(14)The requirements in the Policy Manual for the calculation of initial margin should be considered equivalent to the requirements set out in Delegated Regulation (EU) 2016/2251. In a manner similar to the standardised method for the calculation of the initial margin set out in Annex IV to Delegated Regulation (EU) 2016/2251, the Policy Manual allows for the use of a standardised approach equivalent to the one laid down in that Annex IV. Alternatively, internal or third party models can be used under the Policy Manual to calculate the initial margin where those models contain certain specific parameters equivalent to those set out in Delegated Regulation (EU) 2016/2251, including minimum confidence intervals and margin periods of risk and certain historical data, including stressed periods. AIs must seek formal approval from the HKMA before using an internal or third-party model (except for an industry-wide standard initial margin model which AIs may use after notifying the HKMA of the intent of doing so and the HKMA would conduct post-implementation review of).