For testing purposes, I installed .Net Framework 4 Client Profile. My tests ended and I was to uninstall it, in order to install .Net Framework 4 full. The uninstaller told me to uninstall .Net Framework 4 extended first.
I've already found it and uninstalled, but the question remains: What is .Net Framework 4 extended?
It's the part of the .NET Framework that isn't contained within the Client Profile. See MSDN for more info; specifically:
The .NET Framework is made up of the .NET Framework 4 Client Profile and .NET Framework 4 Extended components that exist separately in Programs and Features.
Got this from Bing. Seems Microsoft has removed some features from the core framework and added it to a separate optional(?) framework component.
To quote from MSDN (http://msdn.microsoft.com/en-us/library/cc656912.aspx)
The .NET Framework 4 Client Profile does not include the following features. You must install the .NET Framework 4 to use these features in your application:
* ASP.NET * Advanced Windows Communication Foundation (WCF) functionality * .NET Framework Data Provider for Oracle * MSBuild for compiling