The optional input to an AnimGraph or AnimLayer.

When used in an AnimLayer, the input node will evaluate to the result of that layers in the parent graph. The same is the case with a linked AnimGraph. When used with linked AnimGraphs or AnimLayers, the input node may also bring over input variables from the parent graph as defined by the graphs signature.

When used on a post process AnimBP, the input will be the final result evaluated by the root node of the main AnimBP on the mesh.

Otherwise it will evaluate to the reference pose.