  The paper focuses on solving one class of Volterra equations of the first
kind, which is characterized by the variability of all integration limits.
These equations were introduced in connection with the problem of identifying
nonsymmetric kernels for constructing integral models of nonlinear dynamical
systems of the "input-output" type in the form of Volterra polynomials. The
case when the input perturbation of the system is a vector function of time is
considered. To solve the identification problem, previously introduced test
signals of duration h (mesh step) are used in the form of linear combinations
of Heaviside functions with deviating arguments. The paper demonstrates a
method for obtaining the desired solution, developing a method of steps for a
one-dimensional case. The matching conditions providing the desired smoothness
of the solution are established. The mesh analogs of the studied integral
equations based on the formulas of middle rectangles are considered.
