The Politzer theorem on equations of motion allows to obtain
an expansion of the hadronic tensor in terms of Feynman-Cutkosky
diagrams, whose "soft" parts result to be strongly constrained.
Several approximate relations among different distribution
functions are derived. Moreover an energy scale is fixed,
determining the Q^2 dependence of many azimuthal asymmetries in
semiinclusive deep inelasic scattering, in Drell-Yan and in e+e-
inclusive anninilation into two hadrons. Two of these theoretical
results are compared with data and measurements in forthcoming
experiments are suggested.