Re: #rdfms-difference-between-ID-and-about

pat hayes wrote:
> 
> >"R.V.Guha" wrote:
> > >
> > > Ok, Aaron, you hit the nail on the head.
> > >
> > > RDF absolutely has to make sense even outside the context of
> > > an enclosing document which can be given a uri. so ...
> >
> >So... what? That doesn't make any sense to me.
> >
> >An RDF document is an XML document.
> 
> ?? It is? I thought that RDF was sets of triples and the XML version
> was just one way to render it into text.

I was fairly careful to say "RDF document," meaning RDF
expressed in RDF/XML syntax.

This discussion is about relative URIs, which are
(at least by my reckoning) a syntactic gizmo.

> Call for clarification: are we supposed to take the XML syntax of RDF
> as definitive, or the triples model?

I'm not sure what you mean by definitive.

To restate my position on this issue:

	* each RDF document (in RDF/XML syntax) denotes
	a set of triples (that can also be expressed in n-triples
	format). The terms in the triples are
	*absolute* URIs or anonymous thingies.

	* the rdf:ID="abc" syntax is little more than
	syntactic sugar; it has the same impact
	on the set of triples as rdf:about="#abc".

	I say "little more" rather than "no more" because
	there's a constraint that no two elements may
	bear the same value in their rdf:ID attributes;
	this constraint is somewhat valuable in detecting
	mistakes.

	* rdf:about="#abc" is also syntactic sugar;
	it's short for ABSURI#abc where ABSURI is
	the absolute URI of the XML document that you
	were parsing (if that's unknown/unspecified,
	so is the absolute form of #abc, and hence
	so is the set of triples that the document
	denotes.)


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/