  The PandaX-III experiment plans to search for neutrinoless double beta decay
(0$\nu\beta\beta$) of $^{136}$Xe in the China JinPing underground Laboratory
(CJPL). The experiment will use a high pressure gaseous Time Projection Chamber
(TPC) to register both the energy and the electron track topology of an event.
This article is devoted to the software side of the experiment. As software
tool we use REST, a framework developed for the reconstruction and simulation
of TPC-based detector systems. We study the potential for background reduction
by introducing appropiate parameters based on the properties of
0$\nu\beta\beta$ events. We exploit for the first time not only the energy
density of the electron track-ends, but also the electron scattering angles
produced by an electron near the end of its trajectory. To implement this, we
have added new algorithms for detector signal and track processing inside REST.
Their assessment shows that background can be reduced by about 7 orders of
magnitude while keeping 0$\nu\beta\beta$ efficiency above 20% for the
PandaX-III baseline readout scheme, a 2-dimensional 3mm-pitch stripped readout.
More generally, we use the potential of REST to handle 2D/3D data to assess the
impact on signal-to-background significance at different detector
granularities, and to validate the PandaX-III baseline choice. Finally, we
demonstrate the potential to discriminate surface background events generated
at the readout plane in the absence of $t_o$, by making use of event parameters
related with the diffusion of electrons.
