<ref group=note>In some cases the overcounting error is benign. An example is the [[Charts on SO(3)|choice of coordinate system used for representing orientations of three-dimensional objects]]. A simple encoding is the [[3-sphere]] (e. g., unit [[quaternion]]s) which is a [[double covering group|double cover]]—each physical orientation can be encoded in two ways. If this encoding is used without correcting the overcounting, then the entropy will be higher by {{math|''k'' log 2}} per rotatable object and the chemical potential lower by {{math|''kT'' log 2}}. This does not actually lead to any observable error since it only causes unobservable offsets.</ref>