| 194 / | HD | CHECK-ACTUATED CONTROL MECHANISMS | 
| 302 | DF | INCLUDING MEANS TO TEST VALIDITY OF CHECK {4} | 
| 303 | DF | .~ By testing material composition {4} | 
| 320 | DF | .~.~ Having magnetic field acting on check {3} | 
| 324 |  | .~.~.~ And magnetically actuated deflector or stop |