You can assign a lifecycle phase to a top task. The following rules apply to assigning lifecycle phases to tasks:
You must associate a lifecycle with your workplan before you can assign lifecycle phases to the top tasks in the workplan.
If your workplan is associated with a lifecycle, you must assign lifecycle phases to each of the top tasks in the workplan. You can only assign phases to tasks that are top tasks in all versions of the workplan.
Each phase can be assigned to only one top task.
Once a top task has a lifecycle phase assigned to it, you cannot move it below the top task level, whether through moving, copying, or indenting. You can change the sequence of top tasks with assigned phases, however.
If you change the lifecycle for a project workplan or project template, the system removes all existing phase assignments to top tasks.
Other Sources
Implementing Oracle Product Lifecycle Management Integration, Oracle Projects Implementation Guide