> 
> All I'm saying is, don't make a virtue out of it. The world would be a
> better place if everyone used the same XML validation language, assuming
> that language met all the requirements (and there's no intrinsic reason why
> one language shouldn't meet all the requirements). Having multiple languages
> coexisting just adds cost and complexity, just as mixing programming
> languages in an application adds cost and complexity. No-one wants to do it
> if they can avoid it.

This is exactly what the W3C XML Schema people said to me when I was
there.  I have had a different opinion since then, and have not changed
my mind.  I do not intend to continue religious discussions here.

But let's review the current status of W3C XML Schema.  REALX NG 
can capture co-occurrence constraints between attributes and elements
but W3C XML Schema cannot.  Schematron can capture advanced integrity
constraints but W3C XML Schema 1.0 cannot.  The W3C XML Schema WG
certainly admits this in "Requirements for XML Schema 1.1".  More 
about this, see "2.2.2.1 Add co-constraints (RQ-38)".  Although 
the W3C XML Schema WG has been trying for five years, W3C XML Schema 
1.1 is still a working draft.  This is a strong empirical reason that 
one language does not meet all the requirements.

Cheers,

-- 
MURATA Makoto (FAMILY Given) <EB2M-MRT@a...>