SYNOPSIS
     #######
     # Subroutine interface
     #
     use File::Revision qw(new_revision num2revision parse_options revision2num revision_file rotate);

     ($file_name, $next_revsion) = new_revision($file, @options);
     ($file_name, $next_revsion) = new_revision($file, \@options);
     ($file_name, $next_revsion) = new_revision($file, \%options);

     $revision_letter = num2revision($revision_number); 

     $options = parse_options($file, @options);
     $options = parse_options($file, \@options);
     $options = parse_options($file, \%options);

     $revision_number = revision2num($revision_letter; 

     $file_name = revision_file($revision_number, $options);

     $file_name = rotate($file, @options);
     $file_name = rotate($file, \@options);
     $file_name = rotate($file, \%options);

     #######
     # Object interface
     #  
     $self = 'File::Revision'; # or
     $self = new $class; # where $class::@ISA contains 'File::Revision'

     ($file_name, $next_revsion) = $self->new_revision($file, @options);
     ($file_name, $next_revsion) = $self->new_revision($file, \@options);
     ($file_name, $next_revsion) = $self->new_revision($file, \%options);

     $revision_letter = $self->num2revision($revision_number); 

     $options = $self->parse_options($file, @options);
     $options = $self->parse_options($file, \@options);
     $options = $self->parse_options($file, \%options);

     $revision_number = $self->revision2num($revision_letter; 

     $file_name = $self->revision_file($revision_number, $options);

     $file_name = $self->rotate($file, @options);
     $file_name = $self->rotate($file, \@options);
     $file_name = $self->rotate($file, \%options);

DESCRIPTIONS
    The "File::Revision" program modules provides the name of a non-existing
    file with a revision identifier based on the a file name $file. This has
    many uses backup file uses. There are no restrictions on the number of
    backup files or the time to live of the backup files.

    A typical use would be to create a backup file for If the revised file
    passes does not pass all validity checks, use the backup file to replace
    or repair the revised file. This minimizes loses import data when
    revising files.

    Better yet, create a temporary file, using one of the temp file name
    program modules. Revise the temp file. Once it passes all valitity
    checks, rename the original file to the backup file and rename the temp
    file to the original file. This allows full use of the original file
    until a validated revison is ready to replace it.

    The "File::Revision" program module also supports limiting the backup
    files and delete the oldest once "File::Revision" reaches the rotation
    limit.

SUBROUTINES
  new_revision

     ($file_name, $next_revsion) = new_revision($file, @options);

    The "new_revision" subroutine returns the name of a non-existing file by
    appending revision letters to the base name of a supplied file. The
    supplied file usually exists.

  num2revsion

     $revision = num2revsion($number)

    The "num2revision" is the inverse of "revision2num" as described below.

  parse_options

     $options = parse_options($file, @options);

    The "parse_options" subroutine pre-process the options and used
    internally by the other routines. The only external ues is as an input
    to the "revision_file" subroutine.

    The "rotate" and "new_revision" subroutine embeds the revision in the
    "$file" input to produce the "$file_name" output as follows:

     "$vol$dir$base$pre_revision$lead_revision$revision$ext"

    The "$vol $dir $base $ext" are obtained from the "$file" input but may
    be overrided by the options "vol dir base ext". The $pre_revision is the
    "pre_revision" option and has a default of '-'. The "$lead_revision"
    comes in play when a the "places" option has a number. It contains just
    enough characters so that "places" revision is exactly

     length(($lead_revision$revision")

    The "lead_revision" default to a '_' for drafing style letter revisions
    and '0' for numeric revisions.

     options       description
     ----------------------------------------------------------
     base          overide the $file_name base
     dir           overide the $file_name dir
     ext           overide the $file_name ext

     lead_places   fill for places

     places        the maximum places of the embedded revision

     revision      the lowest revision embedded in $file_name
                   (new_revision subroutine only)

     rotate        the highest revision embeded in $file_name
                   (rotate subroutine only)

     vol           overide the $file_name vol

  revision2num

     $number = revision2num($revision)

    The "revision2num" subroutine converts a drawing revision letter(s) that
    complies to American industry, US DOD, and International drawing
    practices to a number, where 0 is the drawing release, 1 the 1st
    revision, 2 the 2nd revision and so forth.

    The old DOD-STD-100C which itself cited a slew of American National
    Standards, may itself been superceded by an American National Standard.
    Anyway drawing revisions are pretty the same across commerical, military
    and national boundaries. The US Navy provides DOD-STD-100C free.
    However, comericalized American Nation Standards are not so generous.
    They do not have the American taxpayer to support their generosity.

    DOD-Std-100C 5003.2, Drawing Practices, states

    '5003.2 Revision Letters. Upper-case letters shall be used in
    alphabetical sequence. The letters "I", "O", "Q", "S', "X" and "Z" shall
    be omitted. When revisions are numberous enough to exhaust the alphabet
    the revision following Y shall be "AA" and the next "AB", the "AC", etc.
    Revision letters shall not exceed two characters. The first revision to
    a drawing shall be assigned the letter A. Release (initial issue) of a
    drawing does not constitute a need for a revision letter.'

    The convention is to use rev - for the initial release. The requirement
    that the revision does not exceed two letters, maximum of 400 revisions,
    is not realistic for automation of drawings. The revision for index
    drawings that index large databases can easy exceed this very quickly.

    During the development of software programs, there can easily be more
    than 400 builds. When this happens, for strcit compliance, the drawing
    had to be rolled over to a new drawing and start out with rev -. Isn't
    more sensible to allow more than two letters for revisions, especially
    since it is easy to convert revision letters into a number.

    When using hard paper media, 400 revisions never exist. Management
    lowers the hammer about revision MN. They fire the development team and
    bring in a new one.

    Once there was a software engineer (SE) working on a Laser Printer and
    the lead mechanical engineer (ME) came it and starting examining a part.
    The SE asked him why he was looking so intensely at that part. The ME
    replied that they where going to revise it. SE: "Whey are you revising
    it?" ME: "It is the only part that has not been changed." That is funny
    unless you are the manager paying for it.

    The standard drawing revision conventions is an interesting number
    system with no symbol for zero (absence of a revision is zero) and is
    base 20. The Persians successfully argued that the lack of a zero makes
    the arith twisted back in what is now Iran, Iraq around 600 A.D.
    However, the drafing disciplines never went along with this concept.
    Maybe they feel a symbol for zero makes the arith twisted. Anyway with
    non-zero digit arith there are additions and subtractions of one to
    shift around numbers to line up with the computer arith which uses arith
    with a zero symbol.

    Actually this is being unkind. The reason drafting uses letters is
    because they are trying to make it hard to confuse the drawing revision
    with the drawing number. Then again, the American drafting standards and
    Internationl drafting standards allow letters in the drawing number. In
    other words, do not tried to understand drafting standards or make sense
    out of them. Just live with them.

    Take a look at a base 4 number system without zero.

        digits 1 2 3 4

        Weights  zero base ten
        16 4 1   number 
       --------------------------
                     0
             1       1   
             2       2
             3       3
             4       4
           1 1       5
           1 2       6
           1 3       7
           1 4       8
           2 1       9
           2 4      12 
           3 1      13
           3 4      16
           4 1      17
           4 4      20
         1 1 1      21

        base 10 non-zero digit 
        digits 1 2 3 4 5 6 7 8 9 A

        Weights     zero base ten
        100 10  1   number 
         9A  A  1
       --------------------------
                        0
                1       1   
                2       2
                3       3
                4       4
                A      10
             1  1      11
             9  A     100
             A  1     101
             A  A     110
          1  1  1     111 
          A  A  A    1110

       base 20 non-zero digit

                 1111111112
       12345678901234567890
       ABCDEFGHJKLMNPRTUVWY   

                      non-zero digit 
       400   20   1   number 
                  -       0
                  A       1
                  Y      20
              A   A      21
              A   Y      40
              W   Y     400
              Y   A     401
              Y   Y     420  
  
  revision_file

      $file_name = revision_file($revision_number, parse_options($file, @options));

    The "revision_file" subroutine returns the backup file name for "$file"
    with the "$revision_number" embedded. This subroutine does not check to
    see if the "$file_name" exists. The "rotate" and "new_revision"
    subroutines use it extensively internally.

  rotate

     $file_name = rotate($file, @options);

    The "rotate" subroutine returns is similar to the "new_file" subroutine
    except that it uses "rotate" as the highest revision that will be
    embedded in $file_name. When the subroutine finds that the highest
    revision file exists, it unlinks the oldest revision and rotates the
    rest of the files by renaming them to the next lowest revision. The
    subroutine returns the a "$file_name" with the vacated "rotate" revision
    embedded in the name.

REQUIREMENTS
    Someday.

DEMONSTRATION
     #########
     # perl Revision.d
     ###

    ~~~~~~ Demonstration overview ~~~~~

    The results from executing the Perl Code follow on the next lines as
    comments. For example,

     2 + 2
     # 4

    ~~~~~~ The demonstration follows ~~~~~

         use File::AnySpec;
         use File::Package;
         use File::Path;
         use File::Copy;
         my $fp = 'File::Package';
         my $uut = 'File::Revision';
         my ($file_spec, $from_file, $to_file, $backup_file, $rotate);
         my $loaded = '';

     ##################
     # Load UUT
     # 

     my $errors = $fp->load_package($uut)
     Cannot load File::Revision
            Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 140.
            Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 144.
            Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 149.
            BEGIN not safe after errors--compilation aborted at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 169.
            Compilation failed in require at (eval 12) line 1.

     # 'Cannot load File::Revision
     #      Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 140.
     #      Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 144.
     #      Global symbol "%options" requires explicit package name at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 149.
     #      BEGIN not safe after errors--compilation aborted at E:\User\SoftwareDiamonds\installation\lib/File/Revision.pm line 169.
     #      Compilation failed in require at (eval 12) line 1.
     #      '
     #

     ##################
     # revision2num('-')
     # 

QUALITY ASSURANCE
    Running the test script "Revision.t" verifies the requirements for this
    module.

    The <tmake.pl> cover script for Test::STDmaker automatically generated
    the "Revision.t" test script, "Revision.d" demo script, and
    "t::File::Revision" STD program module POD, from the "t::File::Revision"
    program module contents. The "t::File::Revision" program module is in
    the distribution file File-Revision-$VERSION.tar.gz.

NOTES
  Author

    The holder of the copyright and maintainer is

    <support@SoftwareDiamonds.com>

  Copyright Notice

    Copyrighted (c) 2002 Software Diamonds

    All Rights Reserved

  Binding Requirements Notice

    Binding requirements are indexed with the pharse 'shall[dd]' where dd is
    an unique number for each header section. This conforms to standard
    federal government practices, STD490A 3.2.3.6. In accordance with the
    License, Software Diamonds is not liable for any requirement, binding or
    otherwise.

  License

    Software Diamonds permits the redistribution and use in source and
    binary forms, with or without modification, provided that the following
    conditions are met:

    1   Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

    2   Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.

    SOFTWARE DIAMONDS, http::www.softwarediamonds.com, PROVIDES THIS
    SOFTWARE 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
    NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SOFTWARE
    DIAMONDS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL,EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
    TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,DATA, OR
    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE POSSIBILITY OF SUCH DAMAGE.

SEE ALSO
    Docs::Site_SVD::File_Revision
    Test::STDmaker
    ExtUtils::SVDmaker
Title Page
     Software Version Description

     for

      File::Revision - return a name of non-existing backup file with a revision id

     Revision: -

     Version: 0.01

     Date: 2004/04/29

     Prepared for: General Public 

     Prepared by:  SoftwareDiamonds.com E<lt>support@SoftwareDiamonds.comE<gt>

     Copyright: copyright © 2003 Software Diamonds

     Classification: NONE

1.0 SCOPE
    This paragraph identifies and provides an overview of the released
    files.

  1.1 Identification

    This release, identified in 3.2, is a collection of Perl modules that
    extend the capabilities of the Perl language.

  1.2 System overview

    The "File::Revision" program modules provides the name of a non-existing
    file with a revision identifier based on the a file name $file. This has
    many uses backup file uses.

    The "File::Revision" program module provides options for many different
    capabilites.

    There can no restrictions on the number of backup files or the time to
    live of the backup files. The revision identifier may limited to a
    maximum number of places or unlimited. The revision identifier may be
    numeric or comply to the capital letter drafting revision standards.

  1.3 Document overview.

    This document releases File::Revision version 0.01 providing a
    description of the inventory, installation instructions and other
    information necessary to utilize and track this release.

3.0 VERSION DESCRIPTION
    All file specifications in this SVD use the Unix operating system file
    specification.

  3.1 Inventory of materials released.

    This document releases the file

     File-Revision-0.01.tar.gz

    found at the following repository(s):

      http://www.softwarediamonds/packages/
      http://www.perl.com/CPAN/authors/id/S/SO/SOFTDIA/

    Restrictions regarding duplication and license provisions are as
    follows:

    Copyright.
        copyright © 2003 Software Diamonds

    Copyright holder contact.
         603 882-0846 E<lt>support@SoftwareDiamonds.comE<gt>

    License.
        Software Diamonds permits the redistribution and use in source and
        binary forms, with or without modification, provided that the
        following conditions are met:

        1   Redistributions of source code, modified or unmodified must
            retain the above copyright notice, this list of conditions and
            the following disclaimer.

        2   Redistributions in binary form must reproduce the above
            copyright notice, this list of conditions and the following
            disclaimer in the documentation and/or other materials provided
            with the distribution.

        SOFTWARE DIAMONDS, http://www.SoftwareDiamonds.com, PROVIDES THIS
        SOFTWARE 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
        BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
        FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
        SOFTWARE DIAMONDS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
        SPECIAL,EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
        LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
        USE,DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
        ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
        OR TORT (INCLUDING USE OF THIS SOFTWARE, EVEN IF ADVISED OF
        NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE POSSIBILITY
        OF SUCH DAMAGE.

  3.2 Inventory of software contents

    The content of the released, compressed, archieve file, consists of the
    following files:

     file                                                         version date       comment
     ------------------------------------------------------------ ------- ---------- ------------------------
     lib/Docs/Site_SVD/File_Revision.pm                           0.01    2004/04/29 new
     MANIFEST                                                     0.01    2004/04/29 generated new
     Makefile.PL                                                  0.01    2004/04/29 generated new
     README                                                       0.01    2004/04/29 generated new
     lib/File/Revision.pm                                         1.02    2004/04/29 new
     t/File/Revision.d                                            0.01    2004/04/29 new
     t/File/Revision.pm                                           0.01    2004/04/29 new
     t/File/Revision.t                                            0.01    2004/04/29 new
     t/File/_Drawings_/Erotica.pm                                 0.01    2004/04/29 new
     t/File/File/Package.pm                                       1.16    2004/04/29 new
     t/File/File/AnySpec.pm                                       1.13    2004/04/29 new
     t/File/File/Where.pm                                         1.15    2004/04/29 new
     t/File/Test/Tech.pm                                          1.21    2004/04/29 new
     t/File/Data/Secs2.pm                                         1.18    2004/04/29 new
     t/File/Data/SecsPack.pm                                      0.03    2004/04/29 new
     t/File/Data/Startup.pm                                       0.03    2004/04/29 new

  3.3 Changes

    The changes to the previous version are as follows:

    File-Revision-0.01
        Originated.

  3.4 Adaptation data.

    This installation requires that the installation site has the Perl
    programming language installed. There are no other additional
    requirements or tailoring needed of configurations files, adaptation
    data or other software needed for this installation particular to any
    installation site.

  3.5 Related documents.

    There are no related documents needed for the installation and test of
    this release.

  3.6 Installation instructions.

    Instructions for installation, installation tests and installation
    support are as follows:

    Installation Instructions.
        To installed the release file, use the CPAN module pr PPM module in
        the Perl release or the INSTALL.PL script at the following web site:

         http://packages.SoftwareDiamonds.com

        Follow the instructions for the the chosen installation software.

        If all else fails, the file may be manually installed. Enter one of
        the following repositories in a web browser:

          http://www.softwarediamonds/packages/
          http://www.perl.com/CPAN/authors/id/S/SO/SOFTDIA/

        Right click on 'File-Revision-0.01.tar.gz' and download to a
        temporary installation directory. Enter the following where $make is
        'nmake' for microsoft windows; otherwise 'make'.

         gunzip File-Revision-0.01.tar.gz
         tar -xf File-Revision-0.01.tar
         perl Makefile.PL
         $make test
         $make install

        On Microsoft operating system, nmake, tar, and gunzip must be in the
        exeuction path. If tar and gunzip are not install, download and
        install unxutils from

         http://packages.softwarediamonds.com

    Prerequistes.
         'Data::Startup' => '0.01'

    Security, privacy, or safety precautions.
        None.

    Installation Tests.
        Most Perl installation software will run the following test
        script(s) as part of the installation:

         t/File/Revision.t

    Installation support.
        If there are installation problems or questions with the
        installation contact

         603 882-0846 E<lt>support@SoftwareDiamonds.comE<gt>

  3.7 Possible problems and known errors

    There is still much work needed to ensure the quality of this module as
    follows:

    *   State the functional requirements for each method including not only
        the GO paths but also what to expect for the NOGO paths

    *   All the tests are GO path tests. Should add NOGO tests.

4.0 NOTES
    The following are useful acronyms:

    .d  extension for a Perl demo script file

    .pm extension for a Perl Library Module

    .t  extension for a Perl test script file

    POD Plain Old Documentation

2.0 SEE ALSO
    File::Revision
    Docs::US_DOD::SVD
    Extutils::SVDmaker
