MathML logo

I'm currently creating a university site, which extensively uses MathML 
(DTD XHTML 1.1 plus MathML 2.0). During my work there came up two questions:

1) If I validate the XHTML with the W3C validator, is the MathML part 
valid as well? It might be, as the validator should be a general dtd 
validator.

2) May I use the MathML logo on my website to show, that I use MathML 
and that it is valid? There is no statement on your website about this 
(legal) issue.

Thanks a lot,

Walter Bamberger