Dimensions are usually structured to contain a hierarchy of related members. For example, for relational database users, the Time dimension includes members such as Year, Quarter, and Month. This hierarchy creates an Essbase outline with members such as 2004, Quarter1, and January.
Hierarchies also use attributes to classify members logically within a dimension; for example, a Product dimension with attributes such as Size and Flavor.
You can create hierarchies for a metaoutline while creating OLAP models.