RMS, slope, and zero point of the different SBCRs presented in Table A.1. The first three figures show the RMS (top left), slope (top right), and zero point (bottom left) as a function of the mean wavelength difference between the two passbands used to calculate the colour of the SBCR. The figure at the bottom right shows the slope as a function of the zero point. In grey are indicated the rejected SBCRs. For the sake of clarity, SBCRs with an RMS greater than 0.04 have been removed from the figures.