[OSM-legal-talk] CT clarification: third-party sources

[Anthony]

On Thu, Dec 9, 2010 at 4:46 PM, 80n <80n80n at gmail.com> wrote:
> Share alike is a very simple thing to define.  If you receive
> something you can only distribute it under exactly the same terms that
> you received it.

"Share alike" was a term invented by CC.  They define it, in plain
English, as "If you alter, transform, or build upon this work, you may
distribute the resulting work only under the same or similar license
to this one." (http://creativecommons.org/licenses/by-sa/3.0/)

The context of "alter, transform, or build upon" is that which creates
a derivative work, as opposed to that which creates a collective work.
 Creative commons has created its own, international, definition, but
it roughly mirrors the US definitions (see
http://www.ivanhoffman.com/derivative3.html).

The concept of "share alike" embraces and extends the earlier concept
of "copyleft".  The term "copyleft" is defined by the FSF as "a
general method for making a program (or other work) free, and
requiring all modified and extended versions of the program to be free
as well." (http://www.gnu.org/copyleft/)  "Share alike" works, unlike
"copylefted" works, don't have to be free.