From the Purchase Order list or task purchase order list, Back Orders will contain a prefix of 'BO' as opposed to ‘PO’.

For back orders created from stock purchase orders, the header will say 'Back Order' as opposed to 'Stock Order'.

The back order will contain a link to the original purchase order in the More tab.

The back order will contain a note saying it's made up of unfulfilled items from the original order, and it will also contain an additional note indicating that the order has been split, which copies across from the original purchase order.