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RDF/A and XML Namespaces

From: Pete Johnston <p.johnston@ukoln.ac.uk>
Date: Fri, 29 Oct 2004 13:04:52 +0100
To: public-rdf-in-xhtml-tf@w3.org
Message-ID: <004301c4bdaf$7f842670$2392268a@ulpcpj>

Hi,

I've been lurking here for a while and following the discussion of RDF/A
with interest.

I have one question, which seems rather basic so may already have been
addressed.

If the intent is that RDF/A provides an XML language that can be used in
association with _any_ other XML language, not just XHTML - which is
what I understand from section 2.2 and section 3.2 - i.e. RDF/A is what
I think is sometimes referred to as a "parasite language", then I guess
it will be necessary to namespace-qualify the RDF/A attributes, as is
done in e.g. XLink, XForms etc. (Otherwise, we can't distinguish an
RDF/A rel/rev (etc) attribute from MyHypotheticalML's existing use of
rel/rev (etc) attributes to convey quite different semantics)

I saw Ralph Swick's suggestion that the RDF/A attribute names should be
associated with the http://www.w3.org/2002/06/xhtml2 namespace, and that
sounds good. 

However, my understanding of XML Namespaces is that in an example like

<html xmlns="http://www.w3.org/2002/06/xhtml2"
      xmlns:dc="http://purl.org/dc/elements/1.1/"
>
  <head>
     <link about="http://example.org/doc" rel="dc:creator"
href="http://example.org/person" />
  </head>
<body>

</body>
</html>

the xmlns attribute does not affect the unprefixed attribute names i.e.
the about, rel and rev attribute names are _not_ associated with the
namespace name http://www.w3.org/2002/06/xhtml2 (i.e. this is the case
of the first "Vikram Seth" example in [1]) 

So to ensure that those attribute names _are_ associated with a
namespace name, they would need to be prefixed in XHTML:

<html xmlns="http://www.w3.org/2002/06/xhtml2"
      xmlns:dc="http://purl.org/dc/elements/1.1/"
      xmlns:xhtml2="http://www.w3.org/2002/06/xhtml2"  
>
  <head>
     <link xhtml2:about="http://example.org/doc" xhtml2:rel="dc:creator"
xhtml2:href="http://example.org/person" />
  </head>
<body>

</body>
</html>

Is that right please? Or am I confused? Quite probably ;-)
 
Thanks

Pete

[1] http://www.jclark.com/xml/xmlns.htm

------- 
Pete Johnston 
Research Officer (Interoperability)
UKOLN, University of Bath, Bath BA2 7AY, UK 
tel: +44 (0)1225 383619    fax: +44 (0)1225 386838 
mailto:p.johnston@ukoln.ac.uk 
http://www.ukoln.ac.uk/ukoln/staff/p.johnston/

 
 
Received on Friday, 29 October 2004 12:03:40 GMT

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