Image description: structure of nested programs

This image shows the program structure as follows.


Program-Id. A.
   Program-Id. A1.
      Program-Id. A11.
         Program-Id. A111.
         End Program A111.
      End Program A11.
      Program-Id. A12 is Common.
      End Program A12.
   End Program A1.
   Program-Id. A2 is Common.
   End Program A2.
   Program-Id. A3 is Common.
   End Program A13.
End Program A.

End of image description.