Log record (FCB)  (INT 21h, BFh - Novell NetWare 4.6)

        Entry:
          AH = BFh
          AL = flags
                bit 0: lock as well as log record
                    1: non-exclusive lock
          DS:DX -> FCB
          BX:CX = offset
          BP = timeout in timer ticks (1/18 sec)
          SI:DI = length
        Return:
          AL = error code