https://svn.boost.org/trac10/ticket/12793 <p> Intervals in the ICL containers (set or map) are sorted based on exclusive_less_than. The documentation barely mentions it. AFAIAC this mechanism should be documented extensively (e.g. with nice pictures what happens when overlap) since it drives the ICL library for a large extend. Also lower_bound and upper_bound algorithms are driven by this compare function. Note that ICL does offer a compare functor in its interface but this one is not used in the underlying used set or map. </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/12793 Trac 1.4.3