  In this paper, globally N=1 supersymmetric configurations of intersecting
D6-branes on the Z6-orientifold are discussed, involving also fractional
branes. It turns out rather miraculously that one is led almost automatically
to just ONE particular class of 5 stack models containing the SM gauge group,
which all have the same chiral spectrum. The further discussion shows that
these models can be understood as exactly the supersymmetric standard model
without any exotic chiral symmetric/antisymmetric matter. The superpartner of
the Higgs finds a natural explanation and the hypercharge remains massless.
However, the non-chiral spectrum within the model class is very different and
does not in all cases allow for a N=2 low energy field theoretical
understanding of the necessary breaking U(1)xU(1)->U(1) along the Higgs branch,
which is needed in order to get the standard Yukawa couplings. Also the
left-right symmetric models belong to exactly one class of chiral spectra,
where the two kinds of exotic chiral fields can have the interpretation of
forming a composite Higgs. The aesthetical beauty of these models, involving
only non-vanishing intersection numbers of an absolute value three, seems to be
unescapable.
