Complex objects in the temporal object system

In many engineering applications, changes to the state and/or structure of an object needs to be maintained over a period of time. Existing object-oriented data models allow such changes in the state (referred to as version management) and structure (referred to as schema evolution) of an object. However, when the structure changes, the old structure is replaced by the new one. The authors propose a temporal object system (TOS) which maintains changes to both the structure and the state of an object. Objects in this system are referred to as temporal objects and are allowed to evolve over time. The authors discuss how to extend TOS in order to construct complex temporal objects from an aggregation of temporal objects