...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
A bitmask type (C++ Std [lib.bitmask.types]).
typedef unspecified flags;
Header: boost/asio/ip/resolver_query_base.hpp
Convenience header: boost/asio.hpp