rel-up: Difference between revisions
(added standards that define rel=up and an implementation (the wiki doesn’t let me post an external link, so I put the URL into <nowiki> tags)) |
(added some historical notes (the wiki doesn’t let me post external links, so I put the URLs into <nowiki> tags)) |
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* XHTML vocabulary (<nowiki>https://www.w3.org/1999/xhtml/vocab#up</nowiki>) | * XHTML vocabulary (<nowiki>https://www.w3.org/1999/xhtml/vocab#up</nowiki>) | ||
** and hence XHTML+RDFa Initial Context (<nowiki>https://www.w3.org/2011/rdfa-context/xhtml-rdfa-1.1</nowiki>) | ** and hence XHTML+RDFa Initial Context (<nowiki>https://www.w3.org/2011/rdfa-context/xhtml-rdfa-1.1</nowiki>) | ||
== History == | |||
Historically ''up'' has also been in HTML3 (<nowiki>https://www.w3.org/MarkUp/html3/dochead.html</nowiki>), but could not be found in later editions of HTML, until its use in practice was recognized during the development of HTML5 (<nowiki>https://blog.whatwg.org/the-road-to-html-5-link-relations#rel-first</nowiki>) and hence found its way into HTML5 Working Drafts (<nowiki>https://www.w3.org/TR/2011/WD-html5-20110113/links.html#link-type-up</nowiki>). Then the link relation ''up'' was dropped from HTML5 without prejudice (<nowiki>https://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html</nowiki>) for adding it to other future link relation registries – e.g. this [[existing-rel-values|this microformats WIKI]] – and recognizing that it is a defined standard anyway due to the IANA registry: | |||
<blockquote cite="https://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html">Finally, it was noted that the link relations being dropped are already defined in the IANA registry and could be defined in future registries;</blockquote> | |||
An argument against that decision was that dropping ''up'' from the HTML standard would cause content to show up as invalid in validators and would stop people from using it, which was apparently not the intention when dropping it from the HTML core standard. The counter argument was: | |||
<blockquote cite="https://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html">Since validators do not implement relation checking at all yet and are waiting on a registry solution before doing so, this was also a weak objection.</blockquote> | |||
However, once a registry solution was found – i.e. currently this [[existing-rel-values|this microformats WIKI]] – the new registry failed to add the link relation ''up'' as valid value and validators started to report it as an error. Unfortunately, this caused multiple software projects to remove ''rel=up'' from software such as content management systems (<nowiki>https://github.com/webdevops/TYPO3-metaseo/commit/71f2e1b492dfa6304024594a0c7c3b5bd6bea3e4</nowiki>), documentation tools (<nowiki>https://github.com/sphinx-doc/sphinx/commit/d43259f5f748cd00eba168b54b7b798d3f257911</nowiki>) and bulletin boards (<nowiki>https://www.phpbb.com/community/viewtopic.php?f=74&t=2170174</nowiki>). | |||
== Implementations == | == Implementations == | ||
Revision as of 14:38, 20 June 2018
This article is a stub. You can help the microformats.org wiki by expanding it.
Description
Refers to a parent document in a hierarchy of documents.
Example
A page (https://prlbr.de/galerie/14/am-pranger/) in a photo gallery showcases a photo. The page defines multiple link relations which refer to the
- next page which contains the next photo from the gallery
- previous page from the gallery
- parent page using up, which shows previews of many photos as thumbnails including the current one and includes links to their corresponding pages.
<link rel='next' href='/galerie/14/mustergatte/'>
<link rel='prev' href='/galerie/14/linie-1/'>
<link rel='up' href='/galerie/seite-6'>
next and prev relate to documents on the same hierarchy level while up moves one level up.
Standards
The link relation up is recognized in standards:
- IANA link relations registry (https://www.iana.org/assignments/link-relations/link-relations.xhtml)
- XHTML vocabulary (https://www.w3.org/1999/xhtml/vocab#up)
- and hence XHTML+RDFa Initial Context (https://www.w3.org/2011/rdfa-context/xhtml-rdfa-1.1)
History
Historically up has also been in HTML3 (https://www.w3.org/MarkUp/html3/dochead.html), but could not be found in later editions of HTML, until its use in practice was recognized during the development of HTML5 (https://blog.whatwg.org/the-road-to-html-5-link-relations#rel-first) and hence found its way into HTML5 Working Drafts (https://www.w3.org/TR/2011/WD-html5-20110113/links.html#link-type-up). Then the link relation up was dropped from HTML5 without prejudice (https://lists.w3.org/Archives/Public/public-html/2011Feb/att-0481/issue-118-decision.html) for adding it to other future link relation registries – e.g. this this microformats WIKI – and recognizing that it is a defined standard anyway due to the IANA registry:
Finally, it was noted that the link relations being dropped are already defined in the IANA registry and could be defined in future registries;
An argument against that decision was that dropping up from the HTML standard would cause content to show up as invalid in validators and would stop people from using it, which was apparently not the intention when dropping it from the HTML core standard. The counter argument was:
Since validators do not implement relation checking at all yet and are waiting on a registry solution before doing so, this was also a weak objection.
However, once a registry solution was found – i.e. currently this this microformats WIKI – the new registry failed to add the link relation up as valid value and validators started to report it as an error. Unfortunately, this caused multiple software projects to remove rel=up from software such as content management systems (https://github.com/webdevops/TYPO3-metaseo/commit/71f2e1b492dfa6304024594a0c7c3b5bd6bea3e4), documentation tools (https://github.com/sphinx-doc/sphinx/commit/d43259f5f748cd00eba168b54b7b798d3f257911) and bulletin boards (https://www.phpbb.com/community/viewtopic.php?f=74&t=2170174).
Implementations
- https://addons.mozilla.org/en-US/firefox/addon/link-widgets/
- https://chrome.google.com/webstore/detail/cgddacggfmoggigikjjcogdodjiplibe
- http://www.seamonkey-project.org/
- https://www.drupal.org/project/rel_links