[OSM-legal-talk] Extent of share alike?

Matt Amos zerebubuth at gmail.com
Mon Nov 2 12:33:20 GMT 2009

On 11/2/09, Frederik Ramm <frederik at remote.org> wrote:
> Hallo,
> Matt Amos wrote:
>>> However, my question is, how far does the share alike
>>> section of the Creative Commons licence go. I want to share the map data
>>> with OSM but not the other sections of the work.
>> this lack of clarity is one of the problems with the CC BY-SA license.
>> the short answer is: i'm not sure. the longer answer is: the image you
>> render to the screen must be CC BY-SA licensed,

the even longer answer is... ;-)

> ... not so fast! We generally say that:
> * if you produce an image that contains OSM and other data, then deliver
> this image to the client computer, then the whole image is CC-BY-SA.
> but
> * if you produce two different images, one with OSM and one with other
> data, and the two are overlaid on the client computer (by software
> acting on behalf of the user), then your second image can be licensed
> whatever you want. Only if the user (who is considered to have created a
> derived product by asking software running on his computer to take two
> images and merge them) then further publishes the image - which you may
> or may not allow as the image contains your data! - would the image have
> to be made CC-BY-SA.

does that mean that no-one can redistribute a screenshot of the
application? the CC BY-SA portion would imply that the screenshot
would be CC BY-SA, but the license on the "other layer" of the image
wouldn't allow that.

> Otherwise it would not be possible to e.g. overlay OSM data and CGIAR
> "noncommercial use only" hill shading in an OpenLayers application.

indeed. for what it's worth i think that overlaying data onto CC BY-SA
data/tiles is fine. but i'm not so sure about it that i'd make
something on that basis without retaining a lawyer!



More information about the legal-talk mailing list