A Projection is a particular system of representing real-world locations with numeric coordinates.
A Transform is a function for converting coordinates from one Projection to another.
LatLon is a Projection that interprets coordinates as Latitude/Longitude pairs.
WebMercator is a Projection that corresponds to many commercial tile sets and is commonly used with web mapping APIs.
Depending on the services involved, some projections may have the Y-axis first (ie, use (Y,X) coordinate pairs instead of (X,Y)).
that this method should be called before constructing any Projection objects - Projections constructed before forcing XY mode may have their axes flipped.