When using /wp-links-opml.php all links will show in xml format. Some themes have the possibility to hide certain widgets (e.g. with links) from not-logged in users. Setting all links to private is too easy and conflicts with the latter possibility (no links are shown in the widgets).
Is there another solution in wordpress to hide all the links when using the wp-links-opml.php file (.htaccess and in server configuration yes, but in wordpress)?