Guidelines for the development of AIXM extensions are provided separately for AIXM 5.1 (http://www.aixm.aero/document/aixm-50-extensions) and for AIXM 5.1.1 (https://drive.google.com/open?id=1d9kJli6AT6MiuGDcLgAcMs-Wim5I-cxbiPhwSPc5WAM).
Permission
An AIP Data Set may include extension of the core model, on condition that:
Rule
The Data Set shall remain valid against one of the AIXM BasicMessage schema mentioned.
Rule
The extension schema shall be made available through a public URL.
Rule
A document explaining the purpose of the extension and the usage of each extension element shall be made available to all recipients of the data set.
Recommendation
The UML representation of the extension should be made available to all the recipients of the data set.