I was kinda hoping I could construct a std::map with default data objects, then use serialization to overwrite some of the their member variables. Unfortunately serialization completely replaces the map's data objects. I see in 'collections_load_imp.hpp' what I presume is code to do what I want but it is commented out: template<class Archive, class Container, class InputFunction, class R> inline void load_collection(Archive & ar, Container &s){ // if(0 != (ar.get_flags() & boost::archive::no_object_creation)) // copy_collection<Archive, Container>(ar, s); // else rebuild_collection<Archive, Container, InputFunction, R>(ar, s); Is there any chance that copy_collection will work one day, or has it been abandoned? --- Peter Whaite.