Term Structure and Relationships

Ontology Tree

A large portion of the terms loaded into the databases are ontology terms. They come in a "tree" like structure, where a term may have children -- more detailed, specific terms -- and one or more parents -- more general, broader terms. This structure is used to represent the relationships between terms, and to facilitate the expansion and traversal of terms. The fact that a term may have more than one parent makes it a Directed Acyclic Graph (DAG) rather than a strict tree.