I'll attempt to summarise the discussions from this 'licensing' thread so 
far and to draw some conclusions. It seems to me that we're moving towards a 
general consensus on the main issues, so if we can address any remaining 
concerns then we should hopefully be able to draw this part of the 
discussion to a close pretty soon. Please feel free to comment if you think 
I've got stuff wrong or if you just disagree with it.

The Plan.
---------
The intention is to have an area on povray.org where a collection of 
objects, textures and include files, contributed by the POV-Ray community 
can be held so that anyone can download and use them in their scenes. The 
area will be split into two main parts with (1) an 'ad-hoc' area for new 
submissions and (2) a 'standard' area where contributions adhere to certain 
standards and to a common licensing structure.

Before any author/copyright owner can submit a contribution they must 
confirm either (A) - that they authorise distribution under the common 
license, or (B) that they have included a clear definition of their own 
licensing terms in the work and a standard 'attribution-trap' in their SDL 
to make sure people can't use it without knowing that it has strings 
attached. Only work submitted using (A) - a common license - is eligible for 
consideration for promotion into area (2) - the 'standard' area.

The License
------------
The terms for the common license should be as liberal as possible. The main 
purpose being that the POV-Ray community can then freely enhance these 
contributions over the years without having to get permission from previous 
contributors who may now be uncontactable. It seems that we will probably 
need separate provisions for licensing the source and for licensing the 
resulting generated images.

The main candidate for a common license to cover the submitted Scene 
Description Language files and things like height field files and input data 
files, seems to be the LGPL (Lesser General Purpose License). This 
introduces the concept of a 'library' which is defined as "a collection of 
software functions and/or data prepared so as to be conveniently linked with 
application programs (which use some of those functions and data) to form 
executables.". This permits the library to be redistributed in original or 
modified form under the same terms. Paragraph 7 includes the statement "You 
may place library facilities that are a work based on the Library 
side-by-side in a single library together with other library facilities not 
covered by this License, and distribute such a combined library", which 
seems to me to be consistent with what has been discussed.

The text of the LGPL does seem complicated to me and includes statements 
that I don't fully understand the significance of, but the general spirit of 
the license seems in line with our intentions. Is there anyone out there 
with sufficient legal knowledge to advise on the detail of the LGPL and 
whether we're likely to run into any difficulties if we used it for SDL, 
height fields, data files etc?

The LGPL does not seem to me to explicitly cover images generated using the 
library. I think the discussions in the thread implied that we want images 
to become the property of the person using the files, as I believe is the 
case with files distributed under the includes directory of POV-Ray. I think 
we need to be explicit about generated images, otherwise I think it leaves 
the use of the files unclear. Maybe we could actually use the POV-Ray 
license for this by simply stating that generated images come under those 
same terms.

A potential alternative to the LGPL is the Creative Commons Attribution 
license which seems to be oriented more towards the artistic community. It 
allows modification and redistribution without forcing others to distribute 
derivative works under the same terms, but does include the provision that 
credit needs to be given to the author. The general feeling seemed to be 
that giving credit should not be an absolute requirement of the license. The 
LGPL seems to be the one favoured by most contributors to this thread.

Has anyone come across any other licenses that you believe would cover the 
requirements we've discussed any better than either of these?

Other Stuff
-----------
Authors can add comments into their work to describe the extent of their 
contribution. Also, if the copyright for the original work remains with the 
author, then I don't see any reason why they can't also include a copyright 
notice in the comments (alongside the license statement). Anyone using the 
contribution would be free to decide the appropriateness of maintaining the 
list of credits within those SDL comments. If we ever end up with a 5 line 
contribution containing 200 lines of credits, then someone can do a tidy-up.

We discussed a concern that someone could publish and make money out of our 
work without making any significant changes to our contribution and without 
giving us any credit, but the general consensus seemed to be that, although 
we may get a bit miffed and be a bit grumpy with our friends and family for 
a few days, we'll otherwise live with that.

One question open in my mind (because IANAL), is, if the image generated 
becomes the property of the user, is there any danger that someone could 
incorporate our works in a way that could prevent others from using it. For 
example, could they use the image of a contributed object as part of a 
trademark, or in an advert that associates the object with a well-known 
product and thereby constrains people from using anything resembling their 
trademark or any image that might be associated with their brand?'

 Regards,
 Chris B.

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