RO-Crate is an approach to packaging research data with its associated metadata and identifiers. This enables reproducibility and re-use. 

When you download data from EIDC as a zip file, it contains a special file called ro-crate-metadata.json. This describes the data in a way that helps machines understand and process it (it's machine-readable). 

Find out more at https://www.researchobject.org/ro-crate/about_ro_crate