  We review recent suggestions for testing through B decays the flavor
structure of CP violation in the Standard Model. Relative signs of CP
asymmetries in U-spin related processes can by themselves test the
Kobayashi-Maskawa mechanism in a crude manner. Ratios of charge-averaged decay
rates and certain CP asymmetries may constrain tightly the weak phases
$\gamma=\phi_3$ and $\alpha=\phi_2$.
