Parametric fits to the 3d(N)4s configurations in the III to VI spectra of the iron sequence are reported, using a set of orthogonal operators consisting of electrostatic operators up to four-body character and magnetic operators up to two-body character. The results are presented for all operators. The parameter values behave regularly among neighbouring ions and, for the 3d(N) core, compare well to those for the corresponding 3d(N) configurations. For comparison, ab initio calculated values of some operators are given as well.