18.—(1) Where a collateral-taker exercises a power contained in a security financial collateral arrangement to appropriate the financial collateral the collateral-taker must value the financial collateral in accordance with the terms of the arrangement and in any event in a commercially reasonable manner.
(2) Where a collateral-taker exercises such a power and the value of the financial collateral appropriated differs from the amount of the relevant financial obligations, then as the case may be, either—
(a)the collateral-taker must account to the collateral-provider for the amount by which the value of the financial collateral exceeds the relevant financial obligations; or
(b)the collateral-provider will remain liable to the collateral-taker for any amount whereby the value of the financial collateral is less than the relevant financial obligations.