Folder: /3rdparty This folder contains libraries written and (un?)maintained by people or parties outside the Pcsx2 DevTeam. Libraries or code snippets written by the Pcsx2 team are housed in /common instead. Most of these libs in /3rdparty have been tailored slightly from the original forms downloaded from the net. So if you want to upgrade to a new version you will need to do a proper diff merge. Likewise, if you modify anything in a 3rdparty library you should be sure to tag the modification with your sig or a "pcsx2" or something. Thirdly, you can use Svn Log to check for modifications, however folder renames or svn homesite changes may not have all relevant history necessary to make an accurate merge.