  Direct CP violation beyond the standard model can be produced in charged D
decays to final states with a $K_S$ by small new physics contributions to the
transitions $D^+ \to K^o X^+$, where $X^+$ denotes any positively charged
hadronic state or transitions $D^+ \to K^o \bar K^o K^{(*)+}$, where $K^{(*)+}$
denotes any positive strange state. These transitions are doubly-Cabibbo
suppressed and color suppresed in the standard model and branching ratios are
experimentally observed to be suppressed by two orders of magnitude relative to
the allowed $D^+ \to \bar K^o X^+$ or $D^+ \to \bar K^o \bar K^o K^{(*)+}$,
branching ratio. An even smaller new physics contribution might produce an
observable CP asymmetry in $D^\pm \to K_S X^\pm$ or $D^{\pm} \to K_S K_S
K^{(*)\pm}$ decays. Since such asymmetries are easily checked in the early
stages of any charm production experiment, it seems worth while to check them
before the opportunity is lost in later stages of the analysis, even if no
theoretical model predicts such an asymmetry.
