Assuring interoperability would require the architects and developers of the blockchain layer to be knowledgeable of related database technologies and commonly used data structures. Critical security and privacy requirements of each key stakeholder, e.g. energy and transport regulators, digital infrastructure regulators, financial institutions, would have to be considered in the design as well. It would be very important to maintain the decentralisation when adding external systems, so that all the APIs need to be decentralised as well, creating multiple entry-points to the system and therefore not centralising it by just having one possibility.