The nopCommerce Public License states that it is GPL 3.0 licensed along with "Additional Terms". In the GPL Section 7, "Additional Terms" are allowed to be added as follows (GPL v3 Section 7):
Notwithstanding any other provision of this License, for material you
add to a covered work, you may (if authorized by the copyright holders of
that material) supplement the terms of this License with terms:
a) Disclaiming warranty or limiting liability differently from the
terms of sections 15 and 16 of this License; or
b) Requiring preservation of specified reasonable legal notices or
author attributions in that material or in the Appropriate Legal
Notices displayed by works containing it; or
c) Prohibiting misrepresentation of the origin of that material, or
requiring that modified versions of such material be marked in
reasonable ways as different from the original version; or
Afterwards the GPL also says this:
All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10. If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further
restriction, you may remove that term.
The authors of the nopCommerce License apparently believe that their terms (to include "powered by nopCommerce" on each screen and to hyperlink it to their site) are a form of author attribution or reasonable legal notice as defined in Section 7.
Section 7 technically allows you to remove the term if it turns out that the term is actually a "further restriction" as defined by Section 10:
You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation [for patents]...
So, are the nopCommerce terms (to add the "powered by nopCommerce" to each screen, and to hyperlink to their site) "additional terms" or "additional restrictions"?
It seems like it could be argued either way for this case. On the one hand, the additional terms themselves don't seem to directly prevent anyone from exercising their GPL rights, so that is an argument in favour of the terms being considered Section 7-compliant. On the other hand, the fact that nopSolutions are charging a fee for a separate license seems to contradict Section 10, so that may be an argument in favour of defining the terms as "additional restrictions".
Is nopCommercial Public License really open source?
The OSI definition of open source includes this rule:
- License Must Not Be Specific to a Product
The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution.
Since the additional terms specifically mention "powered by nopCommerce", then there seems to be a potential problem if an open source developer tries to extract parts of source code (which is presumably GPL-licensed) and then place that code in a different product.
Does that developer have to then comply with the nopCommerce additional terms and therefore add "powered by nopCommerce" to the completely different product that she is developing? If so, then the terms would seem to contradict Rule 8 of the OSI definition.
However, GPL Section 7 gives the developer in this case a possible way out -- if she takes code from nopCommerce and uses it in a product which is clearly not directly related to nopCommerce, then at that point it seems quite likely that the "additional terms" are no longer reasonable at that point, and so she could remove those terms, since they are more clearly "additional restrictions" at that point.
For example, if the WordPress authors wanted to adapt some code from nopCommerce into their project, it doesn't seem reasonable that they would have to add "powered by nopCommerce" to every page of WordPress, so WordPress (for example) would have a good argument to say that they could remove the "powered by nopCommerce" terms, when they adapt the code and place it inside their open source product. In practice, someone would actually have to be brave enough to try this and see how nopSolutions respond.