Document references
Attributes of a business document could be tagged as a document reference, which indicates that the document is used as a reference by another originating document for output generation.
The attributes of the business document that should be tagged as document references are the noun ID, as well as the document IDs of the BOD's reference component. Usually, there are components in a business document that hold the information on document references, such as SalesOrderReference in ReceiveDelivery, or PurchaseOrderReference in SupplierInvoice. There is also the generic Document Reference component.
See BPA designer.