Integration with Other Applications > Windchill Workgroup Manager Documentation > ECAD > Advanced Techniques > Managing BOMs > Using BOM Definitions
  
Using BOM Definitions
Every board and schematic Windchill part has an associated BOM definition. The BOM definition links the part to the appropriate BOM attribute map. Windchill then uses this map to create the correct correspondences between the BOM items as exported by the ECAD application, and their representations in Windchill. In addition, the BOM definition tells Windchill what to do in certain special cases (described below).
To edit a BOM definition, perform the following steps:
1. Check the board or schematic document out to the workspace.
2. Click on the Info icon . The document’s info page opens.
3. From the info page, selectActions > Edit BOM Definition. The BOM Definition page opens.
4. In the Attribute Mapping section, use the Select Definition button to open the search results page. This lists all of the documents that are designated as BOM attribute maps.
5. Find the correct BOM attribute map document, select it, and click OK.
6. In the BOM Validation and Processing section, do the following:
a. Under Design Components with Undefined Part Numbers, use the option buttons to select the action that Windchill performs in the event that it encounters parts with undefined numbers. The options are
Ignore
Assign temporary part numbers automatically
Assign part numbers automatically
* 
These are permanent part numbers. Temporary part numbers have a pre-determined prefix (set by the server-side preference ECAD Temporary Part Number Prefix). The user is expected to change these manually.
Do not generate BOM
b. Under Variants, select the check-box if you want Windchill to retrieve variants from the design data.
7. Click OK.
The BOM Definition is now ready to use.