[OSM-legal-talk] License Cut-over and critical mass

[Anthony]

On Mon, Jul 26, 2010 at 5:10 AM, Rob Myers <rob at robmyers.org> wrote:

> On 07/24/2010 05:46 PM, Anthony wrote:
>
>>
>> But that would mean that mashing up CC-BY-SA data with ODbL data would
>> violate CC-BY-SA.
>>
>
> Copyleft licences (or a copyleft licence and a hybrid copyright/DB
> Right/contract law conceptual approximation of sharealike) are *generally*
> mutually incompatible as they require derivative works to be placed under
> the same single licence.
>
> You can however mash-up the produced work under BY-SA.
>

Only if you license the produced work under BY-SA.  Which means *all
elements* of the produced work are under BY-SA.  Which means *the data*
encapsulated in the produced work is under BY-SA.  Which means anybody who
extracts the data back out of the produced work would get the data under
BY-SA.

But looking at the text of the license, I don't think you can do that.  ODbL
Section 4.6 says "If You Publicly Use a Derivative Database or a Produced
Work from a Derivative Database, You must also offer to recipients of the
Derivative Database or Produced Work a copy in a machine readable form..."
But that is incompatible with BY-SA, which says that "You may not offer or
impose any terms on the Work that alter or restrict the terms of this
License or the recipients' exercise of the rights granted hereunder."  A
produced work under BY-SA can be publicly used without offering recipients
the source database.  But a produced work from an ODbL database cannot be
publicly used without offering recipients the source database.

I'm not sure if that's intentional or not.  I suspect the creators of the
ODbL wanted to have their cake and eat it too.  But you can't do that.  If
the data can be used in a produced work under BY-SA, then the data has to be
BY-SA.
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