The format and type of data written is based on the file type chosen within the file
management pop up dialog box.
A selection of Table data files (*.dat) writes the contents of data.pts to a ASCII file;
selecting Interpolated grid files (*.grd) writes the contents of data.grd to a ASCII file;
and a selection of ESRI shapfiles (*.shp) writes the contents of data.pts to a binary file.