Please see the NIR service pages, the governance and API pages combined should detail the foundational knowledge. If there is anything missing on those pages after reviewing them, please reach out to NIR team. https://digital.nhs.uk/services/national-imaging-registry, https://digital.nhs.uk/services/national-imaging-registry/governance, https://digital.nhs.uk/developer/api-catalogue/national-imaging-registry-api