A phantom assembly is a logical grouping of materials. A phantom assembly is usually created within engineering, in order to describe a number of components easily and manage them as a whole. The components in a phantom assembly are placed immediately into the superior assembly. As opposed to this, components in an assembly are first assembled to produce the header material. After this the header material is placed into the superior assembly.
Example: The phantom assembly "set of wheels" contains the components "front wheel" and "rear wheel". The front and rear wheels are placed immediately into the "bicycle" assembly. The "light" assembly contains the materials "bulb" and "reflector". The light components are first assembled and then the light is attached to the bicycle.