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)).
A TLOF is identified by its designator.
In addition its dimension may be described by a lenght and a width.
A TLOF may have a centre point. In AIXM 5 the aimingPoint property will be used to code the centre point by using the ElevatedPoint class.
The surface of a TLOF is encoded by using the SurfaceCharacteristic class (see also Surface Characteristic [SCH])