I had previously proposed that we tag the minimum C++ standard level for Boost libs by adding information to the json meta information in libraries.json for each library. I would like to revisit that proposal, which involved more elaborate suggestions, with this simpler overall proposal: for each Boost C++ library whose minimum C++ standard level is C++11 or above we add a json field called 'cxxstd' whose value corresponds to one of the same values as currently exists in Boost.Build for the 'cxxstd' feature, ie. 11,14,17,20, to the libraries.json file for that library. This json value can then be used in Boost documentation of each library to specify the minimum C++ standard level needed by an end-user in order to use that library. Obviously we can also add "cxxstd": "03" for the many Boost libraries which can still be used at the C++98/C++03 compilation level also, even though I would argue that not having a "cxxstd" json field should mean C++98/C++03 by default. I would be willing to create the necessary PRs for each library, as I have a pretty good internal list of this information. The gist of this proposal is to make it much easier for end-users wishing to use a Boost library to immediately know whether the library they wish to use is usable at the C++ standard compilation level they are using for compilation, without having to spend time searching for such information, which is often not readily available, in the documentation of the library they are considering. I can go ahead and start doing this now, but of course I am willing to listen to what others think about this. But let's not let another round of inertia stop doing at all what should be a simple means of telling end-user's whether a Boost library is at least minimally usable by them in their C++ projects.