ORTF - nobody knows
DIN - nobody knows
DINA - nobody knows
NOS - nobody knows
PS; Kinda joking, but I'd guess that not many here on ts.com know what these stand for. I mean, we all know that they're mic configurations (e.g. 17, 20 or 30cm spacing and 90 or 120 degrees angle of incidence) but we don't know what the acronyms stand for. I know I don't and I've been taping for over 25 years.