You can parameterize the creation of shapes with the <shapetype> element. The <shapetype> element defines a shape type, and you can instantiate shapes of that type. You create a shape type and give it a name with the ID attribute of <shapetype>; you use that shape type with the <shape> element's type attribute.
Here's the attribute list of the <shapetype> element:
<!attlist shapetype %coreattrs; %shapeattrs; adj cdata #implied -- list of adjust values for parameterized paths -- path cdata #implied -- string with command set describing a path -- >
Here are the custom attributes of this element:
adj— A comma-separated list of numbers that are “adjusting” parameters for the formulas that define the path of the shape ...