Custom File Streams

3ds Max Scene files provide the ability to store custom user data that persists with the file. Available in 3ds Max 2019 and higher. In MAXScript, this functionality is exposed in the CustomFileStream and CustomSceneStreamManager interfaces. The CustomSceneStreamManager loads and caches all persistent CustomFileStream objects from the current 3ds Max scene file on load, and saves them on file save (with some exceptions, see "Flag Values" in the CustomSceneStreamManager topic for more information). CustomFileStream objects are identified by a unique case-sensitive name of up to 31 characters.

The CustomFileStream interface can be used to query and write data streams from other (not currently loaded) 3ds Max scene files.

Note: Custom File Stream functionality is exposed in the 3ds Max SDK, but does not depend on any 3ds Max components. This means you can write applications to read and write custom data to 3ds Max scene files independent of 3ds Max. The MAXScript exposure does depend on 3ds Max.