Core Decoration
Core Decoration is the base that every decoration is built on. The Assembly, Surface, Trunk, Clusters and Select decorations each have one inside. It takes the decoration's geometry and settings and packages them as a program that a Grow carries and the Simulate runs once the tree has grown. It also draws the preview while the decoration isn't on a Grow yet.
Core Decoration is hidden from the Tab menu. You only need it to build a decoration of your own; see Custom decorations.
Inputs and settings
Its inputs are geometry, custom_graph and parms. The second passes extra geometry into the decoration's program alongside the first, and the third feeds the decoration's maps. Use Custom Graph switches to the graph set in Custom Graph Override, under Advanced. Preview Skeleton picks the built-in tree it previews on: /trunk (the default), /monopodial or /sympodial. Simulate is the Simulate the decoration belongs to, which is set for you when a Grow carries it. Decoration Name, when its toggle is on, names the decoration's output.
Clusters Decoration
Clusters Decoration bends parts from a library along the branches they sit on, sharing each bent shape between similar branches so the copies stay instances.
Create Proxy
Create Proxy makes a simple stand-in shape for each piece of geometry, such as a box, a hull or spheres. The assembly nodes use it internally; it is hidden from the Tab menu.