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This is the project page for RO, the OBO Relations Ontology


RO is a collection of relations intended primarily for standardization across ontologies in the OBO Foundry and wider OBO library. It incorporates ROCore upper-level relations such as part of as well as biology-specific relationship types such as develops from.



This is the main PURL for the ontology:

For all download products, see the RO OBO page


Currently the optimal way to browse RO is to use Protege and inspect ro.owl

See the list of relations on OntoBee -- note that sometimes OntoBee fails to display the full hierarchy

How to cite

Please cite RO by its GitHub URL or its Zenodo DOI, DOI: 10.5281/zenodo.32899 .

Mailing list

Requesting new relations

Use the GitHub issue tracker and/or the obo-relations mailing list.

How to contribute to RO and join the RO working group

Please see our page on Contributing to RO.