What is Copyleft?

Rod Dixon rodd at cyberspaces.org
Thu Feb 22 19:07:50 UTC 2001

Correct. Your quote from RMS didn't indicate whether he was referring to
static or dynamic linking, but since your example uses dynamic linking, I
assume that is what RMS meant as well. I do not read the copyleft in the
GNU GPL to preclude runtime linking to DLLs. Indeed, to read the copyleft
in that manner would raise serious questions concerning its potential
copyright misuse in my opinion. There is no copyright interest that would
allow a copyright holder to such a thing, and one seeking to undermine the
copyright regime would seem unable to do so as well.

On Thu, 22 Feb 2001, Ryan S. Dancey wrote:

> Here's a question I thought I'd never have to ask.
> What is a Copyleft?
> The reason I ask this question relates to RMS's recent pronouncements about
> Apple's psuedo-open license terms.  He says, in part, that one of the flaws
> of the license is that:
> "It is not a true copyleft, because it allows linking with other files which
> may be entirely proprietary."
> I the working definition of "copyleft" I have been using is:
> "A way of using contract law (through a copyright license) to ensure that
> everyone has the freedom to copy, modify and distribute a given work.  It
> takes the copyright law and turns it inside-out.   Instead of being used to
> limit what you can do with a copyright work, a copyleft ensures that your
> freedom can't be abridged."
> Now, let me say that for the purposes to which RMS developed the GPL in the
> first place, his indication of a "flaw" with the Apple license is completely
> consistent.  However, I would say that the ability to link with non-free
> code, while an incompatibility with the GPL, isn't a copyleft problem.
> If the license allowed a user to link to non-free code, and distribute the
> combination in object-form only, then I would say that it was a copyleft
> problem, because free code would be rendered non-free (the gestalt work
> would have two copyright interests; the Free part, and the non-Free part,
> and thus the work as a whole couldn't be distributed without additional
> permissions).
> If I write a copyleft free program for Windows, I should be able to load and
> link at runtime to any DLL in the system, regardless of whether or not that
> DLL is free code or not, shouldn't I?  How else could a Windows program ever
> be written using the GPL? (I don't know enough about Linux to have an
> opinion about Linux code).
> The copyleft concept is supposed to ensure that any material I use or modify
> which is based on copylefted content has to obey the same terms as the
> original copyleft license, correct?
> The concept of "copyleft" itself shouldn't be so specific as to include
> material related to the linking model of computer software, should it?
> Ryan

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