[OSM-legal-talk] [OSM-talk] ODbL vs CC-by-SA pros and cons

[Anthony]

On Thu, Sep 2, 2010 at 5:39 AM, Richard Fairhurst <richard at systemed.net> wrote:
>> [second message]
>> You must be misreading them.  ODbL is weak copyleft, plus a
>> database rights license, plus a contract agreement.  CC-BY-SA is
>> strong copyleft.  Do you dispute that, or do you claim that these
>> two are in the same spirit?
>
> You weren't asking me :) , but I'd dispute that. I wouldn't say one was
> weaker or stronger than the other: ODbL's share-alike is simply more clearly
> defined for data.

And the LGPL is simply more clearly defined for libraries?

C'mon, that's what "weak copyleft" means.  Not viral for some types of
derived works.

> - routing code designed solely to work with OSM data: copyleft does not
> persist into code
> - printed cartographic map created using OSM data: copyleft persists into
> creative work
> - web cartographic map created using OSM data, styles applied
> programatically: copyleft does not persist into creative work
> - web cartographic map created using OSM data, styles applied manually:
> copyleft persists into creative work
> - printed mashup map created using OSM data: copyleft persists into mashup
> data

Copyleft doesn't "persist into creative work" when the creative work
is not a derivative.  That's true of all copyleft licenses, weak or
strong.  (On the other hand, it's actually not true of the ODbL, as
the ODbL uses contract law to reach where copyright law cannot.)

> - web mashup map created using OSM data: copyleft does not persist into
> mashup data

That's debatable.

> Is one "stronger" than the other? I don't think there's one easy answer.

Frankly, I find it hard to believe that.  Instead of making up a
definition of "stronger" to fit your argument, try looking up what
"strong copyleft" actually means.

> On
> the one hand, ODbL has some provisions which require the end-user to give
> more back: in particular, the GPL-like requirement to release source.

Which has *nothing* to do with the term "strong copyleft" as opposed
to "weak copyleft".

> On the
> other, some items are caught within CC-BY-SA's copyleft and not ODbL's.

Which is *exactly* what the term "strong copyleft" as opposed to "weak
copyleft" means.

> (I'm quite prepared to believe that there may be items that are caught by ODbL's
> copyleft and not CC-BY-SA's, given the existence of "loopholes" in CC-BY-SA
> such as the programatically-generated derivative one.)

Given your arguments on this list, I'd guess you're quite prepared to
believe anything that might help prevent you from admitting that you
are wrong.

The distinction between "strong copyleft" and "weak copyleft" only
applies to derivative works.  The fact that CC-BY-SA does not cover
things that are not the creation of derivative works is not a
loophole, it's a feature.