DIMENSIONS
'(<a href="http://www.j-archive.com/media/2008-11-13_DJ_23.jpg" target="_blank">Jon of the Clue Crew points to a diagram on the monitor.</a>)  To model space in three dimensions, you have to go beyond Descartes' usual letters & label points along <a href="http://www.j-archive.com/media/2008-11-13_DJ_23a.jpg" target="_blank">this</a> axis'
the z-axis