Domain, Range

Alright, I know this is going to sound _really_ stupid, but it's 
something that I need to know so I'm going to ask anyway.

Domain and range are scattered everywhere throughout VisAD, but I never 
seem to get a clear idea of exactly what they are.  Oh, I know the basic 
algebraic definition of the two terms, certainly, but I can't really 
figure out how it applies to the various methods in VisAD.

I'd appreciate any help on this one, and I'll even allow a chuckle or 
two at my expense =)

Thanks,
Vikram Vatsa <v.vatsa@xxxxxxxxxxxxx>