[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, [log in to unmask]]
----- Original Message -----
From: "ext Roland Schwaenzl" <[log in to unmask]>
To: <[log in to unmask]>
Sent: 11 December, 2002 13:54
Subject: Re: RDF typed literals and DC encoding schemes
> Dear Dave, dear Patrick,
>
>
> think it is one of the major problems
> with the current RDF drafts, that they
> say a lot of nice words about datatypes,
> but in fact do not allow to "define"
> any.
>
> I can't see how to get a literal2value
> map in RDF - there doesn't even seem to be
> a standardized way to point to a resource,
> which would provide such a map somehow.
>
> This might be one of the reasons rdf-semantics
> is that weak on datatype entailments.
>
>
> Think there is really missing some piece of
> vocabulary in the rdfs draft as compared
> to the rdf-concepts draft.
RDF explicitly refrains from introducing any mechanism for
defining datatypes. Rather, it defines the characteristics of
members of a class rdfs:Datatype, and defines the semantics of
typed literals in terms of those characteristics.
There are numerous ways to actually define datatypes. XML Schema
is one. Natural language prose is another. Whether or not a datatype
is defined in a machine understandable manner is not relevant.
What matters is that for any RDF application that is dealing
with typed literals (datatype values) it has sufficient
knowledge about the datatypes in question (obtained in whatever
way, parsing of XML Schema, hard coded, etc.) so that it is
able to interpret those typed literals as needed.
It is a strength of RDF datatyping that it is datatype framework
agnostic, and doesn't impose any machinery for how actual
datatypes are defined, but simply provides the machinery for
referring to those datatypes and to their values in terms
of lexical representations.
> I don't think DCMI can issue any recommendation
> based on drafts, which may change till they
> reach W3C recommendation - or at least a level,
> where W3C gives an official "call for implementation"
> level to the papers, which are now just drafts.
Fair enough.
Patrick
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