| 968 / | HD | HOROLOGY |
| 580 | DD | PRODUCING ACOUSTIC TIME SIGNALS BY ELECTRICAL MEANS (for mechanical clocks or watches subclasses 225 and 243) [G04C 21/00] {3} |
| 588 | DD | .~ Producing the signals at adjustable fixed times [G04C 21/16] {7} |
| 597 | DD | .~.~ With provision for a number of operations at different times, e.g., ringing the bells in a school, etc. [G04C 21/30] {3} |
| 601 | | .~.~.~ Adjustable from the different places themselves [G04C 21/32K] |