NADA is a web-based cataloging system that serves as a portal for researchers to browse, search, compare, apply for access, and download relevant census or survey information. It was originally developed to support the establishment of national survey data archives. The application is used by a diverse and growing number of national, regional, and international organizations. NADA, as with other IHSN tools, uses the Data Documentation Initiative (DDI), XML-based international metadata standard.