Hi, I tried the RTL library from the Vault. If I try to compile the example (EarthCoord) I get following errors: compiling test_rtl.cpp (g++) /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp: In member function 'void boost::rel::expression_registry_traverse_functor::operator()(R&, boost::rel::cover_tag) const': /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp:122: error: '<anonymous>' has incomplete type /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp:99: error: forward declaration of 'struct boost::rel::cover_tag' /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp: In member function 'void boost::rel::expression_registry_traverse_functor::operator()(R&, boost::rel::cache_tag) const': /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp:196: error: 'tag' has incomplete type /opt/boost/include/boost-1_33_1/boost/rtl/expression_registry.hpp:98: error: forward declaration of 'struct boost::rel::cache_tag' make[2]: *** [test_rtl.o] Error 1 regards, Oliver