 DivX, Inc. did this on purpose to keep at least partial backward compatibility with AVI, so that players that do not support the new features available to the .divx container format (like interactive menus, chapter points and XSUB subtitles) can at least play that primary video stream (usually the main movie if the DMF file contains multiple video streams like special features like bonus materials).Of course, the DivX codec and tools like Dr. DivX still support the traditional method of creating standard AVI files.Since version 5.0 of DivX, the FourCC (identifying code) for the DivX MPEG-4 Part 2 codec is DX50.