Are there any restrictions when viewing or editing engineering items ?

Yes. For engineering items that are in the Design lifecycle phase, you can't view or edit the Structure components and MPN relationships in the Product Information Management work area.

For engineering items that are in any lifecycle phase other than Design, you can't add or modify the Structure components and MPN relationships in the Product Information Management work area.

However, you can view, edit, or add engineering items using a change order from the Product Development work area.