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On Nov 8, 2009, at 12:42 PM, vincent wrote:

Le 8 nov. 2009 à 18:33, Ty Sarna a écrit :

Okay, it can be no more than a voyage back in time to the aforementioned episode – so, is there any estimation as to the percentage of Sun code in today's NetBSD ZFS port?

What does that have to do with anything? It could be 100% NetBSD code and that wouldn't change anything as far as patents.

I am not sure about this. I think you can't patent a concept, but you could patent an implementation. For example, in the electronics field, you maybe can patent a type of high-quality oscillator, but you cannot claim any property on a different implementation achieving the same goal. If you can code from scratch a FS with the same functionalities as ZFS, I don't figure out how you could be liable to patent suing.

That's not the way patents work. What you've described is more like copyright, where the particular expression of the concept is protected. With patents, it's the concept itself -- but details matter.

Let's consider the case of the famous (and now-expired) RSA patent:,405,829 . Fundamentally -- and I believe this is true throughout the world, though what can be patented differs in different jurisdictions -- a patent consists of two parts, a description of the invention and "claims". The description is just that: it describes how the invention works. A patent is basically a deal between the government and an inventor: the inventor describes the idea in sufficient detail that others can replicate it, learn from it, etc.; in return, the government grants a limited-term monopoly on the *idea*. Precisely what is protected is described by the claims. You infringe a patent if you build something that contains all elements of any one claim. Thus, if you look at claim 1 of the RSA patent, to infringe you'd need a system with a communications channel, an encoder that worked according to that description, and a decoder that worked according to its description. If you built a system that had no communications channel, you wouldn't infringe claim 1. However, you might infringe claim 37, which doesn't speak of a channel.

There's a lot more I won't go into, like the "doctine of equivalents". The net, though, is to the extent that the patent is valid in jurisdictions of interest, you can't evade it by changing code; you probably have to change functionality.

                --Steve Bellovin,

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