2D histograms of the relative differences between various semi-empirical models currently used to calculate the production cross-sections σ_{b → a}. Our reference model is Webber et al. (2003) (Webber 03), and we compare it to the parameterisations from Webber et al. (1990) (Webber 93), Webber et al. (1998) (Webber 98) and Silberberg et al. (1998) (S&T 00). The charges of the parent and child nuclei are given on the vertical and horizontal axes, respectively. The relative difference in each bin is given by the arithmetic mean over the various isotopes of each element. A detailed view provides the most important channels for the B/C ratio studies. For a fragmentation of ΔZ< 4, we also give the first and second moments of the uncertainty distributions.