W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2002

Re: Typed literals: current status

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Mon, 21 Oct 2002 14:28:40 +0100
To: Jeremy Carroll <jjc@hpl.hp.com>
cc: w3c-rdfcore-wg@w3.org
Message-ID: <21586.1035206920@hoth.ilrt.bris.ac.uk>

>>>Jeremy Carroll said:
> 
> Jeremy:
> > But
> >if we had two new types rdf:ClassicLiteral, rdf:ClassicXMLLiteral then we
> >could move all the complexity of XML Literals into a datatype definition.e

These should be in rdfs: given in particular since rdfs:Literal already
exists - http://www.w3.org/TR/rdf-schema/#ch_literal

> Brian:
> > There have been several suggestions along these lines.  I would expect
> such
> > a proposal to get support if it can be done quickly.
> 
> See also Patrick's table in:
> http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Oct/0232.html
> 
> Unless I hear arguments to the contrary (or even simply some opposition) I
> will try writing some text along these lines tomorrow.
> 
> Possible problems I can identify (mainly for DaveB):
> 
> + N-triples syntax - the following two triples are identifcal:
> 
> <a:a> <a:p> <rdf:ClassicLiteral>"foo" .
> <a:a> <a:p> "foo" .
> 
> Since it is work to drop the latter, I would suggest that the former (to be
> more precise with two reserved datatype URIs) is specifically prohibited
> (somewhat ugly).

can we stop using <qname> please?

you mean

forbid:
 <uri1> <uri2> <http://www.w3.org/2000/01/rdf-schema#ClassicLiteral>"foo" .
allow (prefer):
 <uri1> <uri2> "foo" .

forbid:
 <uri1> <uri2> <http://www.w3.org/2000/01/rdf-schema#ClassicXMLLiteral>"blah" .
allow (prefer):
 <uri1> <uri2> XML"blah" .

which is ugly but I'd prefer to add these rules, if we are going down
this route.

> also get the surprising equivalence between RDF/XML docs
> 
> <rdf:Description>
>   <rdf:value rdf:datatype="&rdf;Literal">foo</rdf:value>

&rdfs;Literal (already exists) or should that be &rdfs;ClassicLiteral ?

> </rdf:Description>
> 
> and
> 
> <rdf:Description>
>   <rdf:value >foo</rdf:value>
> </rdf:Description>
> 
> ==
> 
> Another thing, which negatively impacts DaveB, is that it then becomes
> clearer that some of the C14N stuff about XML Literals probably ends up in
> the syntax doc. I could try and work out what.

Please do.


> ===
> 
> Motivations are:
> - uniform framework

+1

> - addresses TBL's desire that XML is not built-in at the lowest level to RDF

+1

> - provides argument why lang tags are part of literal

No languages in above examples; can you add addition examples with them?

> - gives an example of a non-XSD type system that Brian is prepared to
> defend.

Hmm.  You mean that rdf datatyping is sufficient for XSD and and
other [non-XSD] datatype systems.

I also support Frank's comments:

  [[I want to see non-XSD types supported, and I want it to be very
    clear in our specs that they are.]]
  -- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Oct/0222.html

Dave
Received on Monday, 21 October 2002 09:30:36 EDT

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