ITM Content needs an unique ID.

For non-product listed ITM Content, this code goes in the "Code" field in the "Item" tab of the ITM Properties Dialog.

For product listed content, the ITM needs an "ID"  column added to the Product List.

This "ID" links to the "ID" in ProdInfo to pull in the data. It can also link to Labor and Price data if you're using Product Listed tables (as opposed to breakpoint tables).

For the product listed content, when you place a "size" from the product list, the ID automatically gets updated in the "Code" field that you use for non-product listed ITMs.