Flavor symmetry and decays of charmed mesons to pairs of light pseudoscalars

New data on the decays of the charmed particles $D^0$, $D^{+}$, and $D_s^{+}$ to pairs of light pseudoscalar mesons $P$ allow the testing of flavor symmetry and the extraction of key amplitudes. Information on relative strong phases is obtained. One sees evidence for the expected interference between Cabibbo-favored and doubly Cabibbo-suppressed decays in the differing patterns of $D^0\to K_{S,L}{\pi }^0$ and $D^{+}\to K_{S,L}{\pi }^{+}$ decays.