This course format allows to set duration for each section (period) in days, weeks, months or years. Each individual section (period) may override this duration.
The course settings allow automatically collapse or hide past or future periods. For the past periods it is possible to hide them from course view page but have each individual module still accessible through reports and/or gradebook. Also it is possible to hide past periods only if all activities in them are completed and show otherwise.
Current section is automatically highlighted.
Please note that this format takes advantage of the new feature introduced only in 2.8 (see MDL-46937), so it will not work properly on 2.7.