The VSTS version control system has the concept of "binding" and "unbinding" with visual studio solutions that is referenced frequently in error messages that I've come across while testing - but since IMO it's hard to understand the error messages without understanding the terms, here's some pre-release documentation covering the topic courtesy of the UE team:

http://msdn2.microsoft.com/library/0eh3790h(en-us,vs.80).aspx