An outline proposal

Horton, Gareth Gareth_Horton at
Fri Oct 15 19:27:22 CEST 2010

Dave et al,

From this page, it appears the FSF did a patent search on deflate/inflate and came up with nothing. Stac threatened, but nothing came of it.

"Stac claims that a pair of their patents cover the deflate algorithm (US patent numbers 4,701,745 and 5,016,009). Since no one but Netscape seems to have been contacted by Stac, and since both deflate and inflate received a clean bill of health in the Free Software Foundation's patent search, both the PNG Group and Info-ZIP are considerably puzzled by this. More news as it becomes available... 

•29 November 1998 - It's been eight months with nary a peep from Stac or anyone else, so it appears that the Netscape folks misinterpreted something when they brought up supposed PNG patent issues in Mozilla (see above). Note that while it is possible to write an infringing deflate encoder, the one in zlib was very carefully written to avoid all patents, and the deflate specification (RFC 1951) notes this explicitly: `` is strongly recommended that the implementor of a compressor follow the general algorithm presented here, which is known not to be patented per se.''

Anyone with connections to the FSF get something more concrete?


-----Original Message-----
From: sc34wg1study-bounces at [mailto:sc34wg1study-bounces at] On Behalf Of Dave Pawson
Sent: 15 October 2010 10:35
To: ISO Zip
Subject: Re: An outline proposal

On 15 October 2010 09:59, Alex Brown <alexb at> wrote:
> Dave
>> ZLIB Compressed Data Format Specification , and 1951, DEFLATE 
>> Compressed Data Format Specification."
> RFC 1951 claims that  it "[c]an be implemented readily in a manner not covered by patents, and hence can be practiced freely". Whether that's true or not I suppose would only be decided in a court of law in case of dispute.

It was the 'based on' (rather than strictly following) that held my attention.

> As I understand it all the specification we are discussing (OOXML, ODF, EPUB and W3C widgets) make use of the DEFLATE compression method.
> In general, I suspect a consideration of IPR issues will need to take place as part of what we are doing, but first I think we need more facts on the table and a clear idea of what technical features we will want to standardize ...

technical features.. = requirements?
If so +1.

How to get a legal eagle from ISO to help us?


Dave Pawson
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