ch is specified by the user.
Typically, these shapes rely on the details of a concrete graphics
format. At present, shapes can be described using PostScript, via a
file or add-on library, for use in PostScript output, or shapes can
be specified by a bitmap-image file for use with SVG or bitmap (jpeg,
gif, etc.) output. More information can be found on the page 
<A HREF="http://www.graphviz.org/wiki/how-create-custom-shapes">
How to create custom shapes</A>.

<H2><A NAME=sdlshapes>SDL Shapes for PostScript</