinks~~, is being~~ [[glossary#grandfathered\|grandfathered]] since it was such an early use. No future microformats should be developed that use 'rev'.		However, VoteLinks' use of rev has been [[glossary#grandfathered\|grandfathered]] since it was such an early use. No future microformats should be developed that use 'rev', and any use of 'rev' (apart from the "[[glossary#grandfathered\|grand-fathered]]" case of [[vote-links\|VoteLinks]]) is [[glossary#deprecated\|deprecated]] in microformats.

	~~=== When a~~ '~~rel~~' ~~value refers to a relationship to or~~ from ~~a page or document, is it referring to just~~ the ~~page, or the contents~~ of ~~the page, or both? ===~~

	~~The consensus (and convention; '''citation needed'''~~) is ~~that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc~~.

	== See Also ==		== See Also ==

AndyMabbett: {{rel-related-pages}}; fixes

2007-09-24T18:45:57Z

{{rel-related-pages}}; fixes

← Older revision		Revision as of 18:45, 24 September 2007
Line 39:		Line 39:
	=== Are "rel" attributes, and linktypes in general, just document to document? ===		=== Are "rel" attributes, and linktypes in general, just document to document? ===

	The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.		The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.

	=== Is/Was VoteLinks a proper use of rel? ===		=== Is/Was VoteLinks a proper use of rel? ===
Line 51:		Line 51:
	Following the reasoning in the earlier answer to the question of what a rel value means, this link would mean:		Following the reasoning in the earlier answer to the question of what a rel value means, this link would mean:

	The resource indicated by http://www2005.org is a "vote-for" the current document.		:The resource indicated by http://www2005.org is a "vote-for" the current document.

	That clearly doesn't make any sense, and was certainly not the intent of VoteLinks. Ironically, the reverse makes a lot more sense:		That clearly doesn't make any sense, and was certainly not the intent of VoteLinks. Ironically, the reverse makes a lot more sense:

	The current document is a "vote-for" the resource indicated by http://www2005.org.		:The current document is a "vote-for" the resource indicated by http://www2005.org.

	And generalizing to the same cultural usage links as XFN:		And generalizing to the same cultural usage links as XFN:

	The current document, as a proxy for the person who wrote it (e.g. the blogger whose blog it is),		:The current document, as a proxy for the person who wrote it (e.g. the blogger whose blog it is), is a vote-for the resource indicated by http://www2005.org.
	is a vote-for the resource indicated by http://www2005.org.

	Fortunately the "rev" attribute captures this "reverse" relationship semantic, and thus the above example should be written like this:		Fortunately the "rev" attribute captures this "reverse" relationship semantic, and thus the above example should be written like this:
Line 74:		Line 73:
	Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?		Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?

	The short answer is unfortunately "no". Use of "rev" ~~SHOULD~~ be avoided.		The short answer is unfortunately "no". Use of "rev" {{should}} be avoided.

	However, VoteLinks, is being grandfathered since it was such an early use. No future microformats should be developed that use 'rev'.		However, VoteLinks, is being [[glossary#grandfathered\|grandfathered]] since it was such an early use. No future microformats should be developed that use 'rev'.

	=== When a 'rel' value refers to a relationship to or from a page or document, is it referring to just the page, or the contents of the page, or both? ===		=== When a 'rel' value refers to a relationship to or from a page or document, is it referring to just the page, or the contents of the page, or both? ===

	The consensus (and convention) is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.		The consensus (and convention; '''citation needed''') is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.

	== See Also ==		== See Also ==
	* [[existing-~~rel~~-~~values]]~~		{{rel-related-pages}}
	* [[rel-directory]]		* [[rel-directory]]
	* [[rel-examples]]
	* [[rel-license]]		* [[rel-license]]
	* [[rel-payment]]		* [[rel-payment]]
	* [[rel-tag]], [[rel-tag-faq]]		* [[rel-tag]], [[rel-tag-faq]]
	* [[rel-design-pattern]]
	* [[vote-links]]		* [[vote-links]]
	* [http://gmpg.org/xfn/ XFN], [http://gmpg.org/xfn/faq XFN FAQ]		* [http://gmpg.org/xfn/ XFN], [http://gmpg.org/xfn/faq XFN FAQ]

Tantek at 19:07, 23 September 2007

2007-09-23T19:07:00Z

← Older revision		Revision as of 19:07, 23 September 2007
Line 83:		Line 83:

	== See Also ==		== See Also ==
			* [[existing-rel-values]]
	* [[rel-directory]]		* [[rel-directory]]
	* [[rel-examples]]		* [[rel-examples]]

Tantek: Reverted edit of Gazza, changed back to last version by Tantek

2007-05-01T23:26:14Z

Reverted edit of Gazza, changed back to last version by Tantek

← Older revision		Revision as of 23:26, 1 May 2007
Line 12:		Line 12:
	== FAQ ==		== FAQ ==

	===What microformats use rel ===		===What microformats use "rel"? ===
	*[[rel-directory]]		*[[rel-directory]]
	*[[rel-license]]		*[[rel-license]]
Line 21:		Line 21:
	*[http://gmpg.org/xfn/ XFN]		*[http://gmpg.org/xfn/ XFN]

	=== What is the proper use of the rel attribute ===		=== What is the proper use of the 'rel' attribute? ===

	First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.		First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.

	=== What does a rel value really mean ===		=== What does a rel value really mean? ===

	The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.		The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.

	=== Then what does rev mean ===		=== Then what does "rev" mean? ===

	"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.		"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.

	=== Is rel single or bi directional ===		=== Is rel single or bi directional? ===

	Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".		Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".

	=== Are rel attributes and linktypes in general just document to document ===		=== Are "rel" attributes, and linktypes in general, just document to document? ===

	The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.		The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.

	=== Is VoteLinks a proper use of rel ===		=== Is/Was VoteLinks a proper use of rel? ===

	No. The problem with using rel for VoteLinks is made apparent with the following example:		No. The problem with using rel for VoteLinks is made apparent with the following example:
Line 70:		Line 70:
	And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.		And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.

	=== Should rev even be used ===		=== Should 'rev' even be used ===

	Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?		Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?
Line 78:		Line 78:
	However, VoteLinks, is being grandfathered since it was such an early use. No future microformats should be developed that use 'rev'.		However, VoteLinks, is being grandfathered since it was such an early use. No future microformats should be developed that use 'rev'.

	=== When a rel value refers to a relationship to or from a page or document is it referring to just the page or the contents of the page or both ===		=== When a 'rel' value refers to a relationship to or from a page or document, is it referring to just the page, or the contents of the page, or both? ===

	The consensus (and convention) is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.		The consensus (and convention) is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.

Gazza: Changed headings to follow How To Play Guideline 9

2007-05-01T13:19:26Z

Changed headings to follow How To Play Guideline 9

← Older revision		Revision as of 13:19, 1 May 2007
Line 12:		Line 12:
	== FAQ ==		== FAQ ==

	===What microformats use "rel"? ===		===What microformats use rel ===
	*[[rel-directory]]		*[[rel-directory]]
	*[[rel-license]]		*[[rel-license]]
Line 21:		Line 21:
	*[http://gmpg.org/xfn/ XFN]		*[http://gmpg.org/xfn/ XFN]

	=== What is the proper use of the 'rel' attribute? ===		=== What is the proper use of the rel attribute ===

	First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.		First, you can use the [http://www.w3.org/TR/html4/types.html#type-links linktype] as specified in [http://www.w3.org/TR/html4/ HTML 4]. A well known example of this is rel="stylesheet". Second, you "can extend the rel attribute using a [http://www.w3.org/TR/html4/types.html#type-links profile"], but "[http://www.w3.org/TR/html4/types.html#idx-link_type-2 HTML doesn't specify/recommend a profile format]". XMDP can be used to formally define new rel values.

	=== What does a rel value really mean? ===		=== What does a rel value really mean ===

	The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.		The rel values in HTML follow a consistent pattern which at a minimum ''implies'' a deliberate design. rel describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source's perspective. rel="stylesheet" is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) ''is'' a "stylesheet" for the current document. Similarly, rel="help" link states that the resource indicated by the href is "help" (e.g. a help file or FAQ) for the current document. All the rest of the values defined in HTML4 also follow this pattern of being a ''noun'' which labels the resource indicated by the href, from the perspective of the current document.

	=== Then what does "rev" mean? ===		=== Then what does rev mean ===

	"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.		"rev" is the precise opposite (or "reverse") of the "rel" attribute. E.g. a rev="help" link indicates that ''the current document'' is "help" for the resource indicated by the href.

	=== Is rel single or bi directional? ===		=== Is rel single or bi directional ===

	Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".		Though the HTML4 specification is not specific on this point, all the rel values in the HTML4 specification follow a very consistent pattern that indicate a specific directionality to the value of the rel attribute. The ''only'' exception to this is the value "alternate", which, is actually inherently symmetric, so rel="alternate" means pretty much the same thing as rev="alternate". I say pretty much because in theory (and in practice) one of a pair of alternates is likely to be more definitive, and thus one is more a primary resource, with the other being an alternative. In theory you could extend rel with a new value, e.g. "original" which could be used to point back the original version of a document. This could be used for example with translations, where translations of a document would point back to the original with rel="original".

	=== Are "rel" attributes, and linktypes in general, just document to document? ===		=== Are rel attributes and linktypes in general just document to document ===

	The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.		The vast majority of the rel values defined in HTML4 are from a document to a document. rel="stylesheet" is a bit of an exception, as it from an HTML document to a style sheet, which is more like a set of styling rules and instructions than a "document" in the classical sense. Two notable exceptions are rel="copyright" and rel="bookmark" which describe the relationship from the current document to (potentially) only part of a document. The 'rev' attribute adds an interesting perspective on this question. Specifically, [http://www.w3.org/TR/html4/struct/links.html#rev-link 12.3.1 of HTML4] shows an example of two links one using rel and the other using rev which mean the same thing. Thus linktypes in general may be either from a whole document or part of a document to a whole document or a part of a document. For example, the RelTag specification introduces the rel="tag" value, and notes that it indicates a relation from a document or major portion thereof to a document. Finally, XFN probably stretches rel the farthest, as it uses rel to indicate a person to person relationship. This person to person scope was not introduced by XFN, but merely adopted. It was introduced by bloggers who have taken to linking to other bloggers by name and thus using people's blog URLs as proxies for people themselves.

	=== Is~~/Was~~ VoteLinks a proper use of rel? ===		=== Is VoteLinks a proper use of rel ===

	No. The problem with using rel for VoteLinks is made apparent with the following example:		No. The problem with using rel for VoteLinks is made apparent with the following example:
Line 70:		Line 70:
	And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.		And thus VoteLinks has been changed to use "rev" instead of "rel", in order to keep the well known and easily understandable "vote-for", "vote-abstain", and "vote-against" values.

	=== Should 'rev' even be used ===		=== Should rev even be used ===

	Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?		Given that the 'rev' attribute has been more often misused by authors than properly used ([http://code.google.com/webstats/2005-12/linkrels.html Google Code: Web Authoring Statistics: Link Relationships]) is it even a good idea to use rev at all?
Line 78:		Line 78:
	However, VoteLinks, is being grandfathered since it was such an early use. No future microformats should be developed that use 'rev'.		However, VoteLinks, is being grandfathered since it was such an early use. No future microformats should be developed that use 'rev'.

	=== When a 'rel' value refers to a relationship to or from a page or document, is it referring to just the page, or the contents of the page, or both? ===		=== When a rel value refers to a relationship to or from a page or document is it referring to just the page or the contents of the page or both ===

	The consensus (and convention) is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.		The consensus (and convention) is that such rel values are referring to the page itself including its immediate contents, but not for example to embedded contents of like images, objects, frames etc.