Follow-up on the different behavior of the blue and red (G^B and G^R in the text) groups defined from the total B − V color histogram in Fig. 7. The marker coloring is self-evident, except in the scale length (h_r) and central surface brightness (μ₀) scatter plots, where the filled and open circles correspond to disk parameters defined over 24 ≲ μ_B ≲ 26, and 26 ≲ μ_B ≲ 28 mag arcsec^-2, respectively. The black/red diamonds are UM461 and UM500, which belong to G^R but deviate in many of the plots. M_B is the absolute B band luminosity integrated down to r_H in Vega magnitudes. The Hβ equivalent width is taken from Terlevich et al. (1991). The Hα/Hβ ratio, corrected for Galactic extinction, is estimated from the SDSS spectra where such existed.