The Input nodes can build custom Node Graphs. Figure 1 shows a custom Node Graph that contains a MaterialThe representation of the surface or volume properties of an object. In input node. This input is available when you're navigating back out of the custom Node Graph and up to the top level of the OctaneRender® material (Figure 2).
Figure 1: A Material In node is added to a custom Node Graph
Figure 2: The custom Node Graph now has an available Material In input pin