This object indicates whether the timing subsystem automatically switches back to a higher-priority timing reference once it becomes available again after a failure, or stays on whatever reference it failed over to until an operator manually intervenes. This distinction matters because revertive mode can cause a brief clock disturbance every time a flapping preferred reference triggers a switch back, while nonrevertive mode avoids that churn at the cost of staying on a lower-quality backup reference longer than strictly necessary. For example, a device in nonrevertive mode that failed over to a holdover oscillator during a fiber cut would keep using that oscillator even after the fiber is restored, until an admin manually forces a switch back.