Restrictions in license

Ian Lance Taylor ian at
Sun Sep 25 19:12:08 UTC 2005

Brian Behlendorf <brian at> writes:

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

As I recall, OSD #4 was written to permit the QPL which only permitted
source code modifications to be distributed in the form of patchsets
to the original distribution.

As you say, my understanding has always been that qmail doesn't
qualify as open source because it does not permit the distribution of
modified binaries.  You can distribute modified source code, but you
can't distribute binaries built from the modified source code.  That
would seem to violate OSD #3.


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