An object that does not exist in the reference tree for any top-level object is called an orphan. Orphans can be removed from a system without altering its behavior. Use the Orphan Analysis tool to find orphans.
What’s the difference between an orphan and an unreferenced object?
Suppose an unreferred report shows that the copybook GSS3.CPY is not referenced by any object in the project. Meanwhile, a cross-reference report shows that GSS3.CPY references GSS3A.CPY and GSS3B.CPY.
These copybooks do not appear in the unreferred report because they are referenced by GSS3.CPY. Only orphan analysis will show that the two copybooks are not in the reference tree for the GSS program and, therefore, can be safely removed from the project.