This segment contains the BOM structure for the configurable materials. The materials are identified by their instance numbers. This segment also contains the key fields of the BOM item for the components. This ensures that the correct component is read if several BOM items contain the same material.

The PC in order item 10 (instance 00000001) has two diskette drives (instances 00000002 and 00000003) and one documentation package (instance 00000004). The PC in order item 20 (instance 00000005) has one diskette drive (instance 00000006) and one documentation package (instance 00000007). The instances are described in the E1CUINS segments.