The Horizon package comes with an example applet called CoordDemoApplet (located in the examples/CoordDemo directory). This applet illustrates how a dataset's metadata can be converted into an instance of CoordinateSystem which is then used to display coordinate positions of pixels pointed to by the mouse pointer in a display of the data. This section highlights portions of that applet, in particular, the PosTrackerViewer class which displays the data, to show how the coordinate and metadata classes are used to display coordinate positions.