EMP stars having at least one source star model with . Red and green circles denote CEMP ([C/Fe] > 0.7) and C-normal EMP stars, respectively. For evolved EMP stars (log g <  2), [N/H] and log(¹²C¹³C) are shown as light red or green symbols and are considered upper and lower limits, respectively. When available, the correction on the C abundance from Placco et al. (2014a) is taken into account. In this case, the [C/H] ratio before (after) correction is shown by a light (normal) red or green symbol. When available, the observational uncertainty is shown by a black bar. If it is not available, the mean observational uncertainty of the EMP sample (Sect. 3.3) is shown as a grey bar.