APT was (according to the authors) based on Dino Eggs.
It was also written by Atari ST demo crew "The Lost Boys" who two brothers went on to work at Argonaut games and are now still working in the games industry.
I've got 2 or 3 original copies of APT left, I could take a look at the docs and tell you what you wanted to know, or even scan them in.
Alex
Thalion Webshrine
http://thalion.amiga.tm