This is a read-only list of purchase orders, where you will have the ability to open the purchase order directly from the form.
By Default this will only show Outstanding Order however this can be changed by unticking the Show Outstanding Only field at the bottom of the screen.
Outstanding Only - will only show the Purchase Order that the status is Outstanding
To show Receipted or Invoiced, you would need to untick the field to show this.
If the product is set to s Retail Product, this section will not be available