| 342 / | HD | COMMUNICATIONS: DIRECTIVE RADIO WAVE SYSTEMS AND DEVICES (E.G., RADAR, RADIO NAVIGATION) |
| 350 | DF | DIRECTIVE {10} |
| 385 | DF | .~ Beacon or receiver {2} |
| 417 | DF | .~.~ Direction-finding receiver only {14} |
| 422 | DF | .~.~.~ With self-orienting antenna pattern {4} |
| 423 | | .~.~.~.~ Plural antennas {1} |
| 424 | DF | .~.~.~.~.~> Tracking interferometer |