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Re: Question on namespace confusion (more on Re: New syntax spec )

From: Rick Jelliffe <ricko@allette.com.au>
Date: Tue, 18 Sep 2001 17:14:56 +1000
Message-ID: <02b601c14011$9ec42180$4bc8a8c0@AlletteSystems.com>
To: "www-rdf-comments" <www-rdf-comments@w3.org>
From: "Dave Beckett" <dave.beckett@bristol.ac.uk>

>  RDF/XML has been modified to forbid unprefixed
> attributes anywhere in the syntax. i.e. local attribute names are
> not allowed.  

So any existing or future document type that uses unqualified
attributes (i.e. 99% of them) cannot be used with RDF?  
Can you confirm that an RDF document does not allow local
attributes at any level?

Why wouldn't it be a good idea to throw RDF-in-XML as currently
specified completely out the window, and start afresh to
try for what the rest of us actually need: a way of allowing semantic
markup on XML documents. I.e. to start with the XML information
set (including local attributes) as a fact to be worked with rather than
something to be ignored?

> This was done due to widespread confusion about
> namespaces and attributes.  Different deployed applications thought
> that in
>      <eg:property resource="http://example.org/resource2/"/>
> 
> resource actually was eg:resource, others that it was
> (default xmlns namespace):resource, and others recognised it
> as the rdf special attribute that it is.

Well, it is certainly not eg:resource nor defaultNamespace:resource
(see 5.2 "Note that default namespaces do not apply directly to attributes.")
nor rdf:resource, according to the namespaces spec.

A local resource attribute on an element in another namespace might
be RDF's resource, but it is never rdf:resource. 

Sorry for being really thick on this, but I tend to think the refactored
RDF still does not strike at the heart of the problem I have: I know
the XML layer, I know the namespace layer, but RDF by providing home-made 
grammars (whether syntax or information set) lumps together bits of the 
requirements from XML, Namespace and RDF without discipline.

You have a subset of XML (no unprefixed attributes), 
a subset of Namespaces (no unqualified attributes, same thing) and
an unstated set of rules for implying namespaces (e.g. that
<eg:property resource="x"/> is the same as <eg:property rdf:resource="x"/>).
I guess using explicit prefixes on all attribute gets us out of that problem, 
and it does clarify that  most people interested in adding semantic markup 
to their XML documents should safely ignore RDF.

Cheers
Rick Jelliffe

B.t.w. Thanks for the help on this. It looks like the various schema
language champions are all going to make versions of schemas
for RDF, to allow comparison between the approaches of the 
different schema languages. Should be interesting.
Received on Tuesday, 18 September 2001 03:08:50 GMT

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