ρ0−ωInterference

The structure of ${\rho }^0-\omega$ interference is discussed. Applications are made to photoproduction of $3\pi$ states, ${\pi }^{+}{\pi }^{-}$ production in electron-positron colliding beams, as well as in other processes, and lepton-pair photoproduction. The various parameters that appear in all these experiments are discussed, and the correlations of the various results are pointed out.