2n+ 1 rungs. Such an assignment yields an index one current graph with current group
Z12n+ 7 that generates an orientable face 2-colorable triangular embedding of the complete
graph K12n+ 7 or, equivalently, an orientable biembedding of two cyclic Steiner triple
systems of order 12n+ 7. We use our characterization to construct Skolem sequences that
give rise to such current assignments. These produce many nonisomorphic orientable …