[Bug 10652] xs:override and document-level defaults

http://www.w3.org/Bugs/Public/show_bug.cgi?id=10652

C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com> changed:

           What    |Removed                     |Added
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           Keywords|needsDrafting               |needsReview

--- Comment #2 from C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com> 2011-02-02 15:00:23 UTC ---
I propose to resolve this by inserting the following note in the
sequence of notes following Schema Representation Constraint: Override
Constraints and Semantics, immediately following the note reading

   Note: It is Dold&#8242; and not Dold, which is required to correspond to
   a conforming schema. In particular, it is not an error for Dold to
   fail to satisfy all of the constraints governing schema documents,
   while it is an error if Dold&#8242; fails to satisfy them.

The proposed addition:

   Note: The effect of override pre-processing is that any
   declarations and definitions contained within an <override> will
   be substituted for matching declarations and definitions within
   the target set; the resulting schema documents will then be
   processed normally, as described in the relevant portions of this
   specification. This has the effect that the rules for
   document-level defaults (elementFormDefault, attributeFormDefault,
   blockDefault, finalDefault, and so on) are applied not in the
   context of the document containing the <override> (Dnew) but in
   the context of the document containing the original overridden
   declaration or definition (Dold). Unexpected results may be
   minimized if the children of an <override> are made independent of
   the document-level defaults by explicitly specifying the desired
   values for the properties in question.

For the record, I note that I think it would be technically feasible (if
a little fiddly to specify and get right) to supply explicit values 
automatically for all the document-level defaults, before processing 
the included element.  That's not the direction taken in this change 
proposal because it's not the direction taken in the WG's phase-1 agreement
on technical direction.  It can in any case also be done by a utility 
stylesheet anyone could provide for use by schema authors who dislike
the default behavior; it does not need to be written into the XSD spec
and the task does not need to be performed by the schema processor.

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Received on Wednesday, 2 February 2011 15:00:28 UTC