Forum Moderators: not2easy
Disclaimer: I am neither a lawyer nor knowledgeable about the GPL. Much better to find someone who is.
From the GPL
You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
To me, that means on each copy of the source code not on every page that the source code generates.
However, it gets a bit sticky. According to the GPL, section 2.c,
If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)
I believe this is intended for compiled programs run from the command line where many users would be using them without having the source code. But one can certainly consider that a CMS script is interactive. However, it also has the possibility of having a link to a page on licensing and does not need the license displayed on each page (and if it were, it would be important to note that the license applies to the CMS not to the content of the page).
Would it count if you "print" an HTML comment, so the copyright is in the HTML source but not displayed on the page? I'm not sure about that.
The last clause is important. If the program normally displays such a notice, it seems that you are, in fact, legally bound to leave it. Note, however, that PhpBB by default includes a copyright notice at the bottom of each page, but they do not interpret the GPL to mean that you must retain that notice. Their interpretation [phpbb.com] is focussed entirely on the source code:
* If you modify sections of phpBB and then decide to distribute it (which is not compulsory), you must ensure the modified files carry prominent notices stating that you changed the files and the date of any change. If you do distribute modifications, they must be released under the GPL.
* You must retain any copyright notices in the code.
That, I would think would be the normal interpretation, but based on the GPL language, I could imagine a court having a stricter view.
However, they *may* require you to place a note there "generated by this software". But this would be an additional requirement, independently from the GPL. I can't see how generating HTML pages is covered there. The clause ergophobe dug up explicitly talks about programs that "normally read commands interactively", which is not the case for a CMS.
And lastly, just because the author wrote some clause into the license conditions doesn't necessarily mean that the requirements established by that clause are legally enforcible. If in doubt, as always, ask an experienced copyright lawyer.
The clause ergophobe dug up explicitly talks about programs that "normally read commands interactively", which is not the case for a CMS.
As I said, this would be the normal interpretation, but I wonder if the other side had good lawyers how a court might actually come down on this. I don't know, I'm just raising the question.
