2
in language/YOURLANGUAGE/global.php at the end of file there is something like:
//%%%%% LANGUAGE SPECIFIC SETTINGS %%%%%
define('_CHARSET', 'windows-1251');
define('_LANGCODE', 'bg');
// change 0 to 1 if this language is a multi-bytes language
define("XOOPS_USE_MULTIBYTES", "0");
...