This object reports the local transceiver's optical receive power in dBm for this Ethernet port during the archived historical interval, applicable only when the port's media type is fiber. A historical decline in received power helps the admin date when fiber degradation, a dirty connector, or a failing remote transmitter began affecting this link. For example, if this port's link recently started flapping, the admin would review cmEthernetTrafficPortHistoryOPR over the past several days to see whether receive power had already been trending downward beforehand.