modeling new and archival resolved millimeter observations, we have made an improved characterization of the planetesimal belt within the debris disk surrounding the HR 8799 planetary system. This broad emission belt spans from $\sim100-360$ AU, roughly consistent with previous modeling of the spectral energy distribution [@su09] and fitting far-infrared emission images [@matthews14]. The 1.3 millimeter interferometric dataset from SMA and ALMA together recovers the bulk of the disk flux and provides high angular resolution, and we used this combined dataset to fit for basic structural parameters. We next consider implications. In particular, we examine the belt geometry constraints in the context of coplanarity and alignment of the planetary system (§\[sec:geometry\]), the relationship between the belt inner edge and the outermost planet b (§\[sec:planetmass\]), ramifications of the radial surface density profile for collisional excitation mechanisms (§\[sec:stirring\]), and the millimeter spectral index connections to debris disk collisional models (§\[sec:spectralindex\]).

System Geometry {#sec:geometry}
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The model fits to the millimeter emission provide new estimates of the inclination and orientation of the planetesimal belt that can be compared directly to constraints on the orbital elements of the planets. Formation of planets in a thin disk will generally lead to orbital coplanarity and alignment, unless 