  We study the Higgs potential of the next-to-minimal renormalizable SUSY
SO(10) GUT with 120 Higgs representation on top of the "standard" minimal model
Higgs sector spanning over 10, 126bar+126 and 210. All the GUT-scale Higgs
sector mass matrices for the 592 Higgs states of the model are written down in
detail with all the conventions fully specified. The consistency of the results
is checked by the decoupling of 120 and independently by the analysis of the
relevant Goldstone modes. The matching of the Yukawa sector sum-rules driving
the matter fermion masses and mixing at the level of the effective theory is
described thoroughly.
