This is the reverse-direction counterpart to cktCLR, setting the cell loss ratio requirement for reverse-direction traffic on this circuit, with the same 255-means-any-loss-acceptable default and negative-exponent-of-10 encoding. Independent forward/reverse loss targets matter because the criticality of loss can differ by direction, for example a request-response protocol where the small reverse-direction acknowledgments are far more loss-sensitive than the bulk forward data. An admin provisioning such an asymmetric application would set cktRCLR to a tight value like 8 while leaving cktCLR at a looser setting for the bulk forward traffic.