>Just like I have to store the Product Description in the InvoiceDetails table instead of relying on the current description in the Inventory table. Why? Because their distributors are constantly tweaking the descriptions. Sometimes they even change the size without creating a new item number. Wreaks havoc on their inventory control.

Mark,

Again, not a violation of normalization. The two descriptions are NOT the same data. One is "at the time of the transaction" and the other is "current description".