The Gosub command will instruct the current program to call to a specified label.
Gosub LAB1 : LAB1: I = 3 Return
A label can be set with a colon (:) to specify a point for GoTo or GoSub to begin execution.
Labels cannot use reserved keywords, numbers, or include blank spaces.
The following labels are not permitted:
Ladder: 'Reserved keyword 123: 'Number. About 10: 'Blank space.