The last few years have seen a resurgence in the applications of group theory to the problems posed by various characteristics of transition metals and lanthanides. In particular with the commercial availability of more sophisticated experimental tech niques; such as Magnetic Circular Dichroism (M.C.D.), Electron Paramagnetic Resonance (E.P.R. or E.S(pin).R.) and Single Crystal Polarised Spectra; experimental data of a much more sophisticated and selective nature than the old stand-by; absorption spectra and magnetic susceptibility; has become available. This new wealth of high quality...