This read-only Counter tracks the number of frames that would otherwise have been transmitted but were dropped due to an internal OAM sublayer transmit error. An admin treats any nonzero or growing value here as a sign of an OAM-layer malfunction actively causing data-plane frame loss on the port. For example, a sudden increase here alongside application-layer packet loss on that link points to the OAM sublayer itself as the cause rather than the physical medium.