👉 In a hierarchy or classification system, an "echelon" is a type of row in a matrix. It refers to a specific arrangement of columns within a matrix that allows for efficient calculation and manipulation of data. An echelon matrix is a square matrix with all its non-zero entries on the main diagonal (the first column), and these elements are arranged in rows from left to right, first increasing in value by 1, then decreasing in value by 1.