This sets the maximum instantaneous rate, in cells per second, at which this circuit is permitted to transmit, forming the hard ceiling that the switch's traffic-shaping and policing enforces regardless of how much burst allowance exists. An admin provisioning an ATM circuit for a specific access-line speed calculates cktAtmPCR from that speed, dividing by 53 bytes and adjusting for cell overhead, to make sure this circuit's peak cell rate matches what the physical interface can actually sustain. For example, a T1-attached ATM circuit intended to use the full line rate would have cktAtmPCR set to roughly 3622 cells per second, the peak rate corresponding to 1.544 Mbps of ATM cell traffic.