L<FS::legacy_cust_bill> - Legacy data invoice class
-L<FS::part_bill_event> - (Old) Invoice event definition class
-
-L<FS::cust_bill_event> - (Old) Completed invoice event class
-
L<FS::part_event> - (New) Billing event definition class
L<FS::part_event_option> - (New) Billing event option class