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RE: [Fwd: xmlns, uri+name pairs or just uris..? Clarification n eeded.]

From: McBride, Brian <bwm@hplb.hpl.hp.com>
Date: Fri, 11 Aug 2000 07:44:14 +0100
Message-ID: <5E13A1874524D411A876006008CD059F239345@0-mail-1.hpl.hp.com>
To: "'Dan Connolly'" <connolly@w3.org>, www-rdf-interest@w3.org
> >  (b) namespaces of RDF elements *must* be the URI of the 
> schema defining those elements. This is a restriction of XML-NS.
> 
> Again, which text in the RDF spec says that?

I think the intent of this remark was to apply to the names of
elements definiting property values and I would assume the same
rule would apply to the names of attributes defining property
values, in which case ...

     2.2. Basic RDF Syntax

    The RDF data model provides an abstract, conceptual
    framework for defining and using metadata. A concrete syntax
    is also needed for the purposes of creating and exchanging
    this metadata. This specification of RDF uses the Extensible
    Markup Language [XML] encoding as its interchange syntax.
    RDF also requires the XML namespace facility to precisely
    associate each property with the schema that defines the
    property; see Section 2.2.3., Schemas and Namespaces.

This suggested to me that the URI ref associated with the
namespace name of a property is required to be the URI
Ref of the schema defining the property.  Have I
misinterpreted the spec? 

> 
> You should be able to get some RDF statements about any
> RDF property by dereferencing its URI (i.e. the concatenation
> of its namespace name and its local name); this makes
> the whole system self-describing. But this is a *should*,
> not a *must*. There's no way for a spec to mandate the
> behaviour of the network.

I missed that bit when reading the spec.  Could you refer me
to the text that says that, please.

In that case I would be troubled about what the URI Ref that
names a property actually names.  Does it name the property
or does it name the document/document fragment that describes
the property.  The foundation of the web is that URI's denote
one resource; one would <understatement> tinker with that
assumption with considerable care. </understatement>

> 
> 
> > I guess that (a) was motivated by the fact that URIs are 
> more general than XML-NS pairs (namespace;tagname); the 
> problem of the reverse transformation was implicitely solved 
> by (reasonable) asumption that any vocabulary item has the 
> form <schema>#<name> or <schema>/<name>, hence (b).

Is this assumption documented anywhere?

Nit picking aside, this is an area which causes confusion, at
least to new comers like me.  It seems to me that the important
thing is to get some clarifying document out, possibly an update
to the errata and preferably sooner than later.  Is Dan's post
definitive?  If so, can we get the errata doc updated soon please.

Brian McBride
HPLabs.
Received on Friday, 11 August 2000 02:44:20 GMT

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