Category: <b>DOS kernel</b>
<p>
<pre><b>INT 21 - MS-DOS 7.0+ - GENERIC IOCTL - LOCK PHYSICAL VOLUME</b>

	AX = 440Dh
	CX = 084Bh / 484Bh
	    (category code 08h for FAT12/16, 48h for FAT32; minor code 4Bh)
	BH = logical drive number (00h = default, 01h = A:, etc.)
	BL = lock level (00h-03h)
	DX = drive permissions (see <a href=../../it/75/15.html>#01575</a>) for Level 1 lock or second
	    Level 0 lock when formatting
Return: CF set on error
	    AX = error code (01h,02h,etc.) (see <a href=../../it/80/16.html>#01680</a> at AH=59h/BX=0000h)
	CF clear if successful
Desc:	lock all logical volumes on the same physical volume as the indicated
	  drive
Note:	the physical volume must be locked before direct disk writes via
	  INT 13 are permitted by Windows95
SeeAlso: AX=440Dh"DOS 3.2+",AX=440Dh/CX=084Ah,AX=440Dh/CX=086Bh
SeeAlso: AX=440Dh/CX=086Ch
</pre>