  We discuss an orbifold of the toroidally compactified heterotic string which
gives a global reduction of the dimension of the moduli space while preserving
the supersymmetry. This construction yields the moduli space of the first of a
series of reduced rank theories with maximal supersymmetry discovered recently
by Chaudhuri, Hockney, and Lykken. Such moduli spaces contain non-simply-laced
enhanced symmetry points in any spacetime dimension D<10. Precisely in D=4 the
set of allowed gauge groups is invariant under electric-magnetic duality,
providing further evidence for S-duality of the D=4 heterotic string.
