recently i have discovered the joys of using overlapped blocks in sound patches.  however, i'm having a little bit of difficulty understanding exactly WHAT gets overlapped, and what doesn't get overlapped.

it seems to me that control messages and do not get overlapped, and i can't really tell what happens to external audio signals connected to the overlapped patch. 

is there some documentation somewhere on this topic?  or would a kind person like to tell me basically what functions block overlap has?

cheers.  matt