2.4 The Viral Nature of the GPL
If an author A licenses a copy of their work under the GPL to a second person B, then (as discussed above) B receives a license to make and distribute 'derivative works', along with the obligation to license the 'derivative works' under the GPL.
If the 'derivative work' is a modification of the original work (e.g. the same aircraft with additional refinements), it is quite obvious that the modified aircraft must be distributed under the GPL, or not distributed at all.
However, this clause also applies when the 'derivative work' is something entirely different. Suppose author B creates an entirely different and unrelated aircraft but copies, modifies and reuses the autopilot, checklists and a few cockpit instruments from the first aircraft, into the second aircraft. This makes the second aircraft a 'derivative work' of the first aircraft and forces author B to distribute the second aircraft under the GPL. It is said that the GPL of the autopilot, checklists and instruments of the first aircraft has 'infected' the second aircraft and made the entire second aircraft GPL'd. This is seen as a Good Thing by the Free Software Foundation, which would like for everything to be GPL'd, and as a Bad Thing by people who would like to use any license other than the GPL.
Frankly I think of all the things writen in the now deleted topic my premise that this opens up a can of worms with regards ALL planes within every 3rd party repository was the most damning and scariest.
It's my belief that every plane contains at least 10% of code that has been copied from existing work... In fact this has been the advised method of creating new work within flightgear... On many occations I've read the advise being to simple copy a similair plane added the new 3d files and texture and adapt it's animation and flight model xml files.. There are no template files, no blank planes in which to start a new project and as such this amounts to a GPL 'trap' by those in charge of flightgear as all planes are derivative in one way or another.
One of the other issues is the differing treatment of FGmembers versas other 3rd party repositories by core flightgear, their attitude is not consistent, it can be shown to be a colaborated and systematic series of attacks upon FGMembers. When a GPL challenge is initiated towards FGmembers content by an author, more than likely egged on by core flightgear. If the same challenge or similiar challenges weren't issued to ALL 3rd party repositories with regards the viral infection of GPL content then upon entering the courts the judge would not doubt view this as a vendetta towards FGMembers.
It might be that this has no reflection on the outcome with regards FGMembers, however it most definately would have dragged every other 3rd party repository into a similiar court action, as GPL licence does not allow the author to be choosy as to who can and cannot break it's rules..it would not be in GNU's best interest to allow that to stand.
AS it's said...." I think that boats well and truely sailed"