You can tell which by moving the mouse over the control point. Click on a control point to change the direction. You can also enter their coordinates in the text boxes.[br]Check "Show Control Polyogn" to see the line segments connecting the control points.[br]Show/hide the axes and the grid in the xy-plane using the other check boxes.[br]x-axis is Red, y-axis is Green, and z-axis is Blue in right handed coordinate system.