OK so I came up with an idea for multi file Axe programs. The way it is right now doesn't allow one to easily manage these as you have to exit the editor to go buil the whole thing. My idea to fix this would be to check the first line for "..". If it's there, use the following characters as the parent program's name, ie tell Axe to compile not the current program but the one that is indicated. If that's blank, don't do anything.
Example :
Program file called MAIN
.EXEC
prgmSUB
File called SUB :
..MAIN
Disp " Hello, World !"
If you try to compile SUB with any of Zstart's shortcuts it would instead compile (and run if appropriate) MAIN.