[ GiDlist ] How to mesh the facets of a parallelepiped mirro

[Dr. Alex Brailovsky]

I'm using GID-5 to mesh a parallelepiped with tetrahedrons. I need the
surface meshes on the side surfaces to be like mirrors of each other. In
other words, each edge on the side surface should have its mirror image
on the opposite side surface. Is it possible to do?
Thanks,
Alex.