Continuum photon index against intrinsic flux density at rest-frame 2 keV (left) and 2−10 keV integrated flux (right). The colour code is the same adopted in the previous figure. The lighter symbols, when present, show the correction required if local absorption were statistically significant. Here the observed best-fit slope is also plotted for the four faintest objects (red crosses), for which an intrinsic Γ = 1.8 is then conservatively assumed for the sake of discussion (Table 2).