Tb.          Tb.
                     :256b.        256.
                     :256256b.      :256256b.
                     :256256256b     :256256256b
                      256256256     256256256
                      256256256256b    :256256256
                      :256256256256b---^256256256256b
                      :256256256256        ^Tb
                       256256256256256b    __...__