liminfoRDA Reference
Free reference guide: RDA Reference
About RDA Reference
The RDA Reference is a searchable guide to RDA (Resource Description and Access), the international cataloging standard that succeeded AACR2 (Anglo-American Cataloguing Rules, 2nd edition). It is built around the FRBR/LRM (Functional Requirements for Bibliographic Records / Library Reference Model) conceptual framework, covering the WEMI entity hierarchy: Work (abstract intellectual/artistic creation), Expression (specific language or form realization), Manifestation (physical or digital embodiment), and Item (individual copy or instance). Each entry explains entity attributes, relationships, and practical cataloging applications with concrete examples.
This reference is organized into seven categories: WEMI Model (Work, Expression, Manifestation, Item entity definitions and their hierarchical relationships), Core Elements (title, statement of responsibility, edition, publication, identifier attributes), Type Classification (content type, media type, carrier type three-way classification system), Access Points (authorized access points for persons, families, corporate bodies, preferred titles), Subject/Classification (DDC, LCC, LCSH, genre/form terms), Relationships (relationship designators between entities, related works, related expressions), and Tools/Application (RDA Toolkit navigation, MARC 21 field mapping, encoding guidelines).
Designed for librarians, catalogers, library science students, and metadata specialists, this tool provides instant lookup for RDA rules and FRBR entity modeling. Whether you are creating an authorized access point for an author, classifying a new work with DDC and LCC, mapping RDA elements to MARC 21 fields, or understanding the relationship between different expressions of the same work, this reference delivers clear explanations with real cataloging examples. All content runs entirely in your browser.
Key Features
- Complete FRBR/LRM WEMI model reference with Work, Expression, Manifestation, and Item entity definitions, attributes, and relationship hierarchies
- Core element descriptions covering title proper, statement of responsibility, edition statement, publication details, and standard identifiers (ISBN, ISSN, DOI)
- Three-way type classification system reference for content type (text, performed music, cartographic image), media type (computer, audio, video), and carrier type (online resource, audio disc, volume)
- Authorized access point construction rules for persons, families, corporate bodies, and preferred titles with qualifier conventions
- Subject and classification reference covering DDC (Dewey Decimal Classification), LCC (Library of Congress Classification), and LCSH subject headings
- Relationship designator reference for work-to-work, expression-to-expression, and agent-to-resource relationships with specific designator terms
- RDA Toolkit and MARC 21 mapping guide showing correspondence between RDA elements and MARC fields (100, 245, 264, 300, 336-338, etc.)
- Searchable across all seven categories with instant filtering, structured examples, and dark mode support
Frequently Asked Questions
What is the WEMI model in RDA?
The WEMI model defines four hierarchical entities for describing bibliographic resources. Work is the abstract intellectual or artistic creation (e.g., "Romeo and Juliet" by Shakespeare). Expression is a specific realization of a Work in a particular language or form (e.g., the original English text, a French translation, an audiobook narration). Manifestation is the physical or digital embodiment of an Expression (e.g., a specific publisher's edition). Item is an individual copy of a Manifestation (e.g., the copy in a particular library). This hierarchy allows catalogers to precisely describe relationships between different versions and formats of the same intellectual content.
How does RDA differ from AACR2?
RDA replaces AACR2 with a framework based on the FRBR/LRM conceptual model rather than card-based cataloging rules. Key differences include: entity-based structure (Work/Expression/Manifestation/Item) instead of description-focused rules, three-way content/media/carrier type classification replacing GMD (General Material Designation), relationship designators for explicit link typing, and format-neutral principles applicable to digital and non-traditional resources. RDA also separates recording from display, allowing flexible metadata presentation.
What are core elements in RDA?
Core elements are the minimum set of attributes that must be recorded for a valid RDA description. They include: title proper, statement of responsibility, edition statement, numbering of serials, production/publication/distribution/manufacture statements, copyright date, series title, identifier for the manifestation (ISBN/ISSN), content type, media type, and carrier type. Additional core elements exist for specific entity types. The reference details each core element with recording conventions and examples.
How do content type, media type, and carrier type work together?
This three-element classification replaced AACR2's GMD. Content type describes the intellectual form (text, performed music, still image, cartographic image, computer program). Media type indicates the required device (unmediated, computer, audio, video, microform). Carrier type specifies the physical format (volume, online resource, audio disc, videodisc, microfiche). Together they provide precise, granular description: a PDF e-book is text/computer/online resource, while a printed book is text/unmediated/volume. These map to MARC fields 336, 337, and 338.
How do I construct an authorized access point for a person?
An authorized access point for a person follows the form: preferred name + qualifiers as needed for differentiation. The preferred name typically uses the form most commonly found (e.g., "Shakespeare, William" not "Shakespeare, W."). Qualifiers include birth/death dates ("Shakespeare, William, 1564-1616"), fuller form of name, period of activity, profession, or other distinguishing characteristics. For corporate bodies, use the preferred name with hierarchical qualifiers. The reference covers construction rules for persons, families, and corporate bodies with examples.
What are relationship designators and how are they used?
Relationship designators are specific terms that define the nature of relationships between entities. For agent-to-resource relationships: author, editor, translator, illustrator, publisher, etc. For work-to-work relationships: adaptation of, sequel to, supplement to, based on, etc. For expression-to-expression: translated as, revised as, abridged as, etc. These designators provide machine-readable semantic links that enhance catalog discovery. They are recorded in MARC subfield $e (relator term) or $4 (relator code). The reference includes comprehensive designator lists by relationship type.
How does RDA map to MARC 21 fields?
Key RDA-to-MARC mappings include: authorized access point for creator (MARC 100/110/111), title proper (245 $a), statement of responsibility (245 $c), edition (250), publication (264), physical description (300), content type (336), media type (337), carrier type (338), series (490/800/810/830), and identifiers (020/022). Relationship designators go in $e subfields. The reference provides a complete mapping table showing which RDA elements correspond to which MARC fields and subfields.
Is RDA used internationally?
Yes, RDA is an international standard maintained by the RDA Steering Committee (RSC) with representation from library communities worldwide. It has been adopted by national libraries including the Library of Congress, British Library, Library and Archives Canada, Deutsche Nationalbibliothek, and the National Library of Australia, among others. RDA is designed to be language-neutral and format-neutral, making it applicable across different cataloging traditions and resource types. The RDA Toolkit provides translations and localized instruction sets.