From: w8sdz@tacom-emh1.army.mil (Keith Petersen)
Newsgroups: comp.archives.msdos.announce
Subject: All about ARC, ARJ, LZH, ZIP, ZOO, LBR, Compressed and Squeezed files
Summary: Choosing the proper file decompression program and how to find it.
Keywords: simtel20,archives,msdos,compress,arc,zip,arj,lzh,zoo,lbr
Expires: 16 Feb 1993 18:00:00 GMT
Date: Thu, 28 Jan 1993 04:38:14 GMT
Followup-To: comp.archives.msdos.d
Organization: The SIMTEL20 Archives

File: PD1:<MSDOS.STARTER>00-FILES.DOC        Revised December 31, 1992

All about ARC, ARJ, LZH, ZIP, ZOO, LBR, Compressed and Squeezed files

Some of the files in the SIMTEL20 MS-DOS Software Libraries have been
transformed by using one or another of the standard public domain
utilities that either SQueezes, LiBRaries, ARChives, ARJs, LZHs, ZIPs,
or ZOOs files.  Some files in other collections have been compressed.

This transformation is performed to compress the files to minimize
download time, and/or combine several related files into a single
easily-managed file.  You cannot use or run any of these files without
first transforming them back to their original state.

These processed files are specially named with a file type (the last 3
letters of a file name after the '.') that signifies the transformation.
These are:

            .ARC   for files archived with PKPAK.EXE,
            .ARJ   for files archived with ARJ.EXE,
            .LZH   for files archived with LHA.EXE,
            .ZIP   for files archived with PKZIP.EXE,
            .ZOO   for files archived with ZOO.EXE,
            .LBR   for files libraried with LU.EXE, and
            .?Q?   for squeezed files (middle letter is a Q).
            .Z     for compressed files


                          ARC FILES

PKPAK is used to create and maintain file archives.  An archive is a
group of files collected together into one file in such a way that the
individual files may be recovered intact.  PKPAK will automatically
compress member files when adding them to the archive, and PKUNPAK
will expand them upon extraction.  For files with the .ARC extension,
you must have a copy of file PD1:<MSDOS.ARC-LBR>PK361.EXE to extract
the component files.  PK361.EXE is a "self-extracting archive."  When
you run this program, it will produce PKPAK, PKUNPAK and related
documentation.  After you end up with a copy of PKUNPAK you can use
it to extract files.  An example of using PKUNPAK to unpack an ARChive
"FILE.ARC" is:
                     "A>pkunpak file"
You do not need to supply the ARC file type when specifying "file."


                          ARJ FILES

ARJ is used to create and maintain file archives.  An archive is a
group of files collected together into one file in such a way that the
individual files may be recovered intact.  ARJ will automatically
compress member files when adding them to the archive, and will expand
them upon extraction.  For files with the .ARJ extension, you must
have a copy of file PD1:<MSDOS.ARC-LBR>ARJ230NG.EXE to extract the
component files.  ARJ230NG.EXE is a "self-extracting archive."  When
you run this program, it will produce ARJ and related documentation.
After you end up with a copy of ARJ you can use it to extract files.
An example of using ARJ to unpack a ARJ archive "FILE.ARJ" is:
                     "A>arj e file"
You do not need to supply the ARJ file type when specifying "file."


                          LZH FILES

LHA is used to create and maintain file archives.  An archive is a
group of files collected together into one file in such a way that the
individual files may be recovered intact.  LHA will automatically
compress member files when adding them to the archive, and will expand
them upon extraction.  For files with the .LZH extension, you must
have a copy of file PD1;<MSDOS.ARC-LBR>LHA213.EXE to extract the
component files.  LHA213.EXE is a "self-extracting archive."  When
you run this program, it will produce LHA and related documentation.
After you end up with a copy of LHA you can use it to extract files.
An example of using LHA to unpack an LZH archive "FILE.LZH" is;
                     "A>lha e file"
You do not need to supply the LZH file type when specifying "file."


                          ZIP FILES

PKZIP is used to create and maintain file archives.  An archive is a
group of files collected together into one file in such a way that the
individual files may be recovered intact.  PKZIP will automatically
compress member files when adding them to the archive, and PKUNZIP
will expand them upon extraction.  For files with the .ZIP extension,
you must have a copy of file PD1:<MSDOS.ZIP>PKZ110EU.EXE to extract the
component files.  (PKZ110EU.EXE is a "self-extracting archive."  When
you run this program, it will produce PKZIP, PKUNZIP and related
documentation).  After you end up with a copy of PKUNZIP you can use
it to extract files.  An example of using PKUNZIP to unpack an archive
"FILE.ZIP" is:
                     "A>pkunzip file"
You do not need to supply the ZIP file type when specifying "file."


                           ZOO FILES

ZOO.EXE is an archiving program that is similar to PKPAK and ZIP, but
it is not compatible with either.  ZOO can produce archives with long
pathnames in them (directory names as well as the file name) and it
can store comments about each file.  If you want to take apart a ZOO
archive, you will need a copy of ZOO.EXE.  Since it is a program in
development, it's hard to say what its file name will be when you read
this, but searching for ZOO*.* should turn up the correct file.  When
this article was written the current version of ZOO was ZOO210.EXE,
which may be found in the PD1:<MSDOS.ZOO> directory.  The zoo syntax
for file extraction is:
                    "A>zoo e file"
You do not need to supply the ZOO file type when specifying "file."


                           LBR FILES

LU and its relatives (LUP, LUU, LUE, LUT, LU86, LAR etc.), maintain
libraries of files.  Most LU-type programs do not perform any
compression.  Because of this, most people will squeeze files before
adding them to a library if they want to save space.  If you want to
remove the component files from an .LBR file, you should have a copy
of file PD1:<MSDOS.STARTER>LUE220.COM.  This will break up the library
into its component parts, and optionally unsqueeze any .?Q? files at
the same time.  The syntax for LUE would be:
                      "A>lue220 file"
where file was really FILE.LBR.

LUU.COM can be used to create a .LBR file.


                       SQUEEZED FILES

NUSQ.COM is used to unsqueeze, or expand files that have a "Q" as the
middle letter of the file type.  Such files have been squeezed, or
compressed with SQPC.COM or something similar.  These programs use
Huffman Encoding to reduce the size of the target file.  Depending on
the distribution of data in a file it can be reduced in size by 5% to
60% by squeezing it. If you download a file with a file type
indicating that it is squeezed, you will need file
PD1:<MSDOS.STARTER>NUSQ110.COM to expand it before you can use it.
The syntax to unsqueeze a file would be:
                   "A>nusq110 file.tqt"
where file.tqt was the file you wanted to unsqueeze.  You must supply
the full file name and type.


                     COMPRESSED FILES

COMP430D is used to uncompress, or expand files that have a ".Z" file
type.  Such files have been compressed with a Unix-compatible compress
program which uses LZW encoding to reduce the size of the target file.
Depending on the distribution of data in a file it can be reduced in size
by 25% to 70% by compressing it. If you download a file with a file type
indicating that it is compressed, you will need file COMP430D.EXE from
PD1:<MSDOS.COMPRESS>COMP430D.ZIP to expand it before you can use it.
The syntax to uncompress a file would be:
                   "A>comp430d -d file.Z"
where file.Z was the file you wanted to uncompress.  You must supply
the full file name and type.


                       MORE INFORMATION

For more information on ARChives, see the documentation for
PKPAK/PKUNPAK which is included in the PK361.EXE file.  For more
information on ARJ archives, see the documentation for ARJ which is
included in the ARJ230NG.EXE file.  For more information on LZH
archives, see the documentation for LHA which is included in the
LHA213.EXE file.  For more information on ZIP archives, see the
documentation for PKZIP/PKUNZUP which is included in the PKZ110EU.EXE
file.  For ZOO archives, see Rahul Dhesi's excellent documentation
included in ZOO210.EXE and UGUIDE.ZOO.  The doc files included with
the various LU utilities will explain .LBR's, and LUDEF5.DOC explains
the layout of these files in detail.


Keith Petersen
Maintainer of the MS-DOS archive at WSMR-SIMTEL20.Army.Mil [192.88.110.20]
Internet: w8sdz@WSMR-SIMTEL20.Army.Mil    or    w8sdz@Vela.ACS.Oakland.Edu
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