About the RDA Registry and vocabularies

RDA Reference: Data flow and maintenance


General information about RDA Reference

Open Metadata Registry

RDA Reference data are stored in the Open Metadata Registry (OMR) in Resource Description Framework (RDF) linked data format.

The data are exported in multiple RDF formats, or serializations, to a GitHub open file repository with version control named RDA Vocabularies. Each export is a cumulative snapshot of the OMR data. Specific snapshots are designated as releases and given a semantic version number.

RDA Vocabularies (GitHub)

GitHub makes all releases and snapshots available for download, so applications can freeze or roll-back the data.

GitHub also makes all release and change notes available, along with automatic change comparison documentation.

GitHub offers an open active issue management system, used by RDA developers to raise queries, notify errors, and make suggestions for improvement.

RDA Registry

The RDA Registry provides links to download the individual element sets and value vocabularies in the current release of RDA Vocabularies.

The Registry offers additional documentation and tools to RDA developers. These include a Technical Guide, examples of RDA linked data, and machine-actionable maps for transforming RDA data for use by non-RDA applications.

The RDA Registry also provides updated data to the RDA Vocabulary Server whenever a new release is published.

RDA Vocabulary Server

The Vocabulary Server provides a de-referencing service for RDA URIs used in linked data, serving RDF serializations of the vocabularies in response to requests from applications.

The Server runs several services that provide language-specific extractions from the ‘all-languages’ vocabulary serializations available from the RDA Registry, based on specific requests for one or more languages.

Services also extract individual Elements and Concepts/Values from the broader element sets and value vocabularies in order to provide RDF representations of specific URIs.

RDA Toolkit

The Glossary in RDA Toolkit is based entirely on the RDA Reference data.

The RDF/XML serialization available in the current release of RDA Vocabularies is processed with a transform script to extract the relevant data and format it in XML for the Toolkit Content Management System.


The RDA data editor RIMMF3 (RDA in Many Metadata Formats) uses the RDA Vocabularies data to keep up-to-date with RDA Toolkit.

RIMMF3 provides active links from its RDA data input forms to the instructions in RDA Toolkit.

Data maintenance

The OMR allows data to be updated under password control through:

  1. a standard online administrator interface
  2. a batch file import facility within the administrator interface

Single Element and Concept updates

The OMR provides a vocabulary administrator interface which allows an authorized editor to update individual Elements and Concepts/Values, including additions, amendments, and deletions.

Batch updates

The administrator interface includes a data export facility for each element set and value vocabulary. The facility is open and does not require a password. The data are exported as a comma-separated variable (csv) file; a general spreadsheet format.

The file is amended by authorized members of the RSC (currently the Chair and Secretary) using a spreadsheet application.

The file is prepared for re-import to the OMR prior to a scheduled release of RDA Toolkit.

The administrator interface has a data import facility for each element set and value vocabulary. The facility requires both a password and authorization. The data are imported as a csv file.

The OMR rejects malformed data; otherwise processing takes a few seconds.

The batch update procedure is also used for translations of RDA Reference.

Data flow

All updates take place in the OMR. The OMR data are openly available.

From there, data flow to the RDA Vocabularies file repository as snapshots. The RDA Vocabularies files are openly available.

The three primary users of the RDA Vocabularies files are:

  • the Glossary in RDA Toolkit
  • the RDA Registry
  • the RDA Vocabulary Server
  • RIMMF3

RDA data flow diagram