Classified information refers to government-designated data that requires protection in the interest of national security. In the Netherlands, classification levels include staatsgeheim (state secret) with sub-levels zeer geheim (top secret), geheim (secret) and confidentieel (confidential), as well as departementaal vertrouwelijk (departmentally confidential).
Handling classified information is governed by strict legal frameworks and requires specific security clearances, approved storage facilities and controlled distribution channels. Organisations working with government contracts or critical infrastructure must implement additional physical and technical safeguards beyond standard ISO 27001 requirements, including secure rooms, vetted personnel and dedicated communication systems.