In each repository relationship, there is an origin and a destination. Consider this relationship example: Fred drives a black truck. "Person drives vehicle" is the relationship type, Fred is the origin of the relationship, and the black truck is the destination of the relationship.
Don't confuse the terms origin and destination with the terms source and target. For any particular relationship, the source and target are dependent upon whether you are navigating via the collection of origin objects or the collection of destination objects. The origin and destination for the relationship are not dependent upon which collection is being navigated.