The INPUT_ENCODING variable defines which character encoding your terminal is using for the text you write. By default, ircII assumes that your terminal uses ISO-8859-1.
Examples of common encodings:
UTF-8 Unicode encoding, supports almost all languages
ISO-8859-1 Most widely used "latin1" encoding.
ISO-8859-2 Polish, Czech, Slovak, Slovenian, Hungarian
ISO-8859-5 Cyrillic encoding: Russian, Ukrainian, Belarusian
ISO-8859-6 An incomplete Arabic encoding
ISO-8859-7 Greek encoding
ISO-8859-8 Modern Hebrew encoding
ISO-8859-9 Turkish, Maltese, Esperanto
ISO-8859-10 Estonian, Latvian, Lithuanian, Greenlandic, Saami
ISO-8859-11 Thai
ISO-8859-15 Latin1 revised, with Euro for Finnish and French
ISO-8859-16 Albanian, Croatian, Romanian, Gaelic etc with Euro
EUC-JP Doublebyte Japanese JIS-X-0208 encoding
SHIFT-JIS Microsoft doublebyte Japanese encoding
GB18030 Chinese multibyte encoding
CP437 Old IBM PC, compatibles and Atari ST.
CP850 New IBM PC compatibles and IBM PS/2.
HP-ROMAN8 Hewlett Packard Extended Roman 8.
MACROMAN Apple Macintosh computers and boat anchors.
ASCII For American terminals in 7-bit environments.
ISO-2022-JP Traditional 7-bit Japanese JIS-X-0208 encoding
FI For Finns who are stuck with 7-bit terminals.
You can get the complete list of available encodings with the command /EXEC iconv -l if your system has it installed. This variable supersedes the TRANSLATION variable that existed in prior versions with support for multibyte encodings.
See Also: set/irc_encoding set/display_encoding digraph bind/enter_digraph