The default area is the area where the projection is ment to be used and where it is accurate. It is not recommended to use the map projection outside its default area.
public void GetDefaultArea(
out double x0,
out double y0,
out double x1,
out double y1
)member GetDefaultArea :
x0 : float byref *
y0 : float byref *
x1 : float byref *
y1 : float byref -> unit