'duedate' => [ qw(a.duedate a.invnumber) ],
'dunning_date' => [ qw(dunning_date a.invnumber) ],
'dunning_duedate' => [ qw(dunning_duedate a.invnumber) ],
'duedate' => [ qw(a.duedate a.invnumber) ],
'dunning_date' => [ qw(dunning_date a.invnumber) ],
'dunning_duedate' => [ qw(dunning_duedate a.invnumber) ],