Simplify cancellation and NIL cases

[marqh]

The current version of the schemas require a good amount of description for a relatively small message (CNL, NIL, etc.), mostly in the form of OM_Observation information. This should be simplified so that only the necessary information is carried in these cases.

ref: https://software.ecmwf.int/issues/browse/AVXML-17

created:
29/Sep/15 9:10 PM

Reporter:
Aaron Braeckel

[braeckel]

Any changes made should also reflect the ICAO WG-MIE/4 decision that was made regarding the minimum set of content that should be included in IWXXM messages.

[braeckel]

The original concern about NIL and CNL cases was with the unnecessary structure that was carried by requiring time and location information, which was buried under O&M constructs. After reviewing all of the current examples it appears that this issue was resolved with #27 changes - there is no longer any unnecessary structure. Closing this issue.