Linked behavior between the datasets combined in this work. a) Fe/H vs R_co. b) Fe/H vs F_NIR. c) F_NIR vs R_co. d) v2/v1 vs F_NIR. The red curve shows a parametric model of the decrease of F_NIR with increasing size of an inner cavity (see text for details). The three disk categories identified in the multi-dimensional parameter space are illustrated to the bottom. Dust is shown in yellow, and we mark the approximate location of infrared CO emission. Dust depletion is shown as a thinner yellow layer of residual dust, and dust layers that dominate the observed F_NIR are marked in red. GII disks are shown as magenta squares, high-NIR GI disks as green triangles, low-NIR GI disks as cyan (empty) triangles.