Int 2F Fn B711  - DOS 4+ Append - Set Return Found Name State              [-]

   AX = B711h

Note:  if the next INT 21h call (and ONLY the next) is function 3Dh, 43h, or
   6Ch (also 4B03h and 4Eh if /X active), the fully qualified filename is
   written over top of the filename passed to the INT 21h call.  The
   application must provide a sufficiently large buffer.  This state is
   reset after the next INT 21h call processed by APPEND.
BUG:   DOS 4.0 APPEND reportedly overwrites DS:DX instead of DS:SI for
     INT 21/AH=6Ch

See Also: INT 21/AH=4Eh