Full API support for DataCite Metadata Schema 4.4


We are pleased to announce that all DataCite APIs now have full support for metadata schema version 4.4. As of today, all DataCite APIs include full support for the RelatedItem property and the relationType IsPublishedIn

What’s new

When we release a new schema version, our first step is to update the XSD file that defines the schema. This means that when the schema is released, it is possible to include any new property or value when submitting XML metadata directly to DataCite. Some of the ways our members include XML deposits include the DataCite MDS API, Fabrica File Upload, and the “xml” property of the DataCite REST API, which allows XML metadata to be provided as a base64-encoded string.

In addition to updating the XSD file, full schema support involves updates to other places in our systems that enable users to create, update, and retrieve DOI metadata. Most importantly, we need to update the REST API and the Fabrica form interface.

When we released schema 4.4, we did a couple of those updates right away: specifically, we added support in the REST API and Fabrica form for the new values for ResourceTypeGeneral and the new classificationCode property of Subject. Today’s release completes the remaining updates for the RelatedItem property and the relationType “IsPublishedIn”.

As of today:

  • Repositories can create and update DOIs with RelatedItem metadata via the REST API and Fabrica form
  • Anyone can retrieve RelatedItem metadata through the public REST API

How DataCite Members are using Metadata Schema 4.4

We’re excited to see many DataCite Members have already adopted the schema version 4.4 changes. Here’s a snapshot of what adoption looks like so far!

Resource types

Of the newly introduced values for ResourceTypeGeneral, we’re seeing the most usage of Preprint: over 983,000 DOIs, or over 3% of all DataCite DOIs. Most of those preprints come from arXiv, who started automatically assigning DOIs earlier this year. After Preprint, we’re seeing the most usage of JournalArticle, Report, Dissertation, and ConferencePaper among the newly introduced options.

Classification codes

Schema 4.4 introduced a new sub-property of Subject for classification codes. The classificationCode sub-property is intended for use with subject schemes which do not have valueURIs for each subject term. Currently, over 117,000 DOIs use classificationCode. These include DOIs registered since March 2021, as well as DOIs that were registered earlier which have been updated to make use of this new metadata field. Some of the most commonly used subject schemes where DataCite users have included classification codes include:

Related Item

Since schema 4.4 was released, over 80,000 DOIs have been registered with the RelatedItem property through direct XML deposit. 

So far, we are mainly seeing the RelatedItem property used with the relationTypes “IsVariantFormOf” and “IsPublishedIn” to link to resources with type “Text”, “Journal”, “ConferenceProceeding”, and “Book”.

With this release, we hope to make it easier to include the RelatedItem property—no matter what method you use to register DOIs.

What’s next

To help you get started, the Metadata Working Group recently drafted guidance to demonstrate the different use cases, including how to use “IsPublishedIn”. This draft guidance was included in the Request for Comments for schema 4.5, and will be revised for inclusion in the upcoming release of version 4.5.

Are you interested in using the RelatedItem property? If you have any questions about using RelatedItem, please contact us at support@datacite.org or start a conversation on the PID Forum.