this cable is used for older U87 (or other P48 powered mics) with 7pin Tuchel connector, adapting to 3pin Tuchel / DIN pre-amp inputs. As one would hardly find a 3pin DIN input anymore, rewiring the cable to XLR3 would be plausible.
With the 7pin, pin1 is (+), pin2 is (-), pin3 is ground+shield.
Model name could have been UC73, or AC## (adapter cable), but I can't tell exaclty as the offices are closed for the holidays.
Best regards, Martin Schneider / Neumann Mic. Development