The priority function is a protection system for security door locks with double locking cylinders.
The use of this priority function is particularly advisable if keys are inserted from the inside and there is a risk that the door will be pulled shut without the key having been removed from the inside first. The priority function enables the door to be unlocked from the outside even if the key is inserted from the inside.
The priority function is therefore superfluous for knob cylinders and cannot be selected for half cylinders.
If the priority function is integrated in the lock, the lock can be operated from the outside even if the key is already inserted on the inside.