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

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

From: Toby Inkster <tai@g5n.co.uk>
Date: Wed, 16 Dec 2009 12:23:17 +0000
To: Paul Cotton <Paul.Cotton@microsoft.com>
Cc: "public-html@w3.org" <public-html@w3.org>, Mark Nottingham <mnot@mnot.net>
Message-ID: <1260966197.32395.234.camel@ophelia2.g5n.co.uk>
> 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>
Received on Wednesday, 16 December 2009 12:24:02 UTC

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