#CHARSET (since SPIP 1.5) displays the character set being used by the site. By default, its value will be iso-8859-1 (the character set also known as "iso-latin") for versions of SPIP prior to 1.9, or utf-8 (the character set also known as "universal") for versions of SPIP since SPIP 1.9.
This charset can be configured from the site’s configuration page: ecrire/?exec=config_lang ("The site’s charset").