Nitrogen abundance “analysis” of cmfgen model d4v with [N] = 8.78. EW iso-contours for important nitrogen lines are displayed in the T_eff-[N] plane of our fastwind model grid (series “D”, log Q =  −12.8, log g = 4.0). The displayed iso-contours refer to EWs measured from the cmfgen spectra of model d4v. In the ideal case, i.e., if cmfgen and fastwind produce identical results, all iso-contours would cross at a single point located at T_eff = 41 kK and [N] = 8.78. The black box marks the smallest region in parameter space where almost all lines (except for N iiiλ4640) are predicted at the measured value. In particular, five out of eight lines cross around the point T_eff = 41.5 kK / [N] = 8.55, i.e., at a lower abundance (by roughly 0.2 dex) than present in the original cmfgen model.