Update regarding DR 09-0157

[Jirka Kosek]

MURATA Makoto (FAMILY Given) wrote:
> I believe that the problems comes from W3C XML Schema. 
>
> I tried to change xsd:sequence by xsd:all for EG_RPrBase (not EG_RPrContent!). 
> Then, Xerces-J returns an error already.

My bad, I haven't studied how schema is composed and forgot about this
stupid xs:all limitation.

>> E [Xerces] cos-all-limited.1.2: An 'all' model group must appear 
>> in a particle with '{'min occurs'}' = '{'max occurs'}' = 1, and that
>> particle must be part of a pair which constitutes the '{'content type'}' 
>> of a complex type
>> definition.
> 
> Should we just reopen this DR and eliminate the change from the DCOR?

Yes, please.

> BTW, this is a problem of W3C XML Schema.  RNG does not have this
> problem.

We can still implement change in W3C XML Schema, either by:

- refactoring schema a bit and loosing some extensibility points

- loosening content models in W3C XML Schema -- we can use <xs:choice
maxOccurs="unbounded"> instead of <xs:all> as there are no limits on
combining xs:choice with other constructs. This way W3C XML Schema will
allow some invalid instances, but we can use interleave pattern in RELAX
NG to properly model markup. The question is whether we want to diverge
RELAX NG from W3C XML schema.

				Jirka

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