[S II] emission lines and related models for MR 2251−178 (top panel) and PG 1126−041 (bottom panel). The black lines show the spectrum extracted within an aperture of 0.05″ (for MR 2251−178) and 0.5″ (for PG 1126−041) from the systems’ nuclei. The red lines show our best-fit models, with separate contributions from the wings of the BLR Hα (green lines), and the HV- and LV-components of the [S II] doublets (orange and blue lines, respectively).