Best-fit values of the metallicity as a function of radius, up to R₅₀₀ (0.1 R₅₀₀ bins) for the entire sample (C1 – purple dots, C2 – orange squares, C3 – green diamonds, C4 – red triangles). From top left to bottom right: oxygen, magnesium, silicon and iron abundances with respect to solar. The dashed lines represent instead the profile of the emission-measure-weighted input abundances using the same colours. The cyan shaded envelope represents the ±1σ dispersion of the recovered output metallicity for the entire sample. Points are slightly shifted for clarity.