5.2 Identifying Program Units
  You can delimit a main program compilation unit with the
  PROGRAM and END PROGRAM statements. This allows
  you to identify a program with a name other than the file
  name. The program name must not duplicate the name of a
  SUB, FUNCTION, or PICTURE subprogram. For example:
  PROGRAM Sort_out
      .
      .
      .
  END PROGRAM

  If you include the PROGRAM statement in your program,
  the name you specify becomes the module name of the com-
  piled source. This feature is useful when you use object
  libraries because the librarian stores modules by their module
  name rather than the file name. Similarly, module names
  are used by the OpenVMS Debugger and the OpenVMS
  Linker.

  For more information about PROGRAM units, see
  Chapter 13.