Re: XSchema Question 1: RDF

Peter Murray-Rust (peter@ursus.demon.co.uk)
Sat, 30 May 1998 12:24:22

At 07:02 30/05/98 -0400, Paul Prescod wrote:
[... good stuff snipped ...]
>
>we want:
>
><XSC:ELETYPE NAME="IMG">
> <XSC:ContentModel>...</XSC:ContentModel>
> <XSC:Attributes>...</XSC:Attributes>
></XSC:ELETYPE>
>
Thanks for reminding us about namespaces. Another 'obvious' point comes out
of this is that the XSC can be *formally* part of the document instance. In
a way this corresponds to the internal subset - and we have the same
ability to attach 'partial' DTD information to a document - or override
parts of the 'DTD' Example:

<?xml:namespace name="http://www.w3.org/RDF/some/where" prefix="RDF?>
<?xml:namespace name="http://www.xml.org/XSC/some/where" prefix="XSC?>
<!DOCTYPE GREET:greetings SYSTEM "greetings.dtd">
<GREET:greetings xml:lang="fr">
<XSC:ElementType id="GREET:phrase">
<XSC:Attribute id="xml:lang">
<XSC:Type>CDATA</XSC:Type>
<XSC:Default>en</XSC:Default>
</XSC:Attribute>
</XSC:ElementType>
<GREET:phrase>Hello world!</GREET:phrase>
<GREET:phrase xml:lang="fr">Bonjour Tristesse</GREET:phrase>
</GREET:greetings>

This shows how a default attribute can be added through the XSC2DTD
transformation
The main point is that *even using the simplest XSC ideas* we have opened
up considerable power for free. I suspect that when we start using them
we'll get even more ideas. I strongly urge that we explore what we have
already got before being too ambitious.

[There are some unanswered namespace problems here, of course].

P.

Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary
http://www.venus.co.uk/vhg