Posted Oct 11, 2006 2:33 UTC (Wed) by sanjoy
In reply to: you are missing the whole point of the GPL!
Parent article: Similar in spirit?
I don't see any reason why granting an extra permission should be considered less important to the author than making an extra restriction.
The asymmetry is because the GPL is a copyleft license. The "you can remove them" aspect of permissions is not new to the GPLv3. Under the GPLv2, the result would be the same except handled less conveniently. And extra restrictions are forbidden by the GPLv2; the GPLv3 slightly weakens that requirement (and hence weakens the asymmetry). I'll discuss each aspect in turn.
Let's assume that the new contribution is itself not a derivative work or a 'covered work' (in the sense of the GPLv3). If it is, then the author probably cannot add permissions under the GPLv2 or GPLv3, so this discussion would be irrelevant. But even when the new contribution is not a covered work, the combination of new contribution and distributed work is a covered work and subject to the license.
Under the GPLv2, an author would write his or her contribution, and could distribute it under the GPLv2 (by itself or combined with the original work) and also distribute it by itself under a GPLv2+permission license: a multiple-licensing privilege available to the copyright holder. Special cases of GPLv2+permission include distributing under a new-style BSD license or under a public-domain license. Recipients could use it under either license. If they incorporate it into the original work, they would use the vanilla GPLv2 (with no extra permissions). So, the permissions have just been removed. The contribution is still available from the author with the extra permissions, just not available with those permissions when combined with the original work. (Probably the notice of extra permissions, a "notice of licensing", would have to be retained in the combined source code, but the combined work would be distributed under the vanilla GPLv2, so the extra notice would have no effect.)
The GPLv3 makes this process more convenient for the author and downstream recipients. The recipients can, if they want to, maintain the author's extra permission in the source file they distribute, and recipients farther downstream can extract it with those permissions. Whereas with the GPLv2 they would have to find the source distributed by the author.
Restrictions are already (in the GPLv2) treated differently from the above permission scenario, in that the GPLv2 already forbids any restrictions. For example, it forbids a requirement that secondary downstream recipients pay the author $10/copy.
The GPLv3 relaxes this asymmetry slightly by allowing a few specified restrictions. Thereby common, non-show-stopping restrictions, such as from the Apache License, do not make a work GPL incompatible.
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