please help me!!!!

Guys

I have been struggling with the following class of expressions:

P.Q,R,...A,B,C

We have changed our minds a few times about how to do it and worried 
for months. It has become a 'huge' issue!

MathType treats the '...' as <mn> no matter where we put them - is that 
right?
It also treats the ',' invariably as a <mo> is that right?

My other problem is brackets - even where we have brackets within 
brackets, we'd like to just use <mo>(</mo> etc - is that OK? We tried 
<mfence> but we did not get to see the brackets, so didn't like it???

I'd love some help!

Liddy