Object Links 
You can link documents to a large number of SAP objects (for example, materials or customers) in order to document the objects in more detail for various business processes. You create, change, and display object links on the Object Links tab page.
Features
The Object Links tab page is divided into two screen areas:
Object link overview: This provides an overview of all linked objects.
Object link details: This enables you to display the object links of the object that you have selected in the overview.
In Customizing for the document type, you define which object types can be linked to a document info record. You also define how the system handles object links when a new version of a document is created, for example, whether the system automatically deletes or keeps the object link, or whether the user makes this decision.