If the retailer or trading partner sends you line items with no barcode, EAN, or supplier item code then you can set your validation rules to handle the retailer code for a particular retailer in The Order Exchange.

Click "Menu" > "Item" > "Retailer Item Codes" 

Using the drop down bar, Select the Retailer (e.g. SPS RSX Test) > From the column "ItemCode" Select the specific line > Click "Edit"

Insert into the "Retailer Item Code" > Select "Update"