[OT] What is Open Source?

[Huaiyu Zhu]

Jeff Shannon <jeff at ccvcorp.com> wrote:
> There are no limits to the usage of GPL software.  (How 
>many businesses are using Linux?)  What the GPL limits, is 
>derivative works.  You can *use* the software, but when you 
>*modify* it, then you come under the restrictions that the GPL 
>lays out.  (Particularly, when you modify it and then distribute 
>your modified version.)

I think that even if you _modify_ the software, there is still no
restriction from GPL.  A modification follows almost exactly the same rule
as original (except credits, etc).  Only distribution counts.  The GPL
mentions "modify" only to avoid claims like "I modified it, so I can
distribute my modification with my own license" and similar issues.

Think of a printed book.  If you buy one, you can use it in many ways,
including study it and add the knowledge to your own, copy it to make marks
on it in your study, lend it to friends, cite paragraphs for critical
review, cut it to pieces to make paper airplanes, etc.  You can even combine
a theorem from the book with a theorem from another book and prove a theorem
of your own, and publish it.  You can even publish another book using the
ideas you learned.

But you cannot copy it and give/sell the copy to others, modified or not.

The GPL allows you to do all the things you could with a printed book in
terms of using it.  But it gives a little bit more.  It gives you a blanket
permission to copy it and distribute the copies, modified or not, for fee or
not, provided you keep the same license on the copy and follow some
reasonable restrictions (credits, liabilities, etc).

In stark contrast, some of MS licenses (end user license agreements)
actually take away some of the user's rights he would otherwise enjoy on a
purchased printed book.  They essentially sneak in some patent rights,
trademark rights and contracts rights undercover of copyrights.

Huaiyu