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} |
582 | .~ Indicating the time of the day (acoustic indication of time subclass 217) [G04C 21/04] {2} | |
583 | DD | .~.~> By striking mechanism [G04C 21/06] {2} |
586 | DD | .~.~> By electro-acoustic time means [G04C 21/12] {1} |