Create Guranteed Restore point when flashback on is not enabled,

Create Guranteed Restore point when flashback on is not enabled, according to https://docs.oracle.com/cd/B19306_01/backup.102/b14192/rpfbdb002.htm, 5.2.1, f flashback database is not enabled, then the database must be mounted, not open, when creating the first guaranteed restore point (or if all previously created guaranteed restore points have been dropped)., however, I created a guaranteed restore point in this case, not sure if something weird in my case or just the online document is out of date? my is oracle 12c, but I don't see the same document as this one 10.2