Hello, During using library 'program_options' we noticed some issues. The first one is that class 'duplicate_option_error' never uses. /** Class thrown when duplicate option description is found. */ class BOOST_PROGRAM_OPTIONS_DECL duplicate_option_error : public error { public: duplicate_option_error(const std::string& what) : error(what) {} }; And the second one which is critical for us. Is that all errors are forming as one sentence in ENGLISH. And it's an issue to get which exception exactly occured to form your own message in your desired language. For instance class - validation_error. I guess it's really hard and inconvinient to get what message should be thrown. So, what will you advise to do to make this library more "international", so all exception messages are put out in any language which programmer wants.