If b is not zero, and the 3D texture coordinate mode is enabled (see USEXYZTEXCS, 6.4.26), local object coordinates are first transformed into world coordinates, which afterwards are transformed into the coordinate system of the next node in the path to the root of the scene graph, containing the USEABSXYZTEXCS attribute.
If b is zero, local object coordinates are used as 3D texture coordinates.
b must be a number node.