(25)Collateral collected must be of sufficiently high liquidity and credit quality to allow the collecting counterparty to liquidate the positions without suffering a loss due to significant changes in value in case the other counterparty defaults. The credit quality of the collateral should be assessed relying on recognised methodologies such as the ratings of external credit assessment institutions. In order to mitigate the risk of mechanistic reliance on external ratings, however, a number of additional safeguards should be introduced. Those safeguards should include the possibility to use an approved Internal Rating Based (‘IRB’) model and the possibility to delay the replacement of collateral that becomes ineligible due to a rating downgrade, with the view to efficiently mitigating potential cliff effects that may arise from excessive reliance on external credit assessments.