(13)As for the calculation of initial margin, 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, Guideline E-22 allows 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 meet certain requirements which are equivalent to those set in Delegated Regulation (EU) 2016/2251. Internal and third-party models are subject to review by OSFI against the criteria established for compliance.