Tests contents of X and Pop's stack. Then, if X was zero (or False), returns program flow to the line following the most recently executed GoSub instruction.
If a return is attempted when there was no matching GoSub, the SPLat development environment reports an error and the SPLat hardware resets.
This instruction has the alias (alternative name) RetIfF
See also Return, RetIfNZ, RetIfT, RetIfF, Gosub, GoSubIfZ, GoSubIfNZ, GoSubIfT, GoSubIfF