| 340 / | HD | COMMUNICATIONS: ELECTRICAL |
| 500 | DF | CONDITION RESPONSIVE INDICATING SYSTEM {6} |
| 540 | DF | .~ Specific condition {18} |
| 603 | DF | .~.~ Fluent material {7} |
| 612 | DF | .~.~.~ Material level {6} |
| 618 | | .~.~.~.~ Liquid {5} |
| 619 | DF | .~.~.~.~.~> Optical sensor |
| 620 | DF | .~.~.~.~.~> Electrode probe |
| 621 | DF | .~.~.~.~.~> Having sonic sensor |
| 622 | DF | .~.~.~.~.~> Having heat sensor |
| 623 | DF | .~.~.~.~.~> Float sensor {2} |