In general, a hierarchy is a ranked structure with a top level and subordinate levels. In ADO, hierarchical Recordsets are used to represent the parent-child relationship between a record and a chapter. Also in ADO, Record and Stream objects can be used to access hierarchical tree structures such as a folder and documents. ADO MD also includes Hierarchy objects to represent a relationship between the levels of a dimension in an OLAP cube. See also hierarchical Recordsets, parent-child relationship, chapter, tree.