Portfolio Backlog Items (PFBI) are the individual elements (Backlog Items) of a Portfolio Backlog and describe work for the entire Organization. The size of a PFBI is initially not limited. It must be small enough in size or devided (refined in the Portfolio Backlog Refinement) into several individual items that can be done in one Portfolio Cycle, before it can be pulled into the Portfolio Cycle Backlog during the Portfolio Planning.
Portfolio Backlog Items are typically Application or Market versions of Products.