Any location on the navigation mesh can be categorized as one of four terrain types: open space, doors, stairs, and exit. Each terrain type has an effect on the behavior of occupants on that section of the mesh.
Open Space (Room)
Open space provides no explicit constraints on movement. A room consists of open space. In SFPE mode, the maximum walking speed of occupants becomes a function of the occupant density in the room.
Doors (Connecting)
Doors connect two adjacent rooms together. In SFPE mode they act as the main flow control mechanism as discussed in the section, Movement through Doors, but in steering mode, doors merely record the flow between rooms for results viewing.
Stairs
Stairways connect rooms on different levels. They denote areas where the maximum occupant velocity is controlled by an alternate calculation specific to stairways. The specific velocity calculation is given in the stairway section for each simulator mode.
At the top and base of each stairway, there are two doors that cannot be directly edited within the user interface. These doors connect the stairway mesh to the adjacent mesh and function identically to ordinary connecting doors. If there is no mesh adjacent to the stairway at a door, that door will function as an exit door.