Spectral region centered on the Mg II emission line for the XQR-30 sample. The pseudo-continuum (power law + Balmer contribution + Fe II empirical template) and multiple Gaussian lines fit are shown with dashed magenta and green lines, respectively, while the total fit is shown in red. We also show the residuals (in grey) in the lower panels. We note that in few cases the Mg II emission line falls partially (PSOJ007+04, PSOJ009−10, PSOJ183−12, PSOJ065+01) or fully (PSOJ023−02, PSOJ025−11, PSOJ242−12) in a region affected by telluric absorption. Despite the general high S/N of our spectra, given the (much) higher noise in these regions, the fit of these objects could be affected.