This is the value, as at the relevant date, of the assumed diversification benefits between estimated repricing yield curve risks, basis risk and optionality risk, for banking book items in the relevant currency or composite of currencies. This will reduce the interest rate risk in the banking book (IRRBB) capital requirement for the relevant currency or composite of currencies.IRRBB capital requirement represents the regulatory capital that an entity is required to hold against its exposure to IRRBB in accordance with prudential standards.Repricing risk represents the risk of loss in earnings or economic value caused by a change in the overall level of interest rates (that is, a 'parallel shift' in the yield curve). This risk arises from mismatches in the repricing dates of an entity's banking book items.Yield curve risk represents the risk of loss in earnings or economic value caused by a change in the relative levels of interest rates for different tenors (that is, a change in the slope or shape of the yield curve). This risk arises from mismatches in the repricing dates of an entity's banking book items.Basis risk represents the risk of loss in earnings or economic value arising from differences between the actual and expected interest margins on banking book items, where 'margin' means the difference between the interest rate on the items and the implied cost of funds for those items.Optionality risk represents the risk of loss in earnings or economic value due to the existence of stand-alone or embedded options, to the extent that the potential for those losses is not included in the measurement of repricing, yield curve or basis risks.