[OSM-talk] Survey: How to pay the OSM bill

Richard Fairhurst richard at systemeD.net
Thu Jul 12 22:11:57 BST 2007

Rob Myers wrote:

> From a recent discussion on the cc-licenses list regarding the use of
> photographs as illustrations I believe that using maps as an
> illustration wouldn't require the rest of the book to be licenced  
> BY-SA.
> This is because the book isn't a derivative of the map.

I agree. It's a collective work.

> (For those of you who are familiar with Free Software licences; BY-SA
> works more like the LGPL than the GPL.)

I do disagree with you here, though.

The LGPL is pretty clever because it enforces a separation between  
two domains: the "application", and the "library" which the  
application makes use of.

CC-SA, in an OSM context, doesn't enforce any separation between the  
"map", and the "data" which the map makes use of. Consequently if you  
use OSM data, all of your map has to be shared-alike - not just the  

Actually the GPL is a fair comparison with CC-SA. CC-SA has the  
concept of a collective work. So, to be fair, does the GPL. That's  
because the GPL is a software licence, and the equivalent of a  
collective work is "different files on the same filesystem". The GPL  
doesn't insist that, because you have one GPLed program, all software  
on your hard disc has to be GPLed; similarly, CC-SA doesn't insist  
that, because one page of your book is a CC-SA map, every other page  
has to be CC-SAed.

The main difference is that the GPL (and LGPL) require you to publish  
the source, and CC-SA doesn't. But for our purposes as agitators for  
free geodata, a "publish the source" requirement wouldn't be a bad  

LGPL for (geo)data would be a real step forward.

Follow-ups to the neglected legal-talk list? As its maintainer I feel  
some paternal affection for the poor little thing.

(memo to self: do not join in licence debates after 3.5 pints of cider)

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