Breeders who show rabbits tattoo them in the ear. Tattooed rabbits may or may not be registered with the ARBA. They really don't mean anything to anyone other than the breeder. It's just a form of ID for a particular rabbit. When you enter them into a show, you enter the tattoo number for judges to use as ID.
In the US ... ARBA requires a tattoo in the left ear to show. The right ear will contain a tattoo or "R" when the rabbit has been registered through ARBA. The right ear is also used at ARBA nationals to write the coop number in Sharpie marker. The animal is then ID on the show table by the coop number not the tattoo number ... stops judges from putting up an animal they may have seen or put up before ... the first in a class, BOV, BOSV, BOS, & BOB animals will have their tattoo verified. I have a friend who tattoos sold animals with a different ID ... she will write in the ear if they are sold as pets, brood, or if they have a disqualification she will tattoo DQ! Had one come back on the table with a DQ. It was sold as brood with the understanding it would not be shown... when the judge read the tattoo # he discovered he had missed a DQ! The rabbit was rechecked and disqualified for both an incorrect tattoo (according to the entry form) and the white nails! OOPS!