It is sopported by language_base.php for comon and language_convert.php for every language pack. 
The class function of language_convert.php is inherited from language_base.php. 
Explanation of a function is shown below. 
| function name | function | use | 
| use multi-byte function | ||
| convert_encode_to_utf8 ($text, $encode) | convert the text ($text) from the specified character code ($encode) to
      UTF-8 | convert the getting RSS into UTF-8. The code of RSS is judged by encoding of XML. assume UTF-8, when encoding is empty. | 
| convert_from_utf8($text) | convert the text ($text) from the internal character code to UTF-8 | convert the parsed RSS into an internal code. | 
| convert_to_utf8($text) | convert the text ($text) from UTF-8 to the internal character code to UTF-8 | convert the outputing RSS into UTF-8 | 
| shorten_text($text,$max) | truncate the text ($text) with specified width ($max) | make a summary | 
| send_mail ($mailto, $subject, $body, $header) | send encoded mail parameters are same as PHP mail function | use by a command line | 
| use multi-byte function (specially for Japanese environment) | ||
| convert_telafriend_subject($text) | convert the text ($text) from the internal character code to another character code | measures of garble for "tel a friend" | 
| convert_telafriend_body($text) | same as the above | Same as the above | 
| convert_download_filename($text) | same as the above | measures of garble for "download file name" now, not use | 
| convert_sjis_win_mac($text) | convert the text ($text) from EUC-JP to SJIS, when a client PC is Windows or MAC. | measures of garble for "tel a friend" | 
| convert_space_zen_to_han($text) | convert the text ($text) from "zen-kaku" space to "han-kaku" | in searching, "zen-kaku" space is considered delimit of the word | 
| not use multi-byte function | ||
| get_google_url() | get the url of google site which is setted up by this function | this url is the site which searches link information | 
| get_country() | get the name of country which is setted up by this function | this name choice the method of link to the map site | 
| get_happy_linux_url() | get the url of development site which is setted up by this function | this url is the site of poweredby | 
| presume_agent() | presume the agent of web browser | measures of garble for "tel a friend" | 
| function name | default (English) language_base.php | Japanse language_convert.php | other language | 
| use multi-byte function | |||
| convert_encode_to_utf8($text, $encode) | convert from the specified character code  to UTF-8 use PHP utf8_encode function | convert from the specified character code to UTF-8 use PHP mb_convert_encoding function | convert from the specified character code to UTF-8 | 
| convert_from_utf8($text) | convert from UTF-8 to US-ASCII use PHP utf8_decode function | convert from UTF-8 to EUC-JP use PHP mb_convert_encoding function | convert from UTF-8 to the country's character code | 
| convert_to_utf8($text) | convert from US-ASCII to UTF-8 use PHP utf8_encode function | convert from EUC-JP to UTF-8 use PHP mb_convert_encoding function | convert from the country's character code to UTF-8 | 
| shorten_text($text,$max) | use PHP substr function | use PHP mb_strimwidth function | truncate, uniting the country's character code | 
| send_mail($mailto, $subject, $body, $header) | wrapper of PHP mail function | wrapper of PHP mb_send_mail function | mail function is set up, uniting the country's character code | 
| use multi-byte function (specially for Japanese environment) | |||
| convert_telafriend_subject($text) | nothing to do | convert from EUC-JP to SJIS call convert_sjis_win_mac() | no necessary | 
| convert_telafriend_body($text) | nothing to do | same as the above | no necessary | 
| convert_download_filename($text) | nothing to do | same as the above | no necessary | 
| convert_sjis_win_mac($text) | --- | convert from EUC-JP to SJIS use PHP mb_convert_encoding function | no necessary | 
| convert_space_zen_to_han($text) | nothing to do | convert from "zen-kaku" space to "han-kaku" | no necessary | 
| not use multi-byte function | |||
| get_google_url() | http://www.google.com/search? hl=en&q= | http://www.google.co.jp/search? hl=ja&q= | url is set up, uniting the country's character code | 
| get_country() | usa | japan | no necessary require to change a template when differ from the U.S style. | 
| get_happy_linux_url() | http://linux2.ohwada.net/ | http://linux.ohwada.jp/ | no necessary | 
| presume_agent() | presume the agent of web browser | --- | --- |