The general extension adds attributes that are needed for AM: AIXM 5.1.1 extension for AMD and ASRN: AIXM 5.1.1 extension for ASRN.

horizontalResolution, verticalResolution

These attributes do not exist in the “core” AIXM because it was assumed that the resolution is implicit in the latitude, longitude and elevation values. ED-99/Do-272 asks for the resolution to be explicitly stated in the “vres” attribute. Note: The overall statement of “fine”, “medium” or “coarse” should be recorded in the metadata.

• Because of a limitation of the AIXM 5.1 schema, the extension mechanism cannot be applied to Point, Curve and Surface. Only the ElevatedPoint, ElevatedCurve and ElevatedSurface may be extended. Therefore, the horizontalResolution is also added here. As ElevatedCurve is declared in the substitution group for Curve, if necessary to fill the horizontalResolution property, an ElevatedCurve element shall be used instead of Curve. A similar procedure shall apply for Point/ElevatedPoint and Surface/ElevatedSurface.

integrity

All AIXM 5.1 features that are relevant for ED-99/DO-272 shall be extended to include an “integrity” property. Integrity is not in the “core” AIXM as it is a characteristic of a process. If a value is specified in a dataset the author can’t have confidence that that integrity value is preserved at reception of the dataset.

source, revisionDate

All AIXM 5.1 features that are relevant for ED-99/DO-272 should be extended to include a “source” and a “revisionDate” property.

• It must be noted that the preferred option for these items of information is to use the metadata mapping. Metadata is useful for when a dataset is made available in a registry – source and revision dates are certainly items that a query can be built upon.
• However, adding this information in the metadata for each feature instance can be seen as heavy. Therefore, the extension mechanism is provided as an alternative solution. Nevertheless, if all feature instances in the AMDB are from same source and have the same revision date, metadata is not heavy and should be used

As such a simplified metadata schema could be of interest to other applications, all AIXM features are extended with the “integrity”, “source” and “revision”Date” properties, as indicated in the following diagram. A separate namespace is used for this extension.

Using the extension in the correspondence tables

The correspondence tables make use of this extension where appropriate. The extensions are shown in italics as illustrated below.