Position velocity (PV) diagrams for the 32 Sco-Cen clusters using the XU, YV, and ZW spaces. Symbols and colours as in Fig. 4. The median slopes of the fitted linear regressions (solid black lines) are given in the upper left corners. The shaded grey areas are the 1-2-3σ uncertainty ranges. The inverse of the slope gives a time in million years, in brackets, marking the possible onset of expansion. The dashed red slopes are the linear fitting results when using only 25 clusters, after removing seven clusters with peculiar tangential motions, marked with red circles (see Sect. 5.2). In the ZW diagram (right panel), the vertical dashed grey line indicates the approximate location of the Galactic mid-plane, assuming that the Sun is located about 21 pc above the plane (e.g. Bennett & Bovy 2019).