  Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet
fermions N_{1,2,3} to the Standard Model of particle interactions with a new
Z_2 symmetry, it has been shown that Re(eta^0) or Im(eta^0) is a good
dark-matter candidate and seesaw neutrino masses are generated radiatively. A
supersymmetric U(1) gauge extension of this new idea is proposed, which
enforces the usual R parity of the Minimal Supersymmetric Standard Model, and
allows this new Z_2 symmetry to emerge as a discrete remnant.
