;; Traditional
; Assign an empty string:
var =
; Check that a string is empty:
If var =
   MsgBox the var is empty
; Check that a string is not empty
If var !=
   Msgbox the var is not empty


;; Expression mode:
; Assign an empty string:
var := ""
; Check that a string is empty:
If (var = "")
   MsgBox the var is empty
; Check that a string is not empty
If (var != "")
   Msgbox the var is not empty