BOM is used as a data base to identify the many parts and their codes in automobile manufacturing companies. A bill of materials "implosion" links component pieces to a major assembly, while a bill of materials "explosion" breaks apart each assembly or sub-assembly into its component parts. A modular BOM (or variant parts list) can be displayed in the following formats: A single-level BOM (or unit list) that displays the assembly or sub-assembly with only one level of children. Thus it displays the components directly needed to make the assembly or sub-assembly. An indented BOM (or structural parts list) that displays the highest-level item closest to the left margin and the components used in that item indented more to the right. Modular (planning) BOM A single-level BOM resolved to list the effectively needed quantities of components to produce a product (rather than to list each individual part by its logical name) is also called quantity synopsis parts list. A BOM can also be visually represented by a product structure tree, although they are rarely used in the workplace. For example, one of them is Time-Phased Product Structure where this diagram illustrates the time needed to build or acquire the needed components to assemble the final product. For each product, the time-phased product structure shows the sequence and duration of each operation. Configurable BOM A configurable bill of materials (CBOM) is a form of BOM used by industries that have multiple options and highly configurable products (e.g. telecom systems, data-center hardware (SANS, servers, etc.), PCs, cars). The CBOM is used to dynamically create "end-items" that a company sells. The benefit of using CBOM structure is that it reduces the work-effort needed to maintain product structures. The configurable BOM is most frequently driven by "configurator" software, however it can be enabled manually (manual maintenance is infrequent because it is unwieldy to manage the number of permutations and combinations of possible configurations). The development of the CBOM is dependent on having a modular BOM structure in place. The modular BOM structure provides the assemblies/sub-systems that can be selected to "configure" an end-item. While most configurators utilize top-down hierarchical rules syntax to find appropriate modular BOMs, maintenance of very similar BOMs (i.e., only one component is different for various voltages) becomes highly excessive. A newer approach, (bottom-up/rules-based structuring) utilizing a proprietary search engine scheme transversing through selectable componentry at high speeds eliminates the planning