Hmmm!
Functions will work almost anywhere provided you use them as functions ... in Tables, Forms. Queries, Macros, Modules etc.
Type the function name, place the cursor in the middle of it, then hit F1 for help. If the function exists in Access then you'll see the semantics and the appropriate syntax! If it doesn't then you won't.
As ever experimentation is the byword.
Regards,
Chris
Xeotech