which may carry a generation index as determined by the string construction, arise from different sectors of the string Hilbert space. Once the gauge group is broken to the diagonal subgroup this distinction between the species is lost [*except for the pattern of couplings represented by the matrix $\mathbf{\lambda}_{T}$.*]{} The indices $i$ and $j$ carried by the lepton doublets represent internal degeneracies arising from the specific construction. It is natural to identify these indices with the flavor of the charged lepton (up to mixing effects, which we assume to be small).

In a minimal model, with only three lepton doublets charged under the Standard Model $SU(2)_L$, we are obliged to separate the generations, with two arising from one sector of the theory and one from the other. The precise form of the effective neutrino mass matrix will depend on this model-dependent identification, but one property is immediately clear: [*the effective neutrino mass matrix will necessarily be off-diagonal in the charged lepton flavor-basis.*]{}

We will restrict our study to the case of one triplet state with supersymmetric mass $M_T$ as in (\[Wnu\]). If we separate the doublet containing the electron from the other two, by defining $L_i = L_e = (\mathbf{2},1)$ 