4.6.3. Definition of the Persistent Identifier in the database

Furthermore, some functionally relevant information must be provided. For example, the element <persistentIdentifier> determines which metadata type is valid for the persistent identification of a structural unit. This element must exist exactly once, since it is used to check whether a document has already been imported into the repository and, if so, to reject serialization.

Example: Configuration of the PPN as persistent identifier: