Hi, I am serializing a bunch of object that contains boost.units quantities. Boost.Units provides serialization for quantities already. By default, the output file looks ok but I would like to add a class name to the object description. Current, serializing quantity<si::length> q produces: <q class_id="0" tracking_level="1" version="0" object_id="_0"> <value>5</value> </q> Which doesn't give any information about the quantity at hand, not even for the human reading it. So, I tried to use BOOST_CLASS_EXPORT_GUID to register a name for the serialized class, but it is ignored. Ideally I would like to have something like this, with a class_name description for example: <q class_id="0" class_name = "quantity_si_length" tracking_level="1" version="0" object_id="_0"> <value>5</value> </q> Is something like this possible? Below is the working code: #include <fstream> #include <boost/serialization/export.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/units/systems/si/io.hpp> using namespace boost::units; BOOST_CLASS_EXPORT_GUID(quantity<si::length>, "quantity_si_length") //ignored int main(int argc, char *argv[]) { std::ofstream ofs("filename.xml"); boost::archive::xml_oarchive oa(ofs); quantity<si::length> q = 5.*si::meter; oa << BOOST_SERIALIZATION_NVP(q); return 0; }