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- From: jsh@usenix.org (Jeffrey S. Haemer)
-
- Five people have now brought to my attention that my
- recent editorial says the compress/uncompress algorithm is
- copyrighted: Dave Grindelman, Guy Harris, Keith Bostic, Randall
- Howard, and Hugh Redelmeier. That's wrong. It isn't
- copyrighted, it's patented. My apologies to anyone I mislead.
-
- Randall's note contains a lot of interesting details that it's worth posting
- and he's given me permission to post it.
- I've appended it.
-
- Jeff
-
- =====
- [From Randall Howard]
-
- Actually the problem is not that the compress algorithm is copyrighted
- but that it is PATENTED by Welch (the "W" in the LZW name of the algorithm).
- The patent is currently held by Unisys Corporation and they make money
- from licence fees on that patent because of the use of LZW encoding
- in the new high-speed modems. Note that the Lempel-Ziv algorithm
- is apparently not patented, but just the Welch variant as is found in the
- UNIX compress utility. Therefore, at the cost of inventing a new file
- compression standard, it would be possible to escape licence fees by
- using a different variant of LZ compression.
-
- [Editor: Keith Bostic says both are patented:
- original Ziv-Lempel is patent number 4,464,650,
- and the more powerful LZW method is #4,558,302.
- He goes on to say, however, that LZW lacks adaptive table reset
- and other features in compress, and so may not apply.]
-
- The implications of this are that no one may produce the same
- output as compress produces, regardless of the program that produced
- that output, without being subject to the patent. I.e., it is independent
- of the actually coding used, unlike copyright. Therefore, all of the PD
- versions of compress are currently in violation, as is BSD.
-
- Representatives of Unisys at the POSIX.2 meetings claimed that
- the Unisys Legal Department is pursuing the licensing of compress. In fact,
- unlike copyright or trade secret protection, patent protection does not
- diminish because the holder of the patent is not diligent in seeking damages
- or preventing unauthorized use. Witness the large royalty payout by
- Japanese semiconductor companies to Texas Instruments because they held
- the patent on the concept of something as fundamental as integrated circuits.
- This licence payout spans a period of over 20 years. In addition,
- Unisys representatives claim that Phil Karn's PKZIP, which uses the
- LZW compression algorithm, is a licenced user of the Unisys patent and
- that a fee (rumoured to be somewhere in the $10,000 to $20,000 US range)
- has been paid up front in lieu of individual royalties.
-
- The ramifications for POSIX.2a are unclear. Currently, there are members
- of the working group that say that they would object if a patented
- algorithm were required by the standard if ANY FEE WHATSOEVER (even if $1)
- were required to use it. (There are, however, precedents for standards
- working in areas of patents in such areas as networking, modems, and
- hardware bus structures. It appears that we software people have not
- "grown up" as much when it comes to issues of licensing. Who has ever
- hear of "public domain hardware"?) Some people suggested that Unisys
- should allow relatively free use of the patent but should profit from
- publicity rights from a citation in every POSIX.2a product manual that
- contains compress. Therefore, there are currently negotiations underway
- to see what kind of "special deal" Unisys would be willing to cut for the
- use strictly in implementations of POSIX.2a. Depending on the outcome
- of these negotiations, compress would either be dropped, re-engineered,
- or retained.
-
- Volume-Number: Volume 20, Number 101
-
-