If I understand correctly the docs we found, there were 3 "flavors": "Grafik-COLLAGE", "Alpha-COLLAGE", and "X-COLLAGE". I assume the first would be for some sort of clever terminal, the second for non-graphical terminals, and the last one for X servers.

At the time I thought it was odd that the windows ended up aligning at character cell borders, which would indicate a terminal with some form of redefinable character set.