[XML Schema] Use case with external value list

Dear,

Reviewing the http://www.w3.org/TR/2009/WD-xmlschema11-1-20090130/, I find
that a common use case I have cannot be handled by the current draft without
defining external functions (which I don't want to use)

I want to be able to make XPath inside an assertion to deal with a document
containing some allowed values: ZIP Code or even business specific codes

Putting them in the schema makes the schema heavy for nothing (and needs to
convert them to a schema)

This is due to
[[
2.2.12 The statically known
documents<http://www.w3.org/TR/2007/REC-xpath20-20070123/#dt-known-docs>is
the empty set.
]]

I have two proposals :

1) allow all kind of document in the statically know documents

2) or a lesser one that is to use a register mechanism. i.e. something like
<xs:register-document href="zip-code.xml"/>, which allow to track down which
documents are reference at the top of the schema

Regards,

Mohamed ZERGAOUI

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