[<reference> directory listing other]-> [<input> menu option]
[menu option]-> [<choice> 9. Show more]
[9. Show more] yes ->[Set usage menu number]
[Set usage menu number]-> [<reference> directory listing other]
[9. Show more]-> no [<choice> 10. Show previous]
[10. Show previous]-> yes [Set usage menu number]
[10. Show previous]-> no [<choice> is valid other menu option]
[is valid other menu option]-> yes [send directory listing]
[send directory listing]-> [<reference> complete]
[is valid other menu option]-> no [<reference>exit invalid menu option]