This is the highest value recorded during 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 highest transmit frequency recorded in the interval helps characterize how far the laser has drifted high, which similarly points to a wavelength-locker or thermal-control issue. For example, a laser whose outOpticalFrequencyMax keeps creeping upward release after release would be scheduled for proactive replacement before it drifts outside its allocated ITU channel entirely.