Data in demographic surveillance systems (DSS) are normally also stored in database systems, which were designed according to the principles of relational data models. If we take the example of the data base model in the household registration system (HRSII), we can find

• objects (location, individuals, social groups)
• episodes (residence episodes, relationships, memeberships)
• point events (birth, death, inmigration, outmigration)

and some more technical information stored in different tables of the database. Also, the relations of these entities among each other are recorded.