The safety-edge retracting device must function in which door positions?

The safety-edge retracting device is crucial for ensuring the safety of elevator door operations. It is designed to detect obstacles when the doors are moving and can retract or reverse the doors to prevent injury. The requirement for this device to function in the full open and full closed door positions is based on safety regulations and operational standards.

In the full open position, the safety edge functionality allows the system to verify that the area is clear before closing the doors. This is important because it ensures that passengers are not at risk of having doors close on them unexpectedly.

In the full closed position, the safety edge ensures that if an obstruction is detected while the doors are supposed to be completely closed, the system can react appropriately—either by stopping the door from closing or reversing the operation to maintain passenger safety.

This comprehensive functionality across both door positions is integral for the reliability of elevator systems and for compliance with safety standards, which is why it is the correct answer.