Does the OpenSceneGraph have a native file format?

From OpenSceneGraph-3.0 onwards we have new native file formats based on generic serializers that are extensible and support forward/backward compatibility, there is a .osgt ascii text file format, .osgx xml format and .osgb binary format. The extensible of the new formats enables end user application to add serializer wrappers for their own classes enabling them to extend the formats for their own application needs.

Prior to OpenSceneGraph-3.0 there were two native file formats, .osg for ascii, and .ive for binary. The .osg format is extensible and flexible but is slower and less compact than the .ive binary format, but the later suffers from not being forwards compatible and is not extensible so is only suitable for scene graphs that aren't extended by end user applications.

(Wiki editing note: is this correct about the .ive format?)