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   Re: [xml-dev] syntax, model

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On Fri, Oct 24, 2003 at 10:19:19AM -0700, Jeff Lowery wrote:
> So if you took the verbiage of the Data Model, distilled it into formal
> symbolic description in a suitably expressive language, and then used that
> for validating purported Xpath/Xquery data models, whould that be a called a
> schema?

Possibly but it wouldn't be a very useful one.

See the XML Query 1.0 and XPath 2.0 Formal Semantics document [1] if
you are after a more formal description of processing instnces of
the XPath data model.

You could build an instance of the XPath Data Model from anything you
liked (a relational database table is a not unlikely example) as long
as you implemented the necessary properties described in [2].

In some sense, anything that constrains or describes the structure of a
formal system can be called a Schema, but in the context of xml-dev I
think people usually mean a Schema that constrains or describes a family
of XML documents.  Your example would not be a Schema over XML, but
instead it would be a Schema of XML Data Model Instances, which is not
at all the same thing.


[1] http://www.w3.org/TR/xquery-semantics/
[2] http://www.w3.org/TR/xpath-datamodel/

Liam Quin, W3C XML Activity Lead, http://www.w3.org/People/Quin/


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