Dynamical stability of the RZ Dra system as a function of the semi-major axis, a, and eccentricity, e of RZ Dra (AB) D, for the solution presented in Yang et al. (2010). The nominal best-fit orbit for RZ Dra (AB) D presented in that work is located in the center of the red box, at a = 23.88 AU and e = 0.287. The 1σ uncertainties on the semi-major axis and eccentricity are shown by the red crosshairs radiating from the box. The lifetime at each of the 1681 a − e locations plotted in this figure (41 unique a and e values spanning ± 3σ from the nominal best-fit orbit) is the result of 75 distinct simulations, spanning 5 unique values of mean anomaly, M, and 15 unique values of the argument of periastron, ω. The mean lifetime can be seen to vary between ≃100 and ≃1600 years, demonstrating that the system as proposed in Yang et al. (2010) exhibits extreme dynamical instability. (Color version online.)