The calendar is a very important aspect of task lists. When you create a task on opsi you specify its repeating frequency, whether that's daily, weekdays only, every Monday, etc. Depending upon what day you are looking at on the calendar, you will see only the tasks set due for that particular day.
When you first open the task lists view, the calendar will be showing "Today" by default.
With the calendar you are able to jump to future days to set prep counts, add notes, or assign users to tasks for that day. For example, if you are at the end of your evening shift today and want to set your prep for tomorrow, you can click to the next day on the calendar and set the prep amounts for that day.
To access the calendar: