Unique Set ofI=0S-WaveππPhase Shifts

We have found that the forward-backward asymmetry exhibits a very slight ${\Delta }^2$ dependence affording a model-independent extrapolation. When the above method is complemented with a factorization-model analysis, a unique set of $I=0\mathrm{}$ $S$-wave pion-pion phase shifts is obtained, modulo $\pi$. New tests of the absorption model have been made.