The POSIX locale system is used to specify both the language conventions requested by the user and the preferred character set to consume and output. The Encode::Locale module looks up the charset and encoding (called a CODESET in the locale jargon) and arranges for the Encode module to know this encoding under the name "locale". It means bytes obtained from the environment can be converted to Unicode strings by calling Encode::encode(locale => $bytes) and converted back again with Encode::decode(locale => $string).