INTEGER FUNCTION SUBSWTCH(CMDLINE,CMDPTR,SLEN)
C
C THE PURPOSE OF THIS FUNCTION IS TO RETURN A VALUE OF 0 IF
C NO SUBSWITCH IS PRESENT, OR A POSITIVE VALUE IF ONE IS PRESENT
C
C THE FUNCTION UPDATES THE CMDPTR TO THE FIRST CHARACTER OF THE SUBSWITCH,
C IF PRESENT. THE REMAINING SWITCH LENGTH IS ALSO RECOMPUTED.
C
	BYTE
     *		CMDLINE(81)
	INTEGER
     *		CMDPTR,
     *		SLEN

	SUBSWTCH = INDEX(CMDLINE(CMDPTR),':',1,1)
	IF(SUBSWTCH .GT. SLEN)SUBSWTCH = 0
	CMDPTR = CMDPTR + SUBSWTCH
	SLEN = SLEN - SUBSWTCH
	RETURN
	END