Relation between T_S   iii and T_O   iii temperatures inferred from the [S iii] and [O iii] auroral-to-nebular line ratios for the objects studied by PM06, including the three Hii galaxies later observed by H06. The light gray dashed line depicts the locus of equal temperatures (T_S   iii = T_O   iii), while the solid line indicates the error-weighted least-squares fit to the data (see Sect. 2).