NL Unknown (NL-632 or NL-832)

??mm numeric tube manufactured by National Electronics

This is a unknown end-view symbol nixie tube manufactured by National Electronic. The print on the tube is damage, but it appears like this tube is either NL-632 or NL-832 or a number starting with these three digits. Sadly, i have not found any info about this tube. It can display a single "1" or "|" digit, and plus,minus and sinewave symbols in front of it. I think this tube was used in electronic measurement devices like voltmeter, allowing to have a range up to 1999 with only 3 full numeric tubes. The symbols would indicate if its positive,negative or AC voltage.
Brand / Manfacturer National Electronics
Same Types
Likely Tyes
Symbol height in mm ??
Characters / Symbols 1,+,-,sinewave
Decimal point none
Base / Socket B13B
Starting Voltage (typ) tested at 180V, 10kOhm V
Maintaining Voltage (typ) 0 V
Current per Segment 0mA
Reccomend Resistor 0