(8)In order to properly monitor concentration of exposures and systemic risk, it is crucial to ensure that complete and accurate information on exposure and collateral exchanged between two counterparties is submitted to trade repositories. The mark to market or mark to model value of a contract indicates the sign and size of the exposures related to that contract, and complements the information on the original value specified in the contract. Thus, it is essential that counterparties report valuations of derivative contracts according to a common methodology. Furthermore, it is equally important to require reporting of posted and received initial and variation margins pertaining to a particular derivative. Therefore, counterparties that collateralise their derivatives should report such collateralisation details on a trade-level basis. Where collateral is calculated on a portfolio basis, counterparties should report posted and received initial and variation margins pertaining to that portfolio using a unique code as determined by the reporting counterparty. That unique code should identify the specific portfolio over which the collateral is exchanged and should also ensure that all relevant derivatives can be linked to that particular portfolio.