(8)To allow transparency and comparability of contractual arrangements and the ongoing monitoring of those arrangements, the register of information should focus on the operational links between the financial entities and the ICT third-party service providers. To that end, the register of information should use four keys, which, among others, linking relevant data to each other across the templates of the register of information: (i) the reference number of the contractual arrangement between the financial entity signing that arrangement and the direct ICT third-party service provider, (ii) an appropriate identifier of financial entities and ICT third-party service providers, (iii) the function identifier, and (iv) the type of ICT services.