[xml] ISO schematron

[Martijn Faassen <faassen infrae com>]

Hi there,

I found out today that libxml2 has a partial Schematron implementation. 
I went hunting for more information on its status, and found a few 
threads on this list. In the latest thread from july, Daniel says:

> Of course a prerequisite [for complete implementation in libxml2]
> would be to have a final version of the ISO
> spec if this is available, because IIRC it diverged a bit from
> the previous version.

I looked at this last week, and it appears there is indeed a final 
version of ISO schematron available. From www.schematron.com:

May 2006 - Schematron is now published as an ISO Standard

ISO does publish an electronic version of this spec. It's here:

http://standards.iso.org/ittf/PubliclyAvailableStandards/c040833_ISO_IEC_19757-3_2006(E).zip

So, it seems like the prerequisites are met. :)

If this gets implemented, of course we'll be exposing this functionality 
in lxml as well.

Regards,

Martijn