Composite spectra of the low-z sample from ultraviolet to optical rest frame wavelengths. Black line: Stack obtained from the entire sample, shown as a reference. The different composites (shown with the red lines) obtained in each bin are marked as in Table 1 and are shown in separate panels. EW and FWHM are relative to the Hβ emission line and are in units of Å and km s⁻¹, respectively.