Comparison of ABC sources (blue circles) and Roma-BZCAT sources (red circles) in the Gaia g versus b − r color-magnitude plot. Gray points in the background represent random Gaia sources, and the black continuous lines indicate KDE isodensity curves containing 60%, 70%, 80%, and 90% of the Gaia random sources. On top and on the right of the main panel: we present the normalized distributions of the b − r color and g magnitude, respectively, for the ABC, Roma-BZCAT and random sources.