Pro-Electron or EECA Numbering Coding System
First letter	Second letter	Subsequent characters	Suffix
A = Germanium	A = Diode - low power or signal	A10 - Z99	A = low gain
B = Silicon	B = Diode - variable capacitance		B = medium gain
C = Gallium Arsenide	C = Transistor - audio frequency, low power		C = high gain
R = Compound materials	D = Transistor - audio frequency, power		No suffix = gain unclassified
	E = Tunnel diode
	F = Transistor - high frequency, low power
	G = Miscellaneous devices
	H = Diode - sensitive to magnetism
	L = Transistor - high frequency, power
	N = Photocoupler
	P = Light detector
	Q = Light emitter
	R = Switching device, low power, e.g. thyristor, diac, unijunction
	S = Transistor - switching low power
	T = Switching device, low power, e.g. thyristor, triac
	U = Transistor - switching, power
	W = Surface acoustic wave device
	X = Diode multiplier
	Y = Diode rectifying
	Z = Diode - voltage reference
JEDEC Numbering or Coding System
1 = Diode	SA = PNP high frequency bipolar transistor	10 to 9999
2 = Bipolar transistor or single gate field effect transistor	SB = PNP audio frequency bipolar transistor
3 = Dual gate field effect transistor	SC = NPN high frequency bipolar transistor
	SD = NPN audio frequency bipolar transistor
	SE = Diodes
	SF = Thyristor (SCR)
	SG = Gunn devices
	SH = UJT (Unijunction transistor)
	SJ = P-channel JFET / MOSFET
	SK = N-channel JFET / MOSFET
	SM = Triac
	SQ = LED
	SR = Rectifier
	SS = Signal diode
	ST = Avalanche diode
	SV = Varactor diode / varicop diode
	SZ = Zener diode / voltage reference diode