All the value based traits in this library conform to MPL's requirements for an Integral Constant type: that includes a number of rather intrusive workarounds for broken compilers.

Purely as an implementation detail, this means that true_type inherits from boost::mpl::true_, false_type inherits from boost::mpl::false_, and integral_constant<T, v> inherits from boost::mpl::integral_c<T,v> (provided T is not bool)