var $sum_paid; // sum of all allocated prepayments both to order and related invoices
var $alloc; // sum of payments allocated to this document
var $prepayments = array(); // allocation records for this document
var $sum_paid; // sum of all allocated prepayments both to order and related invoices
var $alloc; // sum of payments allocated to this document
var $prepayments = array(); // allocation records for this document