Format of current directory structure (CDS) (array, LASTDRIVE entries):
Offset	Size	Description	)
 00h 67 BYTEs	ASCIZ path in form X:\PATH (local) or UNC form
		  \\SERVER\PATH (network, see notes below)
 43h	WORD	drive attributes (also see note below) (see also AX=5F07h)
		bit 15: uses network redirector	 \ invalid if 00, installable
		bit 14: physical drive		 / file system if 11
		bit 13: JOIN'ed	  \ path above is true path that would be
		bit 12: SUBST'ed  / needed if not under SUBST or JOIN
		bit 11: removable media (WinNT4.0)
		bit 10: hard disk??? (WinNT4.0)
		bit  7: remote drive hidden from redirector's assign-list and
			  exempt from network connection make/break commands;
			  set for CD-ROM drives by MSCDEX (not supported by
 45h	DWORD	pointer to Drive Parameter Block for drive
		  (see #01395 at AH=32h)
---local drives---
 49h	WORD	starting cluster of current directory
		0000h = root, FFFFh = never accessed
 4Bh	WORD	??? seems to be FFFFh always
 4Dh	WORD	??? seems to be FFFFh always
---network drives---
 49h	DWORD	pointer to redirector or REDIRIFS record, or FFFFh:FFFFh
		(DOS 4 only) available for use by IFS driver
 4Dh	WORD	stored user data from INT 21/AX=5F03h
 4Fh	WORD	offset in current directory path of backslash corresponding to
		  root directory for drive
		this value specifies how many characters to hide from the
		  "CHDIR" and "GETDIR" calls; normally set to 2 to hide the
		  drive letter and colon, SUBST, JOIN, and networks change it
		  so that only the appropriate portion of the true path is
		  visible to the user
---DOS 4.0+ ---
 51h	BYTE	(DOS 4 only, remote drives) device type
		04h network drive
 52h	DWORD	pointer to IFS driver (DOS 4) or redirector block (DOS 5+) for
		  this drive, 00000000h if native DOS
 56h	WORD	available for use by IFS driver
Notes:	the path for invalid drives is normally set to X:\, but may be empty
	  after JOIN x: /D in DR DOS 5.0 or NET USE x: /D in older LAN versions
	normally, only one of bits 13&12 may be set together with bit 14, but
	  DR DOS 5.0 uses other combinations for bits 15-12: 0111 JOIN,
	  0001 SUBST, 0101 ASSIGN (see #01644)
	Windows for Workgroups 3.11 network sets the path to the local
	  drive and directory even for network drives; in that case the
	  UNC form \\SERVER\SHARE can be obtained with INT 21/AX=5F02h
	  or INT 21/AX=5F46h. LapLink RemoteAccess does the same even for
	  INT 21/AX=5F02h
	Window NT 4.0 always uses X:\PATH, even for substituted drives (i.e.
	  the CDS will *not* contain the original path prior to SUBST)
	SoftWindows on the Macintosh PowerPC sets \\E for the host drive
SeeAlso: #01644,INT 21/AX=71AAh/BL=00h