Where can i get an online document about file format for 3ds max r3?

You can try asking at http://support.discreet.com/ They have messageboards that cover every aspect of 3dsmax.

If you plan on using the .max format then depending on what you want to do you may run into trouble since the max format mainly stores adresses to the different plugins and its parameters...or something like that. Since basicly all shapealtering animation etc are based on modifiers then you could probably choose one of the other availble formats. Like vrml or ase that translates the scene into something that makes sense outside max.

DX8 comes with a plugin for 3DS Max that allows you to export meshes in their .x file format. This format is well documented.