What should be ensured about the door header in relation to the sill track?

The correct understanding of the relationship between the door header and the sill track is that they should be parallel to each other. This alignment is crucial for the proper functioning of the elevator doors. When the door header is parallel to the sill track, it allows for smooth and consistent operation of the door mechanisms, ensuring that doors open and close correctly without obstruction or misalignment.

If the header deviates from being parallel, it can lead to operational issues such as binding or dragging of the doors, which might cause them to operate inefficiently or even fail. Therefore, maintaining this parallel relationship is essential for effective elevator operation and passenger safety.