1) Support for Borland's C++ Builder 3 was dropped in moving the Regex++ implementation to Boost. Was this dropped because BCB3 can not support Boost, or Regex++, or was it just too much work to get it working with the Boost Regex++ version ? 2) Configuring Regex++ builds. Do I use user.hpp to configure the build, or is this used at the point of usage, or both ? If so, how do I know if BOOST_REGEX_NO_TEMPLATE_SWITCH_MERGE applies to a given compiler, and what does BOOST_REGEX_NO_W32 actually do. Finally what do the locale defines actually do ? Does defining the CPP or C locales constrain the Boost classes to use those locales or is it just setting a default locale which I can switch when instantiating the template classes ?