XML spec and XSD

A few days ago, I started of a pretty length discussion on xml-dev mailing list about the following topic,

"Should the W3C XML specification specify XML Schema (a.k.a XSD) also as a XML validation language, as it specifies DTD (Document Type Definition)."

The XML spec seems to convey, that an XML document is valid, *only* if it's valid according to a DTD. I had a contention to this point, and started of a debate on xml-dev list related to this question. I argued, that since there are now newer XML validation languages like XSD, RelaxNG, Schematron etc, the XML spec now can modify the XML validation definition to refer to other XML Schema languages as well, rather than saying, that XML document is valid *only* if DTD is associated with the XML document.

Unfortunately, may people who spoke on xml-dev, who have been working with XML for long, did not agree to this idea. But alas, I still feel I had/have a valid point about this :(

I am referring to this threaded discussion again here, for records of this blog. Please follow this link, if anybody wants to read this whole discussion.