| 327 / | HD | MISCELLANEOUS ACTIVE ELECTRICAL NONLINEAR DEVICES, CIRCUITS, AND SYSTEMS |
| 1 | DF | SPECIFIC SIGNAL DISCRIMINATING (E.G., COMPARING, SELECTING, ETC.) WITHOUT SUBSEQUENT CONTROL {11} |
| 50 | DF | .~ By amplitude {9} |
| 63 | DF | .~.~ Comparison between plural varying inputs {5} |
| 65 | DF | .~.~.~ Differential input {2} |
| 67 | | .~.~.~.~ Having feedback |