It is of use in situations like first year Science, where subjects have a large enrolment, there are multiple class offerings and students have a lot of class contact hours. If students were free to choose their classes, overcrowding would be inevitable and asking those without a seat to go to an alternative class would not work because of clashes in the students' timetables. It replaces sign-on sheets and gives power to departmental teaching and admin staff to set class limits, reallocate students and print off class lists.
Students can sign-on at any time of the day or night from any computer linked to the Internet.
No more scrambling over corridor sign-on sheets and wondering if the class is full or if your name will be scratched out. They can move themselves to another class at any time. Allocated students can see which class they are in via a personalised timetable on Si-Net. Staff can set class size limits that can't be exceeded. They can decide when sign-on will be available.