All invoices and packing slips contain special bar codes which enable fast and efficient order processing. When you work with a postal delivery company such as DHL or FedEX, you can scan bar codes, without having to type their 13-digit code.
You can manage bar codes through TOOLS > Bar code in the left menu of the back office. This is a very easy process. Move the cursor with your mouse to the bar code field, click it and subsequently use your bar code scanner to scan the bar code in question, only once. The system itself is capable of verifying that an invoice is involved and will connect you automatically to the correct data. These may also be entered manually. Download the bar codes here and the manual here.