| 257 / | HD | ACTIVE SOLID-STATE DEVICES (E.G., TRANSISTORS, SOLID-STATE DIODES) |
| 565 | DF | BIPOLAR TRANSISTOR STRUCTURE {11} |
| 566 | DF | .~ Plural non-isolated transistor structures in same structure {2} |
| 567 | DF | .~.~ Darlington configuration (i.e., emitter to collector current of input transistor supplied to base region of output transistor) {6} |
| 568 | | .~.~.~ More than two Darlington-connected transistors |