Frequently Asked Questions about the Relationship between CrossRef DOIs and DOIs from Other Organizations

Q:  Why are new DOI Registration Agencies (RAs) being created, and how do they relate to CrossRef?”

DOI technology can be used in many applications and by different communities. While CrossRef is the largest and best known DOI RA, and its reference linking service for scholarly publishers is the most widely used DOI application; other RAs also register DOIs for other applications and other communities.

Q. What do we mean by “DOI application”? 

DOIs can be used to provide persistent identification to a variety of content types on the Internet. Examples include reference linking, identifying datasets, and managing the supply chain for books.

Reference Linking for Scholarly Publishers

CrossRef's “application” of the DOI system enables persistent reference links for scholarly content:

  • journal articles
  • books, book chapters, and reference entries
  • conference proceedings articles
  • working papers
  • technical reports
  • databases and datasets

CrossRef DOIs ensure that the online scholarly citation record is robust. They preserve access to scholarly literature as ordinary URLs age and cease to work.

Datasets from National Libraries

Persistence and identification is also desirable for research datasets published by national libraries. Recently, a collaboration of national libraries announced a partnership to provide a DOI application for this purpose, modelled on an approach undertaken by the German National Library of Science and Technology (TIB). The goal is for datasets to be “independent, citable, unique scientific objects.” Effectively the organization would be a “CrossRef for national libraries.”

For more information about this collaboration see the press release issued after the March 2009 International Council for Scientific and Technical Information (ICSTI) meeting.


The ISBN-A is a new DOI application designed to uniquely identify book formats. The ISBN-A is an actionable-ISBN, which means it is linkable. The ISBN-A application is geared towards supply-chain management and selling of e-books, not just scholarly works. Please see the question below for more information on the ISBN-A and how it differs from CrossRef DOIs.

The Difference

These applications of the DOI System behave differently, and serve different communities. CrossRef serves scholarly publishers (very broadly defined). CrossRef DOIs will always be applied to citable objects and will resolve the user either to that object (an article, a book chapter, a dataset, a graph, etc.) or to information that will allow them to locate the object online.

An ISBN-A might do something quite different, like resolve to an online bookshop.  The TIB dataset initiative will offer similar services to CrossRef but for a different community of content providers.


CrossRef will work with the other RAs to ensure all DOI applications are interoperable and to explore possible joint services.

Branding DOIs

CrossRef and the other DOI RAs may need to brand our various DOI services more clearly so that users understand what each provides, and so that users know what to expect when they click a DOI-enabled link. One possible outcome is that we would move away from the generic term "DOI" in favor of a descriptor that explains the particular DOI application.

Q. Which RA should I use if I publish datasets?

If you are a member of CrossRef, register your datasets with CrossRef.  CrossRef was set up to serve scholarly publishers, while the TIB initiative is being created for national libraries. While it will have similar services to CrossRef for national libraries, CrossRef plans to cooperate on making its services interoperable.

Q. Tell me more about ISBN-A. What exactly is it?

International Standard Book Number (ISBN) agencies that are also DOI Registration Agencies have begun to register an identifier called the ISBN-A - “the actionable ISBN”.  An ISBN-A will contain a relevant ISBN in the syntax string of the DOI. 

For example, the ISBN


is the ISBN-A


Since DOI names by nature are “actionable”, i.e. links, then this ISBN-A can be linked using the normal DOI format


Clicking on the link above displays the target page in the user’s browser:

Just as barcodes contain ISBNs to enable certain applications, DOIs can contain ISBNs to make them linkable.

Q. What does an ISBN-A identify?

ISBNs are unique product identifiers assigned to monographs and related products. ISBNs are used in the book industry for sales and inventory.  According to the ISBN Users’ Manual, ISBNs are not assigned to “abstract entities such as textual works.” In practice this means that the different format versions of a book (hardback, paperback, PDF, HTML) are each given a unique ISBN.  An ISBN‑A leverages the widespread use of the ISBN to provide enhanced digital services.

Q. Where does an ISBN-A link lead?

The target or destination of an ISBN-A depends on the service provided by the ISBN Agency. The ISBN Agencies will work with publishers on developing particular applications that use the ISBN-A. For example, Bowker is planning to assign ISBN-As to many items that link to “SEO Title Cards” in Books in Print®.

Q. Who assigns an ISBN-A?

ISBN Agencies that are also DOI RAs may assign ISBN-As.  The Agencies are providing a service to publishers so will work with publishers on appropriate policies. Current agencies assigning ISBN-As include Bowker and the Multilingual European DOI Registration Agency (mEDRA), which is affiliated with the Italian ISBN Agency.

Q. What if I already have assigned CrossRef DOIs to my book titles and book chapters?

You can assign both CrossRef DOIs and ISBN-As to your content; they are completely compatible and complementary. These two types of DOIs are different identifiers used for different purposes. Publishers can choose to adopt those identifiers that provide the services they find most useful for their readers.

Publishers that need an identifier that will differ for different formats of the work can use the ISBN-A.

Publishers who wish to maximize discoverability through reference linking can choose to use CrossRef DOIs. Of course, to assign CrossRef DOIs, a publisher must join CrossRef and agree to certain obligations of the membership association. This relationship ensures persistent linking of scholarly citations and a level playing for all publisher members.

The ISBN Agencies assigning ISBN-As are also DOI RAs. CrossRef will collaborate with ISBN-A providers on metadata and service interoperability. We anticipate that CrossRef metadata could contain ISBN-As; ISBN-A data might also contain CrossRef DOIs.

Further information about the ISBN-A is available from the International DOI Foundation website.

Q. Who are the other DOI Registration Agencies (RAs)?

The International DOI Foundation lists all the DOI RAs on its website.

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