Observed [F/Fe] (top panel) and [F/s] (bottom panel) vs. average s-element enhancements compared with theoretical predictions for 2 M_⊙ and close-to-solar metallicity models. Symbols are the same as in Fig. 1. Data points and theoretical lines are color-coded by [Fe/H]. The continuous portion of the lines represents the theoretical C-rich phase, and the discontinuous portion represents the O-rich phase. Typical uncertainties are shown. See text for details.