Despite how complex a BOM hierarchy can be $($i$.$e$.,$ consider the hierarchy for a jumbo jetliner$),$ all BOMs are stored as simple, single$-$level structures that are then linked to each other; BOMs are not stored as the overall hierarchy.

The structure in Figure $6\mathrm{.}2$ for instance, is stored as three BOMs that are then linked:

The first BOM is for the finished good, with three components $($semi finished good #$1,$ semi$-$finished good #$2,$ and raw material$)$

The second BOM is for semi$-$finished good #$1$ with two components $($raw material #$1,$ and raw material #$2)$

The third BOM is for semi$-$finished good #$2$ with one component $($raw material #$3).$

In the BOM for the finished good, there is a field for each of component materials that indicates if that component has its own BOM.

If the field is set on$,$ it indicates that the component is itself a manufactured item that has its own BOM. The system therefore logically connects the BOM of that component.

If the field is set off, it indicates that the component has no BOM of its own. Thus, the system does not connect a BOM for the component in question.

Suggest why an ERP system would store the product structure of manufactured item as a series of linked, single$-$level BOMs, instead of as one, massive, multi$-$level BOM.

Clue: Consider that sub$-$assemblies can be used in many end$-$products. In a computer manufacturer, the same motherboard assembly can be used in many different computers. In a bicycle company, the same gear assembly can be used in many different bicycles.