A 300mm nib is required for a head-on approach to a gate or door to ensure that the door can be approached and opened by a wheelchair user – the nib allows a wheelchair foot rest (or other mobility aid) to project beyond the line of the door frame, enabling a wheelchair user to reach the door handle.

When the internal approach is not head-on, a nib may not be required for all of the 1200mm (Cat 2)(2,20f) or 1800mm (Cat 3) (diagram 3.3 and 3.24f) distance as indicated, provided that the proposed layout creates the movement space for a wheelchair user to approach the door controls and use the door handles to open the door.