noticed that various BCONs and BHAVs start with these::
"CT - "
"SG - "
"G - "

what do those letters mean?

From my searching throught files, I found that "CT" is used with the "Run Tree By Name" primitive. You have to write the same name of the BHAV in the StR. And it will be run from any object. It is a really usefull primitive when you know how to use it.

I think "SG -" might be for semi global but it's just an asomption.

Just a guess, but since G and SG probably stand for "global" and "semi-global", I kinda assumed that CT followed the pattern and stood for "custom"? (as in LOCAL= 0xFFFFFFFF).

I suspect CT stands for Called Tree, because they're certainly not always private.

that makes much more sense. In fact, Just had that epiphany last night (I'm soooo slow at figgerin' stuff out...) and was coming here to change my post.