Composite spectrum of X-ray detected AGNs at z ∼ 3. The spectrum is obtained by combining the continuum-subtracted (0.15″ × 0.15″) spectra of the X-ray detected type 2 AGNs GS10578-A, COS1656-A, GS551-A, GS133, GS19293, GS20936, by employing a bootstrap method (Perna et al. 2017b); before the combine, all spectra were normalised to the Hβ peak. Red vertical lines identify the main optical lines, while blue lines mark the position of CLs. No CLs are detected in the composite spectrum.