A Simplified Directional Facility (SDF) provides a final approach course similar to with that of the ILS localizer, although it is not as precise as the Localizer. It does not provide glide slope information.
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The approach techniques and procedures used in an SDF instrument approach are essentially the same as those employed in executing a standard localizer approach, except the SDF course may not be aligned with the runway and the course may be wider, resulting in less precision.
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SDF is not explicitly mentioned in PANS-AIM. Hence, for the purpose of this coding guidelines the specific requirements are derived form those specified for the ILS in PANS-AIM.
...frequency,... zero bearing direction
In addtion PANS-AIM ENR 4.1. and also AD2.19/AD 3.18 require
for VOR, station declination to the nearest degree used for technical line-up of the aid
The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information The main class is the VOR which is a specialisation of the NavaidEquipmentit is not covered by this coding guidelines.