Definitive from USSR with overprint (Latvia 1991)

Stamp Definitive from USSR with overprint it reflects the thematic directions:

A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying passengers or goods, or in support of specialized missions, such as defense, research and fishing. Historically, a "ship" was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships are generally distinguished from boats, based on size, shape and load capacity.

The mail or post is a system for physically transporting documents and other small packages; or, the postcards, letters, and parcels themselves. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century national postal systems have generally been established as government monopolies with a fee on the article prepaid. Proof of payment is often in the form of adhesive postage stamps, but postage meters are also used for bulk mailing. Modern private postal systems are typically distinguished from national postal agencies by the names "courier" or "delivery service". Postal authorities often have functions other than transporting letters. In some countries, a postal, telegraph and telephone (PTT) service oversees the postal system, in addition to telephone and telegraph systems. Some countries' postal systems allow for savings accounts and handle applications for passports.

The horse (Equus ferus caballus) is one of two extant subspecies of Equus ferus. It is an odd-toed ungulate mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, Eohippus, into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered Przewalski's horse, a separate subspecies, and the only remaining true wild horse. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior.

Railways - Transportation system made up of metal rails which is designed to allow trains to maneuver on the tracks from one location to the next.

Transport or transportation is the movement of people, animals and goods from one location to another. Modes of transport include air, rail, road, water, cable, pipeline and space. The field can be divided into infrastructure, vehicles and operations. Transport is important because it enables trade between people, which is essential for the development of civilizations.

A modern sailing ship or sailship is any large wind-powered vessel. Traditionally a sailing ship (or simply ship) is a sailing vessel that carries three or more masts with square sails on each. Large sailing vessels that are not ship-rigged may be more precisely referred to by their sail rig, such as schooner, barque (also spelled "bark"), brig, barkentine, brigantine or sloop. There are many different types of sailing ships, but they all have certain basic things in common. Every sailing ship has a hull, rigging and at least one mast to hold up the sails that use the wind to power the ship. The crew who sail a ship are called sailors or hands. They take turns to take the watch, the active managers of the ship and her performance for a period. Watches are traditionally four hours long. Some sailing ships use traditional ship's bells to tell the time and regulate the watch system, with the bell being rung once for every half hour into the watch and rung eight times at watch end (a four-hour watch). Ocean journeys by sailing ship can take many months, and a common hazard is becoming becalmed because of lack of wind, or being blown off course by severe storms or winds that do not allow progress in the desired direction. A severe storm could lead to shipwreck, and the loss of all hands. Sailing ships are limited in their maximum size compared to ships with heat engines, so economies of scale are also limited. The heaviest sailing ships (limited to those vessels for which sails were the primary means of propulsion) never exceeded 14,000 tons displacement. Sailing ships are therefore also very limited in the supply capacity of their holds, so they have to plan long voyages carefully to include many stops to take on provisions and, in the days before watermakers, fresh water.

A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from antlers, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls,[not verified in body] in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone.