Would you like to add an order reference number to your commercial invoices? You can easily do that via the document designer.

To do so, first navigate to Settings >> Document Designer. Next, select Commerce Invoice and edit the active theme you have.

After that, locate where you would like to show the order reference number. Add a heading there (optional). You can do this by adding a heading element or simply duplicating an existing header and changing the text to what you want.

Finally, add a column beneath the heading and add a Text element to it. With the text selected, click the gear icon, and change the text's merge tag to Purchase Order Ref.

Hit the Save button.

You can follow these same steps to add an order reference number to other commercial documents, such as order confirmation, pick tickets, etc.