Colour–colour diagram for BP−RP versus BP−G, separated into the bright (red shades) and faint (blue shades) magnitude range. Top panel: REV passbands. The black dots indicate the positions of the Pickles spectra, the green triangles show the SPSS (filled symbols for bright, open symbols for faint range). Central panel: as top panel, but replacing the G_REV magnitude by the G_c magnitude of this work. Bottom panel: same as top panel, but for the G_c, BP_c, and RP_c magnitudes of this work. The filled dots correspond to the Pickles spectra and the bright range BP passband, open dots for the BP passband for the faint magnitude range. The orange dots show the BaSeL spectra from the bright range, the cyan dots for the faint range. The original colour–colour diagram has been rotated by 30^◦ clockwise and exaggerated in a vertical direction by a factor of 11 for better display. The dashed lines indicate the axis grid in BP−RP and BP−G.