This read-only enumerated value reports whether the device's output clock is currently being supplied by a dedicated clock subboard or generated by the local board itself. Admins check it to understand the physical source of system timing when diagnosing synchronization issues on chassis with optional clock subboards. For example, a value of clock-localboard(2) on a system expected to use its clock subboard would prompt the admin to investigate why the subboard isn't supplying the clock.