Restrictions in license

[Rick Moen]

Quoting Brian Behlendorf (brian at collab.net):

> P.S. - why doesn't the qmail license qualify as an Open Source license 
> given clause #4?  That license restricts my ability to distribute qmail in 
> modified form - but doesn't prevent me from distributing patches. 

Not even severely proprietary licences prevent you from distributing
patches -- at least, not through application of copyright law:  Patches
are not derivative works.

However, please note that Dan's licence does _not_ meets the criteria of
OSD clause #4, in that "patch files" may _not_ be packaged up with Dan's
original tarballs and distributed that way "with the source code for the
purpose of modifying the program at build time".  To quote:

  You may distribute copies of qmail-1.03.tar.gz, with MD5 checksum
  622f65f982e380dbe86e6574f3abcb7c.  [...]  If you want to distribute
  modified versions of qmail (including ports, no matter how minor the
  changes are) you'll have to get my approval.

The "Exception" paragraph at the bottom relates to precompiled _binary_ 
packages with very narrowly constrained changes, not source code.

> The license "explicitly permit"s distributing builds, see the bottom
> of: http://cr.yp.to/qmail/dist.html, but these derived works have to
> behave exactly the same.  So what kind of license was #4 designed to
> allow?

My perhaps fallible recollection of open-source history suggests:  QPL's
original source kept distinct + source patches = tarball model.  One of 
the things Dan's licence forbids.

Apologies if the above is too analytical for license-discuss's tastes:
We might want to discuss djbdns licensing, instead, as that would
facilitate reintroduction of the name-calling that has recently been in
vogue, here.  (Hi, Matthew G.!)

-- 
Cheers,              Never anger a bard, for your name sounds funny and
Rick Moen            scans to many popular songs.
rick at linuxmafia.com                         -- Stephen Savitzky