Start
  first
    task_e1
      task_f1
    task_e2
      task_f2
    task_e3
      task_f3
        struct_synch_merge_1
          excl_choice_1
            return_to_first
  first
    task_e1
      task_f1
    task_e2
      task_f2
    task_e3
      task_f3
        struct_synch_merge_1
          excl_choice_1
            last
              End