pfSense

The per-entry description field, internally called "detail", is not CDATA escaped like the main description field so it cannot take characters that are invalid in XML.

As for the main descr field, it seems on that page we use:

$alias['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");

Which seems to strip out certain chars, like those with umlauts. Not sure why we only use that in certain places (it only shows up 9 times in 5 pages).

etc/inc/easyrule.inc:169:               $alias['descr']   = mb_convert_encoding("Hosts blocked from Firewall Log view","HTML-ENTITIES","auto");
usr/local/www/firewall_aliases_edit.php:287:            $alias['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/firewall_aliases_edit.php:345:            $pconfig['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/interfaces_groups_edit.php:96:            $ifgroupentry['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/interfaces_groups_edit.php:159:           $pconfig['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/interfaces_qinq_edit.php:145:             $qinqentry['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/interfaces_qinq_edit.php:203:             $pconfig['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/services_igmpproxy_edit.php:101:          $igmpentry['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");
usr/local/www/services_igmpproxy_edit.php:117:          $pconfig['descr'] = mb_convert_encoding($_POST['descr'],"HTML-ENTITIES","auto");