The discussion highlights which extinguishment rules:
(a) extinguish all security interests attached to collateral for the benefit of buyers and lessees (including security interests granted by previous owners);
(b) extinguish only security interests granted by the immediate seller or lessor themselves; and
(c) operate where the owner has "lost the right to possession", as in section 45 (for example, presumably (it is unclear) this covers situations where the grantor has leased collateral and the lessee purports to sell collateral).