I18n::charset maps character set names to the names officially registered with iana. for example, 'shift_jis' is the official name of 'x-sjis'.

it also maps character set names to unicode::map, unicode::map8, and unicode::maputf8 conversion scheme names (if those modules are installed). for example, the unicode::map8 scheme name for 'windows-1251' is 'cp1251'.