Ring 0 is one of the privilege levels[?] in which an x86 processor can operate at any time. The others are rings 1[?], 2[?] and 3[?]. Of these most of the operating systems including Linux use only two levels, namely Ring 0 and Ring 3. Ring 0 is the highest privilege level and is the level at which the operating system kernel runs (kernel mode). Ring 3 is the lowest privilege level and is the level at which user applications are run.
... Indian Reservation[?]
Kaibab Indian Reservation[?]
Fort Mojave Indian Reservation[?]
Colorado River Indian Tribes[?]
Chemehuevi Indian Reservation[?]
Fort Yuma Indian ...