Hi Piccolo,
CMV stands for Converted Meteorological Visibility.
According EU-OPS AOM is " A value (equivalent to an RVR) which is derived from the reported meteo visibility by using particuraly conversion factors"
It is the minima for NPA when the required RVR is greater then 2000m.
The conversion factors are equal to those used to convert reported vis to RVR when RVR data is not provided by the tower.
You can find the table in the page 602 of the Jeppesen text booklet vol1.
Example: TWR reports 1100 m visbility and you need a CMV of at least 2100m to fly a VOR aproach. If you are at night time and HIALS and HIRL are operative for the active RWY, the conversion factor is 2, therefore 1100m vis equals to 2200 m CMV. Above minima.