Example spectra representing our four quality flags. Panel A) shows an example of a fringed spectrum. A spectrum with failed spectrophotometry is shown in panel B), wherein the red open squares are the fluxes estimated from the SDSS photometry inside the fibre aperture. Panel C) shows a spectrum with clear splicing problems around observed frame 5700 Å, where the blue and red spectra have been unsuccessfully joined. An example spectrum with broad hydrogen emission lines classified as Seyfert I is shown in panel D).