That is the old, incomplete documentation for my old, outdated RangeEx library. There is a newer, better RangeEx library in the Boost File Vault here: http://www.boostpro.com/vault/index.php?directory=Algorithms

Be sure to get Neil Groves' "range_ex.zip" and not my "old_range_ex.zip".

This is not (yet) an official part of Boost, but it's in the review queue. I don't know if the documentation is online anywhere.