6.3.10.1 AK(1:0) (Authentication Key)

These bits define which of the four secret seeds, G₀-G₃, must be used in an authentication to allow access to the user zone if authentication is selected in the corresponding access register. Each access register may point to a unique authentication secret, or access registers for multiple zones may point to the same authentication secret. In this case, authentication with a single secret seed will open several zones.