I tend to regard the cap and tan colors nevertheless separately.

When the dog is black, the dog has a dark back with which the black, gray or brown color falls evenly to the sides, forming a so-called "cap." The legs, muzzle, belly are red .The most typical, "classic" cap color is Airedale and Welshterriers, as well as German shepherds, many hounds, bloodhounds, bigles, etc.
Unlike the cap, the tan color has always a distinctly distinct outline. The scorpions have a perfectly defined pattern and are located in strictly defined places. Symmetrical sunspots with clearly defined borders, pure red or red color, strictly defined pattern, without intermediate transitional tones and without marks on them, are located on the cheeks and eyebrows on the man, with a subgamation, with two triangles on the chest, on the inner surface of the shoulders and hips, on the pasterns, metatarsals, paws and around the anus. It is most clearly expressed in Dobermans, Rottweilers, English Cockers, Gordon Setters, some Terriers, and others.
Chep color can vary greatly. In some cases, the dog can be almost black or brown with traces of red on the legs, under the tail and weakly expressed yellow dots over the eyes, which is noted, for example, in American cocks. In others, the cap may be so small that the dog looks almost red with a dark stripe on the back. Such dogs are common among Russian hounds. Sometimes the color of the coat may look almost like a tan.
Tanned and temperamental colors can be formed by a combination of both black and yellow, and brown with yellow pigments. A dog with a strongly reduced brown cap may look just red.

Sparkling color is due to the action of alleles ass, as well as ayas or awas. Tanned color - the action of alleles atat. Dogs carrying cchcch alleles have a white or light gray tan. It should be noted that the question of the presence of individual genes responsible for the development of tan and coloring is controversial. So, for example, K.Little considers chepra color as a result of the joint action of genes of taiga and modifier genes. Robinson, Willis and a number of other authors unequivocally asserted the presence of specific alleles of capricious color. At the moment, a specific allele of stained color is not identified, but the researchers do not deny the presence. Moreover, it is suggested that alleles of this kind may have several effects (S. M. Schmutz, 2005).
Such wide boundaries of variations of the color pattern are also associated with the action of modifier genes. In some breeds that have a solid color, individuals that are strongly masked are found in the breeding. This is occasionally noted, for example, in black terriers, leading their origin from the Airedale and Rottweilers. Dogs - carriers of normal tan color from breeding have long been bred. The frequency of the at gene in their population is reduced to a minimum. Genes of the capricious color, strongly masked by appropriate modifiers, periodically remind themselves of themselves, being cleaved in the homozygous state. Externally, a similar modification of the cap color can be manifested by lightly brightening the ends of the paws, points above the eyebrows and hair around the anus. The constant crossing of such individuals with dogs having solid color promotes the accumulation of modifier genes, which more and more approximate the coloration of the coat to the solid color. At a low frequency, such alleles in the population of such individuals can not be rejected from breeding. Such individuals are noted among schnauzers, German and Eastern European shepherds, etc. Often such individuals are considered as representatives of recessive black color.

In many breeds, both alleles occur. Alleles atat contribute to the development of a normal tan color with a clear pattern. Alleles ass contribute to the development of a modified tan drawing, sometimes accompanied by its strong dimming. Blackened burn marks are noted as a vicious color, even in Dobermanns, which are an example of the "classical tan". Sometimes the drawing of a tan comes down to the clarified ends of the paws, the presence of light points above the eyes and a light spot around the anus. Occasionally, clarified zones begin to be seen only at the age of 2-3 years, so the color of such dogs is sometimes mistakenly defined as black. If such "black" dogs are born from tansy, their color should be considered "tan". Such dogs are noted, for example, among American Cockers, however, it is undesirable to let them into breeding, since the stamping color dominates the tan, and the length of the darkened zones over the red ones. It is quite obvious that the darkened tan should be viewed not as a tan, but as a black color. Thus, the Cockers with any elements of the obscurity of the tans for breeding in tan color are undesirable, if not unacceptable.

COLORFUL COLORING DOGS.
Dogs of black color can have a different pattern on the head. Sometimes it is a dark cap on the head with a dark "arrow" between the eyes, in other cases - darkening on the temples and ears, and sometimes the head remains red. The same applies to the picture on the chest. In some cases, the dogs have a completely black chest, in others - a well-defined collar, in the third - a black pigment on the breast may not be at all.

Some greyhounds, for example, saluki, taigans and Afghans, have a form of black hair that is called "dominoes" among the Afghans. The dog of this variation of color has a more or less distinct chopping pattern of completely defined outlines and a specific pattern of the "reverse mask" on the head and anterior part of the body. In this figure she has clearly outlined light eyebrows, light fashion, light cheeks, as well as the chest and forelegs. This white pattern has nothing to do with white spotting. Its noticeable clarification on the zoned-gray background is due to the influence of cchcch alleles.

At Afghans, "dominoes" can be combined with zone gray, tiger and red color.
Apparently, this color represents either a completely certain modification of the cap color, or it is formed during interaction with alleles of the "reverse mask" rmrm. For the greyhounds of the above breeds, the latest version is most likely.
The genes of different loci, modifying the red color, can help clarify the color of the tan to light gray or white, for example, in the Zverg-Schnauzer, East European Shepherds.