15.5mm numeric & letter tube manufactured by Siemens

The ZM1185F a is a clear glass nixie tube manufactured by Siemens. This tube can display number 0 to 5 and the letters E,K,U,R as well. Maybe this tube was used in german elevators where 1-6 indicated the floors and the letters:
E= Erdgeschoss (Ground Floor)
K= Keller (Basement)
U= Untergeschoss (Basement)
R= Reserviert/Revision (Reserved/Revision) There is a very similar version, the ZM1185 which can display the same letters, but has numerals from 1 to 6
Same Types
Likely Tyes
Symbol height (mm)15.5
Display0-5, E,K,U,R
Decimal pointnone
Starting Voltage (typ)170 V
Maintaining Voltage (typ)145 V
Current per Segment2.8mA
Reccomend Resistor8.2kOhm = 3mA