Use this option to define the rotational axis:
Activate this setting if those guide elements being rotated should affect neighboring guide points that are not selected but belong to the same guide (the distance between guide points remains for the most part the same).
Activate this setting if rotating guide elements should not move beneath the hair-covered surface (works only with polygon objects, not with splines, etc.). The guide points may not have a distance from the surface less than the distance defined in Coll. Radius.