The B and P series only affect eumelanin. The B series is known as the Black Series and the P as Pink-Eye Series.
Other genes determine if and how the eumelanin will present on the animal as well as where and what shade the phaeomelanin will be.
B – Normal
b – Chocolate
P – Normal
pg – Partial Pink-Eye (or Pink-Eyed Grey)
p – Pink-Eye