A pair of inbred parental lines (P1 and P2) that differ in the trait of interest and marker genotypes are crossed to produce an F1 generation. All crosses are then derived from these lines. Backcrossing to P1 is encoded by B1, and to P2 by B2. Selfed intercrosses of generation i are encoded by SFi. Randomly mated intercrosses of generation i are encoded by RFi. Recombinant inbreds created by selfing have the code RI1, while those by sib-mating are RI2. Doubled haploids have the code RI0. A test cross of an SFi line to a Pj line is encoded by T(Bj)SFi. The QTL Cartographer manual explains some other crosses that are possible. Note that the UNIX shell may interpret ( and ) so they should either be quoted, or the cross entered into the interactive menu.
Rcross uses the general genetic model developed by Cockerham (1954).