How do you make a function in one file return an array to another program in a different file?

Try putting your array name after the DEF statement's OUT, like this: DEF x OUT y[] or DEF x OUT y$[]

you would do USE "PRG1:FILE", and then calls to LOAD_LVLS work in any slot

Okay.

It says duplicate variable in 1:2 even though the only similarities between the two are the fact that they are string arrays.

I changed MAPS$ to MP$ in the function shown in the first screenshot.

Sorry, I thought I previously had this working, but trying this morning, I can't get it to work. Hmm... maybe I was thinking about a different programming language. Anyway, I did come up with a sort of work-around. If you want to have a look at it, the key is in the screenshot.

Thanks!