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The point.xml file contains pre-defined points which can be referenced by their id in <point> elements. This makes maintenance of coordinates much simpler and significantly improves the readability of your map files. Especially when visualizing airways, SID, STAR or any other procedures.
A point element needs to be defined in the points.xml file:
<points> <point id="COA" lat="N0512053002" lon="E0032119001"/> </points>
You can then reference that point in any map, replacing latitude/longitude or cartesian x/y pairs.
<symbol id="vor_symbol" text="COA" color="symbol_vor_color" lat="N0512053002" lon="E0032119001"/>
could be replaced by:
<symbol id="vor_symbol" text="COA" color="symbol_vor_color" ref="COA" />
Another example …
If you would like to draw a circle around a known VOR beacon …
<circle radius="10" segments="64" r="255" g="0" b="0"> <point lat="N0512053002" lon="E0032119001"/> </circle>
could be replaced by:
<circle radius="10" segments="64" r="255" g="0" b="0"> <point ref="COA"/> </circle>