This construct is intended for all geometry that is placed within the exterior shell of the building. This includes all partitions, doors, etc. on the interior of each floor. You can include space objects, ceiling grids, furniture and equipment in this construct as well. Or, if you wish, you can separate these other objects into their own spaces and grids and furniture constructs.
The various Interior constructs are referenced in the Floor Plans, Composite Model and Section View files.