The BOM (bill of materials) entries in a BOM register are the result of the following: posting of a BOM journal and batch jobs such as Adjust Exchange Rates and Post Inventory Cost to G/L.
Every register shows the first and last entry numbers of its entries. You can see the entries by choosing Register, then Item Ledger or Resource Ledger.
A BOM is a combination of several items, which are shown in the BOM Component table. Since only one entry appears in the BOM register for every BOM, the entry represents several other entries. You can see these other entries in the Item table. There is an entry for every one of the BOM components as well as for the BOM itself in the Item Ledger Entry table.
The BOM entry thus involves one or more negative adjustments to inventory, and these can be seen in the Item Ledger Entry table. There is a negative adjustment to inventory for each of the BOM's components and a corresponding positive adjustment for the BOM itself.
The BOM entries can be seen in the BOM Ledger Entry table.