This Counter64 tallies ATM cells received at ingress and passed onto the circuit with the Cell Loss Priority (CLP) bit set to 0, meaning high-priority cells that networks are expected to preserve preferentially during congestion. This counter is specific to circuits running ATM traffic (per circuitEndPoint1Protocol/circuitFwdTDType), and an admin comparing it against circuitInCLP1Cells gets a sense of what proportion of this circuit's ATM traffic is marked as protected versus expendable under load. For example, a circuit carrying mostly voice-over-ATM traffic would typically show most cells counted here (CLP0) rather than in the CLP1 counter, reflecting a policy of protecting that traffic during congestion.