  In this article we summarize and extend the ideas and investigations on so
called target space dualities of heterotic models with (0,2) worldsheet
supersymmetry as they were partly presented on the String-Math 2011 conference.
After the generic description of the duality, we give some novel examples
involving vector bundles that are not deformations of the tangent bundle but
more generic ones corresponding to SO(10) and SU(5) gauge theories in four
dimensions. We show explicitly that the necessary conditions for a duality also
hold for compactifications of this kind. Finally we will present the results of
the large landscape scan of E_6 models.
