The notation for "n"-fold symmetry is Cn or simply ""n"". The actual symmetry group is specified by the point or axis of symmetry, together with the "n". For each point or axis of symmetry, the abstract group type is cyclic group of order "n", Z"n". Although for the latter also the notation "C""n" is used, the geometric and abstract "C""n" should be distinguished: there are other symmetry groups of the same abstract group type which are geometrically different, see cyclic symmetry groups in 3D.