Function 17h (23)        Rename File, using FCBs

    Changes all matching occurrences of the first filename in the current
    directory to the second filename.

       On entry:      AH         17h
                      DS:DX      Pointer to an FCB that has been modified to
                                 contain two filenames.

       Returns:       AL         00h       If operation is successful
                                 FFh       If operation is unsuccessful

       Network:       Requires Create access rights

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    This function renames files via a modified FCB that contains the drive
    code and original filename in their usual positions, and has a new
    filename beginning six bytes after the original filename (at offset
    11h in the FCB).

       Notes:         The '?' wildcard character may appear in either the
                      first filename or the second filename. A '?'
                      character in the first filename has the conventional
                      meaning: it is used to find files that match this
                      filespec.

                      A '?' in the second filename has a different effect:
                      It means don't change the corresponding character in
                      matching filenames.

                      This function will not rename a file to that of an
                      already existing filename; in that event, the
                      function will terminate, returning FFh in AL.

                      Read-only files are not renamed by this function.