This is the highest value recorded during the current performance-monitoring interval of the Q-factor measured on this channel during the current performance-monitoring interval, expressed in dB, a composite measure of signal quality that correlates with the expected bit error rate. The highest Q-factor seen in the interval shows the best signal quality achieved during the interval, giving a sense of how much margin exists above the worst-case minimum. For example, comparing qFactorMax across channels on the same fiber can help an admin identify which wavelength has the most quality headroom to spare if amplifier gain needs to be re-tilted.