Persistent identifiers (PIDs) are permanent references, for example, to a digital object (file, website, etc.), a person, or an organisation. PIDs make it easier to link to and retrieve publications and research results, as well as connect authors and their works. The Digital Object Identifier (DOI) for objects, the ORCID iD for persons, and the ROR of the Research Organisation Registry for institutions are widely used. They enable direct and permanent access to the corresponding information or documents via resolver services.