307 / | HD | ELECTRICAL TRANSMISSION OR INTERCONNECTION SYSTEMS |
11 | DF | PLURAL LOAD CIRCUIT SYSTEMS {8} |
38 | .~ Selectively connected or controlled load circuits {3} | |
39 | DF | .~.~> Condition responsive |
40 | DF | .~.~> Code-controlled |
41 | DF | .~.~> Sequential or alternating |