  This online material provides the technical detail for ``Heavy electrons and
the symplectic symmetry of spin",(arXiv 0710.1122). Three parts. Part I -
symplectic spins, their properties and gauge symmetries. Part II - derivation
of two-chanel model for tetragonal heavy electron systems with the view to
application to PuCoGa5 and NpPd_5Al_2, symplectic-N mean field theory and
computation of NMR relaxation rate. Part III - brief discussion of the
application to frustrated magnetism in the J1-J2 model, mainly used to test the
method.
