Colour-colour and flux-magnitude diagrams of the sources from the SDSS/eFEDS sample with reliable redshift (12 011 sources) in comparison to those with a reliable photometric counterpart (24 774 sources), as in Fig. 10. The colour-code is based on the spectroscopic success rate (i.e. N(NORMQ = 3)/N(CTP_QUALITY > 1)). The grey contours indicate the same contours as in Fig. 10 for the overall distribution of the X-ray sources with a reliable optical counterpart.