Individual abundance ratios as a function of galactocentric distance, R, for the bulge of M31. Positive and negative values of R refer to different sides of the slit. From left to right, and top to bottom, α elements elements are shown first, namely O, Mg, Si, Ca, and Ti (in order of decreasing atomic number), followed by C, N, and Na. Lines with different colors refer to E-MILES BaSTI (blue) and Padova00 (red), and Cvd18 models (green), respectively. Thick and thin lines are for 1SSP and 2SSP models, respectively, while solid, dashed, and dotted lines plot results of different methods, i.e., full-spectral fitting, full-index fitting, and index fitting, respectively, as shown by the labels in the top–left panel.