The Bills of Material (BOM) screen shows all of your finished goods and assemblies with associated materials and/or routings (labor). This screen also has options to update the standard cost of your purchased materials with the weighted average cost from purchases and a BOM Cost Rollup which will allow you to quickly and automatically total the costs from all materials and routing labor for all of you manufactured items.
The "Standard Cost Update" feature under the Manufacturing | Bills of Material screen will allow you to update the Standard Cost of purchased materials using the current Weighted Average Cost.
The "Cost Rollup" feature under the Manufacturing | Bills of Material screen allows you to update the Standard Cost of Manufactured items based on the materials and labor specified for the item.