Michael Kay wrote:
>> That said, "learning multiple schema languages" is a red 
>> herring.  The fact is, people do use different schema 
>> languages, for whatever reason.
>  
> 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.

A lot of people don't like change.

A lot of people don't want to or don't have time to learn new things.

However, if we actually could avoid such issues, I suspect we'd all 
still be programming in COBOL.

COBOL on Cogs, anyone?

http://www.coboloncogs.org/

Before the mess that was W3C XML Schema, I'll confess that I too was 
hoping for "one schema language to rule them all".

Seeing what a catastrophic tangle that yielded, and how RELAX NG and 
Schematron could address different pieces better, made me think that 
despite our laziness, humans can do better having multiple choices in 
processing tools of any kind.  It's a "virtue", even if it does come at 
a cost.

If NVDL can let users make those choices while reducing the confusion 
generated as soon as multiple languages are in use - what gets processed 
by what, and how - then that's a major win for XML users of all kinds, 
even if they never touch NVDL (or realize that they're using it.)

Thanks,
Simon St.Laurent
http://simonstl.com/