The LD8017 is a clear glass symbol tube manufactured by NEC. It can display the plus and minus sign, the electrical units Omega (for Ohm) and sinewave for AC current. There is also a symbol looking like laying "O" and a sign that looks like a sawtooth symbol! This tube is very rare and special. If you have more info about this tube or the devices it was used in, i would be happy to hear about!