- my $d_orders = $self->order->linked_records(direction => 'to', to => 'SL::DB::DeliveryOrder');
- my @doi = grep { $_->parts_id == $self->parts_id } map { $_->orderitems } @$d_orders;
+Note that the shipped qty is expected not to change within the request and is
+cached in C<shipped_qty> once calculated. If C<< force => 1 >> is passed, the
+existibng cache is ignored.