[Serialization] Class versioning & upward compatibilty

Hello, is serialization class versioning supposed to allow old versions of a program that serializes an old version of a class to load files saved with a newer version that saves some extra data? It doesn't seem to be able to do it, but it would be a very useful feature. The docs mention the fact that new versions can read old version classes, they don't mention if old versions can load newer versions files. Unless I'm missing something, which is not unlikely, it should be relatively easy to implement, the xml readed should simply skip fields that it doesn't recognize. I'm using XML serialization, boost_1_33_0 dated 28-4-05, Visual C++ 7.1 & 8.0 beta 2. Thanks, Flavio Antonioli.