  Lepton number is promoted to an $U(1)_L$ gauge symmetry in a simple extension
of the standard model. The spontaneous breaking of $U(1)_L$ by three units
allows a conserved $Z_3^L$ lepton symmetry to remain, guaranteeing that
neutrinos are Dirac fermions, which acquire naturally small masses from a
previously proposed mechanism. Dark matter appears as a singlet scalar, with
dark symmetry $Z_3^D$ derivable from $Z_3^L$. Muon $g-2$ may be explained.
