The mechanical system may have some slack. To minimize the effect, there is option to use slack correction. The feature works so, that a XY move is first done to small distance short of target position, then to the final position. The idea is that this way, any slack is always on the same side and belt tension is always on the same side and equal.
“Slack Compensation, rot” enables/disables slack compensation on rotary axis. The amount of compensation is 5 degrees.
“Slack Compensation, X/Y” enables/disables slack compensation on X and Y axes. The amount of compensation is in mm’s and set in the box.
“Small moves speed” is the speed used for moves under 1mm.
“Squareness correction” is the relative amount of X axis move correction applied to Y axis moves, so that the actual machine moves are diagonal. For finding the value, see this page.