Mg abundances derived from neutral lines with W_λ,red < 3 × 10⁻5 and high-quality gf values (black bullets), from neutral lines with W_λ,red < 3 × 10⁻5 and/or low-quality gf-values (open bullets), and from singly ionised lines (red bullets) in LTE (left) and NLTE (right). The black horizontal lines and grey-shaded regions correspond to the mean and one sigma standard deviation of the lines marked with filled black bullets. The red horizontal lines correspond to the mean of the singly ionised lines.