  We compute the cross section for leptoproduction of the real photon off the
nucleon, which is sensitive to the deeply virtual Compton scattering amplitude
with power accuracy. Our considerations go beyond the leading twist and involve
the complete analysis in the twist-three approximation. We discuss consequences
of the target and lepton beam polarizations for accessing the generalized
parton distributions from experimental measurements of the azimuthal angular
dependence of the final state photon or nucleon. We introduce several sets of
asymmetries, defined as Fourier moments with respect to the azimuthal angle,
which allow for a clear separation of the twist-two and -three sectors. Relying
on a simple ansatz for the generalized parton distributions, we give
quantitative estimates for azimuthal and spin asymmetries, discuss the
uncertainties of these predictions brought in by radiative corrections, and
compare them with experimental data as well as other theoretical expectations.
Furthermore, we derive a general parametrization of the DVCS amplitudes in the
region of small Bjorken variable.
