This read-write SSMQualityLevel object lets an administrator specify the minimum expected received Quality Level on the OCn/STM interface when it is enabled for QL mode, per its description, applicable only to synchronous interfaces, with a value of none meaning no minimum QL is expected. It matters because if the received SSM quality level falls below this expectation, the system can treat the timing source as unsuitable and avoid selecting a degraded clock. For example, an operator relying on this interface as a backup timing source would set an expected QL floor so a badly degraded upstream clock is automatically disqualified rather than silently accepted.