[MediaWiki-l] how does /images manage to hide its subdirectories?

$ w3m -dump http://abj.jidanni.org/images Index of /images Name Last modified Size Description ------------------------------------------------------------------------------- Parent Directory - README 27-Mar-2012 22:35 203 ------------------------------------------------------------------------------- Only two items shown, the rest involve one knows the URL: $ w3m -dump http://abj.jidanni.org/images/abj Index of /images/abj Name Last modified Size Description ------------------------------------------------------------------------------- Parent Directory - 20061230.jpg ... So how is that hiding done? The relevant .htaccess doesn't seem to concern itself with this.