Just thought I’d share my short overview of Mod, for those interested.

Module or Mod files combine the simple note commands like a MIDI file, but instead of using the MIDI synth built into the computer, it contains audio samples, like you might record into a music sampler. This allows relatively small file sizes without being stuck with general midi instruments.
The programs to create mod files are called trackers, and there are many trackers and formats available.

I first discovered mod music at
http://modarchive.org/