This read-write SSMQualityLevel object lets an administrator specify an assumed Quality Level on the OCn/STM interface, meaningful, per its description, only when the Network Clock Type is option1, transmit QL mode is disabled, and the port is used as an input reference source. It provides a manually configured stand-in quality level for timing purposes when the interface cannot actually receive real SSM quality information. For example, using an older far-end SONET source that doesn't support SSM signaling, an operator would set this assumed QL to the known quality of that source so local clock selection logic can still make an informed choice.