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Re: [Fwd: Using XMLNS in link/@rel]

From: Steven Pemberton <steven.pemberton@cwi.nl>
Date: Fri, 27 Feb 2009 16:08:38 +0100
To: "Mark Nottingham" <mnot@mnot.net>
Cc: www-tag@w3.org, "Dan Brickley" <danbri@danbri.org>, "Ben Adida" <ben@adida.net>, RDFa <public-rdf-in-xhtml-tf@w3.org>, "XHTML WG" <public-xhtml2@w3.org>
Message-ID: <op.up0m0orssmjzpq@acer3010.wlan.cwi.nl>
On Fri, 27 Feb 2009 11:54:24 +0100, Mark Nottingham <mnot@mnot.net> wrote:
> The only place I see this defined is in the RDFa syntax document itself  
> -- do you mean that is the specification of authority?

Yes.

> I note that it specifies /html/@version="XHTML+RDFa 1.0", and it has its  
> own DTD, so in a way I suppose it's not really an extension to XHTML,  
> but a re-definition of it...

Yes. It adds attributes, and meaning to those attributes.

>>> Of course, this conflicts with the Link draft;
>>>  http://tools.ietf.org/id/draft-nottingham-http-link-header-04.txt
>>> which we've worked pretty hard to come to consensus on across a broad
>>> selection of communities (Atom, POWDER, OAuth, HTTP, and
>>> optimistically, HTML5).
>>>
>>> A few observations and questions;
>>>
>>> 1) I'm more than happy to specify in the Link that in XHTML, a link
>>> rel value is indeed a QName, if XHTML chooses to take that position
>>> (although I believe a URI is a better fit than a QName here, as in
>>> most other places). Can we get a current reading from the XHTML world
>>> on this?
>>
>> A CURIE is a URI not a QName, so you're OK.
>
> I haven't paid a lot of attention to them to date, but as far as I can  
> see, a CURIE is most definitely not a URI; at most, it's a shorthand for  
> one.

Sorry for being imprecise, yes a CURIE is a shorthand for a URI. Its  
lexical form is CURIE, its value space is the IRIs:

"Note that while the lexical space of a CURIE is as defined in curie  
above, the value space is the set of IRIs."
http://www.w3.org/TR/rdfa-syntax/#s_curies

> As I said before, the third point is IME the most concerning. Having two  
> subtly incompatible syntax for the same attribute in HTML and XHTML  
> isn't a great situation, but assuming that one is valid to use in the  
> other is far more troublesome.

As I said, a CURIE is an appropriate value for a rel in HTML4. In HTML4  
the rel attribute takes CDATA, and is defined as a space-separated list of  
link types, with no other definition of what a link type is. So a link  
type can be any string of characters that are not spaces. So a CURIE  
matches. However, it is the RDFa spec that assigns meaning to a CURIE.

Hope this helps,

Best wishes,

Steven Pemberton
Received on Friday, 27 February 2009 15:08:56 GMT

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