What are the best practices for obsoleting parts and products? For example, when the latest revision is moved to the “obsolete” state, only that specific revision is affected, while earlier revisions remain available and can still be added to BOMs. In practice, is there typically a process check to ensure that only the latest revision is used when releasing BOMs? And when a new revision is released, should all earlier revisions be obsoleted as well, or are they normally left active?