Revised redshift from the present work vs redshift from the SDSS DR16 pipeline (left) and vs redshift from the QCDR16 (Lyke et al. 2020) (right) for the QSOs with r_z ≥ 2. QSOs with unusual spectra (Sect. 3.5) are marked by blue circles. Black dotted lines: Relations that result when one of the labelled emission lines was interpreted as Lyα in the comparison sample. The dots at z(QCDR16) < 0 indicate sources that are not included in the QCDR16.