Bruno Lowagie

If your interpretation is correct, you "degrade" the AGPL to the LGPL, and that's not what the AGPL is about. I am not a lawyer, but I know Math. In Math, you can prove or disprove something with a "reductio ad absurdum." Let's suppose that you are right, and that company A can use an AGPL library X inside a closed source web application, as long as company A does not modify a single byte of library X. If that is the case, modification of any AGPL library would never lead to the obligation of sharing source code, because one could always introduce a middleman to apply the modification. Company A could use middleman B to apply the desired modification. Middleman B creates library Y, which is library X with the modification. Middleman B releases library Y under the AGPL (as he should). Now if what you claim is true, company A can now use the modified library X (aka library Y) in a closed source application, and you have shot a hole in the AGPL that reduces it to the LGPL in the context of server-side applications. Since it is absurd that the AGPL is equal to the LGPL when used in a web application, your initial premise must be wrong, wouldn't you agree? Don't you agree that there is no such loophole in the AGPL?

Two examples: a Document Management System comes as a war file covered by the AGPL. In that case, you are using the copyrighted work as-is. You add documents to the system, maybe you change some settings, and so on. This use does not lead to any of these documents or settings to become open source. However, suppose that you are creating your own Document Management System using an AGPL library as an essential component, you are creating a work based on that AGPL library in a way that requires copyright permission. According to article 0, this qualifies as modification because you are creating a work "based on" the earlier work. I quote: To "modify" a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a "modified version" of the earlier work or a work "based on" the earlier work. Asking "where in the AGPL does it say that..." doesn't make sense in this case, because the AGPL refers to copyright law where it says "in a fashion requiring copyright permission."