  QED Compton scattering at HERA is discussed in terms of the information it
may reveal on the proton structure at low momentum transfers Q2. Detailed Monte
Carlo studies are performed which show that the analysis of inelastic QED
Compton events allows the extension of present HERA structure function
measurements to a kinematic regime, which up to now was only accessed in fixed
target data. For these studies an improved version of the COMPTON event
generator is used, where special emphasis has been put on modelling the
hadronic final state at low invariant masses.
  As the low Q2 regime is sometimes also discussed in the context of the
collinear approximation and the possibility of measuring the photonic content
of the proton, the Monte Carlo studies are also used to check the validity of
this approach. It is found that the proposed concept of a photon density of the
proton does not provide sufficient accuracy for the description of inelastic
QED Compton scattering.
