5.4.1.1 "Direction" of Data Object References

The feature/interpretation/representation/properties knowledge hierarchy creates some special considerations for which data object specifies (or "holds") the reference. During the reservoir lifecycle, a feature can have many interpretations, an interpretation can have many representations, and a representation may have many properties. However, an interpretation cannot "know" how many future representations will be created, or their UUIDs. In contrast, when a user creates a representation, the user must know and specify which interpretation it "represents." For this reason, the child data object must specify (or hold) the relationship.

Here are the general rules on direction in data object references:

• Parent-child:

• In a one-to-one parent-child relationship, the data object reference is from the parent to the child.
• In a one-to-many parent-child relationship—and always for the "FIRP" relationship (see the example in Section 5.4.2 Example: "FIRP" Relationships ())—the data object reference is from the child to the parent.

• isbasedOn, where one data object is based on another data object defined at the same level. The data object reference goes from one class to another to express that the source object which is BasedOn a target object needed to collect all the information gathered by the target object.