Significant Point vs. Designated Point vs. Waypoint
Before describing the AIXM 5 model for designated points, the terms Significant Point, Designated Point and Waypoint, which sometimes are used differently in the aviation domain, shall be discussed.
Significant Point
A Significant Point is defined by ICAO Annex 11
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In AIXM, the SignificantPoint class could be seen as a 'placeholder' for a Navaid, Runway Point (e.g. a Threshold Position), Airport Reference Point, Aiming Point of a TLOF, Designated Point or a simple Point in space. At a conceptual level, it simplifies the model by significantly reducing the number of relationships. See also topic SignificantPoint [SPN].
Designated Point
A term that is only defined by AIXM. The 'Designated Point' definition is derived from the Significant Point definition, by difference:
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In AIXM, a DesignatedPoint is a specialisation of a SignificantPoint.
Waypoint
ICAO Annex 11 defines waypoint exclusively in the scope of RNAV operations
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The SegmentPoint.waypoint attribute allows to specify if the point is used for Area Navigation (RNAV) procedures/routes. The SegmentPoint class is a generalisation of the TerminalSegmentPoint and the EnRouteSegmentPoint.
Summary
The term Significant Point is the most generic one. It includes Designated Points, but also Navaids, etc. The term Designated Point excludes Navaids and all the other types of Significant Points. It includes, but is not limited to Waypoints. Often, a Designated Point will have an official (ICAO 5 letter code name) designator. The term Waypoint should exclusively be used in the RNAV context.
AIXM
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Model Overview
The figure below shows the main AIXM 5 classes used for the DesignatedPoint concept:
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