How to use global variables in a DEF block with multiple arguments and outputs?

I have a DEF block in my program that gets four arguments and outputs three variables. However, I also need access to a couple of arrays in the program. Is this possible without just adding the arrays as arguments in the function?

variables are always global, unless they are defined inside a function before being defined outside.

Hmm... That's weird. I'm getting an "Uninitialized variable used in 0:608" error on my program. Line 608 is where the function is being called:

CLLSN PX,PVX,PY,PVY OUT PVX,PVY,PG

All of those variables have been initialized. I assumed the error was actually coming from inside the DEF block, because the function carries out fine until it tries reading from some global arrays:

IF TILE[OFSX,OFSY,MAP[TX,TY,0]]!=0 THEN

Variables OFSX,OFSY,TX and TY have all been initiated in the function... Anyways, thanks for the help so far. I didn't realize global variables worked like that, so that's good to know!

ooh, you got the "mystery error" it happens when you don't define the output of a function CLLSN PX,PVX,PY,PVY OUT PVX,PVY,PG I think you also need to use different variables for the output

Wow, that's weird. I just managed to fix it, but... I don't know how. I added G=0 near the beginning of the DEF block, and somehow that fixed it... Even though there was another place where I had a G=1. I really have no idea what was going, but at least it's working right now!