I'm finding an apparent dependency between some non-serialization headers and the use of BOOST_CLASS_EXPORT. If boost/optional.hpp or boost/format.hpp or boost/bind.hpp are included before BOOST_CLASS_EXPORT is used then I get the compilation error: [C++ Error] export.hpp(210): E2102 Cannot use template 'boost::type<T>' without specifying specialization parameters [C++ Error] export.hpp(210): E2293 ) expected If they are included after then everything's ok. This is BCB 5.6.4. This precludes me having optional/bind/format in a precompiled header and also means it's a bit tricky ensuring the correct inclusion order for a large project. Richard ========================================== Here's the code to demonstrate it: #pragma hdrstop #include #include #include #include #pragma link "libboost_serialization-bcb-mt-d-1_33.lib" // !! These can't be included here //#include //#include //#include class A { public: template <class ArchiveT> serialize(ArchiveT & ar, unsigned int) { }; }; BOOST_CLASS_EXPORT(A) // Including here is ok #include #include #include #pragma argsused int main(int argc, char* argv[]) { boost::optional<int> SomeValue; A InstanceOfA; return 0; }