However, they don't use display groups, and they typically don't use EODatabaseDataSources either. This creation process is typically begun when you allocate and initialize an EOEditingContext. The first time defaultCoordinator is invoked, it creates an EOObjectStoreCoordinator.
Subsequent invocations return the same instance.
Consequently, all the editing contexts in an application are connected to EODatabaseContext objects through the same EOObjectStoreCoordinator by default. The remaining objects in the network are created on demand. When a database operation is initiated with a message to an editing context, the request is passed on to its object store coordinator. In the case of a nested editing context configuration, the message is passed down the object network until reaches the editing context's root object store-usually an  EOObjectStoreCoordinator. For example, an objectsWithFetchSpecification message sent to an EOEditingContext percolates through its parent object stores until it  reaches the coordinator as shown in Figure  39 .