This object reports the local transceiver's optical transmit power in dBm for this Ethernet port during the archived historical interval, applicable only when the port's media type is fiber. A historical drop in transmit power helps the admin pinpoint when a local laser began weakening, which is useful evidence when justifying a transceiver replacement. For example, if a far-end device reports degrading receive power, the admin would check this port's own cmEthernetTrafficPortHistoryOPT history to confirm whether the local transmitter itself has been fading.