US PATENT SUBCLASS 340 / 825.42
.~.~.~.~ Polarity controlled


Current as of: June, 1999
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340 /   HD   COMMUNICATIONS: ELECTRICAL

825  DF  SELECTIVE {23}
825.36  DF  .~ Having indication or alarm (e.g., location indication) {4}
825.38  DF  .~.~ Party line {4}
825.41  DF  .~.~.~ Step-by-step impulse {1}
825.42.~.~.~.~ Polarity controlled


DEFINITION

Classification: 340/825.42

Polarity controlled:

(under subclass 825.41) Subject matter where selection is based on whether the pulses are of positive or negative amplitude with respect to ground.