This is a very simple modifier that alters the shared edge between two faces in any quadrilateral or n-gon.
Please right click to download source code for this example.
This modifier is simple to understand. The data interface is quite skeletal and used only to facilitate a scripted create command. There is no specific property sheet for this modifier because the modifier has no additional parameters beyond the parameters from the super-class modifier. The create command is implemented via script in modifier_scripts.ssl
As you examine the code you'll notice several things: