I've just committed Boost.Proto v4 to trunk (http://svn.boost.org/trac/boost/changeset/48079). This version is represents a significant reworking from the version that was reviewed and accepted back in April. Although the code is quite stable now, I have not yet integrated all the feedback about the documentation. It is my intention to bring the docs up to Boost standards in time to get Proto into 1.37. I am leaving the old version of Proto at boost/xpressive/proto for the time being, since some other projects (Xpressive, Spirit2 Qi and Karma) are relying on it. It will be removed at the earliest opportunity. I've also updated the proto.zip archive in the Boost file vault and uploaded the latest docs to: http://boost-sandbox.sourceforge.net/libs/proto/doc/html/index.html Thanks, -- Eric Niebler BoostPro Computing http://www.boostpro.com