  We discuss the hadron tensor of the direct photon production. We study the
effects which lead to the soft breaking of factorization by inspection of the
corresponding QCD gauge invariance. We emphasize that the special role is
played by the contour gauge for gluon fields. We demonstrate that the different
prescriptions in the gluonic pole contributions are dictated by the presence of
initial or final state interactions in diagrams. Moreover, the different
prescriptions that correspond to the initial of final state interactions are
needed to ensure the QCD gauge invariance.
