When adding a new Sales Item, under the Additional tab, there is a field called Class Registration, and below are the options, and a description of what each option does

1. All future schedules of all visible seasons – This option means that the student will be added to all future lessons for all seasons that are marked as “Visible” (seasons where “Visible for Client” is set to “Yes”)
2. All schedules of selected season – If student selected some class schedule from “Season A” – he will also be added to all other schedules of this class in “Season A”.
3. Available quantity of schedules in selected season – “Available quantity” means “Lessons Quantity” field that is set for this sales item. For example if “Lessons Quantity” is set to 6 then student will be registered for six lessons of season he selected (starting from Season start date).
4. Available quantity of schedules in selected season (same day and time) – This option is similar to above but student will be registered only for one day each week, because class may have a schedule multiple days of week so the student can select only one day and time.
5. Selected schedule – the student will be scheduled only for the (one) lesson they selected.
6. All future schedules of current season – Student will be registered for all future schedules (lessons) of the season that in selected in Settings > Seasons as the Current Season.
7. Future schedules of lesson quantity field – If “Lesson Quantity” for sales item is 6 then the student will be registered for the next six future schedules (lessons).
8. First Available schedule – If lesson is scheduled for today but class is full and tomorrow there are some free slots – then student will be registered for tomorrow.