-SquirrelMail internationalization
+
+ *************************************
+ * SquirrelMail internationalization *
+ *************************************
+
+$Date$
+$Revision$
This document should explain how SquirrelMail internationalization works and
provide information about some aspects of implementation.
3. XTRA_CODE functions
4. Display of different charsets
5. IMAP folder names
+6. Plural forms
+7. Language setup
+8. Time zones
-------------------------------
1. Supported languages
Valid language codes are:
* ar - Arabic, windows-1256 charset
* bg_BG - Bulgarian, windows-1251 charset
+* bn_IN - Bengali, utf-8 charset
* ca_ES - Catalan, iso-8859-1 charset
* cs_CZ - Czech, iso-8859-2 charset
* cy_GB - Welsh, iso-8859-1 charset
* zh_CN - Chinese Simplified, gb2312 charset
* zh_TW - Chinese Traditional, big5 charset
+Charset totals:
+* iso-8859-1 = 21
+* iso-8859-2 = 8
+* utf-8 = 5
+* iso-8859-15 = 2
+* iso-8859-7 = 1
+* iso-8859-9 = 1
+* koi8-r = 1
+* koi8-u = 1
+* windows-1251 = 1
+* windows-1255 = 1
+* windows-1256 = 1
+* tis-620 = 1
+* gb2312 = 1
+* big5 = 1
+* euc-jp = 1
+* euc-kr = 1
+
-------------------
2. $languages array
-------------------
-TODO: add explanation of $languages array keys
+$languages array is stored in functions/i18n.php and defines translations
+that are enabled in SquirrelMail.
+
+Format of array:
+ $languages['language_code']['key'] = 'value'
+
+Possible array key names:
+* NAME - Translation name in English. Any 8bit symbols must be html encoded.
+* CHARSET - Charset used by translation
+* ALIAS - 'language_code' should contain short language name
+ (iso-639). 'value' should contain name of other 'language_code'
+ that defines translation with NAME and CHARSET keys.
+ Entry links short language form with long form (language+country).
+ See: http://www.loc.gov/standards/iso639-2/langhome.html and
+ http://www.iso.org/iso/en/prods-services/iso3166ma/02iso-3166-code-lists/list-en1.html
+* ALTNAME - Native translation name. Any 8bit symbols must be html encoded.
+ Name is visible when $show_alternative_names is enabled.
+* LOCALE - Full locale name (in xx_XX.charset format or other format required
+ by php gettext functions). From 1.4.4/1.5.1 'value' can contain
+ array. If php version is older than 4.3.0, system uses only first
+ locale name listed in array. First locale name must be compatible
+ with FreeBSD system locale names.
+* DIR - Text direction. Used to define Right-to-Left languages. Possible
+ values 'rtl' or 'ltr'. If undefined - defaults to 'ltr'.
+* XTRA_CODE - translation uses special functions. (see chapter 3. XTRA_CODE functions)
+
+Each 'language_code' definition requires NAME+CHARSET or ALIAS keys. Other keys are
+optional.
----------------------
3. XTRA_CODE functions
----------------------
-XTRA_CODE functions provides way to change interface behaviour, when translation
-requires special handling of some squirrelmail functions. Functions are enabled
-by setting XTRA_CODE option in $languages array and providing appropriate
-functions. First part of function name is word listed in
-$languages['language_code']['XTRA_CODE'] setting. Second part is one of special
-keywords. Possible values:
+XTRA_CODE functions provide way to change interface behavior, when translation
+requires special handling of some SquirrelMail functions. Functions are enabled
+by setting XTRA_CODE option in $languages array and including appropriate
+functions in functions/i18n.php. First part of function name is word listed in
+$languages['language_code']['XTRA_CODE'] value. Second part is one of special
+keywords. Possible keywords:
* _decode
Used in src/compose.php, src/i18n.php, src/view_text.php, functions/mime.php
Requires mbstring support
--------------------------------
4. Display of different charsets
--------------------------------
-TODO: add explanation of decoding functions
+When SquirrelMail generates html pages, it uses charset defined in translation
+selected by end user. Interface can display emails encoded in different
+charsets. In order to display characters that might be unsupported by user's
+charset, SquirrelMail uses decoding functions that convert non us-ascii symbols
+into html entities. All decoding functions are stored in functions/decode/
+directory.
+
+By default SquirrelMail includes decoding functions that support iso-8859-x,
+windows-125x, utf-8, us-ascii, koi8-r, koi8-u, tis-620, ns-4551_1, iso-ir-111,
+cp855 and cp866 charsets. Other decoding functions are distributed in separate
+packages. Separate packaging of decoding functions is supported from
+SquirrelMail 1.4.4 and 1.5.0. us-ascii decoding replaces all 8bit symbols with
+question marks. utf-8 decoding function does not enable decoding of five and six
+byte utf-8 symbols by default (code is commented) and replaces all incorrectly
+formated 8bit symbols with question marks.
+
+Some decoding functions might require php recode extension or php 4.3+ mbstring
+extension. If your php installation does not support them, you might be using
+slower and cpu/memory intensive functions.
--------------------
5. IMAP folder names
--------------------
-TODO: add explanation about UTF7-IMAP and mbstring
+IMAP folder names use UTF7-IMAP charset. Folder names that are stored in
+conf.pl must be encoded in UTF7-IMAP charset. SquirrelMail uses internal
+functions that convert folder names from/to utf7-imap charset. By default those
+functions work with iso-8859-1 charset. Other charsets are supported only
+when php mbstring extension supports them.
+
+TODO: write independent implementation of charset to utf7-imap conversion.
+
+---------------
+6. Plural forms
+---------------
+From v.1.5.1 SquirrelMail includes support of plural forms. It allows to use
+correct translation forms with numbers. For example. "We have %s squirrel on
+the roof." and "We have %s squirrels on the roof." can be written in one
+function call without checking actual number for squirrels. Gettext functions
+also deal with non English languages that might use different word forms for
+two, five, ten or more units.
+
+Support is provided by ngettext functions that exist in php gettext extension
+from php 4.2.0 and by ngettext function replacements from php-gettext classes
+(http://savannah.nongnu.org/projects/php-gettext). In order to use it correctly
+when php gettext extension does not have ngettext support, SquirrelMail uses
+bindtextdomain and textdomain wrappers that load missing functions.
+
+If plugins want to use ngettext functions without increasing php requirements
+to 4.2.0 with gettext support, they should require SquirrelMail 1.5.1, use
+sq_bindtextdomain function instead of bindtextdomain and use sq_textdomain
+function instead of textdomain function. If SquirrelMail wrapper functions
+are used, there is no need to issue sq_bindtextdomain when plugins reverts to
+SquirrelMail domain.
+
+More information about ngettext and plural forms can be found at:
+http://www.gnu.org/software/gettext/manual/html_chapter/gettext_10.html#SEC150
+
+-----------------
+7. Language setup
+-----------------
+SquirrelMail uses set_up_language() function to setup language environment.
+Environment is setup automatically when include/validate.php is loaded.
+
+SquirrelMail gets interface language from three places:
+ a) user preference. It is set in Options -> Display Preferences -> Language.
+ preference uses language key. If user's preferences are not available (user
+ is not logged in), system tries to extract language value from
+ 'squirrelmail_language' cookie.
+ b) default squirrelmail language that is set in configuration
+ ($squirrelmail_default_language variable).
+ c) preferred language setting provided by browser. It is used only when default
+ squirrelmail language is set to empty string
+
+If language information is not available, SquirrelMail falls back to US English
+translation.
+
+-------------
+8. Time zones
+-------------
+If php install allows modifying environment variable TZ, SquirrelMail allows
+end users to select different time zone in their preferences. It can be set in
+Options -> Personal Information -> Your current timezone. Time zone is
+setup automatically when include/validate.php is loaded.
+
+If TZ variable can't be modified (php is running is safe mode and variable
+is not listed in php safe_mode_allowed_env_vars), user's time zone options are
+not visible and interface use default webserver's time zone.
+
+List of available time zones is stored in locale/timezones.cfg. Current list
+of time zones uses some time zone names that depend on webserver's system
+libraries. These names are not compatible with Windows operating system.
+
+TODO: move time zone information to php array in order to be able to translate
+it and make sure that time zone names are compatible with Windows operating
+system. Or at least provide 'default' and 'strict' time zone options in
+SquirrelMail configuration. Maybe even provide 'custom' time zone list
+options.
+
+If modifications in TZ environment are visible in your webserver's logs (time
+offset is changed), make sure that you can reproduce such behavior in latest php
+version and report bug to php developers. Issue can be fixed by blocking use of
+time zone (php safe mode and TZ is not listed in safe_mode_allowed_env_vars
+setting or forced_prefs plugin) or by attaching special php script with
+putenv('TZ=some time zone') call in php auto_append_file setting (suggestion is
+not tested and you might have to fix all SquirrelMail exit calls).
+
+Please note, that use of auto_append_file provides only temporally workaround
+and does not fix your php setup. Script that runs as unprivileged user, should
+be unable to affect webserver's logging system.
+
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