$conf
$conf : array
Configuration keys for this rule 'prefix' => the path to smileys images inclusive file name prefix, starts with '/' ==> abolute reference if no file names prefix but some folder, terminates with '/' 'extension' => the file extension (inclusive '.'), e.g. : if prefix 'smileys/icon_' and extension '.gif' ':)' whose name is 'smile' will give relative file 'smileys/icon_smile.gif' if prefix '/image/smileys/' and extension '.png': absolute '/image/smileys/smile.gif' 'css' => optional style applied to smileys