The minimal Hilbert bases of the polyhedral cone of 8 x 8 Franklin squares and 8x8 pandiagonal Franklin squares were computed using the software MLP (now called 4ti2) (see [13]; software implementation 4ti2 is available from http://www. 4ti2.de). Let (r,, ry) denote the operator that acts on the space ofnxn matrices by interchanging rows / and j of each matrix, and let (c,, c}) signify the corresponding operator on columns.