Simple dilution models for the Al–O and Na–O anticorrelations. Upper left panel: observed Al–O data. Upper middle panel: dilution model anchored to the mean values of the P and E components (large black points). Error bars here are rms scatter values and the separation into the P, I, and E components is made according to the Al–O data. Upper right panel: same, but following the classical P, I, E classification from the Na–O anticorrelation. Lower panels: same as upper panels, but for the Na–O data. The middle panel refers to the combined GIRAFFE+UVES sample, and the right panel to the UVES data alone.