When you link an invoice, you can choose the production code (prod. code) itself or a purchase that sits on the prod. code. Your choice determines where the invoice is shown.
Linked to the purchase: the invoice is shown under the purchase, and also under the prod. code that the purchase sits on.
Linked to the prod. code only: the invoice is shown on the prod. code, but not under any purchase.
If you link to the purchase, you get more detailed follow-up and can see whether the planned cost of the purchase is being exceeded.
Can I change the link later?
Yes. You can always change the link on an invoice when needed.
What do «linked» and «not linked» mean?
For invoices, «linked» means that the invoice is connected to a planned cost, such as a purchase. Read more in Invoice linking.

