function IsFileName(FileName: String): Boolean;
const ForbiddenChars = ['"', '<', '>', '|', '*', '/', '\', '?']; // verbotene Zeichen

const ForbiddenNames: Array[0..22] of String[6] = ('AUX', 'NUL', 'PRN' ,'CON', 'CLOCK$', // verbotene Namen
'COM1', 'COM2', 'COM3', 'COM4', 'COM5', 'COM6', 'COM7', 'COM8', 'COM9',
'LPT1', 'LPT2', 'LPT3', 'LPT4', 'LPT5', 'LPT6', 'LPT7', 'LPT8', 'LPT9');

var i: Integer;
var p: PChar;
var FileNameU: String;
begin
Result := False;

  if FileName <> '' then // Name darf nicht leer sein
  begin
    i := Length(FileName);

    if FileName[i] <> '.' then // letze Zeichen darf kein Punkt sein
    begin
      p := Pointer(FileName);

      repeat if p^ in ForbiddenChars then
        Exit;
        inc(p);
      until p^ = #0;

      if (i < 7) and (i > 2) then
      begin
        FileNameU := UpperCase(FileName);
        for i := 0 to High(ForbiddenNames) do
        begin
          if CompareStr(ForbiddenNames[i], FileNameU) = 0 then
          Exit;
        end;
      end;

    Result := True;
  end;
  end;
end;