This counter tracks the number of RS (Resynchronization) PDUs transmitted on this port, per the description, sent to realign SSCOP sequence numbering with the far end after a detected inconsistency, without tearing the link all the way down. This is a lighter-weight recovery step than BGN/END, so seeing it fire occasionally is less alarming than link teardown, but a sustained high rate indicates recurring sequence-number desynchronization, often caused by intermittent bit errors on the physical ATM link underneath this port. It's worth pairing with physical-layer error stats when this trends upward.