I found what seems to be an inconsistency in ptr_map in version 1.34.1 versus 1.33.1. The "reference" typedef in 1.34.1 does not appear to be a reference. The following code illustrates what I mean: typedef std::map STDMAP; typedef boost::ptr_map PTRMAP; bool isrefstdmap = boost::is_referenceSTDMAP::iterator::reference::value; bool isrefstdbase = boost::is_referenceSTDMAP::reference::value; bool isrefptrmap = boost::is_referencePTRMAP::iterator::reference::value; bool isrefptrbase = boost::is_referencePTRMAP::reference::value; In version 1.33.1 all bool values equate to true, while in 1.34.1 ptr_map evaluates to false. In case the compiler makes a difference, I'm using VC++ 2005. -- Bill Buklis --