• Store Products in a separate hierarchy.

  • Item stores a Product key.

  • To find an Item's Product, do a lookup in the Product hierarchy using the Product key stored in the Item.

  • Now there are three different kinds of navigation:
    1. Down the hierarchy (e.g. Customer to Order)
    2. Up the hierarchy (e.g. Order to Customer)
    3. Across the hierarchy (e.g. Item to Product)