penguin amplitude interferes with tree-amplitude contributions, notably in $B^+ \to \pi^0
    K^+$ and $B^0 \to K^+ \pi^-$, a CP-violating asymmetry can occur up to the maximum allowed by the ratio of the tree to penguin amplitudes’ magnitudes. This asymmetry, estimated to be about 1/3 in Ref. [@fsi], is not yet excluded by experiment [@CLEOasy]. The enhancement of the penguin amplitude by the intrinsically non-perturbative charm rescattering mechanism seems to fall outside the purview of the essentially perturbative approach of Ref. [@BBNS], so we would not expect to encounter it in that treatment.

The charm rescattering model for suppression of $\pp \to \rho \pi$ and related decays has no [*a priori necessity*]{} for the final state phase to be large [@Suz01]. Additional evidence for such a large final-state phase in closely related processes would be the presence of large direct CP-violating symmetries in $B^+ \to \pi^0 K^+$ and $B^0 \to K^+
\pi^-$, with similar expected asymmetries for the two processes [@Ciu; @KLS; @comb; @MN]. Since the process $B^+ \to \pi^+ K^0$ is not expected to have a tree contribution, we expect it to have a much smaller CP-violating asymmetry. Present data [@CLEOasy] are consistent at the level of 10–20% with vanishing 