Distribution of UFO parameters in the υ_out − log ξ (left panel) and υ_out − log N_H (right panel) planes for our sample. The vertical bars indicate the overall velocity dispersion of the wind in terms of the FWHM of the absorption line. Those AGNs whose UFO velocity is consistent with zero within the global dispersion, namely 3C 111, Q2237+0305, 4C+74.26 and PG 1115+1080 are shown in red. Grey dots represent the UFOs with unconstrained values of σ.