Hi, I'm havving a bad time trying to figure out how to add and log custom keywords using boost/log. I havent been able to understand how exactly attribute keywords (BOOST_LOG_ATTRIBUTE_KEYWORD) bind with logging e.g. using BOOST_LOG_STREAM_WITH_PARAMS(logger, (??) (??)). For instance, if I define a keyword line_number, BOOST_LOG_ATTRIBUTE_KEYWORD(line_number, "LineNumber", unsigned int) and add it to the formmater logging::formatter formatter = expr::stream << "[" << line_number << "]" How do I use BOOST_LOG_STREAM_WITH_PARAMS(logger, (??)) Tanking an exemple from the severities, I should use a keyword parameter defining something like BOOST_PARAMETER_KEYWORD(sometag, line_number) then I should be able to use BOOST_LOG_STREAM_WITH_PARAMS(logger, (line_number = 10)) But those things just don add up together. I for sure missing the logics of the logging ... Thanks for any help! Cheers, mc