[Boost-users] [tr1/config] portably including unordered_<X>

It appears that includes the native when Boost.config says it's able. So if one were writing a portable library that uses boost (or bug-fixing an existing boost component), would including be the way to bring it in, or should one look at BOOST_HAS_TR1_UNORDERED_SET and make a decision that way? There's no mechanism analogous to BOOST_HAS_HASH / BOOST_HASH_<X>_HEADER that has to be navigated, right?