I'm trying some of this film now and trying to figure out what's up. I've tried two rolls now exposed at EI 100 - the first developed in HC110b for 9:30, and the second in D76 1+1 for 12:00, and both are essentially clear film except for highlights that would have been overexposed (skies, reflections, etc) if the exposure were correct.
I'm confident in the camera and metering and both rolls were shot in relatively soft overcast daylight so I'm beginning to suspect the "Foto 100" I have is maybe Aviphot 80 rather than Aviphot 200. Or perhaps Tasma?
The undeveloped film is a sort of light blue color on the emulsion side, and the D76 after development comes out a bright-ish yellow looking much like fresh indicator stop. The film base is completely clear. I understand film with this name has been a number of different actual films over the years.