Analysis of the non-saturated line 4730.04 Å. Left: comparison, averaged in metallicity bins of 0.1 dex, of the line χ² fitting in logarithmic scale (top) and the derived abundance (bottom) values from different local normalisation intervals (Δλ_norm = 1.35, 4.35, 68 Å; taking the shortest interval as a reference, which corresponds to around four times the FWHM of the line in a solar-type star). Right: stellar abundance ratios [Mg/Fe] vs. [M/H] for the local normalisation window Δλ_norm = 1.35 Å (blue points) and Δλ_norm = 4.35 Å (red points). Their respective behaviours were calculated by the mean [Mg/Fe] abundance value per metallicity bin. The reduced number of stars is due to the cut in FWHM_CCF for the non-saturated lines.