version
Per the microformats process, this is a page for researching and brainstorming a rel value for linking to a previous version of a page.
use case
To be able to discover previous versions of a document automatically from a document.
examples
- W3C. Nearly every W3C specification has a link in the header to the "Previous Version".
- ...
formats
revision control systems
Revision control systems (RCS) like:
- CVS
- SVN
- mercurial (hg)
- git
All have ways of representing previous versions of a document.
brainstorming
Several rel values are being considered for linking from a document to a previous version of that document.
- rel=version
- +1 Tantek : this feels like the most human-author-friendly term of these.
- -1 BigBlueHat : lacks directionality; fine for the "this thing is a version case...maybe"
- rel=revision
- Mediawiki uses the term "revision" in the UI when you're viewing a previous version of a page.
- "revision" has a developer feel to it, common terminology in revision control systems (naturally) like git etc.
- -1 BigBlueHat : same issue as above; also revision !== version
- rel=older
- -1 Tantek: "older" feels wrong as a noun.
- ...
current
A related use case is to be able to find the current version of document when looking at an older version. For this, the following rel values are being considered:
- rel=current
- seems like a link to something that is always current, not that it happens to be current right now. - Tantek
- rel=latest
- might mean a specific link to the latest version, though W3C specs use the phrase "Latest Version" to label the link to the always current URL - Tantek
- rel=latest-version
- from 5829
- rel=predecessor-version
- from 5829
- rel=successor-version
- from 5829
- ...
history
MediaWiki pages don't link directly to previous versions, rather they link to a "History" page which then links to previous versions.
We can at least consider brainstorming a link rel to that history page accordingly:
- rel=history - on a link from a page to a document that lists history of that page, perhaps linking to previous versions.
- rel=version-history
- from 5829
Is there any meaningful way to markup (rel value) links from a history page to the page itself or from a history page to previous versions of the page?
canonical
You can already use:
- rel-canonical to link to the canonical version of a page. But this doesn't mean it's a different version, if anything, it may be the exact same content just at a shorter or more reliable/official URL.
FAQ
what about rel prev
What about rel="prev" (or "previous")?
rel=prev (and next) are for sequential navigation/pagination, not historical revisions.
Sequential navigation/pagination and historical versions are totally different, both in how the content works, and in usage.
In pagination, each of the pages has different content and is a sequence like a list, or a series of chapters.
In historical revisions, each page (typically) has mostly the same content with just a few changes/differences between versions.
Pagination is often used as an alternative to delivering the content as a whole, e.g. news articles. Whereas you never see previous historical versions all appended together as if that's "the whole thing".