Int 6F Fn 11  - 10net - Lock Fcb                                           [N]

   AH = 11h
   AL = mode
       01h sequential
       02h random
       03h random block
       CX = number of records
   DS:DX -> FCB (see INT 21/AH=0Fh)

Return:    CF clear if successful
   CF set on error
       AX = error code (see also AH=00h)
       0002h file not found

See Also: AH=12h