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RE: DTDs, W3C Schemas, RELAX NG, Schematron?

• To: 'Don Box' <dbox@m...>, John Cowan <jcowan@r...>
• Subject: RE: DTDs, W3C Schemas, RELAX NG, Schematron?
• From: "Bullard, Claude L (Len)" <clbullar@i...>
• Date: Mon, 24 Jun 2002 09:42:34 -0500
• Cc: xml-dev@l...

I think you are right that value space vs lexical 
space is at the heart of some of the more contentious 
threads.

But that is exactly where this discussion seems to run 
off the rails.  One group believes that syntax and structure 
are the focus and limit of XML and that once past that boundary, 
one is discussing an application language.   Another group 
believes it useful to define a value space, aka, primitive 
types, that any XML application language can use.  Another 
group believes it best to define a means to add pluggable 
types and not to define any set which all applications 
must support.

Data is portable.  Systems interoperate.   How 
much interoperability is wanted or affordable?   What 
options do we lose if we strengthen the coupling to 
a primitive type set?  I don't think I could work 
with relational systems without value types, and we
do seem to share them among that application type 
sensibly; but is that the only application type one 
would have to share them with?

Today, #FIXED looks pretty awesome for its simplicity, 
but of course, one has to read the schema/DTD to "know" it. 
xsi:type looks pretty good, but it is still just a way 
to annotate in accordance with a data dictionary.  Bytes 
must change state and that requires a value space. 

I don't see any way out of this except to define 
a means to plug in types with a non-normative primitive 
set for free.

len


From: Don Box [mailto:dbox@m...]

In case it wasn't obvious, that sentence should have read "What good are
datatypes if one CANNOT work in terms of the value space..."

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