Same as Fig. 14. Top: dashed, green TMAP (=chemically homogeneous) model with O =  −4.72; thin, blue TMAP model with abundance profiles from Dreizler & Wolff (1999), thick, red NGRT (=diffusion) model. Bottom: thick, red NGRT model with an artificially reduced O abundance in the outer atmosphere. Note that in the NGRT models, the line strengths of the generic iron-group element (see text) are overestimated.