Manual:$wgOutputEncoding

Localization: $wgOutputEncoding
The encoding of the output text.
Introduced in version:	pre 1.1.0
Deprecated in version:	1.5.0
Removed in version:	1.18.0 (r87589)
Allowed values:	(string)
Default value:	'UTF-8' 'ISO-8859-1' (prior to 1.5.0)
Other settings: Alphabetical | By function

Details

The encoding of the output text.

LanguageUtf8.php normally overrides this unless you set $wgUseLatin1Manual:$wgUseLatin1 to true.