At the Kona meeting two weeks ago, the C++ committee accepted most of the Diagnostics changes proposed in N2415. See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2415.html Most of Boost.System doesn't change since it already reflects N2415. The committee did, however, change the name of the nested "posix" namespace to "posix_error". For consistency, that means the "Linux" namespace changes to "linux_error" and the "windows" namespace changes to "window_error". As a consequence, the "linux_error" enum changes to "linux_errno". To minimize code breakage, I've added namespace aliases to error_code.hpp: # ifndef BOOST_SYSTEM_NO_DEPRECATED namespace posix = posix_error; # endif # ifndef BOOST_SYSTEM_NO_DEPRECATED namespace Linux = linux_error; # endif # ifndef BOOST_SYSTEM_NO_DEPRECATED namespace windows = windows_error; # endif That was sufficient to prevent any code breakage in the Boost.System and Boost.Filesystem test code, but any user code that actually mentions the linux_errno enum (rather than its constants) will have to be changed. --Beman