A schedule defines a chronologically ordered set of tasks that must be executed for a specific business process, and is the application of a template into the calendar. For example, you can apply the Quarterly template to the Calendar as Q1FY19 Close Schedule for the first Quarter, then apply the template again as Q2FY19 Close for the second quarter.
Schedules have a status of Pending, Open, Closed, or Locked. You can change the status of a schedule from Pending to Open, or from Open to Closed or Locked.
After a schedule is set to Open, it cannot be reset to Pending.
After a schedule is set to Locked, its status cannot be changed.