| 370 / | HD | MULTIPLEX COMMUNICATIONS | 
| 464 | DF | COMMUNICATION TECHNIQUES FOR INFORMATION CARRIED IN PLURAL CHANNELS {9} | 
| 498 | DF | .~ Combining or distributing information via time channels {17} | 
| 503 | DF | .~.~ Synchronizing {6} | 
| 520 |  | .~.~.~ Unique synchronization pulse |