Spectral type against M_bol (derived from (J−K_S)). Colour indicates the maximum SpT variation observed for each star among the epochs it was observed (see Sect. 3.2 for more details). The samples used here are the same as in Fig. 16, but we have represented only those stars observed on more than one epoch. The black cross represents the median uncertainties. The x-axis scale is the same as in Fig. 16 to ease the comparison. Left a): CSGs from the SMC. Right b): CSGs from the LMC.