@jc1 No. The X,Y in interactive maps are the HTML image map coordinates which are used for airport x, y verification in the HTML code.
<area shape="circle" coords="1589,3151,17" ...
The Lat/Long in the Interactive Maps is calculated based on a curved Earth surface and the projection of the current map is not doing this and so there are discrepancies away from the center. In a future release BMS might have a different map projection is my understanding so I will stick to that calculation for now. I can switch the algorithm if preferred.
The X, Y on the map are the tooltip coordinates for the Map airport look up in HTML and not the WDP X,Y
Conversion to WDP is easy:
WDP.Y = 4096- Map.Y
WDP.X = Map.X
The .ini are using coordinate origin in FT from the bottom left corner but the image in HTML uses origin at top left.
Hope this helps to understand the difference. The WDP X,Y have no utilization for the HTML map tag which I need for the airport locations (see HTML code).
See section 7.1 of the manual why the X,Y coordinates are there to support map development and verification.