| 370 / | HD | MULTIPLEX COMMUNICATIONS |
| 464 | DF | COMMUNICATION TECHNIQUES FOR INFORMATION CARRIED IN PLURAL CHANNELS {9} |
| 480 | DF | .~ Combining or distributing information via frequency channels {11} |
| 493 | DF | .~.~ Combined voice and data transmission {2} |
| 494 | ![]() | .~.~.~ Data over voice |