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Re: @rel syntax in RDFa (relevant to ISSUE-60 discussion), was: Using XMLNS in link/@rel

From: Ben Adida <ben@adida.net>
Date: Sat, 28 Feb 2009 08:18:39 -0800
Message-ID: <49A963DF.7050802@adida.net>
To: Sam Ruby <rubys@intertwingly.net>
CC: Julian Reschke <julian.reschke@gmx.de>, noah_mendelsohn@us.ibm.com, Henri Sivonen <hsivonen@iki.fi>, Mark Nottingham <mnot@mnot.net>, HTMLWG WG <public-html@w3.org>, RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>, public-xhtml2@w3.org, "www-tag@w3.org WG" <www-tag@w3.org>
Sam Ruby wrote:
>> Yes, but how does this help in this case?
>>
>> If I have
>>
>>   <head profile="http://example.com/ http://example.org/">
>>
>> and
>>
>>   <a rel="foobar">
>>
>> ...how do I find out which profile/namespace foobar belongs to? It
>> doesn't solve the disambiguation problem.

This was a comment from Julian. Again, I didn't design @profile, I'm
only telling it like it is. One of the big design principles of RDFa was
that, as far as vocabularies are concerned, a fragment should stand on
its own. So I'm not saying that @profile is fantastic, I'm saying that
@profile already exists, and @profile alters the meaning of of @rel values.

And if that's the case, then surely the language one uses (HTML4, HTML5,
XHTML1, XHTML2) is well within its right to process @rel values, because
they're *already* doing it. In fact, it seems impossible to hope that
raw @rel values will mean the same thing across all languages when
previous versions of HTML already have frozen value sets for @rel, and
they're *not* URIs.

At best, we can say that the semantic value of @rel should be a URI.

> I'll also mention that fragments of [X]HTML often appear in places like
> XMPP and Atom.  Places where a <head> element generally don't appear.

Yes, and we specifically wanted to support that use case in RDFa by
making sure that we have one syntax and that vocabularies can be
declared locally. Thus, the Creative Commons fragment that you can
insert in your page is supposed to be free-standing.

Of course, this is in the hopes that XHTML and HTML will interpret @rel
in the same way.

-Ben
Received on Saturday, 28 February 2009 16:19:27 GMT

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