C	CKOVL -- BUILDS .CKO TABLE FILE WHICH CONTAINS THE
C		OVERLAY & MAP FILE DATA
C
C	INPUTS:		MAPFL	MAP FILE SPEC
C
C	OUTPUTS:	.CKO FILE
C			IERR	ERROR FLAG
C			IOVLAY	OVERLAY FLAG
C
C
	SUBROUTINE CKOVL(MAPFL,IOVLAY,IERR)
	BYTE MAPFL(30),REC(132),CKO(30)
	INTEGER IADD,ILGHT,IERR,ALBP2,EXIT1,EXIT2,IOVLAY,IREC
	IERR=.TRUE.
	IOVLAY=.FALSE.
5	ISPOT=LSTRNG(MAPFL,1,30,'.',1,1)
	CALL STRMOV(MAPFL,1,ISPOT,CKO,1)
	CALL STRMOV('.CKO',1,4,CKO,ISPOT)
	CKO(ISPOT+4)="0
	OPEN(UNIT=1,NAME=MAPFL,TYPE='OLD',READONLY,ERR=1000,
     +       ACCESS='SEQUENTIAL')
	OPEN(UNIT=2,NAME=CKO,TYPE='NEW',ACCESS='DIRECT',
     +       ASSOCIATEVARIABLE=IREC,RECORDSIZE=6)
	ISET=0
25	READ(1,10,END=100)NCH,REC
10	FORMAT(Q,132A)
	IF(IOVLAY.EQ..TRUE.)GOTO24
	I1=LSTRNG(REC,1,10,'$$SGD1',1,6)
	IF(I1.LE.0)GOTO24
	DECODE(6,20,REC(27)),IADD
	DECODE(6,20,REC(34)),ILGHT
20	FORMAT(O6)
	IOVLAY=.TRUE.
24	I2=LSTRNG(REC,1,132,'$ALBP2',1,6)
	I3=LSTRNG(REC,1,132,'$EXIT ',1,6)
	I4=LSTRNG(REC,1,132,'$EXIT$',1,6)
	IF(I2.GT.0.OR.I3.GT.0.OR.I4.GT.0)GOTO30
	GOTO25
30	IF(I2.GT.0)GOTO45
42	IF(I3.GT.0)GOTO55
43	IF(I4.GT.0)GOTO65
41	IF(ISET.LT.3)GOTO25
	GOTO50
45	DECODE(6,20,REC(I2+7)),ALBP2
	ISET=ISET+1
	GOTO42
55	DECODE(6,20,REC(I3+7),ERR=25),EXIT1
	ISET=ISET+1
	IF(IOVLAY.EQ..FALSE.)ISET=ISET+1
	GOTO43
65	DECODE(6,20,REC(I4+7),ERR=25),EXIT2
	ISET=ISET+1
	GOTO41
50	IERR=.FALSE.
100	CLOSE(UNIT=1)
	IREC=1
	WRITE(2'IREC)IOVLAY,IADD,ILGHT,ALBP2,EXIT1,EXIT2
	CLOSE(UNIT=2)
2000	RETURN
C
C	MAP FILE NOT FOUND
C
1000	TYPE 1005,MAPFL
1005	FORMAT('$MAP FILE: ',30A1,' NOT FOUND.   ENTER COMPLETE FILE',
     *        ' SPEC>')
	READ(5,1010,ERR=2000)NCH,MAPFL
1010	FORMAT(Q,30A1)
	MAPFL(NCH+1)="0
	GOTO5
	END