  Cabibbo-favored nonleptonic charmed particle decays exhibit large final-state
phase differences in $\bar K \pi$ and $\bar K^* \pi$ but not $\bar K \rho$
channels. It is of interest to know the corresponding pattern of final-state
phases in doubly-Cabibbo-suppressed decays, governed by the $c \to d u \bar s$
subprocess. An experimental program is outlined for determining such phases via
measurements of rates for $D \to K^* \pi$ and $K (\rho, \omega,\phi)$ channels,
and determination of interference between bands in Dalitz plots. Such a program
is feasible at planned high-intensity sources of charmed particles.
