What is FMA (was Common to-hit system)

>>FMA. This method changes die type depending on condition.

What is, by definition the FMA system.	I have all the FT/MT/DS2/and SG2
books, but I admit i have never read any of them cover to cover.  (I've
read the parts that I needed)

Is the FMA the way you use the different die types (e.g. d4, d6, d8,
d10,
d12, d20?) or the chits?

I guess what I've ready I understood the FMA to encompass both he paper
"chits" in combination with the die types.

Not to start a discussion over playing structures : I don't care for the
chits (just something else to keep up with).  but I frequently find that
the die types work wonders.  I think Jon did wonders with an original
idea
(his system), and I use various pieces.

But what is FMA?

thanks in advance

Chris