INT 2fH b711H: Set APPEND.EXE Truename Flag

                                                         Compatibility: 4.0+ 
 Expects: AX    b711H
 Returns: CF    Carry Flag clear (NC) if no error
    Info: This is an oddball.  When you call this fn, it sets a one-shot
          APPEND internal flag which affects what happens on the next call
          to any of:

            3dH    (open file via handle)
            4300H  (get file attribute)
            4eH    (find file)
            6cH    (extended file open/create)

          Each of these DOS fns require an ASCIIZ filespec as a parameter.
          When the Truename flag is set, APPEND overwrites the input
          parameter with the full and actual name of the file.  It then
          resets the internal Truename flag.

          You must be sure to that the filespec parameter you pass to those
          DOS fns has plenty of unused space at the end.  APPEND may expand
          that filespec to as large as 79 bytes (a 2-byte d:, 64-byte
          \path, and a 12-character filename.ext and a terminating byte of

   Notes: This service is available only if APPEND.EXE is loaded.  If you
          just want a flexible way to obtain a fully-qualified
          d:\path\filename.exe (given an ambiguous or partial filename),
          you might try using the undocumented DOS Fn 60H: Query TrueName.

See Also: INT 2fH b7xxH: APPEND.EXE Functions
          INT 2fH: Multiplex Interrupt
          DOS Functions