CMD of the full Gaia DR2 20 pc sample. Subsamples A−D defined in Sect. 2.1 are shown with the same colours (red, magenta, blue, and green) as in Fig. 1. The objects with good astrometry (subsamples A and B) are plotted as filled (large and small) symbols, and those with poor astrometry (subsamples C and D) as open (large and small) symbols. Here and in Fig. 7, the filled magenta symbols are overplotted with open black lozenges for better visibility. The colour cuts applied for WDs by Hollands et al. (2018) and the absolute magnitude limit of M_G >  14 mag used in this study to select UCDs of spectral types > M6−M7 are drawn in the background as thick solid and dashed cyan lines, respectively.