  We have previously described a mathematical formulation for a parton shower
based on the approximation of strongly ordered virtualities of successive
parton splittings. Quantum interference, including interference among different
color and spin states, was included. A practical numerical implementation
strategy was left unspecified. In a subsequent paper, we showed that if we add
the further approximations of taking only the leading color limit and averaging
over spins, we obtain a shower evolution that can be implemented as a Markov
process. In this paper, we outline a strategy for including the correlations
induced by parton spins.
