Texture Render Job renders a rendertarget into an image that can be used by other render targets. This is a workaround for the limitation that Octane can render only one rendertarget at a time and there is also no system in place to render rendertargets as inputs of other rendertargets. Users have to run the texture render job first prior to using its result in a meaningful way.
Figure 1: A typical usage of the Texture Render Job in the Node Graph Editor pane