This is the reverse-direction priority counterpart to cktPriority, but its actual meaning shifts depending on the port's service-type mode: under mono-class it represents this circuit's forward-direction priority in reverse, while under multi-class it represents discard priority instead, so the admin must know the port's mode before interpreting or setting this value correctly. For example, setting cktRPriority to 0 on a multi-class port makes this circuit's reverse-direction traffic the least likely to be discarded under congestion, whereas the same value on a mono-class port would instead be read as a forwarding priority rather than a discard-priority setting.