  We are inspired by the facts that M-theory may reconcile the supersymmetric
GUT scale with that of quantum gravity, and that it provides new avenues for
low-energy supersymmetry breaking, to re-examine a flipped SU(5) model that has
been derived from string and may possess an elevation to a fully-fledged
M-phenomenological model. Using a complete analysis of all superpotential terms
through the sixth order, we explore in this model a new flat potential
direction that provides a pair of light Higgs doublets, yields realistic
textures for the fermion mass matrices, and is free of R-violating interactions
and dimension-five proton decay operators.
