An F1 is a first generation Maine Coon foundation cat. This cat is preferably found in the wild or on a farm. None or only one parent of an F1 is known and registered. An F2 is a second generation Maine Coon foundation cat where both parents are known and registered. An F3 is a third generation Maine Coon foundation cat where both parents and both grandparents are known and registered. An F4 is a fourth generation Maine Coon foundation cat – and so forth.