This reports the received optical power level of this specific DWDM wavelength (optical channel), stored as a milli-scaled fixed-point number (PmInteger32Milli, i.e. the raw integer divided by 1000 gives dBm). Because this reading sits in a Stats-table row that resets only when explicitly cleared rather than on the fixed bin schedule, if this drifts down from where it was provisioned, it usually means this specific wavelength is losing power somewhere upstream -- a bad connector, a fiber cut, or an EDFA amplifier drifting out of gain -- well before the client signal actually drops. For example, a healthy 100G coherent wavelength typically reads around -12.500 dBm (stored internally as -12500); a reading that has slid to -22.000 dBm on this channel while neighboring channels stay flat points at a problem specific to this one wavelength, since this row's last manual clear.