Metadata are an elementary part for making research data usable by researchers and all interested parties now and in the future. They are fundamental in making research data findable and enable their reusability by third parties and over a long period of time. However, research data are often insufficiently and not consistently described with metadata, which makes the reusability of the research data difficult or even impossible.

The HMC platforms’ goal is to overcome those obstacles. It is intended to coordinate the use of metadata within the disciplines and institutions and to support their usage with tools and services.

As part of the Helmholtz Association and its structure, the HMC platform has the ideal prerequisites to achieve this goal. Its division into hubs of the various research areas of the Helmholtz Association, it is possible to initially coordinate within or between related disciplines to determine their metadata requirements, and in a further phase this coordination can be continued by the central office across disciplinary boundaries in order to make metadata usable across disciplines.

Metadata requirements result from the requirements of the scientific disciplines, but also overarching requirements have been developed within the research data community and summarized in the FAIR Data Principles [1]. Following the FAIR Data Principles research data have to be Findable, Accessible, Interoperable and Reusable.

To be Findable:

• F1. (meta)data are assigned a globally unique and eternally persistent identifier.

• F2. data are described with rich metadata.

• F3. (meta)data are registered or indexed in a searchable resource.

• F4. metadata specify the data identifier.

To be Accessible:

• A1 (meta)data are retrievable by their identifier using a standardized communications protocol.

• A1.1 the protocol is open, free, and universally implementable.

• A1.2 the protocol allows for an authentication and authorization procedure, where necessary.

• A2 metadata are accessible, even when the data are no longer available.

To be Interoperable:

• I1. (meta)data use a formal, accessible, shared, and broadly applicable language for knowledge representation.

• I2. (meta)data use vocabularies that follow FAIR principles.

• I3. (meta)data include qualified references to other (meta)data.

To be Re-usable:

• R1. meta(data) have a plurality of accurate and relevant attributes.

• R1.1. (meta)data are released with a clear and accessible data usage license.

• R1.2. (meta)data are associated with their provenance.

• R1.3. (meta)data meet domain-relevant community standards."[1]