We are thinking of using the occupation element to describe someone's role/contribution to the project. The @code attribute could point to a formal taxonomy including Editorial Board Member, Author, etc., while the actual text content could provide a refined version of this specific to the person. Multiple occupation elements could be provide for people with multiple roles, and the Credits page could provide a list of all of the taxonomy types, as links which would generate or jump to detailed tables of the people in those roles.