Position-velocity diagrams obtained by applying the spectro-astrometry technique to the [O III]λ5007 Å line in the slit spectra of PKS 0252–71 and PKS 2135–209. The diagrams show the position of the fitted centroids of the [O III]λ5007 Å emission line spatial profiles, expressed as offsets in parsecs from the host galaxy centre, as a function of velocity measured with respect to the [O III]λ5007 Å rest-frame velocity. The black dotted vertical and horizontal lines mark the zero point of the two axes. The blue dashed lines mark the error weighted mean position of the [O III] spatial profiles offsets at v < 500 km s⁻¹ and at v > 500 km s⁻¹ (shown in blue), while the red dashed line marks their average.