We construct a free and transitive action of the group of bilinear forms Bil(I ∕ I2[1])
on the set of R–products on F, a regular quotient of an even E∞–ring spectrum R
with F*≅R* ∕ I. We show that this action induces a free and transitive action of the
group of quadratic forms QF(I ∕ I2[1]) on the set of equivalence classes of R–products
on F. The characteristic bilinear form of F introduced by the authors in a
previous paper is the natural obstruction to commutativity of F. We discuss
the examples of the Morava K–theories K(n) and the 2–periodic Morava
K–theories Kn.