15.5mm numeric & letter tube manufactured by Siemens

The ZM1185 a is a clear glass nixie tube manufactured by Siemens. This tube can display number 1 to 6 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)
Brand / Manfacturer Siemens
Same Types
Likely Tyes
Symbol height in mm 15.5
Characters / Symbols 1-6, E,K,U,R
Decimal point none
Base / Socket SK-136
Starting Voltage (typ) 170 V
Maintaining Voltage (typ) 145 V
Current per Segment 2.8mA
Reccomend Resistor 8.2kOhm = 3mA