Hi All/Robert, I've been using the enclosed "untracked" wrapper around some things that I've been serializing... but I think I may have been barking up the wrong tree. Does it have any effect? In other words, I suspect that ar << untracked(anyexpression) is equivalent to ar << anyexpression Is that the case? Thanks in advance, -- Dave Abrahams BoostPro Computing http://www.boostpro.com