We consider a phenomenologically viable SO(10) grand unification model of the
unification scale MG around 1016 GeV which reproduces the MSSM at low
energy and allows perturbative calculations up to the Planck scale MP or the
string scale Mst. Both requirements strongly restrict a choice of Higgs
representations in a model. We propose a simple SO(10) model with a set of
Higgs representations {2×10+16ˉ+16+45} and show its phenomenological viability. This model can indeed
reproduce the low-energy experimental data relating the charged fermion masses
and mixings. Neutrino oscillation data can be consistently incorporated in the
model, leading to the right-handed neutrino mass scale MR≃MG2/MP.
Furthermore, there exists a parameter region which results the proton life time
consistent with the experimental results.Comment: 14 pages, no figure, section5 was slightly modifie