Frequently Asked Questions

Q. Is the published set of RDA vocabularies complete and stable?

Yes and no. Further development of the RDA vocabularies is incorporated in the tasks of the RSC Technical Working Group as well as the RDA Development Team. The RSC expects to add, update, and deprecate elements and concepts as the need arises. Version control is applied to versions and releases of the RDA Vocabularies in GitHub and the RDA Registry. The RDA vocabularies are stable in that the canonical URIs will not be changed, and usual good practice will be used when amending or removing classes and properties. For example, if a property is deleted from RDA itelf, it will be deprecated in the RDA Registry but not deleted, according to the Deprecation policy.

Q. Why are the URIs unreadable?

After a great deal of discussion, the JSC (predecessor of the RDA Steering Committee) decided to use opaque URIs for the element sets. This follows the practice established for the value vocabularies, and reflects the international environment of RDA and its translations. The RSC is also aware of the problems associated with using transparent, human-readable URIs as a mnemonic device, especially when the properties and values of bibliographic display labels such as RDA’s relationship designators are still under development. However, English-readable URIs have been declared owl:sameAs to their canonical, opaque counterparts to alleviate any inconvenience this might cause for English-based linked data applications. The same facility may be developed for other languages, based on translations of RDA, in the future. The mnemonic accuracy of these URIs is not guaranteed.

Q. Why do some of the published elements have weird labels and definitions?

This is the result of applying a mechanical device to verbalize RDA labels and definitions to clarify their semantics, specifically the direction of a relationship property, and to create labels and definitions for versions of the properties unconstrained by the RDA domain model based on Functional Requirements for Bibliographic Records (FRBR) and Functional Requirements for Authority Data (FRAD). The methodology, as applied to relationship designator elements, is discussed in RDF representation of RDA relationship designators: a follow-up discussion paper and its appendices. Weird results indicate a failure of the methodology, which will be resolved if at all possible by amending the RDA source text so that automatic synchronization is achieved. If this is not possible, the namespace literals will be amended and synchronized manually. Care will be taken to ensure that the semantics of the element are not changed.

Q. Do the element sets match the elements in RDA?

Yes. The published element sets are based on the RDA Element Analysis Table (in conjunction with the RDA Element Analysis) and the relationship designators listed in Appendices I, J, and K of the RDA Toolkit. There may be a few variations due to time-lag between updates in a new release of RDA, but every effort is made to keep the element sets up to date. In most cases, the Toolkit lags behind the Registry. The most significant difference between the elements in RDA and in the namespace is that the namespace verbalizes the human-readable labels and definitions in RDA, in order to clarify the element semantics in the namespace.

Q. Do the value vocabularies match the vocabularies in RDA?

Yes. The published value vocabularies are the same as the controlled vocabularies listed in RDA Toolkit. There may be a few variations due to time-lag between updates in a new release of RDA, but every effort is made to keep the value vocabularies up to date. In most cases, the Toolkit lags behind the Registry.

Q. What is the procedure for developing and publishing translations of RDA?

Translations of RDA are covered by the Translation Policy for RDA and RDA Toolkit. Procedures for translations of RDA Reference in the RDA Registy are being developed.

Q. Why are the translations of the RDA element sets and value vocabularies incomplete and out of date?

Translations are based on RDA Reference data that reflect the content of RDA as it is developed by the RDA Steering Committee. There is an inevitable time-lag before changes are applied to RDA Reference and the Registry vocabularies. Procedures for minimizing the delay are being developed.

Q. What is RDA Reference?

RDA Reference comprises the RDA element sets and value vocabularies and their translations.

Q. What is the "4-fold path"?

The "4-fold path" is a reference to the methods given in the instructions for recording the relationship between an entity being described and a related entity.

The related entity may be described using three general methods:

  • An unstructured description that is a string. An example is a free text note.
  • A structured description that is a string that aggregates string values from other elements using a form of syntax encoding scheme. An example is a name/title access point.
  • An identifier that is a string. An example is an ISBN or local identifier.

In this context, a "string" is a sequence of alphanumeric symbols and punctuation marks intended primarily for human consumption.

The RDA guidance and instructions are being developed to further generalize these methods of identifying a related entity, and to accommodate an explicit "fourth path" method for linked data applications:

  • A URI for the entity; that is, a "thing".

Q. Why was a new namespace,, used for the published RDA vocabularies instead of the original

The namespace was set up in 2008 following the Data Model Meeting in London in 2007. The domain used was intended to reflect, but not fully brand, the namespace as "RDA", because it could not be assumed that the developments agreed at the meeting would be successful. For various reasons associated with the ongoing development of RDA: Resource Description and Access, the representation of the basic RDA elements in RDF was not approved until 2012. By then, there was a much clearer understanding of the issues of elements for aggregated statements, and elements unconstrained by RDA semantics for use in non-RDA applications. There were also significant differences between the data used to develop the RDA element sets and the elements published in the current version of RDA. It would have taken longer to update the old element sets, with many deprecations, than to republish them using current, approved data.

Q. Did this change in the namespace break things for applications using the old URIs and elements that have not made the transition?

Yes, but every effort was made to bridge the gap between the old and the new. These include redirection from the old element sets to the new namespace, the development of maps between the old and new URIs, and the provision of alternate URIs using the English label of the element as the local part, similar to the construction of the old URIs. A map from the old URIs known to be in use is available. The old element sets had the status of "New-Proposed" and were never officially published.

Q. What about the RDA value vocabularies in the original namespace?

The RDA value vocabularies were moved to namespace in 2015. The old URIs in "Published" status were redirected to the new ones. From August 2016, all the RDA value vocabularies have "Published" or "Deprecated" status. The published value vocabularies are updated as required so that they remain in synchronization with RDA.

Q. Where do I direct questions I have about the RDA Vocabularies that aren’t answered here?

Please email questions about the content of the RDA Vocabularies to the Chair of the RDA Steering Ccmmittee (, Gordon Dunsire. Questions about technical issues can be emailed to Diane Hillmann at Metadata Management Associates (

Q. Where can I find more information about the processes used to develop and maintain the published RDA vocabularies?

See RDA Reference data maintenance and flow for information about the processes used to maintain the RDA vocabularies.