  A quasi two-body QCD factorization is used to study the D0 --> K0S pi+ pi
decays. The presently available high-statistics Dalitz plot data of this
process measured by the Belle and BABAR Collaborations are analyzed together
with the tau- --> K0S pi- nu_tau decay data. The total experimental branching
fraction is also included in the fits which show a very good overall agreement
with the experimental Dalitz plot density distributions. The branching
fractions of the dominant channels compare well with those of the isobar Belle
or BABAR models. We show that the branching fractions corresponding to the
annihilation amplitudes are significant.
