if S.startswith("[") and not S.startswith("[FV."):
            if not S.startswith("[CAPSULE.") \
                and not S.startswith("[VTF.") and not S.startswith("[RULE."):
                raise Warning("Unknown section or section appear sequence error \n(The correct sequence should be [FD.], [FV.], [Capsule.], [VTF.], [Rule.]) At Line ", self.FileName, self.CurrentLineNumber)
            self.__UndoToken()