( b ) l e g a l n a t u r e the national central banks may execute reverse transactions either in the form of repurchase agreements ( ie the ownership of the asset is transferred to the creditor  while the parties agree to reverse the transaction through a retransfer of the asset to the debtor at a future point in time ) or as collateralised loans ( ie an enforceable security interest is provided over the assets but  assuming fulfilment of the debt obligation  the ownership of the asset is retained by the debtor ) 