This table is used for cyrillic languages when system iconv doesn't work. It can be used to read ru/ua properties file.
There are five areas where text can be encoded differently: mibew ($webim_encoding), database ($dbencoding), localization files (first line of properties file), output html page (getoutputenc()), email ($mail_encoding).
In the simplest case we use utf-8 everywhere (don't need iconv).