Regarding your extra brackets, try using

    my $hash_add = {
                       $cat => [{
                           'name' => "$name",
                           'link_name' => "$link_name",
                           'description' => "$desc",
                           'date' => "$today_date"
                    }]
    };

    for (keys %$hash_add) {
        $xml->{policies}->[0]->{$_} = $hash_add->{$_};
    }
[download]

I haven't used XML::Simple myself but judging from your sample I think this will do what you want.

Regarding your sort issue I think you want the extra brackets. In fact, they should all be in own brackets, it seems like. Again, I haven't use XML::Simple myself, but if you have a hash with the category as hash, you don't get it sorted. If you store the category alongside name, date, etc you can have each item represented as a hash (as you do now) and store all the hashes in an array, sorted.

Hope this helps,
ihb

Read argumentation in its context!