RSC
ALAResource Description and Access (RDA) is the international cataloguing standard that replaced the Anglo-American Cataloguing Rules (AACR2), providing a comprehensive framework for describing and providing access to all types of resources held by libraries and other cultural institutions. Through its RDA Registry, the standard also provides a full set of linked data vocabularies — element sets, value vocabularies, and entity classes — that make RDA usable in Semantic Web and linked data environments alongside traditional library systems.
Background
RDA was developed by the Joint Steering Committee for Development of RDA (now the RDA Steering Committee, or RSC), representing library communities in the United States, United Kingdom, Canada, Australia, and Germany. Work began in 2004 as a revision of AACR2 but evolved into a substantially new standard. The first release of RDA came in 2010, with the Library of Congress, British Library, Library and Archives Canada, and National Library of Australia implementing it in 2013 after extensive testing.
RDA is grounded in the conceptual models developed by IFLA, particularly FRBR (Functional Requirements for Bibliographic Records) and FRAD (Functional Requirements for Authority Data), and now aligns with the IFLA Library Reference Model (LRM). This theoretical foundation distinguishes RDA from its predecessor by providing a principled entity-relationship framework for bibliographic description.
Purpose & Scope
RDA provides guidelines and instructions for recording data that describe resources and the entities associated with them. It covers all types of content and media, including traditional print materials, digital resources, audiovisual materials, cartographic resources, and more.
The RDA Registry organizes its content into several categories:
| Category | Contents |
|---|---|
| Element Sets | Properties for describing Agents, Works, Expressions, Manifestations, Items, Nomens, Places, and Timespans |
| Value Vocabularies | Controlled term lists for content type, carrier type, media type, and many other attributes |
| Classes | The entity classes defined in RDA |
| Unconstrained Properties | Domain- and range-free versions of elements for broader interoperability |
| RDA/ONIX Framework | Shared carrier and content categorization with the publishing industry |
Serializations & Technical Formats
The RDA Registry publishes all vocabularies in multiple linked data serializations:
- RDF/XML — Standard RDF serialization
- Turtle — Human-readable RDF format
- N-Triples — Line-based RDF format
- JSON-LD — JSON-based linked data format
All elements have persistent HTTP URIs under the rdaregistry.info namespace, supporting content negotiation. The current release is v5.4.12, available for download from GitHub in both ZIP and tar.gz archives.
Governance & Maintenance
RDA is governed by the RDA Steering Committee (RSC), with representation from major English-speaking library communities and increasingly from international partners. The RSC Technical Team maintains the RDA Registry in association with ALA Digital Reference. The full normative text of RDA is available through the subscription-based RDA Toolkit.
The RDA Vocabularies and RDA Registry are licensed under a Creative Commons Attribution 4.0 International License. Copyright is jointly held by the American Library Association, Canadian Federation of Library Associations, and CILIP (Chartered Institute of Library and Information Professionals).
Technical issues and discussions are managed through the GitHub project, where users can raise issues, view releases, and access the complete vocabulary source files.
Notable Implementations
RDA has been adopted by major national libraries and cataloguing communities worldwide:
- Library of Congress — Primary cataloguing standard since 2013
- British Library — Implemented alongside the Library of Congress
- Library and Archives Canada — Early adopter and co-developer
- National Library of Australia — Implementation partner
- Deutsche Nationalbibliothek — German National Library, contributing to RSC governance
- OCLC WorldCat — Supports RDA records in the world's largest bibliographic database
Related Standards
- FRBR — The conceptual model on which RDA's entity framework was originally built
- MARC21 — The encoding format through which most RDA records are currently transmitted, with RDA-to-MARC mappings provided
- BIBFRAME — The Library of Congress's linked data model, which provides an alternative linked data expression of similar bibliographic concepts