The predicted abundance of elements lighter than Fe, in log ϵ(X), as a function of atomic number, Z, for a 1.3 M_⊙ model of Z = 0.0006 ([Fe/H] =  − 1.4). Abundances are sampled at the tip of the AGB, after the last computed thermal pulse. Included are the approximate locations (in proton number, Z) of some key elements. Predictions are shown for two values of the parameter M_mix = 2 × 10^-3 (points connected by the solid green line) and 6 × 10^-3   M_⊙ (points connected by the red dashed line). This parameter determines the size of the ¹³C pocket and s-process enrichment, see text for details. The derived abundance of the post-AGB star J004441.04 is shown with error bars.