3DS- Max saves files in a proprietary Binary format; the specification is not public.
The actual content of the file is heavily dependent on the plug-in data used t obuild the scene, thus attempting to parse the file outside 3ds max makes little sense (although some data fragments can be extracted) the file format supports certain Windows Shell features line thumbnails, and user info in the header of the file which can be displayed by explorer in a tooltip. The data portion of the file can be optionally compressed using built-in ZIP compression (which means attempts to parse it will need to detect when that compression is used as well as be able to decompress it properly before trying to parse the inner data structures).
If you really need access to the data, you could write a MAXScript that runs within 3ds max.
