Japanese Industrial Standard (JIS)
These part numbers take the form: digit, two letters, sequential number, [optional suffix]
Digits are 1 for diodes, 2 for transistors, and so forth. The letters indicate the type and intended application of the device according to the following code:
SA: PNP HF transistor SB: PNP AF transistor
SC: NPN HF transistor SD: NPN AF transistor
SE: Diodes SF: Thyristors
SG: Gunn devices SH: UJT
SJ: P-channel FET SK: N-channel FET
SM: Triac SQ: LED
SR: Rectifier SS: Signal diodes
ST: Avalanche diodes SV: Varicaps
SZ: Zener diodes
The sequential numbers run from 10-9999. The optional suffix indicates that the type is approved for use by various Japanese organizations. Since the code for transistors always begins with 2S, it is sometimes omitted; for example, a 2SC733 could be marked C733.