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Re: Referring to resources in RDF attributes

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Wed, 18 Apr 2001 18:17:38 +0100
Message-ID: <3ADDCC32.8EFCD267@hplb.hpl.hp.com>
To: Graham Klyne <GK@NineByNine.org>
CC: RDF comments <www-rdf-comments@w3.org>, RDF core WG <w3c-rdfcore-wg@w3.org>

Thank you for raising this issue.  I have added it to the issues list



Graham Klyne wrote:
> A possible RDF issue?
> I recognize RDF core WG is not strictly chartered to make changes to the
> RDF syntax, but there is a small change that I think could greatly enhance
> usability of RDF, if it doesn't break any other rules.
> Currently, resource identifier values specified in attributes such as
> "about", "resource", "aboutEach" and "type" are specified as
> URI-references.  The same resources used in element or attribute names are
> specified as Qnames.
> I have for some time assumed that there is a good reason for Qname syntax
> to be unavailable in attribute values but I recently noticed another
> specification that allows interpretation Qnames in attribute values, which
> leads me to question my assumption.
> In the CC/PP specification [1] examples, DTD entity definitions are used to
> make such attributes more readable, but this has been criticized as being
> incompatible with future directions for XML.  It would be so much easier if
> Qnames could be used here.  I have noticed similar complications in other
> examples of RDF.
> So, what would be the possible problems of allowing Qnames in the RDF/XML
> syntax for the attributes mentioned?
> (a) does it break any assumed processing models?  I don't think so, but I'm
> not certain about this.
> (b) how does one distinguish between a Qname and a 'bare' URI-reference
> (the bare URI form MUST be allowed for backward compatibility)?
> Here's a simple example of the kind of thing I am thinking of:
> Current RDF syntax:
>    <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>             xmlns:rdfs="http://www.w3.org/1999/PR-rdf-schema-19990303#">
>      <rdf:Description about="http://www.example.org/Set">
>        <rdf:type
> resource="http://www.w3.org/1999/PR-rdf-schema-19990303#Class"/>
>        <rdfs:subClassOf
> rdf:resource="http://www.w3.org/1999/PR-rdf-schema-19990303#Container"/>
>      </rdf:Description>
>    </rdf:RDF>
> Using Qnames:
>    <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>             xmlns:rdfs="http://www.w3.org/1999/PR-rdf-schema-19990303#"
>             xmlns:eg="http://www.example.org/Set">
>      <rdf:Description about="eg:Set">
>        <rdf:type resource="rdfs:Class"/>
>        <rdfs:subclassOf rdf:resource="rdfs:Container"/>
>      </rdf:Description>
>    </rdf:RDF>
> #g
> --
> [1] CC/PP draft <http://www.w3.org/TR/CCPP-struct-vocab/>
> ------------
> Graham Klyne
Received on Wednesday, 18 April 2001 13:17:44 EDT

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