A parsable string giving one of the symmetry operations of the
                space group in algebraic form.  If W is a matrix representation
                of the rotational part of the symmetry operation defined by the
                positions and signs of x, y and z, and w is a column of
                translations defined by the fractions, an equivalent position
                X' is generated from a given position X by the equation
                          X' = WX + w
                (Note: X is used to represent bold_italics_x in International
                Tables for Crystallography Vol. A, Part 5)
                When a list of symmetry operations is given, it must contain
                a complete set of coordinate representatives which generates
                all the operations of the space group by the addition of
                all primitive translations of the space group. Such
                representatives are to be found as the coordinates of
                the general-equivalent position in International Tables for
                Crystallography Vol. A (2002), to which it is necessary to
                add any centring translations shown above the
                general-equivalent position.
                That is to say, it is necessary to list explicity all the
                symmetry operations required to generate all the atoms in
                the unit cell defined by the setting used.