This is the highest value recorded during the current performance-monitoring interval of the optical signal-to-noise ratio (OSNR) measured on this channel during the current performance-monitoring interval, expressed in dB. The highest OSNR seen in the interval shows the best signal quality achieved, useful as a reference point for how much margin exists above the worst-case minimum. For example, comparing osnrMax between two channels sharing the same fiber can reveal that one wavelength is favored by the amplifier's gain profile while another sits closer to the noise floor.