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: