(a) Comparison between the C IV (solid line) and Mg II (dashed line) emission line profiles as observed on 1996 February 21. Each line has been transformed into velocity space and normalized to the total flux in a 2000 km s⁻¹ wide bin centered at +2000 km s⁻¹. Note the good agreement between the line profile shapes in the blue and red wings of the lines. The far blue wing of Mg II is contaminated by blended Fe II hence the poor agreement in this region. (b) The high state (epoch 2, solid line) and low state (epoch 5, dotted line) continuum‐subtracted C IV + He II emission lines, scaled to the integrated flux in a 2000 km s⁻¹ wide bin centered at −4000 km s⁻¹. The most significant shape changes occur redward of line center, with the core displaying a deficit of response, whereas the far red wing displays an enhanced response. A similar result is found for Lyα.