Futurebasic/Language/Reference/on expr gosub

Description
This statement calls one of the subroutines indicated by a  or a , according to the value of. If  equals 1, then the subroutine at   or  is called; if   equals 2, then the subroutine at   or   is called, and so on. If  is less than 1, or greater than the number of   's and   's in the list, then the   statement does nothing.