| 968 / | HD | HOROLOGY |
| 524 | DD | DRIVING MECHANISMS FOR CLOCKS BY MASTER CLOCKS [G04C 13/00] {2} |
| 525 | DD | .~ Circuit arrangements; electric clock installations [G04C 13/02] {5} |
| 533 | | .~.~ Pulse transmission systems with additional means for setting the time indication of slave clocks (subclass 532 takes precedence) [G04C 13/03] |