Estimates of the equivalent widths for the N II line at 3995Å for sources with v sin i ≤40 km s⁻¹ plotted against effective temperature. Formal uncertainties in T_eff are half the grid separation, which can be inferred from inspection of the figure. Also shown are theoretical predictions for two gravities; log g = 4.0 dex (solid lines) and 3.5 dex (dotted lines). Black curves are for the SMC baseline nitrogen abundance of 6.5 dex, with other curves showing enhancements of 0.3 dex (blue), 0.6 dex (orange) and 0.9 dex (cyan). SB1 systems are circled.