When was the biggest code change that would make older modules not work with 3.7 X versions. I always hane been a bit curious and no matter what i used as a website mainline code i would test, tweak and adapt things to work with it. It has been PHP-Nuke for about the last 6 years. Adapting the layout from IPB forums into bbtonuke etc. I am just trying to find a starting point to see what changes were made to make lets say 3.6 X mods not work with 3.7 releases.