The results of determination of block elements proposed in [1][2][3][4] mainly for boundary value prob lems with constant coefficients give the methods of their construction, from which it is possible to see the close relation of these elements to a particular bound ary value problem. This circumstance induces the problem on a possible restriction of using block ele ments that have their origin in particular boundary value problems.In this paper, we present results describing the rela tion between the block elements for different bound ary value problems, which show that important rela tions can exist between the block elements of these boundary value problems. The listed set of properties of block elements enables us to use them more widely in various fields.1. The possibilities of the block element method are displayed by its use in a number of polytypic prob lems presented below.In [1][2][3][4], the concept of a block element is intro duced, and a number of examples of particular block elements are given for certain boundary value prob lems. It is shown that the block elements are deter mined by the boundary value problem and can always be constructed for an unambiguously solvable bound ary value problem formulated for a set of partial dif ferential equations of a finite order with constant coef ficients in the region with a piece smooth boundary [5][6][7]. They also can be constructed for the boundary value problems with variable coefficients admitting the separation of variables [8].In the general case of the boundary value problems with variable coefficients, their region of formulation of the boundary value problem is divided by a mesh for using the block element method. The mesh should be so dense that it could be possible to consider the coefficients in a division cell as constant [1][2][3][4]9].A certain practice of applying the block elements shows that their use simplifies the formulation of a number of boundary value problems and also the con struction of their solutions. For example, the block element method makes it possible to solve the bound ary value problems for homogeneous and inhomoge neous sets of partial differential equations in a similar way [7]. For its use, it is unnecessary to construct indi vidually the general solutions of homogeneous differ ential equations and the partial solutions of inhomo geneous equations with the subsequent fulfillment of boundary conditions. In the unsteady boundary value problems, the block element method raises both the edge boundary conditions for sets of partial differential equations and the initial conditions of a boundary value problem [10] to the rank of boundary condi tions; i.e., the initial conditions in the block element method become the boundary conditions. The block element method makes it possible to consider the same boundary value problems in the bounded, semi bounded, and unbounded regions.The block elements enable us to simplify the deri vation of certain important characteristics of the solu tion.For example, the block elements describe t...