Wow, a lot of crossing posts here - thanks to all of the participation! Here's my 5 cents:
1. The APN environment variable is created by APN-#.##.exe installer. If you install by some other means, such as a zip file, or manually relocate your APN directory, you'll need to fix or reestablish the APN environment variable definition in the Windows Computer > System Properties > Advanced System Properties > Environment Variables > System variables applet.
2. Believe it or not, APN does not care about the miame.ini, which perhaps explains why there is no command line option to set it. It is only the integrated compiler that needs to know about the miame.ini. Even if you don't actually use the integrated compiler to explicitly compile programs within APN, APN internally calls the integrated compiler (with some special switches), whenever a program file is loaded or saved in order to obtain a map of the interconnected source files. (The compiler creates the map, and APN uses it without any direct need to access the miame.ini.)
3. The %MIAME% environment variable is created on the fly by the compiler, based on the
-ini switch passed to it. (This is directly analogous to the way A-Shell creates the %MIAME% environment variable on the fly based on the
-i switch passed to it.) But the variable definition only lives for the duration of the compilation (or the A-Shell session). (As Jorge mentions above, both also create %MIAMEFILE% variable which points directly to the miame.ini, but that is irrelevant in the APN context.)
4. A full A-Shell Windows installation isn't actually required for APN. You could set up your miame.ini from scratch, since APN and its integrated compiler don't actually use A-Shell per se; mainly it's just the A-Shell disk environment that it needs. However, configuring and using APN will certainly be easier if you have a local A-Shell/Windows installation. (A working miame.ini will already be available, as will an environment for testing the programs you edit and compile.)
5. Since the APN compiler reads the specified ini file for every program loaded or saved, it might make sense to create a specialized copy of the miame.ini that has just the parts that a are essential to compilation.
I've updated the
APN Wiki to include some of the above information and otherwise attempt to clarify some of these details.