I guess that ZwCAD is proprietary software and his involvement was only as a user of the tool, not a developer of it.
Can you clarify that for us, please, Bruno?
Also, here we preffer the use of the term Free Software (or Libre Software) instead of Open Source. To better understand our political reasoning you can read this:
http://www.gnu.org/philosophy/open-source-misses-the-point.htmlHappy Hacking,
Felipe Sanches