The energy spectrum of the decay pions in τ+ decay was obtained from a sample of 17 898 events. It is found that the spectrum is adequately fitted by a squared matrix element of linear form, |M|2~1+ατ×(MKQmπ2)Y, with ατ=0.131+/-0.008. No evidence for CP noninvariance is found for τ+/- decays. A significant violation of the ∆I=12 rule is observed for K+-->3π decays. Comparison with several theoretical models for K-->3π decays shows fair agreement between experiment and theory.