The current OOS process uses a time scale e.g. 9am to 1pm, I think it should be possible to have the choice to choose between a timescale or on a Period based scaled e.g. P1 OOS. Similar to the choice in cover manager.
This will help with slight overlaps where a student would be marked OOS even when the aren't, for example a student marked OOS 9am-10am, would appear OOS for a period that starts at 10, even though you would assume they would be at this period.
