They're on p 59 of Imai, but I'll post them here for everyone to see. I've put a * by the codes that are on my WWW
watches.
A = *Vertex, Record
F = *Longines, Record, *JLC (JLC not in Imai)
H = *Buren
K = *Timor
L = *Lemania, *Record
M = *IWC, *Grana (Grana not in Imai)
P = *Cyma, *Eterna
Q = Eterna, Lemania
Y = *Omega