Number of Throws
ST	Single Throw	ON-OFF
DT	Double Throw	ON-ON
Number of Poles
SP	Single Pole
DP	Double Pole
3P	Three Pole
4P	Four Pole
nP	n Pole			SP		ST
Relay Configuration
Form A	ST-NO
Form B	ST-NC			SP		DT
Form C	DT break before make
Form D	DT make before break
Switch/Relay Contacts				DP		ST
NO	Normally Open
NOEM	Normally Open Early Make
NC	Normally Closed
NCLB	Normally Closed Late Break			DP		DT
C	Common Contact
Common Relay Configurations
SPST	NO	1 Form A
SPST	NC	1 Form B
SPDT	break before make	1 Form C
SPDT	make before break	1 Form D
DPST	NO	2 Form A
DPST	NC	2 Form B
DPDT	break before make	2 Form C
DPDT	make before break	2 Form D
3PST	NO	3 Form A
3PST	NC	3 Form B
3PDT	break before make	3 Form C
3PDT	make before break	3 Form D