Masking also has to do with what ordinance you have hung and the main thing it's for is to keep the laser from hitting the aircraft or ordnance.
The A-10C has 4 different levels of masking, M1 is the most restrictive and M4 the least. For example, most of the load outs we carry in the 476th (Mav on one side, DRA on the other) it would fall into a Mask Zone 3. As soon as you fire off the mav it should automatically change to Mask Zone 4.
I would assume ED didn’t go into that much detail and I can’t remember if the mask zone number is displayed in the MFCD in DCS like it does in the real jet. Mask Zones are automatically set by the CICU which continuously evaluates the DSMS.