  We update the numerical results for the s-wave pi pi scattering phase-shift
difference delta_0^0 - delta_0^2 at s = m_K^2 from a previous study of isospin
breaking in K to 2 pi amplitudes in chiral perturbation theory. We include
recent data for the K_S to pi pi and K^+ to pi^+ pi^0 decay widths and include
experimental correlations.
