The two reference points used to keep the rotation center and gripper at an even distance when the object is moved in annotation coordinates.
By default, the AnnEditDesigner returns the first two points found in the AnnObject.Points collection of the TargetObject. The designer then uses these reference points to keep the rotate center and gripper at an even distance when the object is moved.
Derived classes can override GetRotationReferencePoints to return any two points to use as the reference points. Usually these are the points at the "top-left" and "bottom-right" edge of the object.
For more information and an example, refer to Implement User Defined Objects with LEADTOOLS Annotations