Redefining redefines

There are situations in which the redefinition of a type, and the subsequent
redefinition of the redefined type, are desirable. One such case is where a
schema user would like to extend a type, not just from the original source
but based on the extension of another schema user's extension (Company C
extends type T from Company B, who picked it up from Company A and redefined
it). 

I notice in the Rec that this is discouraged:

In all cases there must be a top-level definition item of the appropriate
name and kind in the <redefine> <http://www.w3.org/TR/xmlschema-1/> d schema
document. 
		NOTE: The above is carefully worded so that multiple
equivalent <redefine> <http://www.w3.org/TR/xmlschema-1/> ing of the same
schema document will not constitute a violation of clause 2
<http://www.w3.org/TR/xmlschema-1/>  of Schema Properties Correct (§3.15.6)
<http://www.w3.org/TR/xmlschema-1/> , but applications are allowed, indeed
encouraged, to avoid <redefine> <http://www.w3.org/TR/xmlschema-1/> ing the
same schema document in the same way more than once to forestall the
necessity of establishing identity component by component (although this
will have to be done for the individual redefinitions themselves).
Indeed, XML Spy requires that the redefined schema contain a type definition
for a type that is to be redefined - that a redefinition is not sufficient.
So it is not possible to redefine a redefined type.

So the question is, is this something that is likely to change, or will
validators vary on whether or not they support cascading redefines?

Thanks,

Mark


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Mark Feblowitz                                   [t] 617.715.7231
Frictionless Commerce Incorporated     [f] 617.495.0188 
XML Architect                                     [e]
mfeblowitz@frictionless.com
400 Technology Square, 9th Floor 
Cambridge, MA 02139 
www.frictionless.com

Received on Thursday, 13 December 2001 08:11:28 UTC