SUB OPEN. (F$,A$,C%,SIGNEDZ%)
	{FCSCOM.B4S}
	IF INI%<>-1% THEN CALL FCSINI BY REF \ INI% = -1%
	LSET A.$=CHR$(1%)+CHR$(2%+4%+8%)+CHR$(2%+4%+64%)+CHR$(2%)+CHR$(2%+4%)
	! FO.RD,FO.WRT,FO.APD,FO.MFY,FO.UPD
	CALL C. (C%)
	Z% = ABS%(SIGNEDZ%)
	P% = POS ("RWAMU",A$,1%)
	IF P%=0% THEN PRINT "INVALID OPEN. ACCESS MODE =";A$ \ CALL FCSDIE
	A% = ASCII(SEG$(A.$,P%,P%)) ! access mode in binary
	IF POS(F$,":",1%) THEN DEVICE$ = "" ELSE DEVICE$ = "SY:"
	F0$ = DEVICE$ + F$ + CHR$(0%)
	CALL FCSOPN BY REF (FDBADR%(C%-.ZERO.CNL%),C%,A%,F0$,Z%)
	.DEFINE .F.RSIZ%=2% ! Record size (offset from FDB)
	CALL WORDAT BY REF (FDBADR%(C%-.ZERO.CNL%)+.F.RSIZ%,ZGOT%) ! record size actually got
	IF SIGNEDZ%<0% THEN Z% = ZGOT% \ GOTO 50
	IF ZGOT%=Z% THEN 50
	IF Z%=0% THEN 50 ELSE PRINT "OPEN.WRONG RECORD SIZE" \ CALL FCSDIE
50	SUBEND