The Open Source Definition: 3. Derived Works

[Christoph Steinbeck]

I'm going to give a talk on the benefits of the Open Source Principles
for the developement of chemistry software (especially in academia) and
I'll first step through the 9 points of the open source definition. 
I have a problem understanding point 3. Shouldn't it be: "The license
must ... require them to be distributed under the same terms...."
instead of "... must ... allow them to be ...". 

What is the point of letting them change the code and change the license
to whatever they like (proprietory, e.g.).

Any help appreciated.

Regards, 

Chris

--
Dr. Christoph Steinbeck (http://www.ice.mpg.de/departments/ChemInf)
MPI of Chemical Ecology, Carl-Zeiss-Promenade 10, 07745 Jena, Germany
Tel: +49(0)3641 643644 - Fax: +49(0)3641 643665

What is man but that lofty spirit - that sense of enterprise. 
... Kirk, "I, Mudd," stardate 4513.3..