http://developers.de/blogs/damir_dobric/archive/2008/12/31/forward-compatible-data-contracts.aspxWindows Communication Foundation (WCF) data contract system is that contracts can evolve over time in nonbreaking ways. That is, a client with an older version of a data contract can communicate with a service with a newer version of the same data contractenCommunityServer 2008 SP1 (Build: 30619.63)