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Re: So now we have tidy literals...

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Mon, 14 Oct 2002 21:55:45 +0100
Message-Id: <>
To: Dan Connolly <connolly@w3.org>
Cc: Brian McBride <bwm@hplb.hpl.hp.com>, RDF core WG <w3c-rdfcore-wg@w3.org>

Confused or no, I think we're approximately in accord.  I have a slight 
concern about "infoset" popping up in the abstract syntax, but if you mean 
something for which an infoset could be constructed I guess that's about 
the same.

The words I was proposing were:
An untyped literal is either a string literal or an XML literal, either of 
which consists of a sequence of Unicode characters and a language 
code.  See section 3.2 for details.
(noting that typed literals are dealt with in a separate, nearby section).

This isn't meant to be a complete definition -- hence ref section 3.2.

Personally, I'd say the xsd:string and untyped cases are different (i.e. no 
corresponding entailment).  One reason is that (I understand) an xsd:string 
value doesn't have a language.


At 09:34 AM 10/14/02 -0500, Dan Connolly wrote:
> > >> From past discussion, I'm expecting that the answer will be that a
> > >> literal denotes a composite value consisting of a Uniocode string, a
> > >> language code and an XML flag, or something of that kind.  That would
> > >> tally with the current abstract syntax description [1].
> > >
> > >Right, though DanC has been suggesting we consider that we two types of
> > >literals, each a pair of the literal and the string, one is a bare 
> literal
> > >and the other is an xml literal.
> >
> > Yes... I think I came closer to that in the tentative text, which you did
> > not quote.  But mainly, I wanted to make sure we're all facing the same
> > direction now ;-)
>I'm confused by the above.
>It seems to me that the class of Literals is a sort of union:
>         1.a strings, resulting from
>                 <title>abc</title>
>         where no xml:lang dominates the <title> propElt
>         1.b lang-strings, resulting from
>                 <title xml:lang="en">abc</title>
>         2.a XML infoset thingies, resulting from
>                 <title rdf:parseType="Literal">some <em>very</em> good
>                         stuff</title>
>         [some text earlier in a thread said that this was a
>         unicode string; I wouldn't say that; it can be serialized as
>         a unicode string, as we do in n-triples. But that doesn't
>         make it a string]
>         2.b XML infoset thingies, with lang, resulting from
>                 <title xml:lang="en"
>                 rdf:parseType="Literal">some <em>very</em> good
>                         stuff</title>
>         3.a datatype values, resulting from
>                 <date rdf:datatype="&xsd;date">2000-10-12</date>
>         These consist of an absolute URI reference
>         and a unicode string.
>I dunno if we have 3.b lang-datatype-values. I hope not.
>Nor do I know if datatype values of type &xsd;string are
>identical to normal 1.a strings. It seems best, for users,
>if they are, but it's sort of an ugly special case.
>Test case:
>         <rdf:Description rdf:about="#something">
>           <p1>abc</p1>
>           <p2 rdf:datatype="&xsd;string">abc</p2>
>         </rdf:Description>
>         <rdf:Description rdf:about="#something">
>           <p1 rdf:nodeID="X" />
>           <p2 rdf:nodeID="X" />
>         </rdf:Description>

Graham Klyne
Received on Monday, 14 October 2002 16:32:03 UTC

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