This shader passes a 4-by-4 matrix of real numbers through the render tree and shares the output among other nodes connected to its input channels.
These channels are "dummy" inputs that get called and evaluated, but do not have an effect on the final rendered output in the render tree. The primary purpose of these channel ports is to connect multiple Store In Channel shaders, all of which can share (or rather store) the data passing through the node's main input port. For more information, see Data > Render Channel.
