Int 21 Fn 440D  - Ms-dos 7.0 - Generic Ioctl - Unlock Logical Volume       [D]

   AX = 440Dh
   CX = 086Ah (category code 08h, minor code 6Ah)
   BL = drive number (00h=default,01h=A:,etc)

Return: CF set on error
       AX = error code (01h,02h,etc.) (see #1366 at AH=59h/BX=0000h)
   CF clear if successful

Note:  the logical volume must be locked before direct disk accesses via
     INT 13 are permitted by Windows95

See Also: AX=440Dh"DOS 3.2+",AX=440Dh/CX=084Ah,AX=440Dh/CX=086Bh