Ratio of the truncation radius to the first disc scalelength (R_break/h_d1) as a function of the logarithm of the ratio between the disc scalelengths (h_d1/h_d2). This plot visually separates Type II galaxies (green dots) from Type III galaxies (magenta dots). The error bars are directly extracted from the uncertainties on the parameters obtained during the surface brightness profile fitting process.