MathML Accessibility in Gecko

Hi,

Based on the comments posted on 
https://bugzilla.mozilla.org/show_bug.cgi?id=916419, I've drawn up a 
fairly rough interface to expose MathML constructs as an accessible 
tree.  This is located on the Mozilla Wiki at 
https://wiki.mozilla.org/Accessibility/MathML.
The basic idea is to add an interface for the MathML elements that ATs 
can use.  There will also be a corresponding interface for MathML 
tables, similar to the existing interface for HTML tables.  A number of 
new roles and relations will be used to denote the type of MathML 
element as well as relationships between the parent element and its 
child components.

Any comments or feedback on this proposed interface would be great.

Thanks,
Jon