An Unbalanced Hierarchy is a new special type of Entity which supports defining parent-child relations between its members. In an Unbalanced Hierarchy, data is aggregated on the fly along the hierarchy. These structures are typically used in financial reporting or in organization structures and are common to many other business models.
All items are members of the same entity. Each item can have multiple children but one parent only. Items that don't have any children below are called leaves and can store data. Items that don't have parents are called roots.