The concept which allows this is that of the public subject, and the mechanism used is an attribute
The concept which allows this is that of the public subject, and the mechanism used is an attribute (the attribute of identity) on the matter element. This attribute addresses an electronic resource which identifies the subject in question clearly. This resource could be a certain civil servant, publicly document available (for example, the standard of the OIN which defines codes of 2 and country 3-letter), or it could simply be a definitionnelle description in (or outside) one of the matter charts.