This is the native 64-bit counter of high-priority (CLP=0) egress cells on this channel discarded at the CoS queue due to overflow. Because CLP=0 cells are meant to be protected from discard, growth here signals a real capacity shortfall in the egress queue rather than normal congestion shedding. An admin investigating degraded voice or premium data quality on an egress-heavy channel would treat a rising value here as a priority-1 capacity alert.