  We have performed a search for CPT violation in neutral charm meson
oscillations. While flavor mixing in the charm sector is predicted to be small
by the Standard Model, it is still possible to investigate CPT violation
through a study of the proper time dependence of a CPT asymmetry in right-sign
decay rates for $D^0\to K^-\pi^+$ and $\d0b\to K^+\pi^-$. This asymmetry is
related to the CPT violating complex parameter $\xi$ and the mixing parameters
$x$ and $y$: $A_{CPT}\propto{\rm Re} \xi y-{\rm Im} \xi x$ . Our 95% confidence
level limit is $-0.0068<{\rm Re} \xi y-{\rm Im} \xi x<0.0234$. Within the
framework of the Standard Model Extension incorporating general CPT violation,
we also find 95% confidence level limits for the expressions involving
coefficients of Lorentz violation of $(-2.8<N(x,y,\delta)(\Delta a_0 + 0.6
\Delta a_Z)<4.8)\times 10^{-16}$ GeV, $(-7.0<N(x,y,\delta)\Delta a_X<3.8)\times
10^{-16}$ GeV, and $(-7.0<N(x,y,\delta)\Delta a_Y<3.8)\times 10^{-16}$ GeV,
where $N(x,y,\delta)$ is the factor which incorporates mixing parameters $x$,
$y$ and the doubly Cabibbo suppressed to Cabibbo favored relative strong phase
$\delta$.
