CALL_USER
     Calls a program written in another language from within DECTPU.
     CALL_USER parameters are passed to the external program exactly as you
     enter them; DECTPU does not process them in any way.
  Syntax
     string2 := CALL_USER (integer, string1)
  Parameters
     integer    The integer passed to the external program by reference.
     string1    The string passed to the external program by descriptor.
  Note:  For an example of how to use CALL_USER with a BASIC program, see
         the DEC Text Processing Utility Manual.