The data that Euskaltzaindia makes public in the Basque Onomastics Database (Euskal Onomastikaren Datutegia - EODA) are classified into three main sections: personal names, surnames and place names. This division refers to the two main areas that are usually assigned to onomastic science: anthroponymy (personal names and surnames) and toponymy (both from the Basque Country and from outside it).

With this database, the Academy aims to offer its own normative service, expressing, advising or suggesting to society how these proper names should be used in Basque. However, all the information shown in the Database is not the result of work carried out by Euskaltzaindia and, therefore, are not variants endorsed by the Academy. More precisely, the academic spelling of some of the person names, surnames and place names that can be consulted in the database has been fixed by Euskaltzaindia by means of a standard; many others are the result of work by the Onomastics Commission itself, and carry its backing; finally, many are the result of research carried out with appropriate criteria, but come from work carried out by other researchers or research teams and, therefore, have not been expressly approved by Euskaltzaindia.

All the database entries indicate the degree of assurance of the proposed spelling and, in many of them, the user will have to gauge the extent to which each variant is final, provisional or doubtful.