Persistent identifiers (PIDs) are essential for the long-term referencing and preservation of any information resource.
Persistent identifiers for print materials are unique, standardized codes that ensure reliable identification and access to physical publications over time. Common examples include International Standard Book Numbers (ISBNs) for books and International Standard Serial Numbers (ISSNs) for periodicals. These identifiers, and their counterparts for digital resources, i.e. ISBN-A and eISSN, enable efficient description, management, and retrieval of materials in libraries, archives, and digital systems. By linking a specific identifier to a particular edition, media version or format, they reduce confusion, facilitate global distribution, and support accurate citation in academic and professional contexts.
Persistent identifiers for digital materials are unique, stable references assigned to electronic resources, ensuring long-term access and discoverability across changing digital landscapes. Examples include Digital Object Identifiers (DOIs) for scholarly articles and datasets, Handles for digital objects, and Archival Resource Keys (ARKs) for heritage collections. These identifiers link to metadata and resource locations, enabling precise citation, reliable sharing, and robust management of digital assets. These identification systems consist of a unique identifier and a resolution service that ensures accessibility even when a resource’s location changes. PIDs address the frequent problem of broken links (link rot), especially in academic, legal, or medical contexts where access to referenced resources is crucial.
Key Persistent Identifier Schemes:
- The International Standard Book Number (ISBN) is a unique 13-digit identifier used globally to distinguish books and specific editions. The ISBN-A (Actionable ISBN) enhances this system by linking the identifier to digital content or services through a DOI-based web address.
- The International Standard Serial Number (ISSN) is an 8-digit identifier used globally to distinguish periodicals and serial publications.The eISSN complements this system by identifying the electronic versions of continuing resources. The ISSN Portal (https://portal.issn.org) contains the whole set of ISSN associated with the description of the resource.
- The Digital Object Identifier (DOI) is used to identify digital scholarly publications and data objects. DOIs ensure that URLs resolve correctly via a robust infrastructure, supported by agencies like CrossRef and DataCite.
- The Handle system provides unique identifiers for internet resources and underpins the DOI system, maintaining resolution through a central registry.
- The Archival Resource Key (ARK) system allows organizations and institutions to create and manage their own ARK identifiers without relying on a central authority. This decentralization enables flexibility and scalability, making it an attractive choice for diverse institutions such as libraries, archives, and museums. ARKs are governed by the ARK Alliance.
- The Persistent Uniform Resource Locator (PURL) system is a mechanism for creating stable web addresses that point to resources, even if their actual location changes over time. A PURL acts as a redirection service, where the identifier resolves to a current URL stored in a PURL server.
- The Universal Resource Name (URN) system is a standardized identifier framework designed to uniquely name resources in a location-independent manner. Unlike URLs, which specify the location of a resource, URNs focus on persistent identification, enabling reliable referencing even if the resource’s location changes. URNs follow the syntax defined by the Internet Engineering Task Force (IETF) and include a namespace to categorize the type of resource being identified.