“…Its facets and vertex figures are tesselations of tori by squares, 15 2 squares per facet, 9 2 squares per vertex figure. More succinctly, using the notation of Section 10C of [11], P 4 is a quotient of the universal 2 T (15,0), (9,0) Note that the universal polytopes of type {{4, 4} (a,b) , {4, 4} (c,d) } have been classified, except for those where b = d = 0, and a and c are distinct odd integers (see [11] for details). This theorem therefore addresses one of the exceptional cases, as does the next.…”