Distribution of Hβ (left panel), Mgb (middle panel) and Fe5335 (right panel) values as a function of the r-band light-weighted age in three different bins of mass-weighted [Z/H]: 0.3 (orange symbols), 0 (purple symbols), and −0.7 (black symbols), respectively, as measured in our template library (excluding templates with secondary bursts). The green arrow represents the effect on the indices of a 0.1% fraction of a young (70 Myr) stellar population superimposed on a population with 7 Gyr, both with a solar metallicity.