The hardest ones have to do with arriving at shared data definitions. The definition of student will be different for different access control purposes. This education itself is one of the valuable products of the team. Conceptually everybody that anyone at the University has a reason to care about. This is more than students, faculty and staff.
Some units deal with alumni, with vendors, with other educational institutions.
However big you think the potential authentication population is, it's probably bigger. This is not a team activity per se. Byron and Keith see this effort as a natural place for the results of the NST effort to be brought into play. This coordination is only in the initial, exploratory stages. The architects see areas of overlap between the two coming into sharper focus.