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ARC (file format)

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ARC
Filename extension
.arc
.ark
.sue
Internet media type
application/octet-stream
Developed bySystem Enhancement Associates
Type of formatData compression

ARC is a lossless data compression and archival format by System Enhancement Associates (SEA). It was very popular during the early days of networked BBS. The file format and the program were both called ARC. The ARC program essentially made obsolete the use of combinations of the SQ program to compress files and the LU program to create .LBR archives by combining the functions of both compression and archiving into a single program. ARC compresses multiple files into one - but unlike ZIP, not entire directory trees. The .arc format was the subject of quite a bit of controversy in the 1980s - an important event in the open source debate.

.arc is often also used as a file extension for several different file types that have in common that they are some kind of archive files. The Internet Archive uses their own ARC format for storing multiple web resources into a single file [1][2].

History

In 1985, Thom Henderson of System Enhancement Associates wrote a program called ARC[1], based on earlier programs such as ar, that not only grouped files into a single archive file but also compressed them to save disk space, a feature of great importance on early personal computers, where space was very limited and modem transmission speeds were very slow. The archive files produced by ARC had file names ending in ".ARC" and were sometimes called "arc files" as a result.

The source code for ARC was released by SEA in 1986 and subsequently ported to Unix and the Atari ST in 1987 by Howard Chu. This more portable code base was subsequently ported to other platforms including VAX/VMS and IBM 370 mainframes. Howard's work was also the first to disprove the prevalent belief that Lempel-Ziv encoded files could not be further compressed. Additional compression could be achieved by performing a Huffman Squeeze on the LZW data, and Howard's version of ARC was the first program to demonstrate this property. This hybrid technique was later used in several other compression schemes by Phil Katz and others.

Later, Phil Katz developed his own shareware utilities, PKARC and PKXARC, to create archive files and extract their contents. These files worked with the archive file format used by ARC, and were significantly faster than ARC on the IBM-PC platform due to selective assembly-language coding. Unlike SEA, which combined archive creation and archive file extraction in a single program, Katz divided these functions among two separate utilities, reducing the amount of memory needed to run them. PKARC also allowed the creation of self-extracting archives, which could unpack themselves without requiring an external file extraction utility.

Following the System Enhancement Associates, Inc. vs PKWARE Inc. and Phillip W. Katz lawsuit, SEA withdrew from shareware market and developed ARC+Plus.[2] This version includes full-screen user interface, with last known version being 7.12.[3]

SEA was eventually sold to a Japanese Company in 1992.

The ARC format is no longer common on PC desktops but it's still a component in most antivirus scanners, and as such is still a widely used format, if only behind the scenes.

Lawsuits

In the late 1980s a dispute arose between SEA, maker of the ARC program, and PKWARE (Phil Katz Software). SEA sued Katz for trademark and copyright infringement. The most damning evidence at trial was from an independent software expert appointed by the court to compare the two programs. He stated that PKARC was a derivative work of ARC, pointing out that comments in both programs were often identical, including spelling errors.

On August 2 1988, the plaintiff and defendants announced a settlement of the lawsuit, which included a Confidential Cross-License Agreement under which SEA licensed PKWARE for all the ARC-compatible programs published by PKWARE during the period beginning with the first release of PKXARC in late 1985 through July 31 1988, in return for an undisclosed payment. In the agreement, PKWARE paid SEA to obtain a licence that allowed the distribution of PKWARE's ARC-compatible programs until January 31 1989, after which PKWARE would not license, publish or distribute any ARC compatible programs or utilities that process ARC compatible files. In exchange, PKWARE licensed SEA to use its source code for PKWARE's ARC-compatible programs. PKWARE also agreed to cease any use of SEA's trademark 'ARC' and to change the names or marks used with PKWARE's programs to non-confusing designations. The remaining details of the agreement were sealed. In reaching the settlement, the defendants did not admit any fault or wrongdoing.[4] The Wisconsin court order showed defendants was ordered to pay damages to plaintiff for defendants' acts of infringing Plaintiff's copyrights, trademark, and acts of unfair trade practices and unfair competition.[5]

The leaked agreement document revealed under the settlement terms, the defendants had paid plaintiff $22,500 for past royalty payments, and $40,000 for expense reimbursements. In addition, defendants would pay plaintiff a royalty fee of 6.5% of all revenue received for ARC compatible programs on all orders received after the effective date of this Agreement, such revenue including any license fees or shareware registrations received after the expiration of the licence, for ARC compatible programs. In exchange, plaintiff would also pay a commission in the amount of 6.5% of any license fees received by plaintiff from any licensee referred to plaintiff by defendants, whether before or after the licence termination date.[6]

After the lawsuit, PKWARE released one last version of his PKARC and PKXARC utilities under the new names "PKPAK" and "PKUNPAK", and from then on concentrated on developing the separate programs PKZIP and PKUNZIP, which were based on new and different file compression techniques. However, following the renaming, SEA filed a lawsuit against PKWARE for contempt, for continually using plaintiff's protected mark ARC, by turning ARC from noun into verb in PKPAK manual.[7] The US district court of the East District of Wisconsin ruled SEA's motion was denied, and the defendant was entitled to recover the legal cost of $500.[8]

The SEA vs. PKWARE dispute quickly expanded into one of the largest controversies the BBS world ever saw. The suit by SEA angered many shareware users who perceived that SEA was a "large, faceless corporation" and Katz was "the little guy". In fact, at the time, both SEA and PKWARE were small home-based companies. However, the community largely sided with Katz, in part because the technical details of the alleged code plagiarism were not widely understood, but the fact that SEA was attempting to retroactively declare the ARC file format to be closed and proprietary was well understood.

Filename extension

  • .arc (all systems)
  • .ark (adopted by some bulletin boards as a naming convention indicating that the file contained software for CP/M rather than MS-DOS).
  • .sue (due to all the legal issues)

See also

References

  1. ^ Phil Katz
  2. ^ Article: ARC+Plus 7.12. (Software Review) (one of seven evaluations of data compression utility programs in 'Space Savers: Data Compression Utilities') (Evaluation)
  3. ^ Packing Test for Pak/PKArc/PKZip/Zoo/LHArc/Hyper/ARJ/ARC
  4. ^ Joint press release
  5. ^ System Enhancement Associates, Inc. v. PKWare, Inc. and Phillip W. Katz, No. 88-C-447, Judgment for Plaintiff on Consent, E.D. Wisc. (Aug. 1., 1988)
  6. ^ System Enhancement Associates vs. PKware, Inc CONFIDENTIAL CROSS-LICENSE AGREEMENT
  7. ^ System Enhancement Associates vs. PKware, Inc
  8. ^ UNITED STATES DISTRICT COURT EASTERN DISTRICT OF WISCONSIN Case No. 88-C-447
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