Spread of Al as a function of global cluster parameters (metallicity, absolute magnitude, and total masses). M 15, M 92, and NGC 5466, which probably have an underestimated spread, are highlighted accordingly. The metallicity and absolute magnitudes are extracted from Harris (2010). The total masses are computed by McLaughlin & van der Marel (2005; black line) and from a compilation by Boyles et al. (2011; red line). There is probably an anticorrelation with metallicity and maybe a correlation with absolute magnitude.