Colour–colour diagram for sources in the qso_candidates table with classlabel_dsc=‘quasar’, excluding regions around the LMC and SMC. The left column shows sources with 5p/6p solutions (2.64 million sources), the right column shows sources with 2p solutions (0.14 million sources). These numbers refer to plotted sources, i.e. that have all Gaia bands. The colour coding in the upper panel shows the mean DSC-Combmod probability for the quasar class (the field classprob_dsc_combmod_quasar). The colour coding in the lower panel shows the density of sources on a log scale relative to the peak density in that panel.