[SciPy-dev] Python (Enthought Edition) for Windows test release

Robert Kern rkern at ucsd.edu
Fri Jan 28 19:37:13 CST 2005

Joe Cooper wrote:


> Yeah...My position was "I will not include the patented classes, until 
> those patents are confirmed expired".  Eric vetoed that position on the 
> basis that he thinks one of the patented classes is pretty cool. 

Well, yeah. If it weren't cool and useful, it wouldn't be patented.  :-)

> I 
> think there was some debate on whether some or all of the patents were 
> still enforceable.  I suppose we'll have to see.

(Before I begin, I will state that I am not a lawyer; this is not legal 

Which ones? Two of the patents look like they are going to expire this 
summer (assuming the usual 20-year patent term) but not before then. One 
of the patents is still pending.

February 24, 1995
[Note: the title given in the header file has a typo: 
s/Reducting/Reducing/, and the patent number given is just wrong.]

August 28, 1985

Patent pending

June 5, 1985

July 5, 1994

The others have no comments about patents, but I believe they depend on 
the other classes in VTK/Patented.

> Anyway, my understanding is that free distribution is never a problem. 
> So our primary responsibility is to warn people of their existence 
> within the distribution, so they won't use them in commercial software 
> without awareness of their liability...since they have to read the VTK 
> docs to use them, I would guess that would know which classes were 
> questionable.  But I'll add a "README.PATENTED" to the docs directory 
> and docs menu to explain it all.

The problem with this is that patent infringement isn't like GPL 
infringement. GPL's conditions are triggered when you redistribute code, 
but simple use of the software is unrestricted. That's why it makes 
sense to include readline et al. with a warning that if people intend to 
redistribute Enthon binaries, they have to also distribute (or offer to 
distribute) the readline sources. They don't have to think about the GPL 
until they start distributing stuff, in which case, reading licenses is 
something they have to do regardless.

However, patent infringement triggers on *use* for commercial purposes 
(which, as of 2003, now includes essentially all university research as 
well). Anyone using Marching Cubes to make an image is potentially 
infringing on the patent; if and how they distribute the code that makes 
the image is immaterial. Every time a user sits down with Mayavi or 
tvtk, they're going to have to think about which classes to avoid if 
they care about not infringing on the patents.

Now, if Eric has talked with Enthought's lawyer about this, I'll shut up 
about the Windows and Linux releases although I still don't feel right 
about doing it myself for the Mac version.

Robert Kern
rkern at ucsd.edu

"In the fields of hell where the grass grows high
  Are the graves of dreams allowed to die."
   -- Richard Harter

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