+=item details_header [ OPTION => VALUE ... ]
+
+Returns a list representing an invoice line item detail header, if any.
+This relies on the behavior of voip_cdr in that it expects the header
+to be the first CSV formatted detail (as is expected by invoice generation
+routines). Returns the empty list otherwise.
+
+=cut
+
+sub details_header {
+ my $self = shift;
+ return '' unless defined dbdef->table('cust_bill_pkg_detail');
+
+ eval "use Text::CSV_XS;";
+ die $@ if $@;
+ my $csv = new Text::CSV_XS;
+
+ my @detail =
+ qsearch ({ 'table' => 'cust_bill_pkg_detail',
+ 'hashref' => { 'billpkgnum' => $self->billpkgnum,
+ 'format' => 'C',
+ },
+ 'order_by' => 'ORDER BY detailnum LIMIT 1',
+ });
+ return() unless scalar(@detail);
+ $csv->parse($detail[0]->detail) or return ();
+ $csv->fields;
+}
+