This read-create Unsigned32 sets the maximum queue-depth threshold above which WRED drops all yellow (excess) packets outright on a per-COS access-port QoS Shaper, rather than merely probabilistically. It matters because it defines the upper bound of the probabilistic-drop range for yellow traffic; between the yellow min and max thresholds, drop probability ramps up, and beyond the max threshold every yellow packet is dropped. For example, an admin wanting to guarantee that excess traffic never occupies more than a fixed portion of the access-port queue would set cmAccPortQosShaperWredYellowMaxQueueThreshold to that queue-depth limit, beyond which yellow packets are dropped unconditionally.