WHY_JAR.DOC                                              November 1996


    This document describes the advantages of JAR.

    JAR FEATURES:

    1)  JAR has a 16-bit executable (JAR16.EXE) for DOS and a 32-bit
        executable (JAR32.EXE) for Windows 95 and Windows NT.  The latter
        takes full advantage of 32-bit instructions and the "flat" memory
        model.

        Data compressed in one operating system can be decompressed in
        another.  JAR also supports optional filename translation when
        extracting long filenames in DOS.

    2)  A major feature of JAR is the ability to use additional memory for
        better compression.  Unlike most other archivers, the DOS version
        of JAR can use EMS or XMS memory to improve compression.

        Memory usage is fully customizable.  You can specify how much
        memory to use or you can let JAR auto-detect the optimal amount.

        No matter how much memory has been used during compression,
        decompression requires only about 400K of memory.

        The JAR compression engine detects popular file formats to achieve
        an improved compression rate.

        JAR's compression speed is comparable with other archivers.
        Decompression works much faster than compression. JAR32.EXE uses
        32-bit instructions and thus is even more faster and compresses
        better than the DOS version.

        Please note that compression results are highly dependent upon the
        type of data compressed.  We think that today (September 1996) JAR
        achieves the BEST compression rate among ALL other popular
        archivers (ARJ, PKZIP, RAR, UC2, LHA).

    3)  Compared to the popular DOS archivers PKZIP, RAR, LHA, only JAR can
        archive more than 50,000 files at one time.  This enables JAR to
        handle very large disk drives.

    4)  JAR provides the capability of archiving files to multiple volume
        archives no matter what the destination media.  JAR can archive
        files directly to diskettes no matter how large the input files
        are.

        Moreover, JAR allows one the option of changing archive volume size
        or even the option of concatenating all of the volumes into one
        archive.

        The JAR data verification facilities help ensure reliable backups.

    5)  JAR provides the facility to store EMPTY directories within its
        archives.  This makes it easier to do FULL backups and that come
        with EMPTY directories.

    6)  JAR supports multiple CHAPTERS in an archive concept.

        The advantage of a chapter archive over a series of separate
        archives of the same set of files is that space can be saved when
        files to be archived do not change or change slightly. One chapter
        archive can produce the same results as one hundred standard
        archive backups. In other words, one can update a chapter archive
        one hundred times and fully recover any one of those updates.

        Moreover, JAR uses a special compression method to optimize the
        storage of the file and its subsequent modifications. Each chapter
        may have its own comment and lock option. JAR keeps each chapter
        creation and modification time. There are also many special
        commands and options which allow flexibility with multiple
        chapters.

    7)  For data error recovery, JAR can store recovery records into an
        archive which allow the repair of that archive if slightly damaged.
        JAR also has a special command to recover still usable data from
        a VERY damaged archive.

        The JAR archive data structure with its header structure and 32 bit
        CRC provides excellent archive stability and recovery capabilities.
        In addition, JAR is the second archiver after ARJ that allows you
        to test an archive during an archive process. With other archivers,
        you may have already deleted the input files with a "move" command
        before you could test the built archive. There is an option which
        allows one to select an actual byte for byte file compare with the
        original input files during archiving.

    8)  JAR provides a security envelope facility to "seal" JAR archives
        with a unique envelope signature.

    9)  Unlike most other archivers, JAR also stores/restores the file
        creation and access time along with the modification time.

    10) JAR provides a special command which dumps archive header
        information into a readable text file.  This is to aid the
        development of third party JAR support programs.

        JAR also provides a special test command to check the reliability
        of JAR compressing and decompressing gigabytes of files with
        limited free disk space.

    11) The great number of JAR commands and options allow the user
        outstanding flexibility in archiver usage.


    end of document