function JJMESS( msgnum )
c.		Print, on unit 6, the system message for "msgnum".
c.
c.	This routine provides a way of determining the meaning of
c. the return status from a system call; aborting, if desired, on
c. error messages; and returning the status, as an integer, to
c. the caller.
c.
c.	A convienient way to print the system message and get the
c. status as an integer is by using it to call a system service, e.g.
c.
c.	 	iret= JJMESS( SYS$service(...) )
c.
c.	call JJMESSET( iunit, iaction )
c.		To change the defaults of the JJMESS routine.
c.
C.	iunit   == The output unit (0=no_output) .. Default = 6
C.	iaction == the action to be taken on a message
C.		 0 == Print errors, then return .. Default
C.		+1 == Print all messages
c.		+2 == ABORT, and thus TRACEBACK, If ERROR
c. -end.of.info-
c.
	INTEGER MSGNUM
C------
	CHARACTER MSG*255
C.
	DATA JUNIT/6/, JPRALL/0/, JABORT/0/
C.
C...? OUTPUT THE MESSAGE
C.
	IF( JUNIT.NE.0 .AND.
	1 ( JPRALL.NE.0 .OR. .NOT.MSGNUM )) THEN
C.
	  CALL SYS$GETMSG( %VAL(MSGNUM), ILEN, MSG, %VAL(-1) , )
	  WRITE( JUNIT, 110 ) MSGNUM, MSG(1:ILEN )
110	  FORMAT( 1X, Z8, '=', A )
	ENDIF
C.
C...? ABORT THE PROGRAM
C.
	IF( JABORT.NE.0 .AND. .NOT.MSGNUM ) THEN
C.
	  CALL LIB$STOP( %VAL(MSGNUM) )
	ENDIF
C.
	JJMESS = MSGNUM
C.
	RETURN
C.	.........
C.
C++++++
C.
C.
	ENTRY JJMESSET( IUNIT, IACTION )
C------
	JUNIT = IUNIT
	JPRALL = IACTION.AND.1
	JABORT = IACTION.AND.2
	RETURN
C.	.........
		end