>
> There was someone with that need writing to the list a few days ago. It
> seems entirely legitimate to me to apply different schemas to the same
> document at different stages of a workflow, or for senders of documents to
> apply stronger validation criteria than recipients of the same documents.
>
> Michael Kay
> http://www.saxonica.com/
>

Shouldn't it be the case that the validation process necessitates
a 2-stage parsing ? What I mean is that XSD can only do a lexical
validation, a second follow-up stage that validates against the
application semantics is required.

I am not too sure if pushing the logical validation into the
lexical validation stage desirable because that could confuse the purpose
of what I see as two distinct validation stages. The scope
of logical validation is surely more complex than lexical parsing
(eg. valid values depending on the lifecycle of the data, relative
date values, lookup into databases to validate logical constrains, etc).

IMHO, leaving that in the scripting/programming/xslt/xquery space
is surely more flexible and this should generally be the direction rather
than generating dynamic schemas; which IMO would make a system
mind-boggling to debug, wouldn't it ?

Instituting a 2-stage validation makes each of its design and
implementation clean and focused; hopefully resulting in a
more robust and predictable application.
Depending on the application context and whether
type info needs to be extracted from the validation, the XSD
validation stage can be turned off to improve throughput
once the system is stable. I know the latter suggestion
may be controversial to some, but it is an option
if the logical validation is not mangled into the lexical
space.