"If you write code that depends upon these macros, you should be aware that because they are subject to the needs of Boost library developers, small changes are occassionally made which could affect your code. The best way to keep up to date is to monitor discussions on the Boost devlopers list."
I quite dislike "up to date," and can offer various other changes:
Boost libraries are implemented using various configuration macros defined in boost/config.hpp. While Boost library users are not required to include that file directly, or use those configuration macros, such use is acceptable. The configuration macros are well documented as to their purpose, usage, and limitations which makes them easy to use by both Boost library and user code.
Note, however, that the configuration macros are written expressly for the needs of the Boost libraries, not user code, so they can change at any time (though no gratuitous changes are made to them). Boost library problems resulting from changes to the configuration macros are caught by the Boost regression tests, so the Boost libraries are updated to account for those changes. By contrast, Boost library user code can be adversely affected by changes to the macros without warning. The best way to keep abreast of changes to the macros used in user code is to monitor the discussions on the Boost developers list.
I like all of those suggestions, cvs will be updated soon, Thanks! John.