On 11/09/2012 02:35 AM, "Claes Wallin (韋嘉誠)" wrote:
Sorry for bumping this discussion thread this late, but I discovered
Berkeley DB license* ("the BDB") and it made me think about what had
been said here.
Haven't looked at the BDB before, and I find it interesting. Taking into
account only the numbered points, it might be the shortest example of a
copyleft license in use in the field, even close to the shortest
possible. It's close in form to a BSD-like license plus source requirement.
I'm not sure it's truly a (free software) copyleft license, though
it's something similar. It says that the source code that you have to
provide must be "freely redistributable under reasonable conditions".
Does this mean that the conditions in the redistributor's license must
allow royalty-free modification, say? I suppose I would argue yes,
because of how I believe the term "freely redistributable" was
understood in the 1990s.
The FSF claims that the BDB is GPL compatible, I assume because it
not specify anything outside the bare minimum, in particular does not
restrict any "further restrictions".
The FSF (assuming the FSF analyzed the case carefully) must be
assuming that the word "uses" in "any accompanying software that uses
the DB software" would never lead to a result in which you'd have to
provide more source code than you'd have to in a standard GPLv2
situation (as the FSF would interpret that). In other words, the FSF
must be assuming there is an implied "mere aggregation" limitation on
the source code requirement.
Does it even propagate a guarantee
of the four freedoms to modified versions of the software?
I think this depends on how you read "freely redistributable under
It's worth noting that the Sleepycat License was designed with what
bkuhn would call a 'proprietary relicensing' business model in mind
(at least based on the historical material I recall seeing). I suppose
if that's true it might seem to suggest that the Sleepycat License was
meant to be read as having a *broader* copyleft-ish scope than GPLv2
(which would imply that the FSF seemingly erred in classifying it as
GPL-compatible). (Why else would Michael Olson or whoever wrote the
license not have just used GPLv2? Berkeley sentimentality?)