katapyknosis

Could anyone give me a really clear and accurate definition of
katapyknosis and of the different types of katapyknosis (usually we
talk about 1:1 katapyknosis, but imagine there could be other types as
well). Someone asked me what it was and frankly i could explain, but to
say that it is a way of intersecting a interval or something lame.
Could some one explain it to me like i was really dumb (since i am
really dumb). I want to have it clear in my head. I know that this is
talked about in the Chalmers's book Divisions of the Tetrachord, but i
don't have mine with me.

cheers,

kevin parks
seoul, korea
kp87@lycos.com