  Amplitudes of hard {\it exclusive} processes such as \gamma^*(Q^2) N \to
\gamma Y, where Y=N (DVCS) or any other state with a limited mass (M_Y^2 <<
Q^2), factorize into a hard subprocess amplitude and a target (transition) GPD.
The corresponding {\it inclusive} cross section, summed over all states Y of a
given (limited) mass, is then given by the discontinuity of a forward
multiparton distribution. An application to the Drell-Yan process \pi^+ N \to
\gamma^*(x_F,Q^2)+Y allows to explain the observed longitudinal polarization of
the virtual photon at high x_F.
