  We review the development of minimal renormalizable SO(10) Susy GUTs. Using
our $SO(10) \to G_{Pati-Salam} $ label decomposition we calculated the complete
GUT scale spectra and couplings and the threshold effects therefrom. The
corrections to $\alpha_G, Sin^2{\theta}_W $ and $ M_X $ are sensitive functions
of the single parameter $\xi$ that controls symmetry breaking and slow funtions
of the others. Scans of the parameter space to identify regions compatible with
gauge unification are shown. The tight connection between the phenomenology of
neutrino oscillations and exotic ($\Delta B\neq 0 $) processes predicted by
Susy SO(10) GUTs is discussed in the context of the recent successful fits of
all available fermion mass/mixing data using the ${\bf{10 \oplus {\bar
{126}}}}$ Higgs representations and Type I/II seesaw mechanisms for neutrino
mass. We emphasize that {\it{the true output of these calculations should be
regarded as the unitary matrices that specify the orientation of the embedding
of the MSSM within the MSGUT}}. Fermion Mass fitting constraints combined with
GUT spectra can falsify/constrain the MSGUT and its near relatives. An initial
survey indicates that Type I Seesaw neutrino masses dominate Type II and both
are too small in the perturbative MSGUT even when the mixing and mass squared
splitting ratios are as per data. This motivates a detailed study of the MSGUT
constraints using the outputs of the fitting of fermion data, as well as
consideration of modifications/extensions of the MSGUT scenario.

High Energy Physics - Phenomenology