These terms refer to the Registration Codes given to our cats by Feline Registry TICA. They define a Savannah cat generation and generations of its parents. Codes A, B, C or SBT are used for this purpose.
A-registered Savannahs are Savannahs with only one Savannah parent, usually the Savannah mother and a domestic outcross sire (such as one of permissible outcross breeds – Egyptian Mau, Ocicat, Oriental Shorthair or Domestic Shorthair), for instance, F2A Savannah or F3A Savannah. Therefore all F1 Savannah cats are A-registered as one of their parents is a Serval.
B-registered Savannah is one in which both parents are Savannahs, but not all grandparents are Savannahs. For instance, crossing an A-registered Savannah to another A-registered Savannah will give you a B-registered kitten.
C-registered Savannah is when all four grandparents are Savannahs, or two generations of Savannah to Savannah breeding. Crossing a B-registered Savannah to another B-registered Savannah will give you C-registered Savannah offspring.
SBT means that parents, grandparents and great-grandparents are all Savannahs. It is at the SBT (Stud Book Tradition) level that the Savannah is considered a true breed and potentially eligible for Championship with TICA.

According to the TICA breed standard, in the savannah breeding except for serval and savannah cats, only males of Egyptian Mau, Ocicat and domestic shorthair cats and Oriental Shorthair cats may be used.
However, regardless that the Savannah breed was recognized in TICA in 2001 and the standard for savannah cat is already accepted, the breed has continued to evolve to the present day...