THESE ROUTINES WERE DESIGNED TO ALLOW A FORTRAN PROGRAM TO
GET ACCESS TO THE ASSEMBLY LANGUAGE MACROS WHICH INTERFACE
TO FCS.  IT IS ASSUMED THE USER IS FAMILIAR WITH THE 
IAS/RSX-11  I/O OPERATIONS REFERENCE MANUAL.  THE USER SHOULD
READ THIS MANUAL CAREFULLY.  THE USER SHOULD ALSO PAY ATTENTION
TO THE APPENDIX IN THE BACK OF THE MANUAL WHICH DETAILS THE
CONTENTS OF THE FILE DESCRIPTOR BLOCK (FDB).
	IN USING THESE SUBROUTINES THE USER ALLOCATES A 128 BYTE
ARRAY IN HIS FORTRAN PROGRAM TO HOLD THE FDB.  THE SUBROUTINES
USE THIS ARRAY AS THEIR FDB WHEN CALLING THE FCS MACROS.
THUS THE FORTRAN PROGRAMMER HAS COMPLETE ACCESS TO EVERY 
PARAMETER THAT FCS KEEPS IN THE FILE DESCRIPTOR BLOCK.
THE FCS MACROS ALSO RETURN A VALUE TO A TWO WORD I/O STATUS BLOCK.
THE "INIT" SUBROUTINE MODIFIES THE F.BKST FIELD IN THE FDB SO THAT
THE ADDRESS OF THE I/O STATUS BLOCK POINTS TO BYTES 124-128 OF
THE FDB ARRAY.  THUS THE FORTRAN PORGRAMMER CAN EXAMINE BYTES 124-128
OF THE FDB TO SEE WHAT FCS PLACES IN THE I/O STATUS BLOCK AFTER
EACH I/O OPERATION.
	THE USER SHOULD PAY PARTICULAR ATTENTION TO THE FOLLOWING
LOCATIONS IN THE FDB.
F.RTYP	RECORD TYPE BYTE
F.RATT	RECORD ATTRIBUTE BYTE
F.RSIZ	RECORD SIZE BYTE

THE "HOW OPEN CODE" FIELD IS COMPOSED OF TWO BYTES, RACC AND FACC
THEY ARE FOUND IN THE FDB.

F.RACC	RECORD ACCESS BYTE.  BIT 0 THROUGH 3 OF THIS BYTE DEFINE
	THE RECORD-ACCESS MODES.

	BIT 0 =1 TO INDICATE READ$/WRITE$ MODE (FD.RWM); OTHERWISE
	IT IS 0 TO INDICATE GET$/PUT$ MODE
	
	BIT 1 = 1 TO INDICATE RANDOM-ACCESS MODE (FD.RAN) FOR GET$/PUT$
	RECORD I/O;  OTHERWISE, IT IS 0 TO INDICATE SEQUENTIAL ACCESS
	MODE.

	BIT 2 = 1 TO INDICATE LOACATE MODE (FD.PLC) FOR GET$/PUT$
	RECORD I/O; OTHERWISE, IT IS 0 TO INDICATE MOVE MODE.

	BIT 3 = 1 TO INDICATE THAT PUT$ OPERATION IN SEQUENTIAL MODE
	DOES NOT TRUNCATE THE FIELD (FD.INS); OTHERWISE, IT IS 0
	TO INDICATE THAT PUT$ OPERATION IN SEQUENTIAL MODE TRUNCATES
	THE FILE.

F.FACC	FILE-ACCESS BYTE.  THIS BYTE INDICATES THE ACCESS PRIVILEGES
	FOR A FILE.

	BIT 0 = 1 IF THE FILE IS ACCESSED FOR READ ONLY (FA.RD).
	
	BIT 1 = 1 IF THE FILE IS ACCESSED FOR WRITING (FA.WRT).

	BIT 2 = 1 IF THE FILE IS ACCESSED FOR EXTENDING (FA.EXT).

	BIT 3 = 1 IF A NEW FILE IS BEING CREATED (FA.CRE); OTHERWISE
	IT IS 0 TO INDICATE AN EXISTING FILE.

	BIT 4 =1 IF THE FILE IS A TEMPORARY FILE (FA.TMP).

	BIT 5 = 1 IF THE FILE IS OPENED FOR SHARED ACCESS (FA.SHR).

	IF BIT 3 ABOVE IS 0;

	BIT 6 = 1 IF AN EXISTING FILE IS BEING APPENDED (FA.APD).

	IF BIT 3 ABOVE IS 1;

	BIT 6 = 1 IF NOT SUPERSEDING AN EXISTING FILE AT FILE-
	CREATE TIME (FA.NSP).

				RESPECTIVELY SUBMITTED

				PHILIP H. CANNON
				SCIENCE APPLICATIONS, INC.
				SUITE 901
				1211 W 22ND STREET
				OAKBROOK, IL.

						60521

				(312)-655-5960