(13)In a similar manner to the standardised method for the calculation of the initial margin set out in Annex IV to Delegated Regulation (EU) 2016/2251, the margin rules of Singapore allow for the use of a standardised model equivalent to the one laid out in the aforementioned Annex. Alternatively, internal or third-party models may be used to calculate the initial margin where those models contain certain specific parameters, including minimum confidence intervals and margin periods of risk and certain historical data, including stressed periods. Before using an internal or third-party model, and before making any changes thereto, counterparties must notify the MAS and provide all relevant documentation including model methodology, specifications and validation reports to demonstrate that the model complies with the Guidelines on margins.