This read-only TruthValue reports whether an Ethernet Network Port is capable of continuing to send EFM OAMPDUs even when its own receive path is non-operational (unidirectional link fault support). It matters on fiber links where transmit and receive can fail independently, since unidirectional OAM support lets the remote end still learn about a receive-only failure via the still-functioning transmit path. For example, on a fiber pair where only the receive strand has failed, unidirectional OAM support (if enabled per this object) lets the far end still be notified of the fault via the working transmit fiber.