Documents involved in the business process are not independent from each other: For example, a query turns into an offer which then in turn becomes a delivery. It is therefore necessary to get an overview of all the different documents that result from a business process or which relate to each other. It is also useful to be able to jump between these documents in the SAP system and also other connected SAP systems.

It is also important to know what sort of relationships connect the different documents. In the example above the documents "result from", that is, the offer is at once the successor document and also the predecessor document. You therefore want to reduce the relationship to a simple model, through which time and causal connectivities between documents become apparent.

To reach these targets for any document, the object relationship service has been created. This way it is possible to link objects of the Business Object Repository (BOR) with each other. The links are modeled and written by the application by calling a specific interface, the API of the object relationship service. The application must only transfer to this API the Business Object from the BOR and the data from the relationship model.