, diamond, pentagon, 
hexagon, septagon, octagon, el (an right angle between two line segments), circle or compass.  
The el and compass symbols are usually used as stand-alone "compass rose" markers.</p>

<p>Alternatively, the shape can be a user-defined shape of which there are three types: a simple
N-sided 'polygon', a 'starred' polygon (2N vertices with every other on a half radius), or a 
'skeletal' polygon (N points connected to the center by radial lines). This mode requires two 
parameters in additi