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Release Notes

This section highlights important changes that have occurred and important
usage details which you should be aware of before using MHonArc. If you are
upgrading from a previous release, make sure to check for the highlighted
incompatibilites from earlier releases.

NOTE: Read the CHANGES document included in the distribution for a more    
      complete summary of changes to MHonArc.                              

  * Compatibility Notes
      + UPGRADING FROM v2.5.x OR EARLIER: Default iso-2022-jp Converter
        Changed
      + UPGRADING FROM v2.4.x OR EARLIER: DEFRCNAME Change
      + UPGRADING FROM v2.4.x OR EARLIER: HEADER and FOOTER Removed
      + UPGRADING FROM v2.4.x OR EARLIER: MIMEFILTERS API Change
      + UPGRADING FROM v2.1.x OR EARLIER: Database Format Change
      + DOWNGRADING TO OLDER VERSIONS
  * v2.6.0 Notes
      + m2h_text_html::filter: default argument removed
      + SPAMMODE: Applies to message body text.
      + readmail::MAILhead_get_disposition: API change.
  * General Notes
      + Japanese and MHonArc
      + Auto-loaded URL attributes stripped in HTML messages
      + iso8859.pl deprecated
      + TSLICE range setting
      + MHonArc code under the mhonarc namespace
      + HTMLEXT and MSGPREFIX usage warning
      + Applying new MIMEFILTERS settings

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Compatibility Notes

This sections provides notes dealing with compatibility issues if upgrading
from a previous release of MHonArc:

UPGRADING FROM v2.5.x OR EARLIER: Default iso-2022-jp Converter Changed

In v2.6, the default charset converter for iso-2022-jp has changed to the
following:

<CharsetConverters>
iso-2022-jp; MHonArc::CharEnt::str2sgml; MHonArc/CharEnt.pm
</CharsetConverters>

This filter converts all Japanese characters into Unicode character entity
references (e.g. &#x7279;) removing the iso-2022-jp encoding. For some
Japanese locales, this type of conversion may not be desired since some
Japanese-aware processing tools may not support Unicode character entity
references. If you want to preserve the iso-2022-jp encoding, you must
explicitly specify the use of iso_2022_jp::str2html via the 
CHARSETCONVERTERS resource as follows:

<CharsetConverters>
iso-2022-jp; iso_2022_jp::str2html; iso2022jp.pl
</CharsetConverters>

The change to MHonArc::CharEnt::str2sgml as the default converter for
iso-2022-jp was done to make MHonArc as locale neutral as possible in its
default configuration.

For more information about using MHonArc in a Japanese locale, see
(documents in Japanese):
<http://www.shiratori.riec.tohoku.ac.jp/~p-katoh/Hack/Docs/mhonarc-jp/
index.html>
<http://www.shiratori.riec.tohoku.ac.jp/~p-katoh/Hack/Docs/mhonarc-jp/
mhonarc-jp-2_4.html>

UPGRADING FROM v2.4.x OR EARLIER: DEFRCNAME Change

The default value for the DEFRCNAME is now called ".mhonarc.mrc", or
"mhonarc.mrc" under Windows and VMS. The old value was ".mhonarc.rc", or
"mhonarc.rc". If you use the default resource file, you will need to rename
the file to match the filenames used for v2.5 and later.

UPGRADING FROM v2.4.x OR EARLIER: HEADER and FOOTER Removed

The HEADER and FOOTER resources are no longer supported. If you are using
these resources, the HEADER content and FOOTER content will be lost once
v2.5, or later, of MHonArc processes an archive containing these resources.

The HEADER and FOOTER resources have been deprecated for a long time since
they only applied to the main index; the thread index has no equivalent.
The IDXPGBEGIN or LISTBEGIN resources can be used to achieve the same
effect of HEADER. The IDXPGEND or LISTEND can be used to achieve the same
effect of FOOTER.

UPGRADING FROM v2.4.x OR EARLIER: MIMEFILTERS API Change

The API for data filters registered via MIMEFILTERS is not capability with
filters written for v2.4.x and earlier. See CHANGES and the documentation
for the MIMEFILTERS resource for the API.

If you use custom style filters written for v2.4.x, or earlier, you will
need to update them for them to work properly under v2.5, and later.

UPGRADING FROM v2.1.x OR EARLIER: Database Format Change

If you have archives created with v2.1.x, or earlier, the format of
mime-related resources is not compatible with v2.2, and later, versions.
MHonArc will reset the mime-related resources CHARSETCONVERTERS and 
MIMEFILTERS to their default values. MIMEARGS will also be reset to the
default value unless you are upgrading to v2.5.8, or later, where the
MIMEARGS settings will be preserved.

To avoid the resetting of the mime-related resource if you are using
customized settings, you will need to re-specify your settings the next
time you update an archive. If you always specify your resource settings
each time you invoke MHonArc, then your settings should to still take
effect.

You can also use the mha-dbedit program to apply your settings directly
without processing the archive.

DOWNGRADING TO OLDER VERSIONS

CAUTION: Downgrading to an earlier version of MHonArc can corrupt your     
         archives, especially when downgrading to an older version that    
         used different database file storage formats from the current     
         version in use.                                                   

Changes in archive format are not common, so downgrading can be okay
depending on the versions involved. The key versions to watch out for are
the ones noted in this section where database format changes have occured.
The following lists release numbers where a format change occured:

  * 2.0.0
  * 2.2.0
  * 2.5.0

For example, if an archive was last updated with v2.5.0, processing the
archive with a previous release will cause problems.

A possible method for successfully downgrading to a release with
differences in the database format, is to try to reconstruct the database
file using the mha-dbrecover utility contained in the MHonArc version the
archive is being downgraded to.

TIP: The safest way to downgrade is to recreate an archive from the        
     original raw mail data. It is good practice to preserve the raw mail  
     data for cases like this and for general archive recovering situations
     due to file corruption or other system failures.                      

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v2.6.0 Notes

m2h_text_html::filter: default argument removed

The default argument for the m2h_text_plain::filter has been removed. The 
DEFCHARSET can be used instead.

SPAMMODE: Applies to message body text.

If SPAMMODE resource is enabled, it enables the new MODIFYBODYADDRESSES
resource, which enables ADDRESSMODIFYCODE to rewrite addresses in message
text bodies. If you prefer to not have addresses in message bodies modified
when SPAMMODE is enabled, you must explicitly disable the
MODIFYBODYADDRESSES resource.

readmail::MAILhead_get_disposition: API change.

The calling interface to readmail::MAILhead_get_disposition has been
changed to the following:

($disp, $file, $raw, $html_name)  =
              readmail::MAILhead_get_disposition($fields_hash_ref, $do_html);

The $file return value now has special, or invalid, filename characters
converted to underscores.

The $do_html is optional. If a true value, $html_name will be returned as a
representation of the filename suited for inclusion HTML and with character
conversion processing done.

The $raw return value is the raw filename value as specified in the message
header, which may include pathname components. This return value is mainly
for informative reasons and it should not be used by filter code for
security reasons.

The changes are backward compatible, but if you have written custom
filters, you may want to use the new calling convention if you display the
filename in the HTML generated.

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General Notes

Japanese and MHonArc

Information on using MHonArc in a Japanese locale is available at the
following locations (documents in Japanese):
<http://www.shiratori.riec.tohoku.ac.jp/~p-katoh/Hack/Docs/mhonarc-jp/
index.html>
<http://www.shiratori.riec.tohoku.ac.jp/~p-katoh/Hack/Docs/mhonarc-jp/
mhonarc-jp-2_4.html>

Auto-loaded URL attributes stripped in HTML messages

For v2.5, the default text/html filter (mhtxthtml.pl) will disable
auto-loaded URL attributes for some HTML elements -- IMG, BODY, IFRAME,
FRAME, OBJECT, SCRIPT, INPUT -- except for cid: URLs. This behavior can be
disabled if the 'allownoncidurls' filter argument is specified.

The new behavior prevents malicious URLs used to verify mail addresses for
spam purposes, secretly set cookies, or gather some statistical data
without the explicit consent of the reader.

iso8859.pl deprecated

ISO-8859 character set data processing now defaults to using the MHonArc::
CharEnt module in v2.5. The old iso8859.pl library is still provided for
compatibility with older archives, and with v2.6, iso8859.pl directly
invokes MHonArc::CharEnt.

To update archives to use the new settings, you can run the following
command,

+-------------------------------------------------------------------------+
|mha-dbedit -rcfile examples/def-mime.mrc \                               |
|           -outdir /path/to/archive                                      |
+-------------------------------------------------------------------------+

where examples/def-mime.mrc represents the default MIME processing
resources for MHonArc provided within the MHonArc distribution.

NOTE: v2.5.4, and later, generated archives will automatically inherit new 
      CHARSETCONVERTERS if the built-in defaults are being used. However,  
      if you have defined CHARSETCONVERTERS for your archives, you will    
      need to explicitly update your archives if you want the new settings 
      applied to your archives.                                            

TSLICE range setting

The value of the TSLICE resource is used to determine the number of
messages to update, before and after by thread, of each new message added.
To insure that messages within a thread slice are updated when a new
message is added, make sure the before and after ranges specified for 
TSLICE is equal to maximum before and the maximum after range arguments
specifed in the uses of the $TSLICE$ resource variable. For example, if you
have $TSLICE(0;4)$ and $TSLICE(3;3)$ in message layout resources, you
should set TSLICE to 3:4.

If you only use $TSLICE$ once, it is best to set options for thread slice
formatting via the TSLICE resource so you will not have anything to worry
about.

MHonArc code under the mhonarc namespace

If upgrading from v2.1.x, or earlier, any custom filters you have developed
may need to modified. If your filter accessed some main variables, your
filter will not operate properly. All variables that used to be in package
"main" are no longer. The major variables are now in package "mhonarc". For
example, $::OUTDIR is now $mhonarc::OUTDIR. See the MIMEFILTERS resource
page for more information.

HTMLEXT and MSGPREFIX usage warning

See the warnings in the documentation for the HTMLEXT and MSGPREFIX
resources before using them.

Applying new MIMEFILTERS settings

Occasionally, a new release of MHonArc may contain new MIME filters. See
the CHANGES file to check if any new filters have been added.

If you confirm that new filters have been added, and you want to apply them
to your archives, you use the mha-dbedit program using the def-mime.mrc in
the examples directory.

NOTE: v2.5.4, and later, generated archives will automatically inherit new 
      MIMEFILTERS if the built-in defaults are being used. However, if you 
      have defined MIMEFILTERS for your archives, you will need to         
      explicitly update your archives if you want the new settings applied 
      to your archives.                                                    

Example usage of mha-dbedit:

+-------------------------------------------------------------------------+
|mha-dbedit -rcfile examples/def-mime.mrc \                               |
|           -outdir /path/to/archive                                      |
+-------------------------------------------------------------------------+

Change the -rcfile and -outdir pathnames to reflect where you are running
mhonarc and where your archive is located, respectively.

Note, if your archives are using custom settings of MIMEFILTERS, MIMEARGS,
and/or CHARSETCONVERTERS resources, you will need to create a variant
version of def-mime.mrc (included in the examples directory) to include
your settings and use the variant version when updating your archives.

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$Date: 2003/02/04 23:31:19 $
MHonArc
Copyright © 1997-2002, Earl Hood, mhonarc@mhonarc.org

