Where a security interest (original security interest) is extinguished under an extinguishment rule upon the transfer of the collateral, but the collateral finds its way back into the hands of the grantor of the original security interest following the rescission or termination of the sale or lease transaction that extinguished the original security interest, or the expiry of the lease term, the original security interest re-attaches to the collateral in certain circumstances – see section 37 of the PPSA and the discussion at paragraph 21.15.1 to 21.15.8 of Chapter 21 (The Extinguishment Rules).