.NLIST
	.TITLE	VD     - VIRTUAL DISK PREFIX FILE
;
; MODIFIED:   10-APR-80
;
;	L. M. FRASER  FOR RSX11M-PLUS V1.0
;
	LD$VD	= 0	; DEFINE FOR A LOADABLE DRIVER
	V$$D11	= 16.	; CREATE 16 UNITS
;
;	GET UCB OFFSETS.
;
	.MCALL	UCBDF$		;DEFINE UCB OFFSETS
	UCBDF$
;
; DEFINE ADDITIONAL UCB OFFSET.
;
U.NXT	== U.PRM		; EXTENSION BLOCK ADDRESS
U.UFD	== U.PRM+2		; SAVED FILE DIRECTORY NAME
;
; DEFINE EXTENSION BLOCK OFFSETS.
;
X.OFF	= 0			;DISK FILE OFFSETS
X.UCB	= X.OFF+4		;NEXT UCB ADDRESS
X.FLG	= X.UCB+2		;EXTENSION FLAGS
X.FNB	= X.FLG+2		;FILENAME BLOCK
X.LGTH	= X.FNB+36		;LENGTH OF EXTENSION BLOCK
;
; DEFINE EXTENSION FLAG BITS
;
XF.RON	= 1			;ALLOW ONLY READ ACCESS

	.LIST