  We perform a complete analysis of one-loop threshold corrections to the gauge
couplings of fractional D6-branes. This includes besides SU(N) also symplectic,
orthogonal and massless Abelian gauge factors and the full computation of
contributions from discrete and continuous Wilson lines and brane
displacements. Two classes of globally consistent supersymmetric
compactifications with Standard Model spectra on T6/Z6 and T6/Z6' are presented
in detail with the latter exhibiting the potential of supersymmetry breaking
via a hidden sector gaugino condensate. The T6/Z6' Standard Models are
completely classified, and it turns out that out of 768 distinct D6-brane
configurations only 16 different sets of massless spectra and ten distinct
values of gauge couplings at one-loop arise. The gauge threshold corrections
enhance the diversity to 196 nonequivalent models.
