The Collect node is not Octane-specific. It is a Houdini® node used to collect multiple shaders for a single material. It is typically used in the Solaris environment to design shaders for different render engines (OctaneRender ®, Redshift®, Arnold®, etc.). The Collect node is capable of switching shaders depending on which render engine is activated during the rendering process (figure 1).
Figure 1: Arnold, Redshift, Karma, and Octane shaders connected to the Collect node in a MaterialThe representation of the surface or volume properties of an object. Library node