  We explore the use of real fermionization as a test case for understanding
how specific features of phenomenological interest in the low-energy effective
superpotential are realized in exact solutions to heterotic superstring theory.
We present pedagogic examples of models which realize SO(10) as a level two
current algebra on the world-sheet, and discuss in general how higher level
current algebras can be realized in the tensor product of simple constituent
conformal field theories. We describe formal developments necessary to compute
couplings in models built using real fermionization. This allows us to isolate
cases of spin structures where the standard prescription for real
fermionization may break down.
