The complete figure is available online. For guidance regarding its form, we show here the data for one XQSO2 (namely, XBSJ013240.1−133307). Top panel: XMM–Newton data and residuals (pn + combined MOS; red and black crosses and lines, respectively), from Corral et al. (2011), plotted as a function of the observed energy. Central panel: optical spectrum, plotted as a function of the observed wavelength; the strongest emission lines are marked. Bottom panel: rest-frame SED fits: the data [red filled circles, Spitzer; red open pentagons, WISE; green filled square and triangle, data in the R band and at 4400 Å from the literature; brown open star and triangle, OM magnitude and GALEX near-ultraviolet (NUV) flux], plotted as luminosity (λL_λ, normalized to the X-ray luminosity as in Table 1) versus the rest-frame wavelength, are superposed on the corresponding best-fitting template SEDs (blue dotted line, host galaxy; red dashed line, AGN; black solid line, total). In addition to the name (first row) and the redshift (second row) of the source, in the last row of the legend, we summarize the main parameters of the modelling: the morphological type of the host, the QSO template, the adopted extinction curve (see Fig. 3), and the dust extinction. See Section 4 for details.