In October of 2015, the Software Freedom Conservancy (SFC) and Free Software Foundation (FSF) jointly published "The Principles of CommunityOriented GPL Enforcement". That document described what those organizations believe the goal of enforcement efforts should be and how those efforts should be carried out. Several other organizations endorsed the principles, including the netfilter project earlier this month. It was, perhaps, a bit puzzling that the project would make that endorsement at that time, but a July 19 SFC blog post sheds some light on the matter.