W3C home > Mailing lists > Public > public-html@w3.org > December 2009

Re: ISSUE-27: rel-ownership - Chairs Solicit Proposals

From: Mark Nottingham <mnot@mnot.net>
Date: Wed, 30 Dec 2009 10:02:11 +1100
Cc: Paul Cotton <Paul.Cotton@microsoft.com>, "public-html@w3.org" <public-html@w3.org>
Message-Id: <59AB718B-604C-4FC2-949B-8DE5B784BEA2@mnot.net>
To: Toby Inkster <tai@g5n.co.uk>
Hi Toby,

Regarding rev semantics - see Roy's message at:
  http://www.w3.org/mid/2BDD98C6-F223-47DC-AF4B-BCBF6E232813@gbiv.com

This is part of a much larger discussion. While confusion is certainly part of the problem -- and the rev="canonical" debacle was an indication that it's pretty widespread -- there are also people who have very clear but incompatible views of what rev means.

Thanks for the implementation ref; I have a very simple one in Python at <http://gist.github.com/210535>. Any interest in working on a test suite?

Cheers,



On 16/12/2009, at 11:23 PM, Toby Inkster wrote:

>> http://www.mnot.net/drafts/draft-nottingham-http-link-header-07.txt
>> http://www.mnot.net/drafts/draft-nottingham-http-link-header-07-from-6.diff.html 
> 
> Your new explanation on @rev in HTML4 states:
> 
>> some hold that rev reverses	
>> the direction of the link, while others that it reverses the	
>> semantics of the relation itself
> 
> The HTML 4.01 Recommendation defines @rel as:
> 
> 	"the relationship from the current document to
> 	 the anchor specified by the href attribute"
> 	<http://www.w3.org/TR/html4/struct/links.html#adef-rel>
> 
> And @rev as:
> 
> 	"a reverse link from the anchor specified by the
> 	 href attribute to the current document"
> 	<http://www.w3.org/TR/html4/struct/links.html#adef-rev>
> 
> Further it illustrates this with an example (linked to from the @rev
> definition) showing them both in use, stating that the following code in
> Document A:
> 
> 	<LINK href="docB" rel="foo">
> 
> has "exactly the same meaning" as the following code in Document B:
> 
> 	<LINK href="docA" rev="foo">
> 
> The earlier 4.0 Recommendation has word-for-word identical definitions
> and examples. 3.2 is similar <http://www.w3.org/TR/REC-html32#link>.
> 
> I don't doubt that some people are confused by @rev. (If you look hard
> enough, you can find people confused about almost anything.) But given
> that all the relevant recommendations are quite clear in stating that
> @rev reverses the *direction* of the link, it seems disingenuous to
> present them as two equally valid interpretations of the definition of
> @rev.
> 
> I'd suggest changing the wording to something like:
> 
> 	while rev is defined to reverse the direction of
> 	the link, some have implemented it as if it reversed
> 	the semantics of the link type
> 
> Though, that having been said, although I've seen a handful of examples
> where people have mistakenly used @rev instead of @rel, either through
> ignorance or the slip of a finger, I can't remember seeing any which
> *rely* on the mistaken interpretation of it reversing the semantics of
> the link type. For example, I've never seen a page which used, say,
> rel="author" to link to the author and rev="author" to link to people
> who did not contribute to the document.
> 
> PS: in case you're not aware of it, I've implemented a parser for HTTP
> Link headers in Perl, and am in general a big fan of them.
> 
> http://search.cpan.org/~tobyink/HTTP-Link-Parser/lib/HTTP/Link/Parser.pm
> 
> -- 
> Toby A Inkster
> <mailto:mail@tobyinkster.co.uk>
> <http://tobyinkster.co.uk>
> 


--
Mark Nottingham     http://www.mnot.net/
Received on Tuesday, 29 December 2009 23:02:45 UTC

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