Spectroscopic completeness in the XMM-XXL north: we show the fractions of X-ray sources with reliable redshift (⁠|$\rm {Z\_CONF}=3$| and |$\rm {Z\_CONF}=30$|⁠) over the number of all X-ray sources (blue), matched SDSS counterparts (LR_XMM,SDSS > 1.5) (green), and r-band within 15 < r < 22.5 mag (yellow). In addition, we apply the fibre collision correction to the fraction of sources with reliable redshift (dashed lines with empty markers) to obtain the intrinsic spectroscopic completeness. The vertical green dashed lines indicate the flux depths of eROSITA (from left: eRASS:8, eRASS:4, eRASS:2, eRASS:1).