AKC Breed Standard
(Information taken from: https://www.akc.org/dog-breeds/yorkshire-terrier/ )
What is a Breed Standard?
The easiest and clearest way to define a breed standard is to read "A Breeder's Blueprint." The foundation of any purebred dog's knowledge, be it a ring champion or a companion, is its standard—a documented account of the ideal representation of the breed. Perfect type, structure, gait, and temperament are described by standards. Not every dog satisfies every requirement of the breed standard. In actuality, the standard is a conception that directs the creativity of individuals who take purebred dog breeding, exhibition, and performance seriously.
About the Breed: