In a post at the International Community for Project Managers, Tom Mochal briefly outlines six foundational elements to charter a PMO. These elements will ensure a PMO both has purpose and will create value for the business. The six elements are mission, sponsor, customers, stakeholders, products/services, and transitional activities.
Mission is what the PMO does, how, and for whom. Sponsors champion the PMO’s building. Customers are the main targets intended to derive value from the PMO, whereas stakeholders are more broadly affected by or interested in the products/services the PMO renders. Lastly, transitional activities are the actual legwork involved in building and staffing a PMO.
For further elaboration, you can view the original post here: http://www.theicpm.com/blog/item/5527-charter-a-pmo