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Re: Feedback for draft-nottingham-http-link-header-03

From: Ian Hickson <ian@hixie.ch>
Date: Sat, 6 Dec 2008 02:44:49 +0000 (UTC)
To: Phil Archer <phil@philarcher.org>
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>, Eran Hammer-Lahav <eran@hueniverse.com>, Mark Nottingham <mnot@mnot.net>, Drummond Reed <drummond.reed@cordance.net>
Message-ID: <Pine.LNX.4.62.0812060229340.17401@hixie.dreamhostps.com>

On Wed, 3 Dec 2008, Phil Archer wrote:
> 
> HTML 5 has dropped rev for the link element and if the tide is against 
> keeping rev in HTTP Link then the impression being given might be that 
> rev is deprecated everywhere.

Eran asked me to chime in here to give some background on why HTML5 drops 
the "rev" attribute.

It basically boils down to reducing author confusion. As can be seen from 
this thread, even people quite familiar with Web standards and semantics 
have trouble defining exactly what it means. We did some research and 
found a quite startling situation: the most common value for rev="" in the 
HTML pages we examined was rev="made", which is equivalent to 
rel="author", and the second most common value was rev="stylesheet", which 
is a typo. The remaining values were so too rare to examine. Further 
evidence that there was confusion: rel="made" was a common rel="" value, 
though it is likely that in most cases it should have been rev="made" or 
rel="author".

What we concluded from this was that despite the feature (rev="") being 
available for a decade or more, authors don't need it, and don't 
understand it.

We can help authors by making this that they usually misuse invalid, 
because then the validators will catch their errors. (Right now, an HTML4 
validator can't strictly say that rev="stylesheet" was an error, and so 
the error goes undetected even by authors using QA tools.)

The data was published here:
   http://code.google.com/webstats/2005-12/linkrels.html

(More recent but unpublished studies have shown similar results in larger 
and more recent datasets.)

The above was weighed against the (currently mostly theoretical) need for 
rev="" in various fields, such as RDFa, some Microformats, and so on, but 
on the balance we decided that the immediate help to authors was worth 
more to authors and users than these use cases. Helping with this was the 
realisation that rel="" values could always be minted in a way that was 
equivalent to rev="". For example, if someone had rel="foobar" and really 
wanted rev="foobar" to be available too, they could instead just define 
and use rel="rev-foobar".

HTH,
-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Saturday, 6 December 2008 02:45:28 GMT

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