  Hard exclusive reactions are the tool to learn about generalized parton
distributions, which provide a more complete parametrization of the nucleon
than the ordinary parton distribution functions. Recent measurements by the
HERMES collaboration of the exclusive production of photons, i.e.,
Deeply-Virtual Compton Scattering, are summarized and compared to model
calculations, focusing on the measurements and model comparisons relevant to
the extraction of quark orbital angular momentum and on the measurements on
heavy nuclei.
