Stacked residuals with respect to the baseline fit (left), and the Gaussian line scan performed on the data (right). In the panel on the right, the results for two different line widths σ = 1000 km s⁻¹ and 4000 km s⁻¹ are shown in black and red, respectively. Notable transitions relevant for the potential features in the stacked residuals are marked with vertical dashed lines. The wavelengths of the transitions are set to the AGN restframe.