Same profile for [O III]λλ4959,5007 as in Fig. 16 (blue), together with the combined [O II] λλ3726,3729 profile. The velocity for the [O II] lines is centered on 3727.5 Å. The [O II] profile was multiplied by a factor of 2 to match 1.33× [O III] λ5007. We note that [O II] λ3726 only reaches ≈ − 1400 km s⁻¹ on the blue side (when the 118 km s⁻¹ difference between [O II] λ3726 and 3727.5 Å is accounted for). On the red side of [O II] λ3729 the emission is blended with [Fe VII] λ3759, as shown by the inset. The red curve is Savitzky-Golay fitting to the noisy [Fe VII] line profile.