Top: [α/Fe] vs. [Fe/H ], data from DM17. The black line is the updated α separation line, also from DM17. (see text for more detail). Middle: [S/Fe] vs. [Fe/H], with the same α-line as the top panel. Bottom: Average [S/Fe] for each metallicity bin (of width 0.1 dex) per population. The numbers indicate the size of the sample of each population in each bin. Symbols: yellow circles are for the thin disc, blue triangles for the thick disc, red squares for the high-α metal-rich stars, and purple diamonds for halo stars.