Mg-Al anti-correlation. Panels show different GCs, sorted by increasing metallicity from left to right and from top to bottom. Dotted lines indicate the solar abundance ratios, dashed lines the typical halo α-enhanced ratios. The GES UVES data are plotted as cyan diamonds; GIRAFFE data as magenta circles; UVES literature data from the FLAMES GC survey are plotted in gold; NGC 6752 and M 2 data by Yong et al. (2005 and 2014) are plotted in green; M 2 data by Mészáros et al. (2015) are plotted in blue. Typical (median) error bars are reported on the bottom left corner of each panel.