Official RDA: What’s Changing and What It Means for Your Catalogue

The RDA standard that most libraries currently follow — referred to as Original RDA or 3R RDA — is being retired. The Official RDA Toolkit (the post-3R revision) is the forward-going standard, and national libraries and cataloguing networks are transitioning to it.

This article explains what is changing, what the key differences are in MARC records, and how MARCReady’s RDA Helper supports both standards.

The retirement timeline

The Original RDA Toolkit entered a retirement countdown on 11 May 2026. The original site will be taken offline on 12 May 2027.

The Program for Cooperative Cataloging (PCC) — which includes the Library of Congress and member institutions worldwide — announced a rolling implementation period from 1 May 2024 to 30 April 2027. Until specific implementation dates are announced for each PCC programme (BIBCO, CONSER, NACO), records should continue to be created using Original RDA.

Source: RDA Toolkit — Countdown Clock and Transitioning to Official RDA (April 2026); PCC Rolling Implementation Announcement (June 2023)

What is Official RDA?

Official RDA is a restructured and redesigned version of RDA, aligned with the IFLA Library Reference Model (LRM). The original RDA was built around the older FRBR, FRAD, and FRSAD models; Official RDA consolidates these into a single unified model and improves consistency across resource types.

For most working cataloguers, the practical differences appear at the level of MARC encoding — what fields and subfields are required, and how relationships between resources and agents are recorded.

Key changes in MARC records under Official RDA

The following is based on the LC/PCC Official RDA Implementation FAQ (updated February 2026) and the Changes from Original RDA for Monographs report (January 2026).

040 — dual description convention codes

Under Original RDA, field 040 carries $e rda to indicate the cataloguing standard. Under Official RDA with PCC practice, two $e subfields are required:

040 ## $a DLC $b eng $e rda $e pccrda $c DLC

The pccrda code identifies the record as following PCC’s implementation of Official RDA. This dual coding allows systems and cataloguers to distinguish records created under the PCC Official RDA Application Profile.

884 — Description Conversion Information

Field 884 is used to document that a record was converted from another metadata structure or format. It records the conversion process, date, agency, and a URI pointing to the process used. This field supports transparency in shared cataloguing environments where records may pass through multiple systems.

Example:

884 ## $a MARCReady Official RDA conversion $g 2026-05-20 $q MARCReady $u https://marcready.kohasupport.com

Field 884 was added to the MARC 21 standard in 2015 and updated in MARC 21 Update 41 (December 2025). Source: MARC 21 field 884.

What does NOT change for typical monograph records

The following elements remain the same between Original and Official RDA:

• Fields 336, 337, and 338 — same vocabulary and coding
• Field 264 — same structure
• Record Leader and 008 coding
• Most subject, title, and note fields

The majority of MARC records for standard monographs will look very similar to Original RDA records. The most visible changes are in 040 coding and the addition of 884.

Changes that require cataloguer judgement

Two areas of Official RDA change cannot be applied automatically to existing records:

Relationship labels — Official RDA replaces RDA relationship designators in access point fields (1XX/7XX $e) with new PCC Relationship Labels defined in the PCC Metadata Guidance documentation. These depend on the specific relationship between an agent and a work, and require a cataloguer to assess each case.

Aggregate encoding — Collections, anthologies, and other aggregated works have new dedicated encoding guidance under Official RDA. Existing records for these types may need individual review to meet the new requirements. See the MG: Aggregates guidance.

UK implementation

The British Library has published Policy Statements for Official RDA within the Official RDA Toolkit. The UK Committee on RDA (UKCoR) published survey results on UK implementation in Catalogue and Index (December 2025). Further training and events are planned for 2026.

If you follow UK cataloguing practice, consult UKCoR guidance for the UK-specific Application Profile alongside the standard changes described above.

How MARCReady supports both standards

MARCReady’s RDA Helper (under Tools in the editing view) offers two modes:

Current RDA

Applies Original (3R) RDA changes — the prevailing standard still mandated by PCC for most record types:

• Converts field 260 to 264
• Removes the General Material Designation $h from 245
• Adds fields 336, 337, and 338 (content, media, and carrier type)
• Sets 040 $e rda

Official RDA

Applies all of Current RDA, plus the additional MARC encodings required for Official RDA compliance under LC/PCC practice:

• Adds 040 $e pccrda alongside $e rda (dual convention source codes)
• Adds field 884 documenting the conversion (process name, date, agency, URI)

What neither mode handles automatically

The following require cataloguer review and cannot be applied safely in batch:

• Relationship labels in 1XX/7XX $e — depend on the specific agent–work relationship
• Aggregate encoding for collected works and anthologies — requires content analysis
• Institution-specific Application Profile choices

Choosing the right mode

Further reading

• LC/PCC Official RDA Implementation FAQ
• Changes from Original RDA for Monographs: Report (LC/PCC, January 2026)
• Minimum Viable MARC Bibliographic Records (PCC, December 2025)
• RDA Toolkit: Implementing Official RDA
• MARC 21 field 884 — Description Conversion Information
• What is RDA Cataloguing? — background on the core standard
• What MARCReady Can Fix — full list of automated and manual fixes