Highest radial velocity shift between individual spectra plotted against time difference between the corresponding observing epochs. The dashed horizontal line marks the selection criterion ΔRV > 100 km s^-1, the dotted vertical line the selection criterion ΔT < 0.1 d. All objects fulfilling at least one of these criteria lie outside the shaded area and belong to the top candidate list for the follow-up campaign. The filled diamonds mark sdBs, while the blank squares mark He-sdOs.