| 250 / | HD | RADIANT ENERGY |
| 200 | DF | PHOTOCELLS; CIRCUITS AND APPARATUS {11} |
| 216 | DF | .~ Optical or pre-photocell system {11} |
| 221 | DF | .~.~ Controlled by article, person, or animal {1} |
| 222.1 | | .~.~.~ Inanimate article {3} |
| 222.2 | DF | .~.~.~.~> Particle detection |
| 223 R | DF | .~.~.~.~> Conveyor or chute {1} |
| 224 | DF | .~.~.~.~> Article and light ray relatively moved during sensing |