The Open Archives Intiative (O·A·I) vocabulary for Object Re·use and Exchange (Ore) provides a set of basic terms for defining aggregations of resources and the relationships between them. It also introduces the concept of a “Resource Map”, which is an R·D·F graph containing a description of an aggregation conforming to its vocabulary and data model.

The terms for describing aggregations are generally use·ful, and have been extended by models like ; they are included in this ontology. The Resource Map concept and its related terms (, , ) is less obviously use·ful, and has been excluded for now.