| 370 / | HD | MULTIPLEX COMMUNICATIONS |
| 259 | DF | SPECIAL SERVICES {3} |
| 260 | DF | .~ Conferencing {2} |
| 263 | DF | .~.~ Conferee signals combined or distributed via time channels {3} |
| 266 | DF | .~.~.~ Using summation of conferee signals {2} |
| 267 | | .~.~.~.~ Digital summation {1} |
| 268 | DF | .~.~.~.~.~> Including cancellation of certain signals |