$this->export_entities_array[$r]=array('u.login'=>'user','u.firstname'=>'user','u.lastname'=>'user');// We define here only fields that use another picto
$this->export_examplevalues_array[$r]=array('s.client'=>'0 (no customer no prospect)/1 (customer)/2 (prospect)/3 (customer and prospect)','s.fournisseur'=>'0 (not a supplier) or 1 (supplier)');