INT 2F CU - NETWORK REDIRECTOR (DOS 4+) - LOCK/UNLOCK REGION OF FILE
        AX = 110Ah
        BL = function
            00h lock
            01h unlock
        CX = number of lock/unlock parameters (0001h for DOS 4.0-6.1)
        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:  this function is called by the DOS 4.0+ kernel
        the redirector is expected to resolve lock conflicts
SeeAlso: AX=110Bh,INT 21/AH=5Ch

Format of parameter block entry [array, but currently limited to single entry]:
Offset  Size    Description
 00h    DWORD   start offset
 04h    DWORD   size of region

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