Kree8tiv,
The file reference you are looking for has only been available in my experience on controls that have quite respectable look-ahead capabilities, wherein they can look ahead up to 100's and sometimes 1000's of lines. In order for a control to look ahead at a subroutine is one thing, but to look ahead at another seperate file and read its contents is another step. I haven't ran across that info regarding Mach3, but I'm thinking that it's not in that realm.
One of the tech's from DMG explained to me at one time that the lookahead line count is "consumed" by the main program first, which when using embedded sub-routines these are supposedly counted in the main program count, when using sub-routine files that are loaded into the same directory (for instance in main buffer on a Fanuc machine) these lines are looked at ahead after the complete main program, and then those remote files also secondarily. Not ever tested by me, but this is what I was told by a person I know to be a consumate pro.
I've only seen that type of super-functionality on Heidenhain controls and Okuma machines, which are pretty darned pricey. I'd say that asking Art to add this sort of processing control may be more than we really want - as the more power the more $.
My 2cents.
Rgds,
John