source-identity and components (Re: How to scope the note about D and override(E,D))

On Mar 14, 2011, at 12:26 PM, Henry S. Thompson wrote:
> 
> 
> C. M. Sperberg-McQueen writes:
> 
>> Does this work in the general case?  I would expect that it would not
>> suffice to know that type T is being overridden, that it would be
>> necessary to know what the new definition is.
> 
> I guess I'm _proposing_ that we insist on source-identity as the only
> basis for allowing 'multiple' definition/declaration, as we at
> least allow 1.0 processors to do in the perfectly ordinary case of 
> 
> <element name="foo"/>
> <element name="foo"/>
> 
> which 1.0 processors may (must?) treat as an error.

I don't see anything in 1.0 that allows this to be treated as
an error, let alone requires it.

I think those processors which treat this as an error do so because
they think there are two different top-level element declarations
with the same QName.  But since our spec does not define 
component identity, there is no license in the spec for the
assumption that two different element declarations are involved
here.  

I think the most that can be said is that since our spec does not
define component identity, it is probably impossible to determine,
from our spec, whether a schema document like the one you
describe is conformant or not.  That is not really the same thing 
as an explicit statement in the spec that processors MAY 
treat them as conformant, or as non-conformant.

Your suggestion that source identity be taken as a basis
for deciding the issue may run into a similar problem:  is
it possible to prove from the infoset spec that there are 
two distinct elements in the fragment you've given above?
I don't think so; I think claiming that there are two elements
and claiming that there is one element are both compatible
with the infoset spec.  

Am I missing something?


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* C. M. Sperberg-McQueen, Black Mesa Technologies LLC
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Received on Monday, 14 March 2011 19:03:47 UTC