Table 1

First version of the OBO Relation Ontology

Foundational relations
is_a
part_of

Spatial relations (connecting one entity to another in terms of relations between the spatial regions they occupy)
located_in
contained_in
adjacent_to

Temporal relations (connecting entities existing at different times)
transformation_of
derives_from
preceded_by

Participation relations (connecting processes to their bearers)
has_participant
has_agent

Smith et al. Genome Biology 2005 6:R46   doi:10.1186/gb-2005-6-5-r46