Ionization fractions of selected ions as a function of T_eff, for 14 O-star models, as detailed in Krtička & Kubát (2009, KK09); we recalculated these models here using FASTWIND. If not indicated otherwise, fractions are shown at v(r) = 0.5v_∞. As in previous figures, triangles represent models with shocks and crosses indicate those without shocks. This figure largely reproduces the layout of Fig. 8 from KK09, such that differences and similarities between our and their results can be easily recognized. For details, see text.