Currently, re3data offers unrestricted access to comprehensive descriptions of more than 3100 research data repositories from all disciplines and all regions. The repository descriptions are based on the re3data Metadata Schema. More than 10 years of conceptual work have gone into this schema, which has been continually adapted as the repository landscape and the requirements and expectations for a registry of research data repositories have shifted.

The current version 3.1 of the re3data Metadata Schema was released in 2021. Within the ongoing project re3data COREF, we will again revise the re3data Metadata Schema to release version 4.0.

We invite you to participate in the Request for Comments for version 4.0 of the re3data Metadata Schema by commenting on our draft until May 31st, 2023.

Properties that have been changed or were added with this draft are highlighted in the document, we particularly welcome comments on these properties. Your comments are highly appreciated, as we are committed to finding a way to describe research data repositories that fits the needs of our diverse stakeholders. All comments will be discussed and considered for version 4.0 of the re3data Metadata Schema.

Version 4.0 introduces four major changes:

• relatedRepository: The new property relatedRepository offers the option to describe relationships between repositories. Currently, these relationships are restricted to referencing the repository that took over custody of (parts of) the collection after the repository described by the entry was closed.
• fundingInformation: With the new property fundingInformation, information on repository funding can be expressed, including funder names and funder identifiers.
• qualityManagementMeasure: The new property qualityManagementMeasure introduces the opportunity to index specific quality assurance measures the repository implemented.
• contentType: The controlled vocabulary for indexing content types will be switched to the COAR Resource Types 3.1 (dataset with subtypes, image with subtypes, software with subtypes, text without subtypes). This will make it easier to identify whether a repository only stores data, or also text and software.