The serialization library contains some "utility" components which are necessary to make the library function and no boost components existed at the time - and still don't exist - to perform these functions. These components are: extended_type_info - extention to type_info to permit portable export/import of class id and dyamic loading/unloading of components based on this class id. Also implements this functionality on systems which do not support RTTI void_cast - runtime casting between types identified by extended_type_info above. utf8_codecvt_facet - Ron Garcias original component and documentation. BOOST_STRONG_TYPEDEF - assignes identifiable type to primitives. state_saver - save and automatically restore from copy of a state variable on the stack. Dataflow Iterators - adds templated constructor to boost iterators which permits transparent and powerful compile time iterator composition. Used to implemement a myriad of transforms for character strings. smart_cast automatically selects static cast if possible. If not possible, selects a dynamic cast. BOOST_STATIC_WARNING just like BOOST_STATIC_ASSERT - but just emits a warning. I've been unable to make this work for the most recent Intel compilers. Its possible this might change in the future. singleton - a lock free singleton used to make serialization thread-safe without requiring linkage to the threading library. They are documented as "other classes" in the documentation of the boost serialization library. The serialization library also includes tests of all these components. Some of them have names/namespaces in boost. Last year I was prevailed upon by a small group of developers to change the names/namespaces of those components so that they are not in the boost namespace. I've agreed to do that and expect that this change will occur in boost version 1.37. So, BOOST_STATIC_WARNING will become BOOST_SERIALIZATION_STATIC_WARNING, boost::state_saver will become boost::serialization::state_saver, etc. Robert Ramey