The amplitudes of Deeply Virtual Compton Scattering (DVCS) can be parametrized in terms of Generalized Parton Distributions (GPDs). The number of GPDs involved is determined by the target spin alone. However, which of the GPDs is accessible by experiments, depends on the kinematics. In this work the amplitude for DVCS on a spin-0 target is analyzed. The number of GPDs compatible with electro-magnetic gauge invariance is determined. Moreover, for different kinematics the dominant GPDs in an expansion of the amplitude in inverse powers of the hard scale Q is found.