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RDFa Profiles, terms, and predicates (oh my!)

From: Shane McCarron <shane@aptest.com>
Date: Thu, 22 Jul 2010 16:02:42 -0500
Message-ID: <4C48B1F2.1010306@aptest.com>
To: RDFa WG <public-rdfa-wg@w3.org>
I was working on my (implied) action item to update our vocabulary 
document so that it is an RDFa Profile, and I ran into something odd.  
The rules for an RDFa Profile are pretty simple [1].  Shoehorning the 
required predicates into our existing pattern in the vocab document is a 
little daunting though.  I don't want to break what is already there (in 
case someone is depending upon it)... Here is that pattern:

    <dt id="alternate" about="#alternate" typeof="rdf:Property">alternate</dt>
         <dd about="#alternate" property="rdfs:comment"
           datatype="xsd:string"><span>alternate</span>  designates alternate
           versions for a resource.</dd>
       


Each term is defined that way.  All of our terms are defined within a 
containing bucket like this:

    <div id="relrev-properties" about="#relrev-properties" typeof="rdf:Bag">

    <div about="#relrev-properties" rev="rdfs:member">
       

Anyway.... our rules [1] require that in order for a term to be defined, 
it must be the common subject of two predicates; rdfa:term and 
rdfa:uri.  I completely understand why this is an attractive general 
case model.  I can map ANY term to ANY URI.  However, in reality, I 
expect that most vocabularies will be like ours - self-contained.  In 
other words the vocabulary document will define the term, and the URI 
for the term will be within that same document.  In the case above, for 
example, the URI for the term 'alternate' is 
http://www.w3.org/1999/xhtml/vocab#alternate.

With all this in mind, and in the spirit of never duplicating data 
needlessly in an RDFa document, I propose that we modify the RDFa 
Profile rules slightly.  That we say a term is defined by an 'rdfa:term' 
predicate.  That the term itself is the object of that predicate, and 
the URI is the object of an 'rdfa:uri' predicate on the same subject if 
one is provided.  Otherwise, the URI is the same as the subject of that 
predicate.

Questions?  Comments?

[1] http://www.w3.org/TR/rdfa-core/#s_profiles

-- 
Shane P. McCarron                          Phone: +1 763 786-8160 x120
Managing Director                            Fax: +1 763 786-8180
ApTest Minnesota                            Inet: shane@aptest.com
Received on Thursday, 22 July 2010 21:03:18 GMT

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