- It must be associated to a Metadata Description.
- It can be an Input in a Relation Extraction Task.
- It can be a Heuristic Classifier. See MUC
- It can be an Annotated Corpus. (e.g. each relation instance is indicated in a sample set of Passages).
- It can be a set of Instances of the Semantic Relation (i.e. a portion of a populated Ontology). E.g. a table with several OCL relations (Supervised Learning)
- See: Information Extraction, Relation Recognition