Because an XML Schema by definition implies 
a system based on it.  XML is just data until 
it encounters a schema.  After that, the data 
is augmented with information that the original 
XML instance did not specify to enable processing 
the instance also did not specify.  If you need an 
answer to your question, it is in the post-parse 
processing model.

It isn't a bad thing.  It is a processing system 
choice.  XML in and of itself does not have a 
post-parse processing model.  Those who want such 
things are doing the job of writing XML system 
specifications.   Because XML itself does not 
have that as a core definition, lots of choices 
become available and none are right or wrong; 
just more or less feature-rich given the results 
wanted.

Why do some object?  Like you, they are writing 
their own code for the post-parse processing and 
don't desire core XML specifications that force 
any requirements past the initial parse. 

Dr. Goldfarb used to tell me, "everyone wants 
to own the parse" and meant, the rules for how 
to process it's output, that is, the first 
intepretation.   Semiotics teaches that it is not 
bad to have a strictly defined interpretation but 
that there will be many and each contextually dependant. 
XML enables that.  Some are not happy about it.

Defining the context or semantic is THE problem. 
The XML is trivial if you get past "Who gets to 
name the names".

The problem is, that means, as said elsewhere, 
that simply requiring XML support doesn't require 
much and that to guarantee results, one has to be 
more specific to be interoperable.  Therefore,

1. XML 

or

2. ANI/ALI packet support per NENA specification with 
   XML format

The NENA committee starts with 1.  The application 
language implementor starts with two.   Two may 
require datatype support or at least a rigorous 
specification of the datatypes to be expected. 
It might not.

len

From: Gustaf Liljegren [mailto:gustaf.liljegren@[...].se]

Ever since XML Schema started to evolve and the talk about datatypes in XML
took off, I've been wondering secretly why XML validation needs the concept
of datatypes at all. XML is a plain text format, so content validation in
XML should be no different from regular pattern matching. Or why should it?

A string of three digits may be numeric to an application, but stored or
transmitted in XML, it's still just three characaters of plain text. If my
application wants an integer, all I'd do would be to check if all
characters are in the range 0-9. Regular expressions would be enough for
that. If possible, I'd have this check written in the schema, or some
special module of patterns attached to the schema.

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