  If V(R) is the vertex set of a symmetric cycle R in the tope graph of a
simple oriented matroid M, then for any tope T of M there exists a unique
inclusion-minimal subset Q(T,R) of V(R) such that T is the sum of the topes of
Q(T,R).
  If for decompositions Q(T',R') and Q(T",R") with respect to symmetric cycles
R' and R" in the tope graphs of two simple oriented matroids, whose ground sets
have the cardinalities of opposite parity, we have |Q(T',R')|>3 and
|Q(T",R")|>3, then these decompositions satisfy a certain orthogonality
relation.
