Аннотация
The principle of an invariableness of designations of the basic quantities (30-40 quantities) is the basis for uniform system of letter designations of quantities which should not have synonymous (reserve) designations and must to be used strictly in all disciplines. The table of designations of such main quantities are given. At the same time symbols of the basic quantities are polysemantic and can be used for designation of quantities which were not included into the table of the main quantities. The polysemantic term "amount of substance" is offered to replace by unambiguous term "molarity of substance" or in abbreviated form "molarity" and to input a uniform symbol for this quantity.