Each dot represent aiming point for holdover and windage. Gives you a specfic reference for different ranges and cross winds. Zero for 100 yds. Back up to 200 yds, line up cross hairs and fire. Then check the dots to see whitch dot will put you back on zero. That will be the dot you use for 200 yds. Keep working your way out in range. Most mildots are calibrated for a specific round, but it is best to use this procedure to double check. Do the same thing for different wind speeds.