A clock that is coordinated with a master clock. Note 1: Slave clock coordination is typically achieved by phase-locking the slave clock output signal to a signal coherent with, or whose clocking source is traceable to, the master clock. Note 2: If it is necessary to adjust for the transit time of the signal from the master clock to the slave clock, the phase of the slave clock may be adjusted with respect to the signal from the master clock so that both clocks are in phase. Thus, the time markers of both clocks, at the output of the clocks, occur simultaneously.