Fractional contributions larger than 1% to the total F production (modulated at 700 MV) as a function of rigidity. The top panel shows the ranking for CR element progenitors, while the bottom panel shows more details via the ranking of the one-step and two-step channels (reaction paths linking one isotopic progenitor to a CR isotope). The ‘>2’-step channels (not shown) contribute to a total of ∼10%, with about half of this number originating from the multi-step fragmentation of the Fe isotopes. In both plots, contributions starting from the same element share the same colours and line styles.