Log(S/O) as a function of 12+log(O/H) (left) and the ionisation degree, O²⁺/O (right), for H II regions or SFGs of the DESIRED-E sample having both S⁺ and S²⁺ abundances. Panels in the same row of the figure represent log(S/O) ratios calculated using the ICF(S) scheme by Amayo et al. (2021, top panels), Izotov et al. (2006, middle panels) and Dors et al. (2016, bottom panels). The dotted red line represents the mean value of the log(S/O) obtained using each ICF(S). The orange diamonds indicate the mean log(S/O) values considering bins in 12+log(O/H) or O²⁺/O. The black dashed lines and the grey bands show the solar 12+log(O/H) and log(S/O) ratios and their associated uncertainties, respectively, from Asplund et al. (2021).