[NTG-context] What does hangsidefloat do?

Hi all, I've been fiddling around with floats a bit, and seeing a lot of references to "hangsidefloat". It seems to be the solution to all sorts of floating problems, but I can't really see what it _does_. Looking around the source doesn't really tell me either, so anyone care to tell me what it does and what its numeric argument means? Gr. Matthijs