  In addition to the inclusive cross sections discussed within the QCD-parton
model, in the regime of multiple parton interactions, different and more
exclusive cross sections become experimentally viable and may be suitably
measured. Indeed, in its study of double parton collisions, the quantity
measured by CDF was an "exclusive" rather than an inclusive cross section. The
non perturbative input to the "exclusive" cross sections is different with
respect to the non perturbative input of the inclusive cross sections and
involves correlation terms of the hadron structure already at the level of
single parton collisions. The matter is discussed in details keeping explicitly
into account the effects of double and of triple parton collisions.
