
There are different possibilities to write the coordinates when
the enabling \SpecialCoor .
(x,y): This is the default
(r;angle): Polar coordinates
(x1,y1x2,y2): Takes the x coordinate from the first point and the y coordinate from the
second point, which is the same as (x1,y2). In the example there are only the nodes represented
by a dot are defined. It is now no problem to draw the vertical lines without really knowing
the point on the horizontal, it can be build with (Al1).
special angles (PostScript notation) 


