X-Shooter weighted arithmetic mean quasar composite on a linear wavelength scale in light brown. The positions of several prominent emission lines are marked. Overplotted in dark green is the corresponding composite generated from the full sample of SDSS quasars fulfilling the selection criteria and general agreement is observed, albeit with a brighter Balmer continuum in the SDSS-constructed composite. In purple is shown the results from fitting both a pure and a broken power law to the regions specified in Sect. 5 and they are observed to be indistinguishable.