RE: [xml-dev] XML spec and XSD

["Michael Kay" <mike@saxonica.com>]

> 
> But I wonder, why the XML spec (1.0 or 1.1) doesn't mention 
> XSD (i.e, W3C XML Schema language) as also a second XML 
> validation language (i.e, other than DTD)? I am curious to 
> know, was this decision not to mention XSD as a validation 
> technology in XML specs, was a consicous one? If yes, what 
> advantages we have achieved by this decision?

It's a basic issue of architectural layering. XSD has a dependency on XML,
XML has no dependency on XSD. Nothing in the XML spec is affected if XSD
changes.

It's bad enough when you're writing a spec tracking the changes in
technologies you depend on (like Unicode). Introducing unnecessary
dependencies for pedagogic or marketing reasons would be a very bad thing to
do.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay