Temperature and magnetic field best-fit parameters (see Table 3) for different magnetic regions on M dwarfs which are probed by five groups of spectral species. T_mag and f_I are obtained from fitting Stokes I profiles only; B is from fits ofStokes I and V together; f_V is from fits to Stokes V only; for the atoms, T_phot = T_mag (see text for details). To avoid overlaps, some symbols are slightly shifted in the horizontal direction. Uncertainties of the parameters are indicated as thin-line crosses in each panel. The linear fits in panel c are described in Sect. 5.4.