just not seeing something about the spec....

I really do not understand. I have been staring at this stuff and it 
does not make any sense....

Does Firefox correctly implement any MathML? How do we know?

Amaya does this:

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE math PUBLIC "-//W3C//DTD MathML 2.0//EN"
       "http://www.w3.org/TR/MathML2/dtd/mathml2.dtd">
<!-- Created by amaya 9.55, see http://www.w3.org/Amaya/ -->
<math xmlns="http://www.w3.org/1998/Math/MathML">
   <mi>x</mi>
   <msup>
     <mn>2</mn>
   </msup>
</math>

It shows an x squared here.

Yet every version of Firefox I can find does not show the "2" as a 
superscript. I can read the spec and it says this should be a 
superscript. But it is not. But there is other markup that shows we can 
do x with a superscript of 2.

So, I have no idea how to answer this question. Is this supposed to be a 
superscript or not? If Firefox only implements some slice of the 
standard, which slice is that?

thanx - ray