307 / | HD | ELECTRICAL TRANSMISSION OR INTERCONNECTION SYSTEMS |
112 | DF | SWITCHING SYSTEMS {5} |
116 | .~ Condition responsive {4} | |
117 | DF | .~.~> Light, heat, vibratory or radiant energy |
118 | DF | .~.~> Fluid pressure, density, level, velocity or humidity |
119 | DF | .~.~> Mechanical force {1} |
125 | DF | .~.~> Electrical {6} |