From: Kristof Bastiaensen <kristof@...>
Date: 2004-07-20T04:32:15+09:00
Subject: Re: Ruby Specification

On Mon, 19 Jul 2004 18:51:46 +0000, Jeremy Henty wrote:

Hi,

> 
> Pardon my bluntness, but that was foolish of you.  The GPL requires
> you to release all derived works under the GPL too.  If you looked at
> id Software's source and used it in a closed source product of your
> own then id Software would have grounds for suing you for damages.
> 

I am not a lawyer, but I believe this is not correct.
As far as I know, copyright only applies to the code, not to 
the techniques used.  So as long as you are not
copying code directly into your program, you are not in breach
of copyright.  For the GPL a derived work is only derived if it 
uses the same code.  Techniques don't fall under copyright,
but under patent law.  (Wether patents should be allowed for
software is a different discussion).
Of course you could copy the code, change the names of some
variables and functions, and then claim it's your code, but
this would obviously still fall under the copyright case.
However if you just look at the techniques used, and use
them in you code (not verbatim), then there wouldn't be any
grounds to be sued (apart from patents).

Kristof