This read-only counter, in cells, tracks the number of valid CLP=1 cells in the ingress direction of this channel discarded by the traffic policing entity for violating the negotiated PCR. An admin cares because this shows how much already-lower-priority traffic is additionally being cut for exceeding the connection's contracted peak rate, distinct from the CoS-queue-overflow discard counters. For example, a channel showing high UPC discards for CLP=1 traffic but low CoS discards tells the admin the source is simply oversending relative to its contracted rate, rather than the switch itself being congested downstream.