How to check Scheduler maintenance windows in Oracle

List Scheduler maintenance windows, their resource plan, next start, duration, priority, and which window is currently active.

SELECT window_name, resource_plan, enabled, active,
       TO_CHAR(next_start_date,'YYYY-MM-DD HH24:MI') AS next_start,
       duration, window_priority, repeat_interval
FROM   dba_scheduler_windows
ORDER  BY active DESC, next_start_date;