http://blogs.msdn.com/vbertocci/archive/2005/02/18/376276.aspxScatter list of new or (IMHO) notable features of the 2005 version of WS-ReliableMessaging . Overall I'd say that it changed very little, promising symptom of maturity of the specification. Elements at the header level are now called "header block" Exampleen-USCommunityServer 2.1 SP1 (Build: 61025.2)