The following is the overall license for the boost date_time library. This notice is found in all source files related to the library.
Copyright © 2002 CrystalClear Software, Inc.
Permission to use, copy, modify, distribute and sell this software
and its documentation for any purpose is hereby granted without fee,
provided that the above copyright notice appear in all copies and
that both that copyright notice and this permission notice appear
in supporting documentation. CrystalClear Software makes no
representations about the suitability of this software for any
purpose. It is provided "as is" without express or implied warranty.