I like "Student PID" because it uses the old terminology that people are used to. For the other ones (Instructor, Employee, etc), I like "ID". 

Why can't we have "StudentID", "InstructorID", "EmployeeID," "AffiliateID", etc. Does everything have to have "PID" in the name? Also, once we get new EIDs, then maybe there will also need to be "EmployeeIDPrevious" or something.