ST Program clock ?

[Ontime]

What is the function & purpose of a Program clock ? How is it different from a master clock. Example is a mechanical with assorted electric components attached.

 

[harold bain]

Usually they are used to ring bells, for starting and stopping at factories and schools, but could also be used to turn things on and off at preset times.
A master clock may also have a program unit but mainly runs slave clocks.