Some characteristics of the used nucleosynthetic AGB models. We show the C/O and ¹²C/¹³C ratio, and the [s/Fe] and [hs/ls] indexes as a function of the number of third dredge-ups the model has undergone. Each third dredge-up episode is represented by a dot or a cross, depending on the nucleosynthetic model, and they are linked for clarity. The model with metallicity Z = 0.001 is shown as connected black dots, while the models with metallicity Z = 0.003 and Z = 0.006 are represented by grey dots and crosses respectively. The values obtained for the stars in our sample are overplotted as horizontal lines in the same colour (black,grey) as their most appropriate nucleosynthetic model. J050632 is represented by a full, black line, J052043 by a dashed, black line, J053250 by a dotted, black line, and J053253 by a full, grey line.