 
       ALL ABOUT ARCHIVES, LIBRARIES, ZOOS and SQUEEZED FILES
 
Some of the files in the IBM RoundTable Software Libraries have been
transformed by using one or another of the standard public domain
utilities that either SQueezes, LiBRaries, ARChives, or ZOOs files. 
 
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 ARC.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).
 
 
                       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 #43 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.
 
 
                          ARC FILES
 
Arc 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.  ARC will automatically
compress member files when adding them to the archive, and will expand
them upon extraction.  For files with the .ARC extension, you must have
a copy of file #5031 ARC521.COM to extract the component files. 
(ARC521.COM is a "self-extracting archive."  When you run this program,
it will produces ARC.EXE and it's related documentation).  After you end
up with a copy of ARC.EXE you can use it to extract files.  An example
of using ARC.EXE to unpack an ARChive "FILE.ARC" is:
                     "A>arc e file"
You do not need to supply the ARC file type when specifying "file."
 
          (A PARENTHETICAL DETOUR DEVOTED TO SQUASHING)
 
(Another popular ARCing utility: PKARC, differs from ARC.EXE and
ARCE.COM in that it supports "ARC" files which use a unique type of
compression called "SQUASHING."  A file made with PKARC containing
"squashed" members cannot be unarced with ARC.EXE or earlier versions of
ARCE.COM.  In order to process such a file, you must use either PKXARC.COM
or version 3.1B or higher of ARCE.COM.
 
Because we try to keep things as simple and straightforward as possible,
and we feel it is confusing to have a class of "ARC" files that are
different from most ARC files, and which cannot be unARC'd with the
standard utilities, we do not allow files with "squashed" members them
to reside the IBM Roundtable Software Library.  If you want to use PKARC
to a make file to upload to the IBM Roundtable-- feel free to do so, but
please use the "compatibility" switches (-oct) to insure that the resulting
file does not contain any "squashed" members.)
 
                           ZOO FILES
 
ZOO.EXE is a newer archiving program that is similar to ARC, but non -
compatible.  It sometimes produces smaller archives than ARC-type
programs, and it is faster than ARC.EXE, although about the same speed
as ARCE.COM and PKXARC.COM.  (These are other ARC-type utilities).  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 it's file
number will be when you read this, but searching the library for the
'ZOO' keyword, with uploader of R.DHESI should turn up the correct file.
When this article was written the current version of ZOO was ZOO200.EXE
(a self-extracting zoo-archive containing both the program and the
documentation).  The zoo syntax for file extraction is similar to
that of arc:
                    "A>zoo e 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 #960 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.
 

                      MORE INFORMATION
 
For more information on ARChives, see the documentation for ARC which is
included in the ARC521.COM file.  For ZOO archives, see Rahul Dhesi's
excellent documentation including ZOOPLAN1.ARC.  The doc files included
with the various LU utilities will explain .LBR's, and LUDEF5.DOC explains
the layout of these files in detail.
 
                  - Paul Homchick, GEnie IBM RoundTable 11/30/87
                                                updated 03/12/88
