Each relationship collection is attached to an object through an interface. This object is the source object for each relationship in the collection. Each relationship in the collection also has a target object — the object related to the source object.
The words source and target convey the potential for browsing. The source object of a relationship is the object for which you retrieved the collection. The target object of a relationship is the object that can become the target of a step from the source object, through the relationship, to the target object.
Note Source-and-target terminology differs from origin-and-destination terminology. The origin and destination do not change based upon which collection is being used to access a relationship; the source and target do change.
For example, the relationship between Frank and bug 15 has these two articulations:
For this relationship, the origin object is always Frank, and the destination object is always bug 15. The source and target objects, however, depend upon which collection is used to access the relationship. The two relationship collections that contain this relationship are: