Even though the row is indicated by the "first" index and the column by the "second" index, no grouping order between the dimensions is implied by this. The choice of how to group and order the indices, either by row-major or column-major methods, is thus a matter of convention. The same terminology can be applied to even higher dimensional arrays. Row-major grouping starts from the "leftmost" index and column-major from the "rightmost" index, leading to lexicographic and colexicographic (or colex) orders, respectively.