[2] What is this .xxx file type? Where can I find the corresponding compression program?

All the programs mentioned in this section are lossless.
For most programs, one US and one European ftp site are given.
(oak.oakland.edu: 141.210.10.117, garbo.uwasa.fi: 128.214.87.1)
Many other sites (in particular wuarchive.wustl.edu: 128.152.135.4)
have the same programs.

To keep this list to a reasonable size, many programs are not
mentioned here. Additional information can be found in the file
ftp.cso.uiuc.edu:/doc/pcnet/compression [128.174.5.61] maintained by
David Lemson (lemson@uiuc.edu). When several programs can handle
the same archive format, only one of them is given.

Sources for additional lossless data compressors can be found in
garbo.uwasa.fi:/pc/programming/lds_11.zip and
oak.oakland.edu:/pub/msdos/archivers/lz-comp2.zip.
Sources in Pascal are in garbo.uwasa.fi:/pc/turbopas/preskit2.zip.

For Macintosh programs, look on sumex-aim.stanford.edu:/info-mac [36.44.0.6].
For VM/CMS, look on vmd.cso.uiuc.edu:/public.477 [128.174.5.98].
For Atari, look on atari.archive.umich.edu [141.211.165.41]
For Amiga, look on ftp.cso.uiuc.edu:/pub/amiga [128.174.5.59]
	
If you don't know how to use ftp or don't have ftp access, read the
article "How to find sources" which is regularly posted in news.answers.

If you can't find a program given below, it is likely that a newer
version exists in the same directory. (Tell me <jloup@chorus.fr>)

A very short description of the compression algorithm is given for
most programs. For the meaning of LZ77, LZ78 and LZW, see question 70
in part 2 of the FAQ.) If you are looking for the file format of a
specific compression program, get the sources of the decompressor.

ext:  produced by or read by

.arc: arc, pkarc for MSDOS. (LZW algorithm)
	wuarchive.wustl.edu:/mirrors/msdos/starter/pk361.exe
	garbo.uwasa.fi:/pc/arcers/pk361.exe

      arc for Unix
        wuarchive.wustl.edu:/mirrors/misc/unix/arc521e.tar-z
	garbo.uwasa.fi:/unix/arcers/arc.tar.Z
        Contact: Howard Chu <hyc@umix.cc.umich.edu>

      arc for VMS
	wuarchive.wustl.edu:/packages/compression/vax-vms/arc.exe

      arcmac for Mac
	mac.archive.umich.edu:/mac/utilities/compressionapps/arcmac.hqx

      arc for Amiga
	ftp.funet.fi:pub/amiga/fish/001-100/ff070/arc.lha

.arj: arj for MSDOS (LZ77 with hashing, plus secondary static Huffman
          encoding on a block basis)
        Contact: Robert K Jung <robjung@world.std.com>
        wuarchive.wustl.edu:/mirrors/msdos/archivers/arj241a.exe
	garbo.uwasa.fi:/pc/arcers/arj241a.exe

      unarj for Unix. Decompresses only. (There is no arj compressor for Unix.
        Don't post a request.)
        wuarchive.wustl.edu:/mirrors/misc/unix/unarj241.tar-z
	garbo.uwasa.fi:/unix/arcers/unarj241.tar.Z

      unarj for Mac
        mac.archive.umich.edu:/mac/util/compression/unarjmac.cpt.hqx      

      unarj for Amiga
	ftp.funet.fi:pub/amiga/utilities/archivers/unarj-0.5.lha

.bck: VMS BACKUP. BACKUP is *not* a compression program. Do "help backup".

.cpt: Compact Pro for Mac
        sumex-aim.stanford.edu:/info-mac/util/compact-pro-133.hqx [36.44.0.6]

      For Unix:
	sumex-aim.stanford.edu:/info-mac/unix/macutil-20b1.shar
        ftp.cwi.nl:/pub/macutil2.0b3.shar.Z

.exe: self-extracting MSDOS executable (creates files on disk when run)
      Run the file, or try unzip, lha or arj on it.

.exe: compressed MSDOS executable (decompresses itself in memory then runs
      the decompressed code). To get the original uncompressed .exe:
        oak.oakland.edu:/pub/msdos/execomp/unp330.zip
      To create such files:
        oak.oakland.edu:/pub/msdos/execomp/lzexe91e.zip
	nic.funet.fi:/pub/msdos/windows/util/winlite1.zip (for Windows exe)

.gif: gif files are images compressed with the LZW algorithm. See the
      comp.graphics FAQ list for programs manipulating .gif files. See
      suffix .Z below for source of LZW.

.gz, .z:  gzip (or pack, see .z below). gzip uses the same algorithm as
          zip 2.0 (see below); it can also extract packed and compressed files.
      For Unix, MSDOS, OS/2, VMS, Atari, Amiga, Primos:
	prep.ai.mit.edu:/pub/gnu/gzip-1.2.4.tar  (or .shar or .tar.gz : source)
	prep.ai.mit.edu:/pub/gnu/gzip-msdos-1.2.4.exe (MSDOS, lha self-extract)
	garbo.uwasa.fi:/unix/arcers/gzip-1.2.4.tar.Z  (source)
	garbo.uwasa.fi:/pc/arcers/gzip124.zip         (MSDOS exe)
	ftp.uu.net:/pub/archiving/zip/VMS/gzip123x.exe (VMS exe)
        mac.archive.umich.edu:/mac/util/compression/macgzip0.2.cpt.hqx (Mac)
        src.doc.ic.ac.uk:/computing/systems/mac/info-mac/cmp/mac-gzip-02.hqx
        mac.archive.umich.edu:/mac/development/source/macgzip0.2src.cpt.hqx

.ha:  ha 0.98 for MSDOS (improved PPMC - 4th order Markov modeling)
	garbo.uwasa.fi:/pc/arcers/ha098.zip

.hap: Hamarsoft HAP 3.00 archiver. Contact: harald.feldmann@almac.co.uk
        garbo.uwasa.fi:/pc/arcers/hap300re.zip

.hqx: Macintosh BinHex format.. (BinHex is *not* a compression program,
	it is similar to uuencode but handles multiple forks.)
       for Mac:
	 mac.archive.umich.edu:/mac/utilities/compressionapps/binhex4.0.bin

       for Unix:
         sumex-aim.stanford.edu:/info-mac/cmp/mcvert-215.shar.gz
         garbo.uwasa.fi:/mac/arcers/mcvert-215.shar

       for MSDOS:
         wuarchive.wustl.edu:/mirrors/msdos/xbin23.zip

.lha:
.lzh: lha for MSDOS (LZ77 with a trie data structure, plus secondary static
          Huffman coding on a block basis)
	oak.oakland.edu:/pub/msdos/archiver/lha213.exe   (exe)
	oak.oakland.edu:/pub/msdos/archiver/lha211sr.zip (sources)
	garbo.uwasa.fi:/pc/arcers/lha255b.exe

      lharc for Unix. (LZ77 with hash table and binary trees, plus secondary
          Huffman coding)
           Warning: lharc can extract .lzh files created by
           lharc 1.xx but not those created by lha. See lha for Unix below.
        wuarchive.wustl.edu:/mirrors/misc/unix/lharc102a.tar-z
	garbo.uwasa.fi:/unix/arcers/lha101u.tar.Z

      lharc for VMS. Same warning as for Unix lharc.
	wuarchive.wustl.edu:/packages/compression/vax-vms/lharc.exe

      lha for Unix. Warning: all doc is in Japanese.
	wuarchive.wustl.edu:/mirrors/misc/unix/lha101u.tar-z
	garbo.uwasa.fi:/unix/arcers/lha-1.00.tar.Z
          Contact: lha-admin@oki.co.jp or oki@wbg.telcom.oki.co.jp

      lha for Mac
        mac.archive.umich.edu:/mac/utilities/compressionapps/maclha2.0.cpt.hqx

      lha for Amiga
	ftp.funet.fi:pub/amiga/utilities/archivers/LhA_e138.run


.pak: pak for MSDOS (LZW algorithm)
        wuarchive.wustl.edu:/mirrors/msdos/archivers/pak251.exe
	garbo.uwasa.fi:/pc/arcers/pak251.exe

.pit: PackIt (Macintosh)
       for Mac:
         sumex-aim.stanford.edu:/info-mac/util/stuffit-151.hqx  [36.44.0.6]

       for Unix:
         sumex-aim.stanford.edu:/info-mac/cmp/mcvert-215.shar.gz
         garbo.uwasa.fi:/mac/arcers/mcvert-215.shar

.pp: PowerPacker (Amiga)
	ftp.funet.fi:pub/amiga/fish/501-600/ff561/PPLib.lha

.sea: self-extracting archive (Macintosh)
         Run the file to extract it. The self-extraction code can be
         removed with:
 	 mac.archive.umich.edu:/mac/utilities/compressionapps/desea1.11.cpt.hqx

.sdn: used by the Shareware Distribution Network.
      Try the decompressors for .pak or .arj (see above)

.shar:  Shell archive. This is not a compression program. Use "sh foo.shar"
        to extract.

.sit: Stuffit for Macintosh
       for Mac:
         sumex-aim.stanford.edu:/info-mac/util/stuffit-lite-30.hqx [36.44.0.6]

       for Unix:
         sumex-aim.stanford.edu:/info-mac/cmp/unsit-15-unix.shar [36.44.0.6]

       for Amiga:
	 ftp.funet.fi:pub/amiga/utilities/archivers/unsit-1.5c2.lha

       for MSDOS:
	 garbo.uwasa.fi:/pc/arcers/unsit30.zip

.?q?: Squeeze for MSDOS (do not confuse with other 'squeeze' below).
      Static Huffman coding.
	oak.oakland.edu:/pub/msdos/starter/sqpc12a.com (squeeze)
	oak.oakland.edu:/pub/msdos/starter/nusq110.com (unsqueeze)

.sqz: Squeeze for MSDOS (do not confuse with other 'squeeze' above)
      LZ77 with hashing.
	wuarchive.wustl.edu:/mirrors/msdos/archivers/sqz1083e.exe
        garbo.uwasa.fi:/pc/arcers/sqz1083e.exe

.tar: tar is *not* a compression program. However, to be kind for you:
      for MSDOS
	oak.oakland.edu:/pub/msdos/starter/tarread.exe
	garbo.uwasa.fi:/pc/unix/tar4dos.zoo

      for Unix
        tar (you have it already. To extract: tar xvf file.tar)

      for VMS
	wuarchive.wustl.edu:/packages/compression/vax-vms/tar.exe

      for Macintosh
        sumex-aim.stanford.edu:/info-mac/util/tar-30.hqx

      for Amiga:
	ftp.funet.fi:pub/amiga/fish/401-500/ff445/Tar.lha

.tar.Z, .tar-z, .taz: tar + compress
      For Unix:     zcat file.tar.Z | tar xvf -
      with GNU tar: tar xvzf file.tar.Z
      for MSDOS:
	garbo.uwasa.fi:/pc/unix/tar315us.zip (MSDOS exe)
        ftp.kiae.su:/msdos/arcers/tar315sr.zip (sources)
      Other OS: first uncompress (see .Z below) then untar (see .tar above)

.tar.gz, tar.z, .tgz: tar + gzip
      For Unix: gzip -cd file.tar.gz | tar xvf -
      with GNU tar: tar xvzf file.tar.gz
      for MSDOS: oak.oakland.edu:/pub/msdos/archiver/tar315us.zip
                 garbo.uwasa.fi:/pc/unix/tar315us.zip
      Other OS: first uncompress (see .gz above) then untar (see .tar above)

.td0: (compressed MS-DOS floppy image produced by TeleDisk)
      oak.oakland.edu:/pub/msdos/diskutil/teled212.zip

.uc2: UC2 for MSDOS and OS/2. (LZ77 with secondary static Huffman encoding on
	 a block basis, and dynamic dictionaries shared among files.)
	Contact: desk@aip.nl
      garbo.uwasa.fi:/pc/arcers/uc2ins.exe

.z:   pack or gzip (see .gz above). pack uses static Huffman coding.
      To extract, see .gz above.

.zip: pkzip 1.10 for MSDOS. (LZ77 with hashing, plus secondary static
          Shannon-Fano encoding on whole file)
           Contact: pkware.inc@mixcom.com
         wuarchive.wustl.edu:/mirrors/msdos/zip/pkz110eu.exe.
         garbo.uwasa.fi:/pc/goldies/pkz110eu.exe.
           Note: pkz110eu.exe is an 'export' version without encryption.

      zip 1.1 for Unix, MSDOS, VMS, OS/2, ... (compatible with pkzip 1.10.
	 For corresponding unzip, see unzip 5.1 below).
	 ftp.uu.net:/pub/archiving/zip/zip11.zip

      arcutil 2.0 for VM/CMS (unzip only, not yet compatible with pkzip 2.04)
         vmd.cso.uiuc.edu:/public.477/arcutil.* [128.174.5.98].

      pkzip 2.04g for MSDOS. (LZ77 with hashing, plus secondary static
           Huffman coding on a block basis)
	 oak.oakland.edu:/pub/msdos/zip/pkz204g.exe
         garbo.uwasa.fi:/pc/arcers/pkz204g.exe

      zip 2.0.1 and unzip 5.1 for Unix, MSDOS, VMS, OS/2, Amiga, ...
          Compatible with pkzip 2.04g (LZ77 with hashing, plus secondary static
          Huffman coding on a block basis). Contact: zip-bugs@wkuvx1.wku.edu
          (On SGI, do not confuse with the editor also named 'zip'.)
            
	 ftp.uu.net:/pub/archiving/zip/zip201.zip          (source)
	 ftp.uu.net:/pub/archiving/zip/unzip51.tar.Z       (source)
	 ftp.uu.net:/pub/archiving/zip/MSDOS/zip20x.zip    (MSDOS exe)
	 ftp.uu.net:/pub/archiving/zip/MSDOS/unzip51x.exe  (MSDOS exe)
	 ftp.uu.net:/pub/archiving/zip/VMS/unz51vms-vax.exe  (VAX self-extract)
	 ftp.uu.net:/pub/archiving/zip/VMS/zip20x-vms.zip  (Vax/VMS exe)
	 ftp.uu.net:/pub/archiving/zip/OS2/*               (OS/2 exe 16&32 bit)
           See also AMIGA, ATARI, MAC, NT, SCO_UNIX and SOLARIS subdirectories.
	 ftp.uu.net:/pub/archiving/zip/zcrypt21.zip        (encryption source)
         (Non US residents must get the crypt versions from garbo,see below)

	 garbo.uwasa.fi:/unix/arcers/zip201.zip    (source)
	 garbo.uwasa.fi:/unix/arcers/unzip51.tar.Z (source)
	 garbo.uwasa.fi:/pc/arcers/zip20x.zip      (MSDOS exe)
	 garbo.uwasa.fi:/pc/arcers/unz51x3.exe     (MSDOS exe)
         garbo.uwasa.fi:/unix/arcers/zcrypt21.zip  (encryption source)

       for Macintosh:
         mac.archive.umich.edu:/mac/util/compression/unzip2.01.cpt.hqx
	 mac.archive.umich.edu:/mac/util/compression/zipit1.2.cpt.hqx
	 ftp.uu.net:/pub/archiving/zip/MAC/mac-unzip-51.hqx

.zoo: zoo 2.10 for MSDOS (algorithm copied from that of lha, see lha above)
      Contact: Rahul Dhesi <dhesi@cirrus.com>
	 wuarchive.wustl.edu:/mirrors/msdos/zoo/zoo210.exe
	 garbo.uwasa.fi:/pc/arcers/zoo210.exe

      zoo 2.10 for Unix, VMS
         oak.oakland.edu:/pub/misc/unix/zoo210.tar.Z
	 garbo.uwasa.fi:/unix/arcers/zoo210.tar.Z

      zoo for Mac
 	 mac.archive.umich.edu:/mac/utilities/compressionapps/maczoo.sit.hqx

      zoo for Amiga
	ftp.funet.fi:pub/amiga/utilities/archivers/Zoo-2.1.lha

.F: freeze for Unix (LZ77 with hashing, plus secondary dynamic Huffman
         encoding)
     wuarchive.wustl.edu:/usenet/comp.sources.misc/volume35/freeze/part0[1-3].Z
     ftp.inria.fr:/system/arch-compr/freeze-2.5.tar.Z
     Contact: Leonid A. Broukhis <leo@s514.ipmce.su>

.Y: yabba for Unix, VMS, ... (Y coding, a variant of LZ78)
  wuarchive.wustl.edu:/usenet/comp.sources.unix/volume24/yabbawhap/part0[1-4].Z
  ftp.inria.fr:/system/arch-compr/yabba.tar.Z
  Contact: Dan Bernstein <djb@silverton.berkeley.edu>

.Z: compress for Unix ('the' LZW algorithm)
      It is likely that your Unix system has 'compress' already. Otherwise:
	wuarchive.wustl.edu:/packages/compression/compress-4.1.tar
        (not in .Z format to avoid chicken and egg problem)

    compress for MSDOS
	oak.oakland.edu:/pub/msdos/compress/comp430[ds].zip
	garbo.uwasa.fi:/pc/unix/comp430d.zip
	garbo.uwasa.fi:/pc/source/comp430s.zip

    compress for Macintosh
        sumex-aim.stanford.edu:/info-mac/util/maccompress-32.hqx

    compress for Amiga
	ftp.funet.fi:pub/amiga/utilities/archivers/compress-4.1.lha

    compress for Vax/VMS
	wuarchive.wustl.edu:/packages/compression/vax-vms/lzcomp.exe
	wuarchive.wustl.edu:/packages/compression/vax-vms/lzdcmp.exe