  The decomposition of nonlocal operators (and of their matrix elements) into
an (infinite) series w.r.t. geometric twist is used to introduce (new) parton
distributions, generalized parton distributions and hadron wave functions of
definite twist. Their comparision with the conventional distributions (of
definite dynamical twist) leads to Wandzura-Wilczek like relations,
Burkhardt-Cottingham like sum rules and allows for power corrections of the
various distribution amplitudes. Some general aspects are reviewed.
