Use the command Set Active to change the status of a part's structure from Preliminary to Active.
When you create a new part with a revision, the part revision structure control is given the default status value Preliminary, which means that this revision is not yet ready for use. When you finish developing the part and the structure is ready for use, you activate it. This prevents users from changing an approved structure. This may be very important if the part revision is manufactured. The part’s structure control is set to active, and the status change signals that this part can be used in structures when needed. Note that setting the structure control for a part from Preliminary to Active is irreversible. If you need to make changes to an active part, you have to create a new revision of the part.
The structure control of all levels below the current part must be active.