A contract of Prisme SA is a contract with direct participation features. At the closing date, the fair value of the underlying items falls by 1,000 euros. The entity's share of those items (variable fee) is 20%, and the fulfilment cash flows that do not vary with the underlying items are nil (case data). Write a short justification explaining why this fall adjusts the contractual service margin rather than going directly to profit or loss, and by what amount.