We consider an infinite matrix $G$ with nonnegative entries and with all its columns tending to 0. We investigate those properties of $G$ which allow us to express $G$ in the form $$ G=(I+S+S^2+\dots)A\eqno(1) $$ where $I$ is the identity matrix, $S$ is a substochastic matrix and $A$ is a diagonal matrix with positive entries on the diagonal. These properties are 1) $G$ is nondegenerate in a sense, 2) the vector $e$ with all its components equal to 1 is the limit of an increasing sequence of the potentials of nonnegative measures, 3) the principle of domination holds. These properties are also necessary for representation (1).