Links. The buying chain is navigable end to end: an order's page offers its goods receipts; a receipt offers the invoice that matches it and any landed cost adjustments standing on it; an invoice offers the payment that settles it. Each link creates the next document with the known facts carried across, and appears only when you hold that document's create permission (1.5). The supplier's 360° page (§4.6) gathers the whole relationship per supplier.
Prints. The purchase order prints as the document you send the supplier — the formal statement of what you agreed. The goods receipt prints as your receiving record; the payment as the advice the supplier reconciles against. Your print preferences (0.6) shape them all.
Documents. As in Sales (§3.7), every print files itself into the document library under your file plan, attached to its record (Chapter 14) — a supplier's disputed invoice can be re-produced from the invoice itself, years later, exactly as posted. Files you attach — the supplier's signed terms, a freight bill awaiting its adjustment — inherit the record's visibility.