The figure below shows the main AIXM 5 classes used for the touch down and lift off (TLOF) concept.
The TouchDownLiftOff class is used for defining a load bearing area on which a helicopter may touch down or lift-off.
A TLOF may be situated on an Runway (of type equal-to 'FATO') or directly at an AirportHeliport. (i.e. The TLOF may form an integral part of the FATO or be situated apart at an airport/heliport).
A TLOF is identified by its designator.
In addition it its dimension may be described by a lenght and a width.
It has may have an aimingPoint that is defined by using the Point ElevatedPoint class.
The surface of a TLOF is encoded by using the SurfaceCharacteristic class (see also Surface Characteristic [SCH])