The original article uses right wing extermism as an example, but the description of the system translates to "constitutional fidelity". So its probably safe to assume that this will be looking for any kind of extremism that could be anti-constitutional. Always important to remember from a german perspective that it was the communists and socialists that held the line of resistance and were some of the first to be oppressed during the rise of the nazi regime, whatever your views on the politics are.