A model in which nodes are organized into a tree-like structure. A hierarchy model contains a top-level node, child nodes, a relationship from the top-level node to a child node, and relationships from child nodes to other child nodes. Each node in the model corresponds to a code list.

For example, you might create a location hierarchy. In the hierarchy model, you define the Region code list as the top-level node. You add the Country code list as a child node and then create a hierarchy model relationship from the Region node to the Country node.