Re: [xml-dev] Is there a way to reuse and extend an enumeration in XML schema

["William J. Kammerer" <wkammerer@novannet.com>]

Thanks. That sounds much like the proposed solution in §4.6, Code List
Schema Usage, in Universal Business Language (UBL) Code List
Representation (Version: 1.1 draft 17 January 2005), at
http://lists.oasis-open.org/archives/ubl-dev/200502/pdf00000.pdf.  But
that one relied on "substitutionGroup" and would have required changes
to the published UBL schemas (e.g., abstract="true" and some extra
derivations).

I'm reading you to say that "redefine" is not a dead-end  approach.  UBL
still has the requirement that document instances be validated against
the authority code list, if those instances refer to the published
schemas.  But the top level schema could be a relatively small "wrapper"
schema that could be replaced in toto by the user's wrapper (modeled
after UBL's wrapper) when any of the code lists had to be modified.

Does anyone have examples of such redefinition? - or want to make some
using UBL's schemas?  And as an aside, is there anything
"substitutionGroup" does that "redefine" can't do better?

William J. Kammerer
Novannet
Columbus, OH 43221-3859 . USA
+1 (614) 487-0320

----- Original Message ----- 
From: "Henry S. Thompson" <ht@inf.ed.ac.uk>
To: "William J. Kammerer" <wkammerer@novannet.com>
Cc: "XML Developers List" <xml-dev@lists.xml.org>
Sent: Monday, 07 March, 2005 08:18 AM
Subject: Re: [xml-dev] Is there a way to reuse and extend an enumeration
in XML schema


W3C XML Schema v.1 does not provide for redefinition-in-place of
simple types by extension, as it were.

It only provides for redefinition-in-place by restriction.

It follows that the only way to achieve redefinition-in-place of
codelists is to initially define the codelist type as an unconstrained
NMTOKEN, and redefine _that_ by restriction at deployment time.

That then would allow local extension by changing the redefinition.

In other words, published schema uses synonym for NMTOKEN as
codelisttype, and then redefines that restricting it to the desired
enumeration in a wrapper schema, which is what people actually use.

Those needing a larger code list use a different wrapper schema which
redefines using their larger list.

In haste, hope this helps as a sketch,

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of
Edinburgh
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