Are plug-ins OSS?

[revent]

A shorter answer is that any work that specifically requires the use of a GPL'd program in order to function is a derivative work and must be GPL'd, unless the owner of the program declares that he will not enforce the GPL with respect to that particular derivative work.

[Henrik]

3DS files are 3D models generated by the use of 3D design programs.
There's nothing about them that's specific to Celestia.

Well, is this the case or not? There still seems to be some confusion about this. If 3ds is a standard 3d format then it can be considered output from those other programs, and will not need to be GPLed. However if they are specifically designed for Celestia and only work with Celestia then they may be derivative works. If this is the case Chris must decide wether he considers them derivative works (ie. all of revent's reasoning would apply). In any case it would help if Chris clarified it.

[selden]

Gee.

I'm glad you all have cleared this up.

I'm going to have to delete all of my Celestia pages. They are not and cannot be made GPL compliant.

[chris]

I certainly did not intend for the GPL to extend to all add-ons created for Celestia. As far as I'm concerned, add-on creators are free to distribute their works under whatever terms they like, though I encourage keeping them in the spirit of OSS. If the Celestia distribution requires some additional text to clarify this, then I'll add it . . .

--Chris