As ε 2T is obtained from Monte Carlo, differences between **data** and Monte Carlo give rise to systematic uncertainties. Several components contribute to this systematic uncertainty:  • There is a systematic uncertainty related to the extrapolation of the 15-bin yield to the full result, due to our limited knowledge of the φ spectrum in B decays. Since only about 60% of B meson decays are well understood (see Section II), mismodeling of the remaining 40% can affect the result.