  We present supersymmetric, tadpole-free d=4,N=1 orientifold vacua with a
three family chiral fermion spectrum that is identical to that of the Standard
Model. Starting with all simple current orientifolds of all Gepner models we
perform a systematic search for such spectra. We consider several variations of
the standard four-stack intersection brane realization of the standard model,
with all quarks and leptons realized as bifundamentals and perturbatively exact
baryon and lepton number symmetries, and with a U(1)_Y vector boson that does
not acquire a mass from Green-Schwarz terms. The number of supersymmetric Higgs
pairs H_1 + H_2 is left free. In order to cancel all tadpoles, we allow a
"hidden" gauge group, which must bechirally decoupled from the standard model.
We also allow for non-chiral mirror-pairs of quarks and leptons, non-chiral
exotics and (possibly chiral) hidden, standard model singlet matter, as well as
a massless B-L vector boson. All of these less desirable features are absent in
some cases, although not simultaneously. In particular, we found cases with
massless Chan-Paton gauge bosons generating nothing more than SU(3) x SU(2) x
U(1). We obtain almost 180000 rationally distinct solutions (not counting
hidden sector degrees of freedom), and present distributions of various
quantities. We analyse the tree level gauge couplings, and find a large range
of values, remarkably centered around the unification point.
