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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.

See the site Menu for more info, or the ROGuide


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 .

Mail List


See ROGuide

Examples of usage

See UsageExamples

Requesting new relations

Use the github issue tracker and/or the obo-relations mail list.

Shortcut Relations

RO includes a number of macro or shortcut relations. E.g

For more information, see Shortcut Relations


RO combines multiple relations from different biological sub-domains into one ontology. Sometimes these relations are very specialized and of limited use outside that domain. For more on extracting specific modules, see:

See RO Modules.

RO replaces OBO_REL

The predecessor of RO was OBO_REL. Many of the relations in OBO_REL have been ceded to BFO. See DifferencesWithOldRO

Coordination with BFO

For details on how RO coordinates with BFO, See ROAndBFO .

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