lgb: https://enterpriseforever.com/profile/?u=6
Cool!
I suspected that he was active in the community here once I saw his location, and that he had developed an Enterprise emulator.
The .REL files do not have to have the same base name as the source files, and back in the day (and still for EXDOS 3) we would assemble the sensibly-named .MAC source files to a less-sensibly-named two letter .REL file, for example START.MAC would assemble to ST.REL, REBOOT.MAC would assemble to RE.REL etc to shorten the L80 command line length!
Hahaha ... nice workaround for the problem, much better than using lib80!
I've applied that trick and have got IS-DOS building with just simple XCPM calls.
I am not surprised, XCPM is very hacked together by lgb and he did warn us that not all functions are supported! 
Now that I can see the source code and understand what it is doing ... it is a very, very nice solution to get the old source code building on a modern computer!
I like having RunCPM too as an alternative, the critical thing with both of them being that they just accesses files on your regular PC, and that there is no need for using disc images.
That keeps the source editable with modern editors, and usable with "modern" tools such as grep/diff/patch.
It also allows using Source-Code-Control systems such as GIT or PERFORCE, which might be cool is you get to the point of having multiple people working on code, or want to keep a formal log of the changes that are made.
SCC is something that us programmer-types didn't ever really have to think about in the 1980s, but is such an important part of modern software development.
