XSD Definitions

I am the lead developer on a small open source project that will be making
great use of MathML in conjunction with .NET's XML framework. I am looking
for a formal definition file (preferably XSD, however DTD would be
sufficient) of MathML 2.0, and was wondering how to obtain it. Our software
will host a component whose sole objective is to generate well-formed MathML
documents (using both Presentation and Content elements) and in order to do
this we will need its formal specification.

Thank you for your support!

Zac Harvey