This object reports the optical transmit power level of this port, encoded as a real number multiplied by 1000, so a raw value of -1500 represents -1.5 dBm. Admins monitor this to confirm the port's laser is outputting power within its expected range, since a falling transmit power reading can indicate a failing optical transmitter. For example, a TxPwr reading near 0, roughly 0 dBm, confirms the transmitter is operating at typical output power for a 10GbE optical interface.