This read-write TruthValue enables or disables Quality Level (QL) mode on a Synchronous-Ethernet-capable port; when enabled, the port peers Sync Status Message (SSM) slow-protocol PDUs on receive and periodically transmits its own SSM PDUs. Admins turn this on when the network needs full SSM-based clock-quality negotiation, so downstream equipment can automatically select the best available timing source rather than relying on a fixed assumption. For example, in a ring topology with multiple potential clock sources, enabling cmEthernetNetPortQLModeEnabled lets the port participate in SSM exchange so the network can automatically fail over to a backup timing source if the primary degrades.