| 137 / | HD | FLUID HANDLING |
| 551 | DF | WITH INDICATOR, REGISTER, RECORDER, ALARM OR INSPECTION MEANS {6} |
| 553 | DF | .~ Position or extent of motion indicator {3} |
| 556 | DF | .~.~ Indicator element rigidly carried by the movable element whose position is indicated {1} |
| 556.3 | DF | .~.~.~ Movable indicator element is a pointer {1} |
| 556.6 | | .~.~.~.~ Pointer integral with handle |