Comment by int_19h

Perforce is broadly similar to SVN in semantics, and the same branching logic applies to both. Basically if you have the notion of long-lived main branch and feature branches (and possibly an hierarchy in between, e.g. product- or component-specific branches), you need to flow code between them in an organized way. Forward/reverse integration simply describes the direction in which this is done - FI for main -> feature, RI for feature -> main.