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Re: Reworked sections on datatypes and literals

From: Graham Klyne <GK@NineByNine.org>
Date: Thu, 31 Oct 2002 09:36:42 +0000
Message-Id: <>
To: "Patrick Stickler" <patrick.stickler@nokia.com>
Cc: "RDF core WG" <w3c-rdfcore-wg@w3.org>

Patrick, I will consider your comments but please be aware that some are in 
opposition to other comments we have received so I must use my 
judgement.  Thanks for checking this -- from your responses I see no deep 
problems, from which I take some comfort.


At 10:36 AM 10/31/02 +0200, Patrick Stickler wrote:
>A few comments:
>1. You say
>    "RDF uses the datatype abstraction defined by XML Schema Part 2: 
> Datatypes."
>I think it is better to say
>    "RDF uses a datatype abstraction compatable with XML Schema..."
>since RDF datatyping does not include everything defined by
>XML Schema, and we don't need nor want to create tighter dependendencies
>with other specs than we need to. RDF Datatyping is not XML Schema
>Datatypes. It's simply compatable with XML Schema Datatypes.
>2. Regarding rdfs:XMLLiteral, it reads
>    "With one exception, the datatypes used in RDF have a lexical space
>     consisiting of a set of strings. The exception is rdfs:XMLLiteral, whose
>     lexical space is a set of pairs of strings and language identifiers, and
>     the value obtained through its datatype mapping depends on the language
>     identifier."
>Is this exception for XML literals really justified? If we are supposed to
>treat XML literals the same as any other kind of literal, why not disregard
>the xml:lang scope for them as well? Especially since it is straightforward
>to define an xml:lang value for the XML literals directly. I.e., they are
>literals within the RDF/XML instance, not part of the RDF/XML instance itself.
>The fact that they happen to also be XML should not cause them to be infected
>with syntactic machanisms specific to the RDF/XML serialization.
>3. Could you expand
>    "The predefined XML Schema datatypes [XML-SCHEMA2] are expected to be
>     widely used for this purpose."
>to something akin to
>    "The predefined XML Schema datatypes [XML-SCHEMA2] are expected to be
>     widely used for this purpose; though one is not limited only to the
>     predefined XML Schema datatypes nor to XML Schema defined datatypes
>     in particular. Any datatype which conforms to this specification may
>     be used."
>4. The statement
>    "XML Schema Datatypes [XML-SCHEMA2] provides an extensibility framework
>     suitable for defining new datatypes for use in RDF."
>suggests that RDF will understand XML Schema datatype specifications in some
>manner. Perhaps it should be deleted. It's enough to simply say that datatypes
>are not defined by RDF, and those familiar with XML Schema will know how to
>define new types. This goes hand-in-hand with #3 above, which clarifies that
>users *can* define and use other datatypes than the pre-defined XML Schema
>simple types.
>[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, 
>----- Original Message -----
>From: "ext Graham Klyne" <GK@NineByNine.org>
>To: "RDF core WG" <w3c-rdfcore-wg@w3.org>
>Sent: 30 October, 2002 18:42
>Subject: Reworked sections on datatypes and literals
> > Starting with Brian's comments, and then employing a lot of editorial
> > discretion, I've done a major rework on the sections about datatypes and
> > literals.
> >
> > The main goal of this rework was to progressively introduce the concepts,
> > so the datatypes section has been moved ahead of literals, and the 
> datatype
> > examples have been split across the two sections.
> >
> > The rework is attached to this message.  It's not very long -- I'm posting
> > the two sections to solicit feedback from the group, and make sure I
> > haven't distorted the intent in any way.  (There's still an issue of
> > requiring a lexical representation for each value [1] outstanding, which I
> > haven't got round to addressing yet, so please don't flame me on that just
> > yet.)
> >
> > #g
> > --
> >
> > [1] http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Oct/0396.html
> >
> >
> >
> > -------------------
> > Graham Klyne
> > <GK@NineByNine.org>
> >

Graham Klyne
Received on Thursday, 31 October 2002 05:11:57 UTC

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