Staff can set class size limits that can't be exceeded. They can decide when sign-on will be available. Class lists can be produced at any time- no more indecipherable scrawls and typing up by the office. Staff can even use Sign-on as a way to allocate students to particular classes if this is preferable to students signing on themselves. More optimal matching of class sizes to teaching room capacities can be achieved.
Staff can require students to choose the lecture or practical stream they'll attend by signing-on.
When the class is full, no more signons will be accepted. Come the first week, do some roll checking with the help of the lecture theatre attendants. Complicated course plans involving many students can be handled with the Allocation component of the system. The Faculties of BACS and EPSA have used the Allocation function for several semesters now for Science students. The Sign-on component started off in second semester 1999 in a handful of departments.