Service management is the universe of discourse (UoD) of this Recommendation. This UoD comprises products, customers, accounts, contracts, deals, addresses, prices and various segments and relationships between these. The focus of this Recommendation is on end-user terminology as defined in an external terminology schema and which puts requirements on other schemata and implementations. As such, this Recommendation focuses on the definition of object and reference classes, and provides most identifiers and name bindings (i.e., subordinate object indicated by reversed arrowheads) for these. It also provides some attribute groups and attributes which are essential to define the data structure. Other attributes, e.g., to indicate entity history, are not covered. Also data structures for orders are not covered.