Fermion currents on asymmetric orbifolds

We systematically classify asymmetric Zd-orbifold models of the heterotic string with twist-untwist intertwining currents. A large part of the asymmetric orbifold models is interpreted as Narainʹs toroidal compactifications. We obtain a new observation on the asymmetric orbifold models which can be geometrically interpreted as toroidal compactifications.