You can view predecessors of certificate types of a selected Task model and its WBS. This information is also displayed for Planned Tasks and imports.
Certificate predecessors have been added to the secondary panel of the Task model managers and imports manager. By clicking on an in progress task model, you can view the relative certificate types shared by other subsystem with in a WBS systemization.
For more information see Managing Certificate Exceptions
You cannot proceed to complete a task model or a task with pending predecessors unless you have manage rights for the system.