A BifoldDoor is hinged in the middle as well as on the side. It has two door elements. You can also make the door a double door, with four door elements.
The topic for each kind of door describes its unique controls and behavior. Most door parameters are common to all kinds of doors,see Doors
In the door's Parameters rollout, the three check box controls below the Frame area are specific to BifoldDoors.
Double Door: Turn this on to make the door a double door.
Flip Swing: Turn this on to make the door swing in the opposite direction from the default.
Flip Hinge: Turn this on to make the door hinged on the opposite side from the default.
This check box is disabled while Double Door is turned on.
For an explanation of how to create a door see Doors