This item specifies the transformation (Q,q) of the atomic coordinates from the setting used in the CIF [(x,y,z) referred to the basis vectors (a,b,c)] to the reference setting given in _space_group.reference_setting [(x',y',z') referred to the basis vectors (a',b',c')]. The value given in Jones-Faithful notation corresponds to the rotational matrix Q combined with the origin shift vector q in the expression: (x',y',z') = Q(x,y,z) + q Q is a premultiplication matrix of the column vector (x,y,z). It is related to the inverse transformation (P,p) by: P = Q^-1 p = Pq = -(Q^-1)q where the P and Q transformations are applied as follows: atomic coordinates (x',y',z') = Q(x,y,z) + q Miller indices (h',k',l') = (h,k,l)P symmetry operations W' = (Q,q)W(P,p) basis vectors (a',b',c') = (a,b,c)P + p This item is given as a character string involving the characters x, y and z with commas separating the expressions for the x', y' and z' components. The numeric values may be given as integers, fractions or real numbers. Multiplication is implicit, division must be explicit. White space within the string is optional.