--- Douglas Gregor
Every Boost library has its own license agreement for users. However, minimum requirements for that license agreement are specified at http://www.boost.org/more/lib_guide.htm#License, which specifies in part that each library's license agreement (with the user)
"Must grant permission to copy, use and modify the software for any use (commercial and non-commercial) for no fee. "
So every Boost library grants permission _to the user_ to copy, use, and modify the software for any use for free. Libraries with more restrictive open-source licenses (e.g., the GNU Public License), are _not_ eligible for inclusion in Boost because they do not meet the Boost license requirements (one of which is "Must not require that the source code be available for execution or other binary uses of the library").
So in your example, using the Boost libraries does _not_ require you to open-source your application or library, because no Boost library is allowed to require that.
Thanks so much for the clarification. Noel __________________________________________________ Do You Yahoo!? Yahoo! Health - your guide to health and wellness http://health.yahoo.com