The question arises: are these orientation permutations chemically meaningful? Looking at the PESs for the three examples of chemical implementations of the AB4 T-4 E-mode configuration space, it is clear that each shows a network of local minima separated by saddle points of modest energies. Despite the high energies and bond-breaking behaviour at and near the symmetric linear SL-4 polytopes, depending upon the chemical elements involved, orientation permutations between the lowenergy configurations are feasible and hence chemically relevant.