Residuals from the best-fitting j − M laws at fixed M. The case of no offset from the best-fitting relation is represented with a dashed black line, while the grey band shows the scatter of the relation. Left and right panels include, respectively, the disc scale length (see Table 1) and the gas fraction as colour-coded third parameters. The main conclusions from this figure are that at fixed M_* galaxies with a higher j_* have larger R_d, and at fixed M_bar galaxies with lower f_gas have a lower j_bar.