
   @PRODUCT_LONG  @{r74}@{d}@{_}


   This product is an OS/2-hosted add-on for ARJ v @COUNTERPARTS for DOS. It may be
   used  separately  from  the DOS  package  but  it doesn't  contain  the
   documentation found in DOS release.

   ***********************************************************************
   ***                                                                 ***
   ***  THIS PRODUCT IS DEVELOPED  SEPARATELY FROM THE MAINSTREAM ARJ  ***
   ***  PACKAGE AND  THEREFORE IS NOT  UPDATED SYNCHRONOUSLY WITH ARJ  ***
   ***  FOR DOS.                                                       ***
   ***                                                                 ***
   ***********************************************************************


   INTRODUCTION

      This file describes the features specific to the OS/2 port. It is
      suggested that you read the general README file prior to this one.


   SYSTEM REQUIREMENTS

   16-bit version:

      *  OS/2 version 1.2 or higher, or Windows NT v 3.10 or higher.
   For OS/2 systems:
      *  A 80286 or higher CPU.
      *  512K of free memory
   For Windows NT systems:
      *  1024K of free memory

   32-bit version:

      *  OS/2 version 3.0 with Fixpak 25 or higher
      *  A 80386SX or higher CPU.
      *  1024K of free memory (512K for each subsequent  instance after
         the first one has been started)
      *  IBM LIBC and Unicode runtime  support (installed by default as
         a mandatory component)


   IMPLEMENTATION ISSUES

      *  External garble modules are provided as OS/2 DLLs. You may not
         use DOS  modules  with  ARJ/2, or vice  versa. The  encryption
         algorithm  is  the  same, so  ARJ/2 garbled  archives can   be
         processed under DOS.

      *  ARJ/2  sets  the  "Host OS" to  "OS/2"  on its  archives. When
         extracting  any such  archive with ARJ  for DOS,  some unusual
         behavior  may  occur. Versions  of ARJ  prior to 2.50  convert
         high-ASCII  characters in  filenames to  7-bit  characters  by
         ignoring the  high  bit. So, the  filename  "TEST"  will  be
         converted to "1TEST1" on extraction.

         ARJ/DOS also strips high  bit from  archive comments, but only
         if the archive  was created  by ARJ/2. Archives  created  with
         ARJ/DOS  and  then  processed   under OS/2  are not  affected.

         Beginning  with version  2.72, ARJ/DOS considers  the ARJSFXJR
         archives created  under OS/2 to be hostile  to the DOS version
         of ARJSFXJR and  therefore cannot  modify them. In such cases,
         it's advised to use the "-2d" switch under OS/2.

      *  ARJ/2 uses the  default OS/2 error  handler that will normally
         display  pop-up menus  prompting  for action.  The  -&  option
         installs batch error and  exception handler (new feature since
         ARJ/2 v 2.62.08). Remember  that the  ampersand  character  is
         used  in OS/2 to start  two  processes  consequently, so  this
         switch will actually split  the command line. Type -^& instead
         of -& to install the error handler.

      *  ARJSFXJR  archives will  display  ANSI sequences  if the  ANSI
         support is enabled  in the  current OS/2 session (it's enabled
         by default in OS/2).

      *  By default, ARJ/2 stores extended attributes among with files.
         To  disable  EA  storage  and thus revert  to  the traditional
         header format, use  the "-2e" option. See  a special dedicated
         section below for details on EA handling.

      *  "-2p<n>:<d>" can be used to adjust the  priority of ARJ/2. The
         knowledge  of OS/2 scheduling system  is required to  use this
         option. It can dramatically increase performance but slow down
         other processes. The <n> can be equal to 1, 2, 3 or 4:

          1 = idle-time priority
          2 = regular priority
          3 = time-critical priority
          4 = fixed-high priority

         Priority delta values can be given in <d> (defaults to 0). The
         range  for <d> is -31 to 31.  So, "-2p2"  corresponds  to  the
         regular  process  priority, and "-2p3:31"  gives  the  maximum
         time-critical priority.

      *  ARJSFXJR does  not  support  long filenames  under Win95  DOS.
         ARJSFXJR in ARJ/2 supports OS/2 long filenames.


   EXTENDED ATTRIBUTES HANDLING

      Beginning  with  version  2.62.10,  the  extended  attributes  (also
      referenced to  as  EAs) can  be  backed  up  and   restored  without
      needing  any external  utilities. This is  achieved  by  compressing
      and storing EAs as a part of file header.

      Restrictions on EA support:

      *  The multivolume restart  feature (-jn) will not  work  if EAs are
         enabled. You'll  have to  disable EAs  with -2e  prior  to  using
         -jn, or to recreate the archive if the EAs are precious.

      *  Hollow mode archives do not support EAs.

      A set of new options has been introduced to let  the user control EA
      handling:

      *  "-2c" restricts  EA  handling  to  critical  EAs  only.  Archived
         non-critical  EAs  will not  be  restored.  When  an  archive  is
         created, only critical EAs will be saved.

      *  "-2e" specifies EA inclusion  filter. With no  parameters  given,
         it disables EA  handling at  all. Otherwise, an  expression  that
         follows  it  is  interpreted  as  a   wildcard  that   limits  EA
         inclusion to a  particular EAs. Multiple  options can be  entered
         to represent a set of EA names but list files are not allowed.
         Examples:

         ARJ a test

         In this example, all EAs will be preserved.

         ARJ a no_eas -2e
         ARJ x no_eas -2e

         EAs will neither be packed nor restored.

         ARJ a documents -2e.LONGNAME

         In this case, only .LONGNAME EAs will be handled.

         ARJ a test -2e.CLASSINFO -2e.ICON*

         .CLASSINFO and .ICON* (i.e. .ICON, .ICON1, .ICONPOS) EAs  will be
         be packed and restored.

         It's wise  to specify "-2e.*" when backing up  your OS/2  desktop
         or  configuration  files.  The system  EAs  start with  dot (".")
         while application EAs start with application name.

      *  "-2l" allows to  convert  .LONGNAME  extended  attributes  (these
         represent icon titles used in  WPS) to file names, when possible.
         This feature  simplifies moving document  files away from an OS/2
         system installed on a FAT volume.

         If  the icon  title (and  so  the  extended  attribute)  contains
         line breaks, wildcard characters  or other symbols, real filename
         will be used instead and the .LONGNAME EA will be preserved.

         This option is ignored during extraction. "-2e" and "-2x" have no
         effect  on  this  option  (but  .LONGNAME EAs are  not  saved  if
         .LONGNAME EA handling is implicitly or explicitly disabled).

      *  "-2x" specifies an  exclusion  filter. It must be followed  by an
         exclusion  EA name  specification. The  rules  are  the  same  as
         with "-2e". Also, the  two options  may  work together, providing
         both an inclusion and an exclusion rule. For example:

         ARJ a backup_ -r -p1 -h#2 -2e.* -2x.FED* c:\projects

         may be used to  create  regular back-ups of your  work directory,
         including all system EAs  but  excluding  EAs  created  with FED
         (Fast Editor  Lite, an  editor written  by Sergey I. Yevtushenko,
         evsi@naverex.kiev.ua) - that program  does not follow traditional
         EA naming  conventions  and  uses  system-alike  EAs  for  anchor
         position marks.

      Extended  attributes are  also  supported in ARJSFXV self-extractors
      where they are stored using the  same  technology as with  usual ARJ
      archives.

      The presence of EAs  is  indicated  by a "(EA: ...)" message when  a
      file is packed. Note that this size  may differ from  the one  given
      when the file  is unpacked - the  former is  the EA  structure  size
      and the latter is the space allocated  for EA storage. The number of
      EAs and the size of EA structure is  also displayed when the archive
      is listed with "ARJ v" command.


   KNOWN PROBLEMS

      *  On FAT volumes under Windows NT, both long filenames and short
         filenames may be used to specify a filename. If you refer to a
         file  with its  short name (e.g. "ARJ a lntest LONGFI~1.TXT"),
         the short filename will be stored as entered from console. So,
         no LFN equivalent is placed  into the  archive, and if  a file
         with a  similar long  filename exists in the  archive, it will
         not be replaced.

      *  REARJ/2 may  behave incorrectly  if  the  command  interpreter
         (specified   with  COMSPEC=   environment  variable)  is   not
         compatible with CMD.EXE. It's also unwise to  rename REARJ.EXE
         since  it  calls itself recursively  when  converting archives
         within archives (/a).

      *  No LIBC is supplied with fixes prior to XR_W032. For use  with
         32-bit ARJ/2, the  LIBCS.DLL, LIBUNI.DLL and UCONV.DLL  may be
         obtained in the OS/2 v 4.00 release (9.023). XR_W032 and later
         CSDs do not require any special action.


      End of document
