Standard Elementary Diagram Symbols - SUPPLEMENTARY CONTACT SYMBOLS &Terms

SPST: Single Pole, Single Throw
SPDT: Single Pole, Double Throw
DPST: Double Pole, Single Throw
DPDT: Double Pole, Double Throw
N.O.: Normally Open
N.C.: Normally Closed
T.O.: Timed Open
T.C.: Timed Closed
PUT: Programmable Unijunction Transistor
SCR: Silicon Controlled Rectifier
Triac: Bidirectional Triode Thyristor
UJT: Unijunction Transistor