RT-Remind limiting to past due tickets

I want to only email summaries of past due tickets.

I see there is a section in the script:

Get hold of the tickets we’re after, sorted by priority

my $tickets = new RT::Tickets($RT::SystemUser);
$tickets->LimitStatus(VALUE => 'new');
$tickets->LimitStatus(VALUE => 'open');
$tickets->LimitStatus(VALUE => 'stalled') if $showall;
$tickets->LimitQueue(VALUE => $queue->Id);
$tickets->OrderBy(FIELD => 'Priority', ORDER => 'DESC');
my $user = RT::User->new($RT::SystemUser);

I assume that there is a value for Due Date?

Could someone tell me what entry I should add to limit to only past-due