This is the average value over the current performance-monitoring interval of the actual optical carrier frequency measured at this port's output during the current performance-monitoring interval, expressed in MHz. The average transmit frequency over the interval is what's compared against the ITU-grid channel this transmitter was provisioned for, to catch any systematic drift before it causes interference with a neighboring channel. For example, if outOpticalFrequencyAvg on a transponder drifts closer to the edge of an adjacent DWDM channel's passband over time, an admin would flag that unit for wavelength-locker recalibration before it causes crosstalk.