Hello Robert, hello all, I know it is stated in the boost::serialization library documentation that per definition always the latest version of a class goes to the archive. I wonder if there is a way to change this behaviour and choose the version number for my class at runtime. Obviously this feature would be useful in a system of two dependent modules where either the producer or the consumer could by updated to a newer version without the other one being neccessarily updated too. Maybe this has already been discussed but I could not find anything about it on the web. However my strong suspicion is that there is no such option within the library and I will have to provide a solution within the affected classes. Another thing: I specialize boost::archive::detail::heap_allocator<T> for my types to use my own memory management :-) Any objection to that? Finally I want to thank Robert Ramey for his fabulous library and his always timely and helpful answers. I think from the user perspective he stands as a positive example for others. Regards, -- Christian Pfligersdorffer EOS Software Engineering