The role and value of detailed data inventories in government. Making openness part of holistic data governance, with GDPR, and infosec - Local governments have a broad range of tasks, and hold a corresponding variety of data. They also need to address information security, the implementation of the GDPR, and open data at the same time. Ideally these form into a comprehensive data governance approach, but are often treated separately. Experience from creating data inventories for 6 different Dutch government bodies shows how data inventories can support data governance, embracing privacy, security and openness all by design.