According to the AIXM Design Team "compared to the last candidate release, there is one significant change: the gml:id attribute is now mandatory for AIXM "objects" also, such as ContactInformation, VerticalStructurePart, etc. This is a side effect of deriving all AIXM Objects from AbstractGML, which was considered necessary in order to avoid the risk that GML-aware applications do not see certain geometrical information, if hidden inside a non-GML object such as VerticalStructurePart.
Concerning the GML profile, the intention is to develop and to maintain a "GML profile for aeronautical data" through OGC. The GML profile is probably the highest priority after the publication of AIXM 5.1."
COMSOFT will quickly update its AIXM 5 database CADAS-AIMDB to this latest release. All current projects and installations will immediately benefit from this effort and will soon operate using the final AIXM 5.1 version.