The number of sliding doors in a structure, module, group of structures, or other object is the total quantity of doorway openings within the object (both inside [between rooms] and at its perimeter) where the door slides sideways along a track.

This number includes entrance doors, vestibule doors, doors between rooms, doors leading to balconies or terraces, and all other similar doors belonging to the same object. It does not include doors which do not extend down to the floor (such as shower doors) or doors not intended for people to pass through (such as cabinet doors).

The counted item is a doorway opening whose door moves sideways along a track. Interior and perimeter openings are included, while the floor-reaching and pedestrian-passage conditions exclude the stated shower and cabinet doors.