# Schedule rules

Cron expression format and timezone constraints for scheduled jobs.



Validation rules applied to the `schedule` and `timezone` fields by [Create](/api/scheduled-jobs/create) and [Update](/api/scheduled-jobs/update).

* `schedule` is a 5-field cron expression (`minute hour day-of-month month day-of-week`).
* Minimum granularity is 5 minutes. Anything more frequent is rejected.
* `timezone` must be a valid IANA timezone name (for example `UTC`, `America/New_York`, `Europe/Sofia`).