Observational aspects of symmetries of the neutral B meson system

We revisit various results, which have been obtained by the BABAR and Belle Collaborations over the last 13 years, concerning symmetry properties of the Hamiltonian, which governs the time evolution and the decay of neutral B mesons. We find that those measurements, which established CP-violation in B meson decay, 13 years ago, had as well established T (time-reversal) symmetry violation. They also confirmed CPT symmetry in the decay (TCPT = 0) and symmetry with respect to time-reversal (ε = 0) and to CPT (δ = 0) in the B0 anti B0 oscillation. (orig.)