Fourteen-cluster classification of the noiseless spectra, with the mean spectra (in black) and their dispersion (in grey) for every class. N is the number of members in each class. All the spectra were normalised by their mean values between 505 and 581 nm, a region where the spectra have no emission lines. The scale is the same for all panels and all other figures of spectra throughout this paper. The dispersion corresponds to the 10% and 90% quantiles for each monochromatic flux. The classes are sorted by ascending average T_main.