| 968 / | HD | HOROLOGY |
| 920 | DD | SYNCHRONIZATION [G04G 7/00] {2} |
| 922 | | .~ By radio [G04G 7/02] {2} |
| 923 | DD | .~.~> Provided with arrangements to prevent synchronization by interfering signals [G04G 7/02B] |
| 924 | DD | .~.~> The timepiece preparing itself on set times on the reception of the synchronizing signal [G04G 7/02C] |