Hello, I would like to add some diagnostic messages during compile time, potentially enumerating one or more types as well. static_assert is great for simple messages but falls a bit short due to inability to list types and such. I wonder if BOOST_MPL_ASSERT_MSG is the right answer, however, I am getting the following errors: BOOST_MPL_ASSERT_MSG( std::is_base_of<xnode, Node>::value , "requested type is not a node" , (types<node_type>) ); 1>i:\source\kingdom software\cppxml\xml\domain\parts\xnode.h(111): warning C4002: too many actual parameters for macro 'BOOST_MPL_ASSERT_MSG' It's an error message, but not the one(s) I am expecting. Do I need to enable something, preprocessor definition, something like that? Best regards, Michael Powell