1. FILE MENU.  It contains "open", "save", "save PS" and "quit" items.  
   "save PS" will save the picture as a post script file.


2. SIZE MENU.  One can choose the radius of the knot tube here.  The 
   default value is 2.


3. COLOR MENU.  There are three ways to color the knot.  
   (i)   "periodic": The color is changed periodically when traveling 
          along the knot.  Default period is 1, and can be changed by 
         "set color period".

   (ii)  "depth":  The color is determined by the z-coordinate of the 
          point.  

   (iii) "single": Use single color.

   With "choose knot color" one can choose several preset single 
   colors for the knot.  

   The next two items will bring up color editors for the knot (with
   single color) and the background.  Click on the toggle buttons of
   the color editor to bring up the color map.  

   The beckground color is specified by the diffuse color on the 
   color editor.  

   The last item prints the command "color_period" for setting 
   color period.  See "On commands" for more details.


4. RENDER MENU.  Rendering by line is the fastest.  Rendering by tube
   is the default, and is probably the best.  When the vertex number
   is small, rendering by cylinder-ball will show round vertices, but
   it is slow when vertex number is large.  The 4th menu item prints
   the command for setting the tube sides.  Try commands "t 1", "t 2"
   "t 3" and "t 10" to see the difference.  

 
5. OPTIONS MENU.  
   (i)   The first item toggles antialiasing on/off.  When it is 
         turned on, it set antialiasing level to 10.  See "On 
         commands" for more details.

   (ii)  The second item toggles rough run on/off.  When rough run is
         on, each vertex of the knot is moved according to its own 
         gradient.  This method approaches the minimal energy faster
         for many knots, but it is not accurate.  

   (iii) "add pinch force".  This item is important when one wants to 
         find the minimum number of edges to represent a knot.  If 
         this is off, the "delete" command will only try to delete 
         vertices without changing the other vertices.  If "add 
         pinch force" is on, it add some extra force on certain edges,
         trying to pinch it to a point so that certain vertex can be
         removed.

   The other two items prints commands for setting antialiasing level
   and pinch edge.  See "On commands".


6. HELP MENU.  Print these help messages.