in akc registration it is supose to be by main color 2nd 3rd ie white, black,tan or white , black, red but colors are not correctly identified all the time. tan and red , lemon genticical speaking are all the same color so it is the eye of the beholder more than anything else.,
Genetical only bi color is red and white. Black and white does not exist but it is possilble for white to mask all the tan marking in a highly piebold dog