Final log(X/H) vs. EW diagrams for Si, O, and N, resulting from the abundance analysis of BD +46 4374. The microturbulence providing the lowest dispersion of line-by-line abundances is indicated at the top of each panel along with the associated mean and abundance dispersion. Red and blue dots indicate lines from different ions (red dots: Si iii, O ii and N ii; blue dots: Si iv, and N iii); gray dots correspond to the lines excluded from the analysis (see also Sect. 4 and Table 4). The gray horizontal band corresponds to the adopted value and its uncertainty.