If two “A” registered Savannahs are crossed, “B” registered kittens result. “B” means both parents are Savannahs, but the cat has at least one grandparent of a different breed.
Cross two “B” registered Savannahs and you have a “C” registered kitten. “C,” tells both parents and grandparents are Savannahs, but at least one great grandparent is of a different breed.
When you cross two “C” registered Savannahs, an SBT Savannah kitten results. A kitten with “SBT” in its registration number has three generations of Savannah to Savannah matings in its pedigree – parents, grandparents, great grandparents. It is impossible to have SBT Savannah kittens before the fourth generation. The SBT designation is what is needed to show in Championship Class.
The system can be a bit more complicated, however, since the filial (F) generation i.e., the generation removed from the serval, works independently from the A, B, C, and SBT designations. For example, if you breed an F3 A to an F5 C, you will get an F4 B. And if an outcross was used to breed to any generation, those kittens would be “A.” That is, if an F3 C were bred to an outcross, kittens would be F4 A kittens.