Left: in the log ([Oiii] λ5007/Hβ) vs. log ([Oii] λλ3726 + 3729/Hβ) diagram, the different regions where galaxies of different types are mixed (color-code according to the reference K06 diagnostic). The curves are the ones from the Lamareille (2010) diagnostic. Center and right: the same points as in the associated left panels, but now in the D_n(4000) vs. diagram. For clarity, we plot the different types in two panels. The solid lines show the adopted demarcation lines (see text for details). The dashed line in top-right panels is the separation adopted by Stasińska et al. (2006).