Location of the objects shortlisted as candidate UCDs via astrometric selection, for an example 20 × 20 deg² region, in a colour-magnitude (left) and a reduced proper motion (right) diagram built using Gaia EDR3 sources with parallaxes larger than 10 mas (dark blue dots). The vertical and horizontal red lines mark the boundaries for a source to be shortlisted as candidate UCD. Sources fulfilling these conditions are overplotted in yellow.