Prototypical convergence behavior for three different kinds of model calculations (see legend and text). Displayed is the maximum relative change of temperature (regarding all grid-points, dashed) within two consecutive iteration steps, and the corresponding mean of the maximum change within all specified occupation numbers, where the averaging has been performed over all depth-points with τ_Ross ≤ 1. Left panels: mean maximum change within occupation numbers from explicit elements (HHeN in black and red, HHe in blue); right panels: mean maximum change within occupation numbers from selected background elements. Upper and lower panels: convergence behavior for our hottest dwarf (d2v, see Table 2) and supergiant (s2a) model, respectively. Our convergence criterion for the temperature is displayed by a horizontal dotted line. The vertical lines display the onset of the detailed CMF calculations within λ_min and λ_max (dotted), the update of the photospheric structure (dashed), and the onset of the Ng-extrapolation scheme for the C, N, O resonancelines (dashed-dotted). See text.