An analysis of the sub-layers for the 2-block H∞-optimal control problem is made in this paper. The sub-layers are characterized by a 2-block H∞ control problem through the concept of the diagonalizing matrix pair. This matrix pair is constructed from the modified 1-block H∞-optimal control problem and its maximal Schmidt pair. The optimal H∞-norm of the sub-layers which can possibly be attained is independent of any different optimal solution.
