Provision of IWXXM for the delivery of non-aerodrome observations

[blchoy]

Tim Hailes mentioned that BoM borrows the TAC METAR format to deliver observational information at waypoints. The following are the adaptations they have made to the format to provide the observations:

METAR KMG 090430Z AUTO 36026KT 9999 // NCD 13/08 Q1020
METAR MTB 090430Z AUTO 29007KT 9999 // NCD 14/03 Q//// 

In IWXXM METAR iwxxm:aerodrome has a fixed type of aixm:AirportHeliport and there is no way of borrowing this to deliver waypoint observations in IWXXM format. In IWXXM-SX, the basic construct iwxxm:MeteorologicalFeature has its iwxxm:orginatingCentre defined to be Any type. This means that any reports defined by extending iwxxm:MeteorologicalFeature will have the freedom to choose their own way of representing the originating centre:

Of course there will be constraints implemented in Schematron to limit the choice of types to be used with iwxxm:originatingCentre, but that would be much more flexible than existing legacy formats.