In practice, If you want to extract the subset of code for which the copyleft sunset
clause applies from a project that has been licensed under copyleft-next for more than
fifteen years; you would go to the revision control system, then roll back the commit
history 15 years earlier, - for example if you are doing this in 2021 you would roll back
the commit history to 2006 -; The resulting revision history tree from the top commit
backwards is licensed under copyleft-next but the copyright protection of the license is
similar to Apache 2.0 not GPL. As each year passes you can move one year up in the
revision control history and get more code under a permissive license with patent
protections.