The Basic Breed Standard as Approved by the AKC on April 12, 1966
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General Appearance
A compact, neat, well proportioned, long-haired toy terrier.  The blue and tan coat is to be parted on the face, and down from the base of the skull to the end of the tail, hanging evenly and very straight down both sides of the body.  A high head carriage and self-confident attitude give an appearance of vigor and importance.
Head
To be small and rather flat on top, the skull is not to be domed.  The muzzle is to be fairly short and proportionate, the bite is to be either scissors bite or level. neither undershot nor overshot and teeth sound. A scissors bite or a level bite is accepted. The nose is black. Eyes are medium in size and not too prominent; dark in color and sparkling with a sharp, intelligent expression. Eye rims are dark. Ears are small, V-shaped, carried erect and set not too far apart.
Body
Well proportioned, compact. The back is rather short, the top-line level; height at shoulder the same as at the rump.
Legs and Feet
Forelegs are to be straight; elbows neither in nor out. Hind legs straight when viewed from behind; stifles moderately bent when viewed from the side. Feet are round with black toenails. Dewclaws are generally removed from hind legs, and may be removed from forelegs as well.
Tail
Docked to medium length.  Carriage is slightly higher than the level of the back.
Coat
Quality, texture and quantity of coat are of utmost importance. Glossy, fine and silky hair is to be moderately long and perfectly straight (not wavy) on body. To give ease of movement and a neater appearance, It may be trimmed to floor length, if desired. The hair on the head is long; tied in the middle of the head with one bow, or parted down the middle and tied with two bows. Hair on muzzle is very long. Hair should be trimmed short on tips of ears and may be trimmed on feet to give them a neat appearance.
Colors
Young puppies are black and tan and normally have a darker body color than adults.  There may be an intermingling of black hair with the tan until maturity.
In adults, coloring is of utmost importance, to which the following color requirements apply:
Blue: Dark steel-blue; not silver-blue and not mixed with fawn, bronzy or black hairs.
Tan: Tan hairs are to be darker at the roots, gradually lightening to a light tan at the tips.  No sooty or black hair should be interspersed with the tan.
Color on Body
The blue color is to extends from back of neck to root of tail. Hair on tail is an even darker blue, especially at the end.
Headfall
Rich, golden tan; deeper in color along the sides of head, at base of ears and on the muzzle, with ears being a deep and rich tan.  The tan color should not extend down back of neck.
Chest & Legs
Should be a bright, rich tan, not extending above the elbows nor above the stifles.
Weight
Must not exceed seven pounds.
American Kennel Club