18.The Standards requires banks to have a thorough understanding of all structural features of a securitisation transaction that would materially affect the performance of the bank’s exposures to the transaction. Common structural features that are particularly relevant include those related to the payment waterfall incorporated in the structure, which is the description of the order of payment for the securitisation, under which higher-tier tranches receive principal and interest first, before lower-tier tranches are paid. Credit enhancements and liquidity enhancements also are important structural features; these may take the form of cash advance facilities, letters of credit, guarantees, or credit derivatives, among others. Effective due diligence also should consider unusual or unique aspects of a particular securitisation structure, such as the specific nature of the conditions that would constitute default under the structure.