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Re: Nested Substitutiongroups, how to?

From: <noah_mendelsohn@us.ibm.com>
Date: Fri, 17 Oct 2003 17:33:43 -0400
To: "Jack Lindsey" <tuquenukem@hotmail.com>
Cc: jawsoap@hotmail.com, jeni@jenitennison.com, xmlschema-dev@w3.org
Message-ID: <OFE802F54F.D728E3BE-ON85256DC2.0076742E@lotus.com>

Coincindently, I just posted to a different thread an explanation of some 
of the underlying issues relating substitution groups across namespaces 
[1].  Noting that you're new to schemas, this may be a bit detailed for 
your taste, but skimming it will probably give you at least some sense of 
underlying mechanisms that might want to know about if you keep working 
with schemas.  The bottom line is:  the principle place where namespaces 
show up in a non-uniform way in the schema language is in the fact that 
each schema document can talk about at most one targetNamespace.  In most 
all other respects, the mechansisms are completely orthogonal to the 
namespace question.  Whatever you can do within substitution groups 
involving a single namespace you can just as well do using more or less 
arbitrary combinations of multiple namespaces.  The note describes some of 
the mechanisms and terminology that support this conclusion.  Hope this 

[1] http://lists.w3.org/Archives/Public/xmlschema-dev/2003Oct/0058.html

Noah Mendelsohn                              Voice: 1-617-693-4036
IBM Corporation                                Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142

"Jack Lindsey" <tuquenukem@hotmail.com>
Sent by: xmlschema-dev-request@w3.org
10/17/03 10:27 AM

        To:     jeni@jenitennison.com, jawsoap@hotmail.com
        cc:     xmlschema-dev@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        Re: Nested Substitutiongroups, how to?

Brilliant!  Would this work across namespaces?

                 /       |    \    \
  Q:SmallGroup   P:X  P:Y P:Z
      /   |    |   \
  Q:A Q:B Q:C Q:D

X,Y and Z have to be globally defined to participate in a 
anyway. Assuming their Complex Types were also globally defined (i.e. 
and incestuously derived by extension from each other, could this be a 
viable mechanism for extending a class hierarchy established in one 
namespace from a second namespace, so that the leaves could inherit common 

features from both namespaces?

Cheers Jack

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Received on Friday, 17 October 2003 17:36:15 UTC

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