INT 2F U - NETWORK REDIRECTOR (DOS 4+) - LOCK/UNLOCK REGION OF FILE
AX = 110Ah
BL = function
00h lock
01h unlock
DS:DX -> parameter block (see below)
ES:DI -> SFT
SFT DPB field -> DPB of drive containing file
SS = DOS DS
Return: CF set on error
AL = DOS error code (see INT 21/AH=59h)
Notes:  called by DOS 4.0+ kernel
the redirector is expected to resolve lock conflicts
SeeAlso: INT 21/AH=5Ch

Format of parameter block:
Offset  Size    Description
00h    DWORD   start offset
04h    DWORD   size of region

See also: 2F110B

2F110A - NETWORK REDIRECTOR (DOS 4+) - LOCK/UNLOCK REGION OF FILE