[OT] What is Open Source? (was Re: ANN: Twisted 0.16.0...)

[Huaiyu Zhu]

Gerhard Häring <gh_pythonlist at gmx.de> wrote:
>Quoting http://www.fsf.org/licenses/license-list.html
>
>    """
>    The License of Python 2.0.1, 2.1.1, and newer versions.  This is a
>    free software license and is compatible with the GNU GPL.  Please
>    note, however, that intermediate versions of Python (1.6b1, through
>    2.0 and 2.1) are under a different license (see below).
>    [...]
>    """

Thank you for pointing this out.  I thought it was classified by FSF as
compatible with GPL.  I did not know that it was actually classified as free
software.

I had the impression that the FSF only admits a software as free if its
licence guarantees it to be free forever in all derived versions (copyleft).

Reading that page again, the criteria appears to be just that the current
version is free.  

Whether they have changed the definition in recent years, or whether I have
misunderstood this issue from the beginning, I don't know.

So now my mental picture is 

   (copyleft) is subset of (free) is subset of (open source)

It is also refreshing to see that

   (public domain) is subset of (free)


Huaiyu