This read-only counter tallies cells discarded specifically because of Partial Packet Discard, the mechanism that, once congestion begins mid-frame, drops the remaining cells of a frame already in progress rather than passing along a now-guaranteed-to-be-corrupted partial frame. Admins use this alongside chanEpdDiscCells to fully account for frame-based discard activity on a channel - PPD catches frames that started before congestion hit, while EPD catches new frames after congestion is already present. For example, high chanPpdDiscCells relative to chanEpdDiscCells would suggest congestion is arriving abruptly mid-burst rather than building gradually before new frames start.