| 327 / | HD | MISCELLANEOUS ACTIVE ELECTRICAL NONLINEAR DEVICES, CIRCUITS, AND SYSTEMS |
| 1 | DF | SPECIFIC SIGNAL DISCRIMINATING (E.G., COMPARING, SELECTING, ETC.) WITHOUT SUBSEQUENT CONTROL {11} |
| 2 | DF | .~ By phase {1} |
| 3 | DF | .~.~ Comparison between plural inputs (e.g., phase angle indication, lead-lag discriminator, etc.) {5} |
| 5 | | .~.~.~ With input derived from feedback |