MediaWiki:Apihelp-json-param-utf8
From Balthazar
If specified, encodes most (but not all) non-ASCII characters as UTF-8 instead of replacing them with hexadecimal escape sequences. Default when formatversion is not 1.
If specified, encodes most (but not all) non-ASCII characters as UTF-8 instead of replacing them with hexadecimal escape sequences. Default when formatversion is not 1.